PBS Mice Research Articles

Early Life Stress in the Pristane Model of Systemic Lupus Erythematosus increases cardiovascular risk but not kidney disease severity earlier in disease progression

Experiencing Early Life Stress (ELS), such as physical/verbal abuse before the age of 18, has become an increasingly apparent concern in the context of lifelong health. Systemic Lupus Erythematosus (SLE) is one autoimmune condition linked with ELS, predominantly affects women, and has high CVD burden. Exposure to ELS independently increases the risk of CVD and SLE, so we have developed a model to study this gap. The mouse model of ELS, maternal separation with early weaning (MSEW), combined with the pristane model of SLE mimics the accelerated disease (shown by earlier production of autoantibodies, increased vascular stiffness, and vascular dysfunction at 4 months post injection (p.i.) opposed to 7 months p.i.) in ELS. We hypothesized that the accelerated disease and CVD burden in MSEW+SLE mice, as opposed to normally reared (NR)+SLE mice, arose from severe kidney damage and increased blood pressure. MSEW mice were separated from dams for 4 hours/day (postnatal day 2 to 5) and 8 hours/day before weaning at day 17. NR litters were weaned at postnatal day 21. MSEW or NR female mice were randomly administered PBS or pristane through i.p. injection. Urine was collected at 4 months and 7 months p.i. to test for kidney damage markers and telemetry was utilized. MSEW animals develop increased Anti-Smith autoantibodies at 4 months p.i while SLE NR animals had no difference in titer levels compared to NR PBS mice. However, we found no difference in urine NGAL (Neutrophil Gelatinase-Associated Lipocalin) at 4 (p=0.32) or 7 months p.i. (p=0.6) or urine proteinuria 7 months p.i. (p=0.9) between groups. Blood pressure between MSEW+SLE and NR+SLE mice at 4, 5, and 6 months p.i. compared to control mice was not different. At 7 months p.i., SBP in NR+SLE (140.3 ± 10.22, n=4), MSEW+SLE (140.28 ±9.32, n=4) was not statistically greater than the NR/MSEW controls (128.1 ± 3.16, n=5 NR, n=7 MSEW). Ejection fraction in NR+SLE (66.04 ± 3.24, n=3), MSEW+SLE (75.17 ±3.19, n=2) compared to NR/MSEW controls (64.36 ± 2.49, n=5 NR, n=4 MSEW) was slightly changed over time. We see that at 6 months p.i. PWV and adventitial wall thickness is greater in MSEW+SLE (2.89 mm/sec ± 0.11) mice compared to both NR+SLE mice (2.047 mm/sec ± 0.16) and NR control mice (1.49 mm/sec ± 0.12, p=<0.001, F= 26.02), but at seven months PWV is not different between MSEW+SLE (2.94 mm/sec ± 0.13) mice compared to both NR+SLE mice (2.63 mm/sec ± 0.32, p=0.30). The acceleration of autoantibodies and PWV in MSEW+SLE mice, but not kidney or heart function indicates a specific impact on larger vessels and autoimmune cells in SLE. This work furthers the understanding of how ELS accelerates cardiovascular burden in autoimmune diseases and early identifying targets to prevent worsened outcomes in patients exposed to childhood trauma. Crohn’s and Colitis Foundation NIH R25 PROmoTE NIH T32 PRIME F31HL165863-0 NIH P01 HL158500. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract A040: Assessing the ability of Fc3TSR to remodel the tumor microenvironment and enhance efficacy of immunotherapies and chemotherapy in a murine model of pancreatic ductal adenocarcinoma

Abstract Introduction: Pancreatic Ductal Adenocarcinoma (PDAC) has a poor survival rate due to late diagnosis where metastasis has often occurred. Angiogenesis, the process by which new vessels form from pre-existing vasculature, is crucial for tumor growth and metastasis. Tumors aggressively upregulate expression of pro-angiogenic factors, stimulating rapid vessel formation. These vessels often lack pericyte coverage and have dysfunctional morphology, leading to high interstitial fluid pressure (IFP). Impaired perfusion and high IFP impede therapy uptake. Fc3TSR is a novel fusion protein derived from the potent angiogenic inhibitor thrombospondin 1, which we have shown to normalize vasculature in ovarian cancer, significantly decreasing tumor size and improving uptake of many therapies. In this study, we evaluated Fc3TSR’s ability to remodel the tumor microenvironment to induce tumor regression and to enhance efficacy of other therapies. Methods: We developed an orthotopic syngeneic murine model of PDAC, whereby we surgically injected 2.5 × 104 murine PDAC cells (KPC) into the tail of the pancreas of C57BL/6 mice. Tumors were allowed to progress for 14 days before intraperitoneal (IP) administration of Fc3TSR (0.158mg/kg) or PBS (control) on day 14 and 21. Gemcitabine (GEM) chemotherapy treated mice received either daily, metronomic dosages of GEM, or weekly, maximum tolerated dosages GEM starting on day 23. Checkpoint inhibitor mice received either PD-L1 (25ug) or CTLA4 (25ug) checkpoint inhibitors on day 23 and 26. Mice were euthanized on day 30 and tumors and the draining lymph nodes were collected and weighed. 1 hour before euthanasia, Fc3TSR and PBS mice were IP injected with Hypoxyprobe (Pimonidazole Hydrochloride) and tumors were immunostained for markers of blood vessels and tumor hypoxia. Results: Fc3TSR induced tumor regression when compared to PBS, but GEM at either dosage did not further enhance this effect. Following Fc3TSR, PD-L1, but not CTLA-4 checkpoint inhibitors significantly reduced tumor size when compared to mice pre-treated with PBS. Fc3TSR treatment also reduced the area of tumor hypoxia. Tumor vasculature is currently being imaged and analyzed for Fc3TSR’s effect on vessel morphology. Conclusion: Our data suggests that normalizing the tumor microenvironment can enhance the uptake and efficacy of combination therapies. Enhanced perfusion could facilitate the migration of activated immune cells and may enhance immune responses in PDAC patients. Here we demonstrate a novel approach to optimize therapeutic efficacy in advanced stage PDAC. Citation Format: Bianca Garlisi, Caroline Aitken, Sylvia Lauks, Julia Stewart, Duncan Petrik, Jack Lawler, Jim Petrik. Assessing the ability of Fc3TSR to remodel the tumor microenvironment and enhance efficacy of immunotherapies and chemotherapy in a murine model of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A040.

Modulatory Effects of Hydatid Cyst Fluid on a Mouse Model of Experimental Autoimmune Encephalomyelitis.

The reduced burden of helminth parasites in industrialized countries is probably one of the reasons for the increased prevalence of autoimmune disorders such as multiple sclerosis (MS). The current study aimed to evaluate the potential preventive effects of hydatid cyst fluid (HCF) on the disease severity in an EAE mouse model of MS. EAE-induced mice were treated with HCF before and after EAE induction. An RT-PCR-based evaluation of IFN-γ, IL-1β, TNF, T-bet, IL-4, GATA3, IL-17, RoRγ, TGF-β, and FOXP3 expression levels in splenocytes and an ELISA-based analysis of IFN-γ and IL-4 levels in cell culture supernatant of splenocytes were performed. Histopathological examinations of mice during the study were also conducted. The expression levels of T-bet, IL-4, GATA3, TGF-β, and FOXP3 in EAE + HCF mice were significantly higher compared to EAE + PBS mice. In the EAE + HCF group, the expression levels of IFN-γ, IL-1β, and TNF were significantly lower than in the EAE + PBS group. The histopathological results showed significantly reduced inflammation and demyelination in EAE + HCF mice compared to EAE + PBS mice. Our study provides proof-of-concept in the EAE mouse model of MS that helminth-derived products such as HCF have a potential prophylactic effect on MS development and present a novel potential therapeutic strategy.

Amphotericin B-Loaded Extracellular Vesicles Derived from Leishmania major Enhancing Cutaneous Leishmaniasis Treatment through In Vitro and In Vivo Studies.

Recent studies have shown an increasing number of patients with cutaneous leishmaniasis (CL) who do not respond to pentavalent antimonials as the first line of treatment for CL. Nanocarriers such as extracellular vesicles (EVs) are efficient vehicles that might be used as drug delivery systems for the treatment of diseases. Therefore, we aimed to isolate and characterize the EVs of Leishmania major, load them with Amphotericin B (AmB), and investigate the toxicity and efficacy of the prepared drug form. The EVs of L. major were isolated, characterized, and loaded with amphotericin B (AmB), and the EVs-Amphotericin B (EVs-AmB) form was synthesized. Relevant in vitro and in vivo methods were performed to evaluate the toxicity and efficacy of EVs-AmB compared to the control. The anti-leishmanial activity of the EVs-AmB showed a higher percentage inhibition (PI%) (P = 0.023) compared to the AmB at different concentrations and time points. Obtained data showed a significant increase in the lesion size and parasite load in the lesion, PBS, and EVs mice groups in comparison with EVs-AmB, AmB, and Glucantime groups (P < 0.05), EVs-AmB had a significant decrease in lesion sizes in comparison with AmB (P < 0.05). Results showed that EVs-AmB decreased its toxicity to the kidneys and liver (P < 0.05). EVs-AmB improved the efficacy of AmB in mouse skin lesions and reduced hepatorenal toxicity. Furthermore, EVs could be a promising nanoplatform for the delivery of AmB in CL caused by L. major.

GFAP Upregulation by Astrocytes May Attenuate Phospho‐Tau Levels in a Tauopathy Mouse Model

AbstractBackgroundAstrocytes react to amyloid‐β plaques and phospho‐tau (pTau) neurofibrillary tangles in the Alzheimer’s disease brain but their net effect on these Alzheimer’s neuropathological hallmarks remains controversial. A well‐known feature of these so‐called “reactive astrocytes” is the upregulation of the intermediate filament glial fibrillary acidic protein (GFAP), which is thought to be necessary for astrocyte process motility and glial scar formation. Here we asked whether this cytoskeletal remodeling helps reactive astrocytes control the burden of pTau species and/or protect synapses and neurons.MethodWe overexpressed human GFAP isoform 1 specifically in astrocytes of 4‐month‐old, sex‐balanced, THY‐Tau22 mice (Thy1.2‐MAPT G272V/P301S 1N4R, GFAP mice, n = 11)—when neurofibrillary tangles start to appear in the hippocampal CA1 subfield—using a viral transfer strategy with single retro‐orbital intravenous injection of AAV‐PHP.B (2.5×1011 vg) and the gfaABC1D promoter. We euthanized the mice at 11 months of age (i.e., prior to the tauopathy plateau) and performed immunohistochemical and/or biochemical analysis of astrocyte, tau, and synaptic markers. Negative control groups consisted of THY‐Tau22 littermates injected with either phosphate‐buffered saline (PBS mice, n = 9) or an AAV‐PHP.B vector encoding the enhanced green fluorescent protein (EGFP mice, n = 10).ResultsImmunohistochemistry confirmed the astrocyte‐specific expression of human GFAP with an apparent integration in their intermediate filament network. We observed statistically significant reductions or marginally significant trends toward decrease in hippocampal SDS‐soluble levels AT8/pTauSer202/Thr205 and AT8‐immunoreactive area fraction, and a shift of AT180/pTauThr231 from SDS‐soluble (decreased) to TBS‐soluble (increased) hippocampal protein fractions, in GFAP vs. EGFP and/or PBS mice, but no changes in soluble or insoluble total tau or AT270/pTauThr181 across groups. In the cortex, we detected no changes in soluble or insoluble total tau, AT8/pTauSer202/Thr205, or AT270/pTauThr181 levels, nor in AT8‐immunoreactive area. Lastly, we found no significant differences across groups in brain weight, cortical or hippocampal areas, nor in the cortical levels of synaptophysin, Psd95, or the glutamate transporters Eaat1/Glast‐1 and Eaat2/Glt‐1.ConclusionOur findings indicate that GFAP upregulation by astrocytes—a classic feature of reactive astrogliosis—may attenuate neuronal pTau burden in a tauopathy mouse model. Ongoing work will further elucidate whether this aspect of reactive astrocytes impacts pTau‐induced neurodegeneration.

Mouse skeletal muscle adaptations to different durations of treadmill exercise after the cessation of FOLFOX chemotherapy.

FOLFOX (5-fluorouracil, leucovorin, oxaliplatin) chemotherapy is a treatment for colorectal cancer that can induce persistent fatigue and metabolic dysfunction. Regular exercise after chemotherapy cessation is widely recommended for cancer patients and has been shown to improve fatigue resistance in mice. However, gaps remain in understanding whether the early systemic and skeletal muscle adaptations to regular exercise are altered by prior FOLFOX chemotherapy treatment. Furthermore, the effects of exercise duration on early metabolic and skeletal muscle transcriptional adaptations are not fully established. Purpose: Investigate the effects of prior FOLFOX chemotherapy treatment on the early adaptations to repeated short- or long-duration treadmill exercise, including the fasting regulation of circulating metabolic regulators, skeletal muscle COXIV activity and myokine/exerkine gene expression in male mice. Methods: Male C57BL6/J mice completed 4 cycles of FOLFOX or PBS and were allowed to recover for 4-weeks. Subsets of mice performed 14 sessions (6d/wk, 18m/min, 5% grade) of short- (10min/d) or long-duration (55min/d) treadmill exercise. Blood plasma and muscle tissues were collected 48-72h after the last exercise bout for biochemical analyses. Results: Long-duration exercise increased fasting plasma osteocalcin, LIF, and IL-6 in healthy PBS mice, and these changes were ablated by prior FOLFOX treatment. Slow-oxidative soleus muscle COXIV activity increased in response to long-duration exercise in PBS mice, which was blocked by prior FOLFOX treatment. Fast-glycolytic plantaris muscle COXIV activity increased with short-duration exercise independent of FOLFOX administration. There was a main effect for long-duration exercise to increase fasting muscle IL-6 and COXIV mRNA expression independent of FOLFOX. FOLFOX administration reduced muscle IL-6, LIF, and BDNF mRNA expression irrespective of long-duration exercise. Interestingly, short-duration exercise suppressed the FOLXOX induction of muscle myostatin mRNA expression. Conclusion: FOLFOX attenuated early exercise adaptations related to fasting circulating osteocalcin, LIF, and IL-6. However, prior FOLFOX treatment did not alter the exercise adaptations of plantaris muscle COXIV activity and plasma adiponectin. An improved understanding of mechanisms underlying exercise adaptations after chemotherapy will provide the basis for successfully treating fatigue and metabolic dysfunction in cancer survivors.

Effects of a Lacticaseibacillus Mix on Behavioural, Biochemical, and Gut Microbial Outcomes of Male Mice following Chronic Restraint Stress.

The effect of supplementation with Lactobacillus strains to prevent the consequences of chronic stress on anxiety in mouse strains sensitive to stress and the consequences on gut microbiota have been relatively unexplored. Thus, we administered a Lacticaseibacillus casei LA205 and Lacticaseibacillus paracasei LA903 mix to male BALB/cByJrj mice two weeks before and during 21-day chronic restraint stress (CRS) (non-stressed/solvent (NS-PBS), non-stressed/probiotics (NS-Probio), CRS/solvent (S-PBS), CRS/probiotics (S-Probio)). CRS resulted in lower body weight and coat state alteration, which were attenuated by the probiotic mix. S-Probio mice showed less stress-associated anxiety-like behaviours than their NS counterpart, while no difference was seen in PBS mice. Serum corticosterone levels were significantly higher in the S-Probio group than in other groups. In the hippocampus, mRNA expression of dopamine and serotonin transporters was lower in S-Probio than in S-PBS mice. Few differences in bacterial genera proportions were detected, with a lower relative abundance of Alistipes in S-Probio vs. S-PBS. CRS was accompanied by a decrease in the proportion of caecal acetate in S-PBS mice vs. NS-PBS, but not in the intervention groups. These data show that the probiotic mix could contribute to better coping with chronic stress, although the precise bacterial mechanism is still under investigation.

Effective treatment of metastatic sentinel lymph nodes by dual-targeting melittin nanoparticles

Sentinel lymph node (SLN) metastasis is an important promoter of distant metastasis in breast cancer. Therefore, the timely diagnosis and precise treatment are crucial for patient staging and prognosis. However, the simultaneous diagnosis of metastasis and the implementation of imaging-guided SLN therapy is challenging. Here, we report a melittin-loaded and hyaluronic acid (HA)-conjugated high-density lipoprotein (HDL) mimic phospholipid scaffold nanoparticle (MLT-HA-HPPS), which dually-target to both breast cancer and its SLN and efficiently inhibit SLN metastasis in the LN metastasis model. The melittin peptide was successfully loaded onto HA-HPPS via electrostatic interactions, and MLT-HA-HPPS possesses effective cytotoxicity for breast cancer 4T1 cells. Moreover, the effective delivery of MLT-HA-HPPS from the primary tumor into SLN is monitored by NIR fluorescence imaging, which greatly benefits the prognosis and treatment of metastatic SLNs. After paracancerous administration, MLT-HA-HPPS can efficiently inhibit primary tumor growth with an inhibition rate of 81.3% and 76.5% relative to the PBS-treated control group and HA-HPPS group, respectively. More importantly, MLT-HA-HPPS can effectively inhibit the growth of the metastatic SLNs with an approximately 78.0%, 79.1%, and 64.2% decrease in SLNs weight than those in PBS, HA-HPPS, and melittin-treated mice, respectively. Taken together, the MLT-HA-HPPS may provide an encouraging theranostic of SLN drug delivery strategy to inhibit primary tumor progression and prevent SLN metastasis of breast cancer.Graphical

Reduced immunogenicity of a live Salmonella enterica serovar Typhimurium vaccine in aged mice.

Non-typhoidal Salmonella (NTS) is responsible for a high burden of foodborne infections and deaths worldwide. In the United States, NTS infections are the leading cause of hospitalizations and deaths due to foodborne illnesses, and older adults (≥65 years) are disproportionately affected by Salmonella infections. Due to this public health concern, we have developed a live attenuated vaccine, CVD 1926 (I77 ΔguaBA ΔclpP ΔpipA ΔhtrA), against Salmonella enterica serovar Typhimurium, a common serovar of NTS. Little is known about the effect of age on oral vaccine responses, and due to the decline in immune function with age, it is critical to evaluate vaccine candidates in older age groups during early product development. In this study, adult (six-to-eight-week-old) and aged (18-month-old) C57BL/6 mice received two doses of CVD 1926 (109 CFU/dose) or PBS perorally, and animals were evaluated for antibody and cell-mediated immune responses. A separate set of mice were immunized and then pre-treated with streptomycin and challenged orally with 108 CFU of wild-type S. Typhimurium SL1344 at 4 weeks postimmunization. Compared to PBS-immunized mice, adult mice immunized with CVD 1926 had significantly lower S. Typhimurium counts in the spleen, liver, and small intestine upon challenge. In contrast, there were no differences in bacterial loads in the tissues of vaccinated versus PBS aged mice. Aged mice exhibited reduced Salmonella-specific antibody titers in the serum and feces following immunization with CVD 1926 compared to adult mice. In terms of T cell responses (T-CMI), immunized adult mice showed an increase in the frequency of IFN-γ- and IL-2-producing splenic CD4 T cells, IFN-γ- and TNF-α-producing Peyer's Patch (PP)-derived CD4 T cells, and IFN-γ- and TNF-α-producing splenic CD8 T cells compared to adult mice administered PBS. In contrast, in aged mice, T-CMI responses were similar in vaccinated versus PBS mice. CVD 1926 elicited significantly more PP-derived multifunctional T cells in adult compared to aged mice. These data suggest that our candidate live attenuated S. Typhimurium vaccine, CVD 1926, may not be sufficiently protective or immunogenic in older humans and that mucosal responses to live-attenuated vaccines decrease with increasing age.

214-LB: Activating and Disrupting the Liver–Alpha-Cell Axis Respectively Enhances and Impairs Amino Acid Metabolism and Alpha-Cell Growth

Amino acids control alpha cell secretion and growth, while glucagon stimulates hepatic amino acid uptake and ureagenesis, forming the liver-alpha cell axis. Patients with nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes have increased levels of glucagon and amino acids pointing to a disrupted liver-alpha cell axis. Both glucagon agonism and antagonism are explored for diabetes and NAFLD therapy but their effects on the axis are unclear. Female C57Bl/6JRj mice were treated with a long-acting glucagon analogue (GCGA, NNC9204-0043, Novo Nordisk A/S) or PBS twice daily, or once weekly with a GCGR antibody (GCGR Ab, REGN1193, Regeneron) or control antibody (Ctl. Ab, REGN1945, Regeneron) . After four weeks, total plasma amino acids were decreased by 48% in GCGA mice (P=0.0006) and increased by 285% in GCGR Ab mice (P&amp;lt;0.0001) versus week 0. At week 4, 18 of 19 amino acids were reduced in GCGA mice and increased in GCGR Ab mice. Asparagine changed the most in both groups, with a mean fold change of 0.21 and 7.50 in GCGA and GCGR Ab mice, respectively. Plasma urea index ([urea]/[amino acids]) was increased by 36% in GCGA mice (P=0.055) and decreased by 61% in GCGR Ab mice (P=0.001) . Liver RNA-sequencing revealed opposite effects of GCGA and GCGR Ab on expression of amino acid transporters (e.g. Slc43a) and ureagenesis genes (e.g. Ass1) . Activity of carbamoyl phosphate synthetase 1 was increased by 27% in GCGA versus PBS mice (P=0.007) and decreased by 33% in GCGR Ab mice versus Ctl. Ab (P=0.002) . GCGA lowered pancreas weight and glucagon content by 15% (P=0.004) and 95% (P&amp;lt;0.0001) compared to PBS. Conversely, GCGR Ab mice had a 34% increase in pancreas weight versus Ctl. Ab (P=0.0009) . Thus, chronically increased GCGR signaling leads to hypoaminoacidemia and decreased alpha cell mass, while chronically decreased GCGR signaling leads to hyperaminoacidemia and increased alpha cell mass. These changes must be considered when developing glucagon-based therapeutics. Disclosure E. E. Christensen: None. J. J. Holst: Advisory Panel; Novo Nordisk, Board Member; Antag Therapeutics, Bainan Biotech. N. J. Wewer albrechtsen: Research Support; Mercodia AB, Novo Nordisk, Regeneron Pharmaceuticals Inc., Speaker's Bureau; Merck &amp; Co., Inc., Mercodia AB. K. D. Galsgaard: None. C. D. Johansen: None. S. Trammell: None. A. B. Bomholt: None. J. Hunt: None. T. Kruse: Employee; Novo Nordisk. J. F. Lau: Employee; Novo Nordisk A/S, Stock/Shareholder; Novo Nordisk A/S. T. Grevengoed: None. Funding Nicolai J. Wewer Albrechtsen is supported by NNF Excellence Emerging Investigator Grant ? Endocrinology and Metabolism (Application No. NNF19OC0055001) , EFSD Future Leader Award (NNF21SA0072746) and DFF Sapere Aude (1052-00003B) . Novo Nordisk Foundation Center for Protein Research is supported financially by the Novo Nordisk Foundation (grant agreement NNF14CC0001) .

Effects of contraction and feeding on skeletal muscle protein synthesis during the initiation of cachexia

Muscle contraction and feeding are potent regulators of skeletal muscle protein synthesis. Cancer cachexia can suppress muscle protein synthesis through Akt/mTORC1 signaling suppression. Cachexia also suppresses acute contraction‐induced muscle protein synthesis. However, the cancer environment’s impact on the combined feeding and contraction activation of protein synthesis during the initiation of cachexia is not well understood. Therefore, we examined the cancer environment’s effect on the muscle protein synthesis response to an acute bout of muscle contraction with and without feeding.METHODSMale C57BL/6J (B6; N=36) were injected with 1 x 106 Lewis Lung Carcinoma (LLC) cells or PBS subcutaneously in the right flank and were monitored for up to 30 days. Following an overnight 12hr fast, mice were given ad libitum access to a food pellet for 1hr (fed) or fasted for an additional hour (fast). Subsequently, mice were subjected to low‐frequency electrical stimulation (LFES) for 30 minutes and sacrificed 3hrs post. Puromycin was injected 30min before sacrifice for protein synthesis measurements. Gastrocnemius muscle was examined for protein expression and values normalized to the contralateral limb.RESULTSIn PBS mice, LFES induced rpS6 (9.5‐fold) and protein synthesis (4.7‐fold). LFES induced rpS6 (1.7‐fold) and protein synthesis (0.9‐fold) in LLC mice. Overall, rpS6 and protein synthesis were lower in the LLC mice compared to PBS. Feeding increased muscle rpS6 and protein synthesis in PBS mice (p&lt;0.001) but not in LLC (p=0.821 and p=0.642) mice. Feeding and LFES synergistically induce rpS6 and protein synthesis in PBS mice; however, this was not present in LLC mice.CONCLUSIONWe report that contraction’s ability to increase muscle protein synthesis is suppressed in mice initiating cachexia. The ability for feeding to increase muscle protein synthesis is also suppressed in mice initiating cachexia. Notably, the combined effects of feeding and contraction were insufficient to synergistically improve muscle protein synthesis as in healthy mice. Future studies should determine why feeding was not sufficient to induce muscle protein synthesis in mice initiating cachexia.

Induction of broadly reactive influenza antibodies increases susceptibility to autoimmunity.

Infection and vaccination repeatedly expose individuals to antigens that are conserved between influenza virus subtypes. Nevertheless, antibodies recognizing variable influenza epitopes greatly outnumber antibodies reactive against conserved epitopes. Elucidating factors contributing to the paucity of broadly reactive influenza antibodies remains a major obstacle for developing a universal influenza vaccine. Here, we report that inducing broadly reactive influenza antibodies increases autoreactive antibodies in humans and mice and exacerbates disease in four distinct models of autoimmune disease. Importantly, transferring broadly reactive influenza antibodies augments disease in the presence of inflammation or autoimmune susceptibility. Further, broadly reactive influenza antibodies spontaneously arise in mice with defects in B cell tolerance. Together, these data suggest that self-tolerance mechanisms limit the prevalence of broadly reactive influenza antibodies, which can exacerbate disease in the context of additional risk factors.

Treatment with Soluble Activin Type IIB Receptor Ameliorates Ovariectomy-Induced Bone Loss and Fat Gain in Mice

IntroductionIn postmenopausal osteoporosis, hormonal changes lead to increased bone turnover and metabolic alterations including increased fat mass and insulin resistance. Activin type IIB receptors bind several growth factors of the TGF-β superfamily and have been demonstrated to increase muscle and bone mass. We hypothesized that ActRIIB-Fc treatment could improve bone and muscle mass, inhibit fat accumulation, and restore metabolic alterations in an ovariectomy (OVX) model of postmenopausal osteoporosis.Materials and MethodsFemale C57Bl/6 N mice were subjected to SHAM or OVX procedures and received intraperitoneal injections of either PBS or ActRIIB-Fc (5 mg/kg) once weekly for 7 weeks. Glucose and insulin tolerance tests (GTT and ITT, respectively) were performed at 7 and 8 weeks, respectively. Bone samples were analyzed with micro-computed tomography imaging, histomorphometry, and quantitative RT-PCR.ResultsBone mass decreased in OVX PBS mice compared to the SHAM PBS group but ActRIIB-Fc was able to prevent these changes as shown by µCT and histological analyses. This was due to decreased osteoclast numbers and function demonstrated by histomorphometric and qRT-PCR analyses. OVX induced adipocyte hypertrophy that was rescued by ActRIIB-Fc, which also decreased systemic adipose tissue accumulation. OVX itself did not affect glucose levels in GTT but ActRIIB-Fc treatment resulted in impaired glucose clearance in both SHAM and OVX groups. OVX induced mild insulin resistance in ITT but ActRIIB-Fc treatment did not affect this.ConclusionOur results reinforce the potency of ActRIIB-Fc as a bone-enhancing agent but also bring new insight into the metabolic effects of ActRIIB-Fc in normal and OVX mice.

Development of Anti-CD99scFvs for the Treatment of Acute Myeloid Leukemia

CD99 has gained much attention in recent years as a novel therapeutic target in hematological malignancies, due to its upregulation in acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). We have recently shown that targeting CD99 with a knockdown approach or with commercial antibodies results in antileukemia activity in AML cells. We have also developed anti-CD99 nanoparticles and demonstrated excellent in vitro and in vivo antileukemia activity. Here we report the development of human single chain variable fragment targeting CD99 (anti-CD99 scFv) and the preclinical activity in AML cells and in AML xenograft mouse model. The anti-CD99 scFv was developed by inserting CD99scFv DNA sequence into the pFUSE vector, encoding pATL103-CD99 scFvs. To produce anti-CD99 scFv, the plasmids were transfected in Expi293 (HEK293T) cells. Then the medium was harvested and underwent two cycles of dialysis. To determine product purity, proteins were analyzed on SDS-PAGE gel stained with Coomassie blue. For each 240ml cell culture media with recombinant CD99 plasmids, we obtained about 1-2mg anti-CD99 scFv. The binding affinity of CD99 scFv to CD99 surface protein was assessed in 293T cells (CD99 null cells) which exhibited no binding and in MOLM-13 cells and MV4-11 (CD99 positive AML cells) which demonstrated strong binding. Treatment with 5uM of anti-CD99 scFv significantly reduced cell viability in both leukemic cell line MOLM-13 and MV4-11 (MOLM-13: 35.14%, P= 0.008; MV4-11: 30.17%, P=0.002) and primary AML patient blasts (29.37%, P=0.048) compared with control cells. Colony forming assay showed that anti-CD99 scFv treated AML blasts exhibited less number of colonies compared with control cells (plating efficiency (PE): 0.035% vs 0.12%). We also established the in vivo antileukemia activity of anti-CD99 scFv using MOLM-13 cells (FLT3-ITD positive AML cells) NOD scid gamma (NSG) xenograft mouse model. MOLM-13 (2.5x10^6) cells were engrafted into NSG mice via IV tail injection (N=4 mice per group). Mice were treated with PBS (group 1) or 4mg/kg of anti-CD99 scFV on days 10, 14, 18 and 22 post cell engraftment. Mice were euthanized on day 24 and levels of leukemia engraftment were assessed by flow cytometry measurements of huCD45 staining of cells collected from the bone marrow and the peripheral blood and compared between the two groups. Mice treated with four doses of 4mg/kg CD99scFv demonstrated significant reduction in leukemia engraftment in the bone marrow assessed by flow cytometry measurements of huCD45 staining compared with the PBS mice group (huCD45%: 39.7 vs 56, P = 0.0017). In conclusion, we report the development of anti-CD99 single chain variable fragments for the treatment of AML. Our study demonstrates good binding affinity and specificity and a promising preclinical antileukemia activity both in AML cells and in xenograft mouse model. DisclosuresYaghmour: Jazz: Consultancy, Honoraria; Astellas: Consultancy; Takeda: Consultancy; Incyte: Consultancy.

Macrophage depletion impairs adequate cardiac repair in mouse models of myocardial infarction with variable transmurality - insights from multimodality molecular imaging

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft (DFG) Introduction Balanced myocardial tissue inflammation following acute myocardial infarction (MI) is needed for optimal cardiac repair. Macrophages contribute to wound healing, but may also be deleterious. Purpose We investigated the impact of macrophage depletion on early cardiac inflammation and later functional outcome in two models of MI with variable transmurality. Methods C57BL/6N mice received clodronate-liposomes for macrophage depletion (n = 49) or control PBS-liposomes (n = 23). After 24h, mice underwent permanent occlusion (PO) or transient ischemia-reperfusion (I/R, 60min) of the left coronary artery or sham surgery. Cardiac inflammation was assessed on MI + 1d, 3d, and 7d by CXCR4-targeted PET/CT using 68Ga-pentixafor. 99mTc-sestamibi SPECT/CT and cardiac magnetic resonance (CMR) calculated infarct sizes and left ventricular (LV) function at 1wk and 6wks. 18F-NaF PET/CT measured tissue microcalcification at 4wks. Imaging signals were validated by ex vivo autoradiography and immunohistochemistry. Results Clodronate macrophage depletion did not affect infarct size compared to PBS, but perfusion defects at 6wks were significantly larger after PO compared to I/R (%LV, 32 ± 11 vs 14 ± 10, p = 0.01). In both models, infarct CXCR4 expression was higher after macrophage depletion vs PBS at all timepoints (%injected dose (ID)/g; d3: PO: 1.4 ± 0.2 vs 0.9 ± 0.1; I/R: 1.4 ± 0.2 vs 1.0 ± 0.02; p &amp;lt; 0.05), and confirmed by ex vivo autoradiography. Immunostaining demonstrated fewer macrophages and higher neutrophil content within the myocardium after macrophage depletion vs PBS at 1d, 3d, and 7d post-MI. Acute LV rupture after PO was more frequent in macrophage-depleted than PBS mice (37% vs 17%). Conversely, surviving PO mice showed a similarly impaired ejection fraction (EF) after macrophage depletion vs PBS at 6wks (%, 32 ± 9 vs 32 ± 11, p = 0.84). No acute LV rupture was observed after I/R, but macrophage depletion led to worse EF (%, 42 ± 11 vs 54 ± 3, p = 0.1). Macrophage-depleted mice exhibited a dense intracavity thrombus adherent to the infarct wall after either injury, as visualized on CMR at 1wk. 18F-NaF PET identified active calcification localized to the thrombus region 4wks after MI, which was colocalized to CT opaque regions at 6wks. Conclusion Macrophage depletion impairs cardiac repair via several mechanisms including neutrophil-dominated inflammation, LV thrombus formation and tissue calcification. This observation underscores the requirement of macrophages for effective healing and may explain adverse response to broad anti-inflammatory therapy in myocardial ischemia.

Targeted Remodeling of the Tumor Microenvironment Via Mechanical Stimulation Defines a Novel Therapeutic Strategy in Myeloma Bone Disease

Multiple myeloma (MM) patients develop devastating osteolytic bone disease causing non-healing bone fractures and pain. MM cells in the bone marrow microenvironment stimulate osteoclast activity and inhibit osteoblast and osteocyte function leading to massive bone resorption and therefore destruction. Bones have the capacity to locally adapt to changing loads and for self-repair and remodeling as dramatically seen in athletes during training. In this study we determined if mechanical loading can counterbalance osteolytic bone disease in the presence of established MM. We hypothesized that mechanical stimulation increases bone formation and decreases bone resorption by activating known bone (re)modeling pathways, which are deleteriously altered by MM cells in bone. We performed in vivo cyclic axial compressive tibial loading (Fig. 1) to MOPC315.BM BALB/c injected mice (n=19) with established MM bone disease (Fig. 2, bioluminescence imaging). The bone (re)modeling response to mechanical loading (5d/wk, over 3 wks) was investigated by longitudinal in vivo microCT imaging at days 14, 18, 23, 28 and 33 (Fig. 3, 4). Loading was administered to the left tibia starting 14 days after i.t. injection of left limbs of MOPC315.BM (n=10) and PBS (n=7) mice (left limb: εmax=2000µε determined by strain gauging, right limb was nonloaded). 15 mice served as nonloaded control mice (Fig. 3). We also analyzed a group of loaded, but not injected mice (n=10). MicroCT data (Fig. 3), such as cortical thickness (Ct.Th), cortical bone area (Ct.Ar) of loaded left limbs demonstrate that metaphyseal cortical bone formation was significantly greater and cortical porosity (Ct.Po) was lower compared to nonloaded control limbs. Our data provide for the first time an indication that mechanical loading counteracts MM induced bone loss over time. To further study mechanisms of mechanotransduction we used a small scale cell culture bioreactor system to analyze mechanical stimulation of human mesenchymal stem cells (hMSCs) and the translation of mechanical forces into biochemical signals. The bioreactor system allows for analysis of molecular mechanisms of mechanotransduction using a transcription factor activator protein (AP1) luciferase reporter gene construct. Cyclic stretching of telomerase immortalized hMSCs (hMSC-TERT cells) which were stably transfected by an AP1 construct resulted in stimulation of AP1 activity as measured by luciferase gene expression. We analyzed how MM cells interfere with mechanotransduction when co-cultured with hMSC-TERT cells. Our data show that in presence of MOPC315.BM cells and 2 (MM1S, INA-6) out of 4 human MM cell lines hMSCs can be mechanically stimulated and have osteogenic activity. In contrast the human MM cell lines Amo-1 and U266 inhibit the hMSC-TERT response to mechanical stimulation under these conditions. Biochemical and molecular genetic studies are underway to determine how MM cells in bone alter known bone (re)modeling pathways and which yet unanticipated factors regulate the anabolic response to mechanical loading in the MOPC315.BM model. Our study provides a first fundamental understanding of the mechano-biological mechanisms of anabolic bone adaption during MM bone disease in response to mechanical stimuli. We conclude that mechanical loading in the form of exercise has the potential to be a potent novel anabolic strategy for primary and secondary prevention of MM bone disease. Moreover dissection of the underlying molecular pathways will identify new targets for innovative antimyeloma strategies. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Dissolving cholesterol crystals reduces aortic valve stenosis development in mice

Abstract Background Aortic valve stenosis (AS) is the most common valve disease worldwide and is associated with a very high morbidity and mortality. Until today, aortic valve replacement is the only therapeutic option available. Analysis of explanted human aortic valves has shown that atherosclerosis-like lesions, that contain cholesterol crystals (CC), are present in stenotic aortic valve cusps. It has been demonstrated that CCs can activate the NLRP3 inflammasome and hereby trigger a complex, IL-1b driven, inflammatory response. 2-hydroxypropyl-β-cyclodextrin (CD) is a cyclic oligosaccharide that can increase the solubility of CCs, which results in a reduction of CC-load and therefore could inhibit the pro-inflammatory immune response. Methods Severe AS was induced in 10 weeks old C57BL/6-J (WT) and Apolipoprotein-E-deficient (ApoE) mice. Acoronary springwire was used to induce an endothelial injury under echocardiographic guidance. AS development was confirmed via ultrasound examinations. ApoE mice were fed a cholesterol-rich western diet and concomitantly received daily injections of 2g/kg/d CD via subcutaneous injection. CCs were visualized with laser reflection confocal microscopy. Serum cholesterol analysis were performed via mass GC-MS-SIM. Results In order to evaluate whether hyperlipidemia aggravates AS development, WT and ApoE mice were fed a cholesterol-rich diet and subjected to our model of wire-induced AS. Trans-aortic valve peak velocity levels of ApoE mice were significantly increased six weeks after injury compared to WT mice. Histological analysis of these mice showed large CC-deposits in the aortic valves of ApoE mice. Next, CC solubility was increased in a group of ApoE mice, control mice only received PBS injections. Interestingly, mice treated with CD displayed a significantly reduced peak blood velocity over the aortic valve compared to PBS mice. Left ventricular ejection fraction remained unchanged. Serum cholesterol analysis was performed to analyze the effect of CD on cholesterol metabolism. 27-hydroxycholesterol, an endogenous oxysterol of cholesterol metabolism, which reduces the potential for the conversion of free cholesterol into crystals was significantly increased in CD treated mice. The levels of cholesterol precursors were unchanged, indicating that CD doesn't influence de-novo synthesis of cholesterol. Intestinal absorption of cholesterol was also not affected by CD, as assessed by quantification of phytosterols in the serum of CD and PBS treated mice. Conclusion These results underline the importance of hyperlipidemia in the pathogenesis of AS. Particularly CCs seem to act as an important inflammatory trigger in the development of AS. Increasing the solubility of cholesterol through CD reduces AS development in mice and could, as it is already considered safe in human, act as a possible therapeutic option. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): DFG, German Research Foundation

Lemon Exosome-like Nanoparticles-Manipulated Probiotics Protect Mice from C.d iff Infection.

SummaryClostridioides difficile (C. diff) is the leading cause of antibiotic-associated colitis. Here, we report that lemon exosome-like nanoparticles (LELNs) manipulated probiotics to inhibit C. diff infection (CDI). LELN-manipulated Lactobacillus rhamnosus GG (LGG) and Streptococcus thermophilus ST-21 (STH) (LELN-LS) decrease CDI mortality via an LELN-mediated increase in bile resistance and gut survivability. LELN-LS treatment increases the AhR ligands indole-3-lactic acid (I3LA) and indole-3-carboxaldehyde (I3Ald), leading to induction of IL-22, and increases lactic acid leading to a decrease of C. diff fecal shedding by inhibiting C. diff growth and indole biosynthesis. A synergistic effect between STH and LGG was identified. The STH metabolites inhibit gluconeogenesis of LGG and allow fructose-1,6-bisphosphate (FBP) to accumulate in LGG; accumulated FBP then activates lactate dehydrogenase of LGG (LGG-LDH) and enhances production of lactic acid and the AhR ligand. Our findings provide a new strategy for CDI prevention and treatment with a new type of prebiotics.

Abstract 5326: Cholecystokinin receptor antagonist decreases fibrosis in pancreatic cancer microenvironment to improve uptake and efficacy of chemotherapy

Abstract Background: Although pancreatic cancer cells respond to chemotherapeutic agents in cell culture, many of these drugs are less effective in vivo. This decreased response to chemotherapy in animal models and human subjects is in part attributed to the dense stroma of the pancreatic tumor microenvironment (TME) that impedes penetration of drugs. Pancreatic stellate cells and tissue fibroblasts have cholecystokinin (CCK) receptors and when these receptors are activated, they promote collagen deposition and increase fibrosis in the TME. We have previously shown that CCK receptor antagonists can decrease fibrosis and change the T-cell infiltrates of the TME in pancreatic tumors. We hypothesized that an oral CCK receptor antagonist, proglumide, would improve the efficacy of gemcitabine by decreasing fibrosis in the TME and improving uptake of chemotherapy. Methods: 500,000 mT3 murine pancreatic cancer cells were injected subcutaneously into the right flank of 40 C57/BL6 female mice. One week after the mice had measurable tumors (baseline), mice were divided into 4 groups (N=10 mice each) with equal mean tumor volumes. Treatment groups included: PBS control (100µl IP twice weekly); proglumide in drinking water (0.1 mg/ml); gemcitabine (100mg/kg, 100µl IP twice weekly); and combination of gemcitabine and proglumide. Tumors were measured weekly and the volumes were calculated. Mice were euthanized per protocol when the tumor diameter reached 20mm; tumors were removed, then flash frozen for gemcitabine measurement via mass spectrometry. Results: Tumor volumes demonstrated a rapid growth rate in the PBS control mice with a slope of 184.2±2 (mm3/week), whereas growth rates for proglumide (75±2) and gemcitabine monotherapy (72±14) were 2.6-fold slower, and also 3.4-fold slower for mice treated with both gemcitabine and proglumide (55.6±12; p&amp;lt;0001). By day 62, when all of the control PBS mice had died, survival in the other groups was: 70% for proglumide, 90% for gemcitabine only, and 100% for the combination-treated mice. On day 87, survival was as follows: control 0%; proglumide 40%, gemcitabine 50%, and the combination group 70%. Mean gemcitabine drug uptake, as measured by mass spectrometry, was 4-times higher in the tumors of mice treated with combination therapy (729 pg/ml) compared to the gemcitabine concentration in tumors of mice treated with monotherapy (173pg/ml). Kaplan Meier survival curve revealed significant improved survival in mice treated with the combination of gemcitabine and proglumide (p=0.001) compared to PBS. Conclusion: CCK receptor blockade with proglumide decreases fibrosis in pancreatic cancer TME allowing greater tumor uptake of gemcitabine and improving efficacy by slowing tumor growth and improving survival. Strategies to improve first-line therapies for patients with pancreatic cancer may improve overall survival of this disease. Citation Format: Zoe X. Malchiodi, Hong Cao, Martha Gay, Sunil Bansal, Benjamin A. Weinberg, Amrita Cheema, Narayan Shivapurkar, Jill P. Smith. Cholecystokinin receptor antagonist decreases fibrosis in pancreatic cancer microenvironment to improve uptake and efficacy of chemotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5326.

Early or Late Bacterial Lung Infection Increases Mortality After Traumatic Brain Injury in Male Mice and Chronically Impairs Monocyte Innate Immune Function.

Respiratory infections in the postacute phase of traumatic brain injury impede optimal recovery and contribute substantially to overall morbidity and mortality. This study investigated bidirectional innate immune responses between the injured brain and lung, using a controlled cortical impact model followed by secondary Streptococcus pneumoniae infection in mice. Experimental study. Research laboratory. Adult male C57BL/6J mice. C57BL/6J mice were subjected to sham surgery or moderate-level controlled cortical impact and infected intranasally with S. pneumoniae (1,500 colony-forming units) or vehicle (phosphate-buffered saline) at 3 or 60 days post-injury. At 3 days post-injury, S. pneumoniae-infected traumatic brain injury mice (TBI + Sp) had a 25% mortality rate, in contrast to no mortality in S. pneumoniae-infected sham (Sham + Sp) animals. TBI + Sp mice infected 60 days post-injury had a 60% mortality compared with 5% mortality in Sham + Sp mice. In both studies, TBI + Sp mice had poorer motor function recovery compared with TBI + PBS mice. There was increased expression of pro-inflammatory markers in cortex of TBI + Sp compared with TBI + PBS mice after both early and late infection, indicating enhanced post-traumatic neuroinflammation. In addition, monocytes from lungs of TBI + Sp mice were immunosuppressed acutely after traumatic brain injury and could not produce interleukin-1β, tumor necrosis factor-α, or reactive oxygen species. In contrast, after delayed infection monocytes from TBI + Sp mice had higher levels of interleukin-1β, tumor necrosis factor-α, and reactive oxygen species when compared with Sham + Sp mice. Increased bacterial burden and pathology was also found in lungs of TBI + Sp mice. Traumatic brain injury causes monocyte functional impairments that may affect the host's susceptibility to respiratory infections. Chronically injured mice had greater mortality following S. pneumoniae infection, which suggests that respiratory infections even late after traumatic brain injury may pose a more serious threat than is currently appreciated.