Innate Inflammatory Responses Research Articles

Circadian disruption dysregulates lung gene expression associated with inflammatory lung injury.

Circadian systems drive the expression of multiple genes in nearly all cells and coordinate cellular-, tissue-, and system-level processes that are critical to innate immunity regulation. We examined the effects of circadian rhythm disorganization, produced by light shift exposure, on innate immunity-mediated inflammatory lung responses including vascular permeability and gene expression in a C57BL/6J murine model of inflammatory lung injury. A total of 32 C57BL/6J mice were assigned to circadian phase shifting (CPS) with intratracheal phosphate-buffered saline (PBS), CPS with intratracheal lipopolysaccharide (LPS), control (normal lighting) condition with intratracheal PBS, and control condition with intratracheal LPS. Bronchoalveolar lavage (BAL) protein, cell counts, tissue immunostaining, and differentially expressed genes (DEGs) were measured in lung tissues at 2 and 10 weeks. In mice exposed to both CPS and intratracheal LPS, both BAL protein and cell counts were increased at both 2 and 10 weeks compared to mice exposed to LPS alone. Multiple DEGs were identified in CPS-LPS-exposed lung tissues compared to LPS alone and were involved in transcriptional pathways associated with circadian rhythm disruption, regulation of lung permeability, inflammation with Rap1 signaling, and regulation of actin cytoskeleton. The most dysregulated pathways included myosin light chain kinase, MAP kinase, profilin 2, fibroblast growth factor receptor, integrin b4, and p21-activated kinase. Circadian rhythm disruption results in exacerbated immune response and dysregulated expression of cytoskeletal genes involved in the regulation of epithelial and vascular barrier integrity-the mechanistic underpinnings of acute lung injury. Further studies need to explore circadian disorganization as a druggable target.

STING contributes to lipopolysaccharide-induced tubular cell inflammation and pyroptosis by activating endoplasmic reticulum stress in acute kidney injury

Recently, innate immunity and inflammation were recognized as the key factors for acute kidney injury (AKI) caused by sepsis, which is closely related to high mortality. Stimulator of interferon genes (STING) has emerged as a critical component of innate immune and inflammatory responses. However, the role of STING in the pathogenesis of septic AKI remains unclear. This study demonstrated that the STING was significantly activated in tubular cells induced by lipopolysaccharide (LPS) in vivo and in vitro. Tubule-specific STING knockout attenuated LPS-induced renal dysfunction and pathological changes. Mechanistically, the STING pathway promotes NOD-like receptor protein 3 (NLRP3) activation. STING triggers endoplasmic reticulum (ER) stress to induce mitochondrial reactive oxygen species (mtROS) overproduction, enhancing thioredoxin-interacting protein activation and association with NLRP3. Eventually, the NLRP3 inflammasome leads to tubular cell inflammation and pyroptosis. This study revealed the STING-regulated network and further identified the STING/ER stress/mtROS/NLRP3 inflammasome axis as an emerging pathway contributing to tubular damage in LPS-induced AKI. Hence, targeting STING may be a promising therapeutic strategy for preventing septic AKI.

Macrophage immunophenotypes in Jorge Lobo’s disease and lepromatous leprosy- A comparative study

Jorge Lobo's disease (JLD) and lepromatous leprosy (LL) share several clinical, histological and immunological features, especially a deficiency in the cellular immune response. Macrophages participate in innate and adaptive inflammatory immune responses, as well as in tissue regeneration and repair. Macrophage function deficiency results in maintenance of diseases. M1 macrophages produce pro-inflammatory mediators and M2 produce anti-inflammatory cytokines. To better understand JLD and LL pathogenesis, we studied the immunophenotype profile of macrophage subtypes in 52 JLD skin lesions, in comparison with 16 LL samples, using a panmacrophage (CD68) antibody and selective immunohistochemical markers for M1 (iNOS) and M2 (CD163, CD204) responses, HAM56 (resident/fixed macrophage) and MAC 387 (recently infiltrating macrophage) antibodies.We found no differences between the groups regarding the density of the CD163, CD204, MAC387+ immunostained cells, including iNOS, considered a M1 marker. But HAM56+ cell density was higher in LL samples. By comparing the M2 and M1 immunomarkers in each disease separately, some other differences were found. Our results reinforce a higher M2 response in JLD and LL patients, depicting predominant production of anti-inflammatory cytokines, but also some distinction in degree of macrophage activation. Significant amounts of iNOS + macrophages take part in the immune milieu of both LL and JLD samples, displaying impaired microbicidal activity, like alternatively activated M2 cells.

Inhibition of Toll-like Receptor 4 Using Small Molecule, TAK-242, Protects Islets from Innate Immune Responses.

Islet transplantation is a therapeutic option to replace β-cell mass lost during type 1 or type 3c diabetes. Innate immune responses, particularly the instant blood-mediated inflammatory reaction and activation of monocytes, play a major role in the loss of transplanted islet tissue. In this study, we aimed to investigate the inhibition of toll-like receptor 4 (TLR4) on innate inflammatory responses. We first demonstrate a significant loss of graft function shortly after transplant through the assessment of miR-375 and miR-200c in plasma as biomarkers. Using in vitro models, we investigate how targeting TLR4 mitigates islet damage and immune cell activation during the peritransplant period. The results of this study support the application of TAK-242 as a therapeutic agent to reduce inflammatory and innate immune responses to islets immediately following transplantation into the hepatic portal vein. Therefore, TLR4 may serve as a target to improve islet transplant outcomes in the future.

Immunologic basis for development of keratoconjunctivitis sicca in systemic autoimmune diseases: Role of innate immune sensors

The literature is filled with citations reporting an increased incidence of chronic dry eye disease, also known as keratoconjunctivitis sicca, in patients with systemic autoimmune diseases such as rheumatoid arthritis, Sjögren's Syndrome, systemic sclerosis and lupus. As the most environmentally exposed mucosal surface of the body, the conjunctiva constantly responds to environmental challenges which are typically self limited, but when persistent and unresolved may provoke pathogenic innate and adaptive immune reactions.Our understanding of the pathophysiological mechanisms by which systemic autoimmune diseases cause dry eye inducing ocular surface inflammation continues to evolve. Conjunctival immune tone responds to self or foreign danger signals (including desiccating stress) on the ocular surface with an initial non-specific innate inflammatory response. If unchecked, this can lead to activation of dendritic cells that present antigen and prime T and B cells resulting in an adaptive immune reaction. These reactions generally resolve, but dysfunctional, hyper-responsive immune cells found in systemic autoimmune diseases that are recruited to the ocular surface can amplify inflammatory stress responses in the ocular surface and glandular tissues and result in autoimmune reactions that disrupt tear stability and lead to chronic dry eye disease. We here propose that unique features of the ocular surface immune system and the impact of systemic immune dysregulation in autoimmune diseases, can predispose to development of dry eye disease, and exacerbate severity of existing dry eye.

RNA sequencing reveals differential long noncoding RNA expression profiles in bacterial and viral meningitis in children

BackgroundWe aimed to investigate the involvement of long non-coding RNA (lncRNA) in bacterial and viral meningitis in children.MethodsThe peripheral blood of five bacterial meningitis patients, five viral meningitis samples, and five healthy individuals were collected for RNA sequencing. Then, the differentially expressed lncRNA and mRNA were detected in bacterial meningitis vs. controls, viral meningitis vs. healthy samples, and bacterial vs. viral meningitis patients. Besides, co-expression and the competing endogenous RNA (ceRNA) networks were constructed. Receiver operating characteristic curve (ROC) analysis was performed.ResultsCompared with the control group, 2 lncRNAs and 32 mRNAs were identified in bacterial meningitis patients, and 115 lncRNAs and 54 mRNAs were detected in viral meningitis. Compared with bacterial meningitis, 165 lncRNAs and 765 mRNAs were identified in viral meningitis. 2 lncRNAs and 31 mRNAs were specific to bacterial meningitis, and 115 lncRNAs and 53 mRNAs were specific to viral meningitis. The function enrichment results indicated that these mRNAs were involved in innate immune response, inflammatory response, and immune system process. A total of 8 and 1401 co-expression relationships were respectively found in bacterial and viral meningitis groups. The ceRNA networks contained 1 lncRNA-mRNA pair and 4 miRNA-mRNA pairs in viral meningitis group. GPR68 and KIF5C, identified in bacterial meningitis co-expression analysis, had an area under the curve (AUC) of 1.00, while the AUC of OR52K2 and CCR5 is 0.883 and 0.698, respectively.ConclusionsOur research is the first to profile the lncRNAs in bacterial and viral meningitis in children and may provide new insight into understanding meningitis regulatory mechanisms.

Ion Transport Basis of Diarrhea, Paneth Cell Metaplasia, and Upregulation of Mechanosensory Pathway in Anti-CD40 Colitis Mice.

Anti-Cluster of differentiation (CD)-40-induced colitis, driven by innate inflammatory responses in the intestine, is a potent animal model exhibiting IBD pathophysiology including diarrhea. However, the ion transport basis of diarrhea and some key mucosal pathways (Paneth cells, stem cell niche, and mechanosensory) in this model have not been investigated. Mucosal scrapings and intestinal tissue from control and CD40 antibody (150µg) treated Rag2-/- mice were examined for gut inflammation, Paneth cell numbers, expression of key transporters, tight/adherens junction proteins, stem cell niche, and mechanosensory pathway via hematoxylin and eosin staining, quantitative polymerase chain reaction, and western blotting. Compared with control, anti-CD40 antibody treatment resulted in a significant loss of body weight (P < .05) and diarrhea at day 3 postinjection. Distal colonic tissues of anti-CD40 mice exhibited increased inflammatory infiltrates, higher claudin-2 expression, and appearance of Paneth cell-like structures indicative of Paneth cell metaplasia. Significantly reduced expression (P < .005) of downregulated in adenoma (key Cl- transporter), P-glycoprotein/multidrug resistantance-1 (MDR1, xenobiotic transporter), and adherens junction protein E-cadherin (~2-fold P < .05) was also observed in the colon of anti-CD40 colitis mice. Interestingly, there were also marked alterations in the stem cell markers and upregulation of the mechanosensory YAP-TAZ pathway, suggesting the activation of alternate regeneration pathway post-tissue injury in this model. Our data demonstrate that the anti-CD40 colitis model shows key features of IBD observed in the human disease, hence making it a suitable model to investigate the pathophysiology of ulcerative colitis (UC).

Investigation of Oral Microbiome and Innate Inflammatory Response to Allogenic Stem Cell Transplant

Investigation of Oral Microbiome and Innate Inflammatory Response to Allogenic Stem Cell Transplant

Lactobacillus rhamnosus dampens cytokine and chemokine secretion from primary human nasal epithelial cells infected with rhinovirus.

To investigate the effect of Lactobacillus rhamnosus on viral replication and cellular response to human rhinovirus (HRV) infection, including the secretion of antiviral and inflammatory mediators from well-differentiated nasal epithelial cells (WD-NECs). The WD-NECs from healthy adult donors (N=6) were cultured in vitro, exposed to different strains of L. rhamnosus (D3189, D3160, or LB21), and infected with HRV (RV-A16) after 24 h. Survival and adherence capacity of L. rhamnosus in a NEC environment were confirmed using CFSE-labelled isolates, immunofluorescent staining, and confocal microscopy. Shed virus and viral replication were quantified using TCID50 assays and RT-qPCR, respectively. Cytotoxicity was measured by lactate dehydrogenase (LDH) activity. Pro-inflammatory mediators were measured by multiplex immunoassay, and interferon (IFN)-λ1/3 was measured using a standard ELISA kit. Lactobacillus rhamnosus was able to adhere to and colonize WD-NECs prior to the RV-A16 infection. Lactobacillus rhamnosus did not affect shed RV-A16, viral replication, RV-A16-induced IFN-λ1/3 production, or LDH release. Pre-exposure to L. rhamnosus, particularly D3189, reduced the secretion of RV-A16-induced pro-inflammatory mediators by WD-NECs. These findings demonstrate that L. rhamnosus differentially modulates RV-A16-induced innate inflammatory immune responses in primary NECs from healthy adults.

High-Density Lipoproteins at the Interface between the NLRP3 Inflammasome and Myocardial Infarction.

Despite significant therapeutic advancements, morbidity and mortality following myocardial infarction (MI) remain unacceptably high. This clinical challenge is primarily attributed to two significant factors: delayed reperfusion and the myocardial injury resulting from coronary reperfusion. Following reperfusion, there is a rapid intracellular pH shift, disruption of ionic balance, heightened oxidative stress, increased activity of proteolytic enzymes, initiation of inflammatory responses, and activation of several cell death pathways, encompassing apoptosis, necroptosis, and pyroptosis. The inflammatory cell death or pyroptosis encompasses the activation of the intracellular multiprotein complex known as the NLRP3 inflammasome. High-density lipoproteins (HDL) are endogenous particles whose components can either promote or mitigate the activation of the NLRP3 inflammasome. In this comprehensive review, we explore the role of inflammasome activation in the context of MI and provide a detailed analysis of how HDL can modulate this process.

The Involvement of Cysteine-X-Cysteine Motif Chemokine Receptors in Skin Homeostasis and the Pathogenesis of Allergic Contact Dermatitis and Psoriasis.

Members of the C-X-C motif chemokine receptor (CXCR) superfamily play central roles in initiating the innate immune response in mammalian cells by orchestrating selective cell migration and immune cell activation. With its multilayered structure, the skin, which is the largest organ in the body, performs a crucial defense function, protecting the human body from harmful environmental threats and pathogens. CXCRs contribute to primary immunological defense; these receptors are differentially expressed by different types of skin cells and act as key players in initiating downstream innate immune responses. While the initiation of inflammatory responses by CXCRs is essential for pathogen elimination and tissue healing, overactivation of these receptors can enhance T-cell-mediated autoimmune responses, resulting in excessive inflammation and the development of several skin disorders, including psoriasis, atopic dermatitis, allergic contact dermatitis, vitiligo, autoimmune diseases, and skin cancers. In summary, CXCRs serve as critical links that connect innate immunity and adaptive immunity. In this article, we present the current knowledge about the functions of CXCRs in the homeostasis function of the skin and their contributions to the pathogenesis of allergic contact dermatitis and psoriasis. Furthermore, we will examine the research progress and efficacy of therapeutic approaches that target CXCRs.

Tryptophan metabolites relieve intestinal Candida albicans infection by altering the gut microbiota to reduce IL-22 release from group 3 innate lymphoid cells of the colon lamina propria.

Invasive candidiasis may be caused by Candida albicans (C. albicans) colonization of the intestinal tract. Preventing intestinal damage caused by Candida albicans infection and protecting intestinal barrier function have become a critical issue. Integrated analyses of the microbiome with metabolome revealed a remarkable shift of the gut microbiota and tryptophan metabolites, kynurenic acid (KynA), and indolacrylic acid (IA) in mice infected with C. albicans. The transcriptome sequencing indicated that differentially expressed genes were significantly associated with innate immune responses and inflammatory responses. The results of this study suggest that KynA and IA (KI) can alleviate intestinal damage caused by Candida albicans infection in mice by reducing intestinal permeability, increasing intestinal firmness, alleviating intestinal inflammation, and reducing the secretion of interleukin-22 (IL-22) in the 3 groups of colon innate lymphoid cells (ILC3). We performed a fecal microbiota transplantation (FMT) experiment and found that the intestinal barrier function, inflammation, and IL-22 secretion of ILC3 in the colon lamina propria of the recipient mice subjected to C. albicans infection and KI treatment were consistent with the trends of the donor mice. Our results suggest that tryptophan metabolites may directly regulate colon lamina ILC3 to promote intestinal resistance to C. albicans invasion, or indirectly regulate the ILC3 secretion of IL-22 to play a protective role in the intestinal barrier by affecting intestinal microorganisms, which may become a potential target for alleviating intestine borne C. albicans infection.

TLR4 signalling: the key to controlling EV71 replication and inflammatory response.

Hand, foot, and mouth disease (HFMD) is a common infectious disease caused by enterovirus 71 (EV71) that frequently affects children, leading to severe infections in some cases. In general, when infection occurs, the body upregulates inflammatory responses to eliminate pathogenic microorganisms to protect the host from infection. However, EV71 may inhibit host's innate immunity to promote virus infection. At present, it is not fully understood how EV71 hijack the host cells for its own replication. Toll-like receptor 4 (TLR4), a natural immune receptor, historically associated with bacterial endotoxin-induced inflammatory responses. However, it is still unclear whether and how TLR4 is altered during EV71 infection. In this study, we observed a reduction in both TLR4 protein and gene transcript levels in RD, GES-1, and Vero cells following EV71 infection, as detected by RT-qPCR, immunofluorescence staining and western blot. Furthermore, we observed that the TLR4 downstream molecules of MYD88, p-NF-κB p65, p-TBK1 and related inflammatory cytokines were also reduced, suggesting that antiviral innate immune and inflammatory response were suppressed. To determine the impact of TLR4 changes on EV71 infection, we interfered EV71-infected RD cells with TLR4 agonist or inhibitor and the results showed that activation of TLR4 inhibited EV71 replication, while inhibition of TLR4 promote EV71 replication. Besides, EV71 replication was also promoted in TLR4 siRNA-transfected and EV71-infected RD cells. This suggests that down-regulation the expression of TLR4 by EV71 can inhibit host immune defense to promote EV71 self-replication. This novel mechanism may be a strategy for EV71 to evade host immunity.

The non-pathogenic protozoon Leishmania tarentolae interferes with the activation of NLRP3 inflammasome in human cells: new perspectives in the control of inflammation.

Innate immune responses against infectious agents can act as triggers of inflammatory diseases. On the other hand, various pathogens have developed mechanisms for the evasion of the immune response, based on an inhibition of innate immunity and inflammatory responses. Inflammatory diseases could thus be controlled through the administration of pathogens or pathogen-derived molecules, capable of interfering with the mechanisms at the basis of inflammation. In this framework, the NLRP3 inflammasome is an important component in innate antimicrobial responses and a major player in the inflammatory disease. Parasites of the genus Leishmania are master manipulators of innate immune mechanisms, and different species have been shown to inhibit inflammasome formation. However, the exploitation of pathogenic Leishmania species as blockers of NLRP3-based inflammatory diseases poses safety concerns. To circumvent safety issues associated with pathogenic parasites, we focused on Leishmania tarentolae, a species of Leishmania that is not infectious to humans. Because NLRP3 typically develops in macrophages, in response to the detection and engulfment microorganisms, we performed our experiments on a monocyte-macrophage cell line (THP-1), either wild type or knockout for ASC, a key component of NLRP3 formation, with determination of cytokines and other markers of inflammation. L. tarentolae was shown to possess the capability of dampening the formation of NLRP3 inflammasome and the consequent expression of pro-inflammatory molecules, with minor differences compared to effects of pathogenic Leishmania species. The non-pathogenic L. tarentolae appears a promising pro-biotic microbe with anti-inflammatory properties or a source of immune modulating cellular fractions or molecules, capable of interfering with the formation of the NLRP3 inflammasome.

Crosstalk Between Microglia and Müller Glia in the Age-Related Macular Degeneration: Role and Therapeutic Value of Neuroinflammation.

Age-related macular degeneration (AMD) is a progressive neurodegeneration disease that causes photoreceptor demise and vision impairments. In AMD pathogenesis, the primary death of retinal neurons always leads to the activation of resident microglia. The migration of activated microglia to the ongoing retinal lesion and their morphological transformation from branching to ameboid-like are recognized as hallmarks of AMD pathogenesis. Activated microglia send signals to Müller cells and promote them to react correspondingly to damaging stimulus. Müller cells are a type of neuroglia cells that maintain the normal function of retinal neurons, modulating innate inflammatory responses, and stabilize retinal structure. Activated Müller cells can accelerate the progression of AMD by damaging neurons and blood vessels. Therefore, the crosstalk between microglia and Müller cells plays a homeostatic role in maintaining the retinal environment, and this interaction is complicatedly modulated. In particular, the mechanism of mutual regulation between the two glia populations is complex under pathological conditions. This paper reviews recent findings on the crosstalk between microglia and Müller glia during AMD pathology process, with special emphasis on its therapeutic potentials.

Nuclear RPSA senses viral nucleic acids to promote the innate inflammatory response

Innate sensors initiate the production of type I interferons (IFN-I) and proinflammatory cytokines to protect host from viral infection. Several innate nuclear sensors that mainly induce IFN-I production have been identified. Whether there exist innate nuclear sensors that mainly induce proinflammatory cytokine production remains to be determined. By functional screening, we identify 40 S ribosomal protein SA (RPSA) as a nuclear protein that recognizes viral nucleic acids and predominantly promotes proinflammatory cytokine gene expression in antiviral innate immunity. Myeloid-specific Rpsa-deficient mice exhibit less innate inflammatory response against infection with Herpes simplex virus-1 (HSV-1) and Influenza A virus (IAV), the viruses replicating in nucleus. Mechanistically, nucleus-localized RPSA is phosphorylated at Tyr204 upon infection, then recruits ISWI complex catalytic subunit SMARCA5 to increase chromatin accessibility of NF-κB to target gene promotors without affecting innate signaling. Our results add mechanistic insights to an intra-nuclear way of initiating proinflammatory cytokine expression in antiviral innate defense.

Abelson Helper Integration Site 1 haplotypes and peripheral blood expression associates with lithium response and immunomodulation in bipolar patients

RationaleIn bipolar disorder (BD), immunological factors play a role in the pathogenesis and treatment of the illness. Studies showed the potential link between Abelson Helper Integration Site 1 (AHI1) protein, behavioural changes and innate immunity regulation. An immunomodulatory effect was suggested for lithium, a mood stabilizer used in BD treatment.ObjectivesWe hypothesized that AHI1 may be an important mediator of lithium treatment response. Our study aimed to investigate whether the AHI1 haplotypes and expression associates with lithium treatment response in BD patients. We also examined whether AHI1 expression and lithium treatment correlate with innate inflammatory response genes.ResultsWe genotyped seven AHI1 single nucleotide polymorphisms in 97 euthymic BD patients and found that TG haplotype (rs7739635, rs9494332) was significantly associated with lithium response. We also showed significantly increased AHI1 expression in the blood of lithium responders compared to non-responders and BD patients compared to healthy controls (HC). We analyzed the expression of genes involved in the innate immune response and inflammatory response regulation (TLR4, CASP4, CASP5, NLRP3, IL1A, IL1B, IL6, IL10, IL18) in 21 lithium-treated BD patients, 20 BD patients treated with other mood stabilizer and 19 HC. We found significantly altered expression between BD patients and HC, but not between BD patients treated with different mood stabilizers.ConclusionsOur study suggests the involvement of AHI1 in the lithium mode of action. Moreover, mood-stabilizing treatment associated with the innate immunity-related gene expression in BD patients and only the lithium-treated BD patients showed significantly elevated expression of anti-inflammatory IL10, suggesting lithium’s immunomodulatory potential.

Radiation-Induced Innate Neutrophil Response in Tumor Is Mediated by the CXCLs/CXCR2 Axis

The early events that lead to the inflammatory and immune-modulatory effects of radiation therapy (RT) in the tumor microenvironment (TME) after its DNA damage response activating the innate DNA-sensing pathways are largely unknown. Neutrophilic infiltration into the TME in response to RT is an early innate inflammatory response that occurs within 24–48 h. Using two different syngeneic murine tumor models (RM-9 and MC-38), we demonstrated that CXCR2 blockade significantly reduced RT-induced neutrophilic infiltration. CXCR2 blockade showed the same effects on RT-induced tumor inhibition and host survival as direct neutrophil depletion. Neutrophils highly and preferentially expressed CXCR2 compared to other immune cells. Importantly, RT induced both gene and protein expression of CXCLs in the TME within 24 h, attracting neutrophils into the tumor. Expectedly, RT also upregulated the gene expression of both cGAS and AIM2 DNA-sensing pathways in cGAS-positive MC-38 tumors but not in cGAS-negative RM-9 tumors. Activation of these pathways resulted in increased IL-1β, which is known to activate the CXCLs/CXCR2 axis. Gene ontology analysis of mRNA-Seq supported these findings. Taken together, the findings suggest that the CXCLs/CXCR2 axis mediates the RT-induced innate inflammatory response in the TME, likely translating the effects of innate DNA-sensing pathways that are activated in response to RT-induced DNA damage.

Abstract A011: Targeting the FES tyrosine kinase in antigen presenting cells to enhance anti-tumor cytotoxic lymphocyte responses

Abstract For cytotoxic lymphocytes (CTLs) to effectively kill cancer cells, inflammatory signals from antigen presenting cells (APCs) are required. Targeting the signaling pathways that regulate production of these inflammatory cytokines represents an exciting strategy to bolster CTL activation in the context of cancer immunotherapy. Achieving optimal levels of CTL activation is critical to the success of immunotherapy treatments. Compelling advancements in CTL therapies including CAR-T cells and immune checkpoint inhibitors are showing great promise for improving patient outcomes. However, enhancing the innate immune system’s ability to strengthen anti-tumor CTL immune responses has been explored to a lesser extent. We intend to fill this gap by studying the APC-intrinsic role of the non-receptor tyrosine kinase FES in regulating the production of inflammatory cytokines. The first evidence of FES’s potential immune regulating role came from observations of increased lipopolysaccharide (LPS) sensitivity in fes-null mice. A transgenic mouse model of breast cancer expressing activated HER2/Neu in the mammary glands showed delayed tumor onset in mice targeted with a fes mutation that catalytically inactivated FES; and this delay correlated with increased immune infiltration and inflammation in pre-malignant mammary tissue. Previous studies have implicated FES in the activation of the SHP-2 phosphatase in macrophages, which can suppress toll-like receptor (TLR) pathways. TLR pathways govern strong innate inflammatory responses, including the expression of the so-called signal 3 cytokines required for full CTL activation (e.g. IL-12, IFNα/β). We therefore hypothesized that disrupting FES in APCs will relieve suppression of inflammatory cytokine production pathways, leading to increased CTL activation and cancer cell cytotoxicity. To investigate the impact of FES disruption on inflammatory signaling cascades, immunoblotting analysis of proteins in these signaling pathways was conducted on LPS-stimulated fes−/− and WT mouse bone marrow derived macrophages or dendritic cells. qRT-PCR was used to measure inflammatory cytokine transcript levels, including IFNα/β, IL-12, IL-1β and TNFα. To compare the ability of WT and fes−/− macrophages to present antigen and activate CTLs, OT-1 CTLs were co-cultured with OVA-presenting WT or fes−/− macrophages; and then evaluated by flow cytometry for IFNγ production. Evidence of increased activation of downstream mediators of TLR signaling including NFκB and TBK1 were seen in fes−/− macrophages and dendritic cells post LPS stimulation. fes−/− macrophages displayed increased inflammatory cytokine mRNA production in response to LPS stimulation. Finally, CTLs showed increased IFNγ expression when co-cultured with LPS-stimulated fes−/− macrophages compared to WT macrophages, indicating a higher degree of activation by fes−/− macrophages. The immunosuppressive function of FES makes it an actionable target for improving the efficacy of cancer immunotherapies and anti-cancer adaptive immune responses. Citation Format: Natasha Dmytryk, Brian Laight, Peter Greer. Targeting the FES tyrosine kinase in antigen presenting cells to enhance anti-tumor cytotoxic lymphocyte responses [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A011.

One-Carbon Metabolites Promote Systemic Inflammation, Gut Dysbiosis, and a Myeloid Lineage Differentiation Bias

TET methylcytosine dioxygenase 2 ( TET2) loss-of-function mutations induce a pre-malignant state known as clonal hematopoiesis of indeterminate potential (CHIP). CHIP occurs in approximately 10% of people over 65 years of age and confers a 10-fold greater risk of developing hematological malignancy. Several environmental factors, including radiation, sleep deprivation, atherosclerosis, and diet, have been associated with the expansion of pre-malignant clones in CHIP patients. It has previously been shown that hematopoietic Tet2 deficiency in mice triggers a pro-inflammatory state with increased intestinal permeability, gut bacterial translocation, and accelerated clonal expansion. Gut microbes themselves can exert an influence on myeloid leukemia progression through synthesis of compounds including short-chain fatty acids (SCFAs), which promote intestinal barrier integrity. Dietary levels of one-carbon metabolites and cofactors have been found to alter gut microbial composition, affecting SCFA production and intestinal permeability, in disease-free adults. Given the connection between diet, SCFAs and gut permeability, we sought to determine the impact of dietary one-carbon metabolites on gut microbial composition and function in CHIP progression. We performed competitive bone marrow transplantation assays with Tet2+/- cells in mice supplemented with altered one-carbon metabolites: a control diet, high or low methionine diets, high or low folate diets, and high or low vitamin B12 supplementation. Mice were treated for a total of 7 months before timed sacrifice. Altered supplementation of the one carbon metabolites tested did not influence the competitiveness of Tet2-deficient cells in peripheral blood, spleen or bone marrow, however, high vitamin B12 levels promoted a myeloid differentiation bias in the spleen and bone marrow. Plasma cytokine analysis also showed that high vitamin B12 supplementation caused increased circulating inflammatory cytokines (IL-1b, IL-23, IL-27, CCL3/4, CXCL2). Based on this strong inflammatory phenotype, we performed scRNA-sequencing of splenic Tet2+/- CD11b+ cells. These data confirmed a neutrophilic cell expansion in the spleens of vitamin B12-treated mice along with increased expression of innate inflammatory genes S100a8/9 and Lyz2 as well as IL-1 b and Cxcl2 in the neutrophil clusters. Gut microbial-dependent inflammation is known to drive TET2-dependent myeloproliferation, thus we collected fecal samples before timed sacrifice and performed shotgun sequencing. Vitamin B12 supplementation decreased alpha diversity and the composition of genera that produce butyrate, an SCFA known to promote intestinal barrier integrity. Metagenomic analysis revealed increased amino acid metabolism and fatty acid biosynthesis in the gut microbiome of vitamin B12-supplemented mice, along with decreased butanoate metabolism, suggesting an alteration in microbial function that could influence SCFA content. To test whether these alterations in SCFA-producers led to increased gut permeability, we performed fluorescence in situ hybridization (FISH) against bacterial ribosomal 16S in livers from our mouse cohorts and observed increased levels of bacterial dissemination in mice with vitamin B12 supplementation. Our findings suggest that vitamin B12 supplementation in mice exacerbates the myeloid lineage differentiation bias of Tet2+/- hematopoiesis, possibly due to decreased gut barrier integrity which contributes to a heightened innate inflammatory response. This study highlights the potential for micronutrients of one-carbon metabolism to influence CHIP progression through maintenance of proper gut microbial homeostasis.