Bone Marrow Cultures Research Articles

BAFF induces CXCR5 expression during B cell differentiation in bone marrow

B cell activating factor (BAFF) plays an important role in antibody production through differentiation and maturation of B cells mainly in secondary lymphoid organs. On the other hand, the role of BAFF in the bone marrow, the primary lymphoid organ of B cell development, has not been well elucidated. Here, effects of BAFF in bone marrow B cell development were examined by using BAFF-deficient mice. When mRNA expression levels of B cell differentiation markers including Cd19, Bcl2, Igμ, Il7r and Cxcr5 were compared between bone marrow of wild-type and BAFF-KO mice, a lower level of Cxcr5 expression was found in the KO mice. Additionally, protein expression of CXCR5 on IgM+ cells in the bone marrow was decreased by BAFF deficiency. In vitro studies also confirmed the effect of BAFF on CXCR5 by IgM+ cells; culturing bone marrow cells from BAFF-KO mice with BAFF in vitro increased the proportion of CXCR5+ cells in IgM+ cells compared with non-treated bone marrow cells. In addition, BAFF synergized with TNF-α and IL-6 to increase the expression of CXCR5+ on IgM+ cells. The BAFF-mediated up-regulation of CXCR5 expression was reproduced by using CD19+ cells purified from BAFF-KO bone marrow cells, suggesting that BAFF directly affects B-lineage cells in bone marrow to promote CXCR5 expression. Together, this study suggests that BAFF has an important role in B cell differentiation in bone marrow by directly inducing CXCR5 expression which affect their migration to secondary lymphoid organs.

Mechanically conditioned multilayered angle-ply collagen scaffolds promote annulus fibrosus regeneration

Annulus fibrosus (AF) injury, as a result of intervertebral disk degeneration (IVDD) or herniation, is very difficult to heal due to its avascular characteristics. Tissue engineering strategies have become increasingly promising to treat IVDD. However, in light of the fact that AF displays an anisotropic microstructure that results in gradient mechanical properties, fabrication of tissue engineered AF remains challenging. In this study, we fabricated micropatterned collagen scaffolds with angle-ply structure mimicking the microstructural features of AF. Following that, we cultured bone marrow mesenchymal stromal cells (BMSCs) in the scaffolds and applied cyclic stretching to them to mechanically stimulate the cells. We found that aligned cells under mechanical loading showed elevated expression of matrix anabolism-related genes and proteins. Further studies indicated that Caveolin-1 (CAV1) might mediate the nuclear translocation of Yes-associated protein (YAP) in response to external mechanical cues of microgroove-patterned membranes and mechanical loading. Micropatterned collagen membranes, with cells aligning at ±30° along the longitudinal dimension, were rolled up together to form an angle-ply and multilayered tissue. After being implanted into the caudal vertebra in a rat model for 4 weeks, biomimetic tissues showed improved restoration of the disk. In general, our biomimetic collagen membranes exhibit great potential in terms of AF regeneration, with AF-like heterogeneous microstructures that satisfy the biomechanical property of the native disk.

A Novel Anti-Osteoporosis Mechanism of VK2: Interfering with Ferroptosis via AMPK/SIRT1 Pathway in Type 2 Diabetic Osteoporosis.

Type 2 diabetic osteoporosis (T2DOP) is a chronic bone metabolic disease. Compared with traditional menopausal osteoporosis, the long-term high glucose (HG) microenvironment increases patients' risk of fracture and osteonecrosis. We were accumulating evidence that implicated ferroptosis as a pivotal mechanism of glucolipotoxicity-mediated death of osteocytes and osteoblast, a novel form of programmed cell death resulting from uncontrolled lipid peroxidation depending on iron. Vitamin K2 (VK2), a fat-soluble vitamin, is clinically applied to prevent osteoporosis and improve coagulation. This study aimed to clarify the role and mechanism of VK2 in HG-mediated ferroptosis. We established the mouse T2DOP model by intraperitoneal injection of streptozotocin solution and a high-fat and high-sugar diet. We also cultured bone marrow mesenchymal stem cells (BMSCs) in HG to simulate the diabetic environment in vitro. Based on our data, VK2 inhibited HG-mediated bone loss and ferroptosis, the latter manifested by decreased levels of mitochondrial reactive oxygen species, lipid peroxidation, and malondialdehyde and increased glutathione in vitro. In addition, VK2 treatment was capable of restoring bone mass and strengthening the expression of SIRT1, GPX4, and osteogenic markers in the distal femurs. As for further mechanism exploration, we found that VK2 could activate AMPK/SIRT1 signaling, and knockdown of SIRT1 by siRNA prevented the VK2-mediated positive effect in HG-cultured BMSCs. Summarily, VK2 could ameliorate T2DOP through the activation of the AMPK/SIRT1 signaling pathway to inhibit ferroptosis.

Disseminated cryptococcal infection with pulmonary involvement presenting as diffuse cavitary nodules in an immunocompromised patient: a case report

BackgroundDisseminated cryptococcal infection is especially prone to occur in immunosuppressed hosts. We herein report the case of an immunosuppressed girl with disseminated cryptococcal infection in whom pulmonary cryptococcosis (PC) presented as diffuse cavitary pulmonary nodules, a finding which has rarely been reported.Case presentationA 16-year-old immunocompromised girl presented with fever and a non-productive cough. A chest computed tomography (CT) scan revealed diffuse pulmonary nodules with cavities. Subsequent results were consistent with disseminated cryptococcosis with Cryptococcus identified in her blood, bone marrow and cerebrospinal fluid cultures. Thus, the patient was diagnosed with disseminated cryptococcal infection with PC, cryptococcus meningitis, cryptococcus osteomyelitis and cryptococcus sepsis. After antifungal treatment, the patient demonstrated both clinical and chest radiological improvement.ConclusionThe atypical clinical manifestations of a disseminated cryptococcal infection and the rare manner of chest CT findings of PC reported in our case are easy to misdiagnose. It is necessary to carry out a thorough search for a definitive diagnosis using various methods.

Loss of N-acetylglucosaminyl transferase V is involved in the impaired osteogenic differentiation of bone marrow mesenchymal stem cells.

The imbalance of bone resorption and bone formation causes osteoporosis (OP), a common skeletal disorder. Decreased osteogenic activity was found in the bone marrow cultures from N-acetylglucosaminyl transferase V (MGAT5)-deficient mice. We hypothesized that MGAT5 was associated with osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and involved in the pathological mechanisms of osteoporosis. To test this hypothesis, the mRNA and protein expression levels of MGAT5 were determined in bone tissues of ovariectomized (OVX) mice, a well-established OP model, and the role of MGAT5 in osteogenic activity was investigated in murine BMSCs. As expected, being accompanied by the loss of bone mass density and osteogenic markers (runt-related transcription factor 2, osteocalcin and osterix), a reduced expression of MGAT5 in vertebrae and femur tissues were found in OP mice. In vitro, knockdown of Mgat5 inhibited the osteogenic differentiation potential of BMSCs, as evidenced by the decreased expressions of osteogenic markers and less alkaline phosphatase and alizarin red S staining. Mechanically, knockdown of Mgat5 suppressed the nuclear translocation of β-catenin, thereby downregulating the expressions of downstream genes c-myc and axis inhibition protein 2, which were also associated with osteogenic differentiation. In addition, Mgat5 knockdown inhibited bone morphogenetic protein (BMP)/transforming growth factor (TGF)-β signaling pathway. In conclusion, MGAT5 may modulate the osteogenic differentiation of BMSCs via the β-catenin, BMP type 2 (BMP2) and TGF-β signals and involved in the process of OP.

Hypoxia Induces M2 Macrophages to Express VSIG4 and Mediate Cardiac Fibrosis After Myocardial Infarction.

M2 macrophage-mediated tissue repair plays an important role in acute myocardial infarction (AMI). Additionally, VSIG4, which is mainly expressed on tissue-resident and M2 macrophages, is crucial for the regulation of immune homeostasis; however, its effects on AMI remain unknown. In this study, we aimed to investigate the functional significance of VSIG4 in AMI using VSIG4 knockout and adoptive bone marrow transfer chimeric models. We also determined the function of cardiac fibroblasts (CFs) through gain- or loss-of-function experiments. We showed that VSIG4 promotes scar formation and orchestrates the myocardial inflammatory response after AMI, while also promoting TGF-β1 and IL-10. Moreover, we revealed that hypoxia promotes VSIG4 expression in cultured bone marrow M2 macrophages, ultimately leading to the conversion of CFs to myofibroblasts. Our results reveal a crucial role for VSIG4 in the process of AMI in mice and provide a potential immunomodulatory therapeutic avenue for fibrosis repair after AMI.

Red Ginseng Extract and γ-Aminobutyric Acid Synergistically Enhance Immunity Against Cancer Cells and Antitumor Metastasis Activity in Mice.

The effects of combined administration of red ginseng (RG) extracts and gamma-aminobutyric acid (GABA) on immunostimulatory activity and tumor metastasis inhibition were investigated in mice. For the immunostimulatory activity, splenocyte proliferation, natural killer (NK) cell activity, including the production of granzyme B (GrB) and interferon gamma (IFN-γ), and serum level of cytokine such as IFN-γ, interleukin (IL)-17, and IL-21 were assessed. Peyer's patch cells obtained from mice administered with RG+GABA were cultured, and the cytokine level in the culture supernatant and bone marrow (BM) cell proliferation activity were examined. The proliferative activity of splenocytes was significantly higher in the RG-GABA treatment group than in RG or GABA alone (P < .05). In the experimental tumor metastasis model, oral administration of RG+GABA showed a higher antitumor metastatic effect compared to that of RG or GABA alone. Oral administration of RG+GABA significantly augmented NK cell-mediated cytotoxicity against YAC-1 tumor cells. In addition, the production of GrB and IFN-γ was stimulated in the culture supernatant of NK cells and YAC-1 cells. Serum concentrations of IFN-γ, IL-17, and IL-21 in mice with RG+GABA were significantly higher compared to the corresponding blood levels in mice administered with RG or GABA alone. The RG+GABA group showed significant BM cell proliferation and increased production of IL-6 and granulocyte-macrophage colony-stimulating factor compared to that in the monotherapy groups. Therefore, RG may have a synergistic effect with GABA for enhancing the host defense system such as BM proliferation and NK cell activity in a tumor metastasis model.

Chicken CSF2 and IL-4-, and CSF2-dependent bone marrow cultures differentiate into macrophages over time.

Chicken bone marrow-derived macrophages (BMMΦ) and dendritic cells (BMDC) are utilized as models to study the mononuclear phagocytic system (MPS). A widely used method to generate macrophages and DC in vitro is to culture bone marrow cells in the presence of colony-stimulating factor-1 (CSF1) to differentiate BMMΦ and granulocyte-macrophage-CSF (GM-CSF, CSF2) and interleukin-4 (IL-4) to differentiate BMDC, while CSF2 alone can lead to the development of granulocyte-macrophage-CSF-derived DC (GMDC). However, in chickens, the MPS cell lineages and their functions represented by these cultures are poorly understood. Here, we decipher the phenotypical, functional and transcriptional differences between chicken BMMΦ and BMDC along with examining differences in DC cultures grown in the absence of IL-4 on days 2, 4, 6 and 8 of culture. BMMΦ cultures develop into a morphologically homogenous cell population in contrast to the BMDC and GMDC cultures, which produce morphologically heterogeneous cell cultures. At a phenotypical level, all cultures contained similar cell percentages and expression levels of MHCII, CD11c and CSF1R-transgene, whilst MRC1L-B expression decreased over time in BMMΦ. All cultures were efficiently able to uptake 0.5 µm beads, but poorly phagocytosed 1 µm beads. Little difference was observed in the kinetics of phagosomal acidification across the cultures on each day of analysis. Temporal transcriptomic analysis indicated that all cultures expressed high levels of CSF3R, MERTK, SEPP1, SPI1 and TLR4, genes associated with macrophages in mammals. In contrast, low levels of FLT3, XCR1 and CAMD1, genes associated with DC, were expressed at day 2 in BMDC and GMDC after which expression levels decreased. Collectively, chicken CSF2 + IL-4- and CSF2-dependent BM cultures represent cells of the macrophage lineage rather than inducing conventional DC.

Detecting Leishmania in dogs: A hierarchical-modeling approach to investigate the performance of parasitological and qPCR-based diagnostic procedures.

Domestic dogs are primary reservoir hosts of Leishmania infantum, the agent of visceral leishmaniasis. Detecting dog infections is central to epidemiological inference, disease prevention, and veterinary practice. Error-free diagnostic procedures, however, are lacking, and the performance of those available is difficult to measure in the absence of fail-safe "reference standards". Here, we illustrate how a hierarchical-modeling approach can be used to formally account for false-negative and false-positive results when investigating the process of Leishmania detection in dogs. We studied 294 field-sampled dogs of unknown infection status from a Leishmania-endemic region. We ran 350 parasitological tests (bone-marrow microscopy and culture) and 1,016 qPCR assays (blood, bone-marrow, and eye-swab samples with amplifiable DNA). Using replicate test results and site-occupancy models, we estimated (a) clinical sensitivity for each diagnostic procedure and (b) clinical specificity for qPCRs; parasitological tests were assumed 100% specific. Initial modeling revealed qPCR specificity < 94%; we tracked the source of this unexpected result to some qPCR plates having subtle signs of possible contamination. Using multi-model inference, we formally accounted for suspected plate contamination and estimated qPCR sensitivity at 49-53% across sample types and dog clinical conditions; qPCR specificity was high (95-96%), but fell to 81-82% for assays run in plates with suspected contamination. The sensitivity of parasitological procedures was low (~12-13%), but increased to ~33% (with substantial uncertainty) for bone-marrow culture in seriously-diseased dogs. Leishmania-infection frequency estimates (~49-50% across clinical conditions) were lower than observed (~60%). We provide statistical estimates of key performance parameters for five diagnostic procedures used to detect Leishmania in dogs. Low clinical sensitivies likely reflect the absence of Leishmania parasites/DNA in perhaps ~50-70% of samples drawn from infected dogs. Although qPCR performance was similar across sample types, non-invasive eye-swabs were overall less likely to contain amplifiable DNA. Finally, modeling was instrumental to discovering (and formally accounting for) possible qPCR-plate contamination; even with stringent negative/blank-control scoring, ~4-5% of positive qPCRs were most likely false-positives. This work shows, in sum, how hierarchical site-occupancy models can sharpen our understanding of the problem of diagnosing host infections with hard-to-detect pathogens including Leishmania.

Disseminated Mycobacterium chimaera infection favoring the development of Kaposi's sarcoma: a case report.

Disseminated Mycobacterium chimaera infection is an emerging disease in people undergone to cardiothoracic surgery, which need to be suspected also with atypical presentations. We report the case of a 74-year-old man with fever of unknown origin, purple nodules on both feet and a history of open-heart surgery. Imaging investigations showed an abscess near aortic bioprosthesis but screening for endocarditis resulted negative and pyrexia did not respond to antibiotic therapy. A biopsy of cutaneous lesions showed HHV8-related Kaposi's sarcoma, so bone marrow biopsy was executed with evidence of HHV8 localization. Bone marrow and urine mycobacterial cultures resulted positive for M. chimaera and a specific antimicrobial therapy was started, with apyrexia after 7 weeks. M. chimaera infection should be always investigated as a possible etiology of fever of unknow origin in people with a history of open-heart surgical intervention, even with negative mycobacterial blood cultures. The possible role of disseminated infection in inducing immunodepression with the occurrence of other opportunistic diseases (such as Kaposi's sarcoma) cannot be excluded.

Retinol-Loaded Poly(vinyl alcohol)-Based Hydrogels as Suitable Biomaterials with Antimicrobial Properties for the Proliferation of Mesenchymal Stem Cells

Polyvinyl alcohol (PVA) hydrogels are well-known biomimetic 3D systems for mammalian cell cultures to mimic native tissues. Recently, several biomolecules were intended for use in PVA hydrogels to improve their biological properties. However, retinol, an important biomolecule, has not been combined with a PVA hydrogel for culturing bone marrow mesenchymal stem (BMMS) cells. Thus, for the first time, the effect of retinol on the physicochemical, antimicrobial, and cell proliferative properties of a PVA hydrogel was investigated. The ability of protein (3.15 nm) and mineral adsorption (4.8 mg/mL) of a PVA hydrogel was improved by 0.5 wt.% retinol. The antimicrobial effect of hydrogel was more significant in S. aureus (39.3 mm) than in E. coli (14.6 mm), and the effect was improved by increasing the retinol concentration. The BMMS cell proliferation was more upregulated in retinol-loaded PVA hydrogel than in the control at 7 days. We demonstrate that the respective in vitro degradation rate of retinol-loaded PVA hydrogels (RPH) (75-78% degradation) may promote both antibacterial and cellular proliferation. Interestingly, the incorporation of retinol did not affect the cell-loading capacity of PVA hydrogel. Accordingly, the fabricated PVA retinol hydrogel proved its compatibility in a stem cell culture and could be a potential biomaterial for tissue regeneration.

Inhibiting the biogenesis of myeloid-derived suppressor cells enhances immunotherapy efficacy against mammary tumor progression.

While immune checkpoint inhibitors (ICIs) have transformed the therapeutic landscape in oncology, they are effective in select subsets of patients. Efficacy may be limited by tumor-driven immune suppression, of which 1 key mechanism is the development of myeloid-derived suppressor cells (MDSCs). A fundamental gap in MDSC therapeutics is the lack of approaches that target MDSC biogenesis. We hypothesized that targeting MDSC biogenesis would mitigate MDSC burden and bolster tumor responses to ICIs. We tested a class of agents, dihydroorotate dehydrogenase (DHODH) inhibitors, that have been previously shown to restore the terminal differentiation of leukemic myeloid progenitors. DHODH inhibitors have demonstrated preclinical safety and are under clinical study for hematologic malignancies. Using mouse models of mammary cancer that elicit robust MDSC responses, we demonstrated that the DHODH inhibitor brequinar (a) suppressed MDSC production from early-stage myeloid progenitors, which was accompanied by enhanced myeloid maturation; (b) augmented the antitumor and antimetastatic activities of programmed cell death 1-based (PD-1-based) ICI therapy in ICI-resistant mammary cancer models; and (c) acted in concert with PD-1 blockade through modulation of MDSC and CD8+ T cell responses. Moreover, brequinar facilitated myeloid maturation and inhibited immune-suppressive features in human bone marrow culture systems. These findings advance the concept of MDSC differentiation therapy in immuno-oncology.

Comparative Analysis of Commercially Available Typhoid Point-of-Care Tests: Results of a Prospective and Hybrid Retrospective Multicenter Diagnostic Accuracy Study in Kenya and Pakistan.

Blood and bone marrow cultures are considered the gold standard for the diagnosis of typhoid, but these methods require infrastructure and skilled staff that are not always available in low- and middle-income countries where typhoid is endemic. The objective of the study is to evaluate the sensitivity and specificity of nine commercially available Salmonella Typhi rapid diagnostic tests (RDTs) using blood culture as a reference standard in a multicenter study. This was a prospective and retrospective multicenter diagnostic accuracy study conducted in two geographically distant areas where typhoid is endemic (Pakistan and Kenya; NCT04801602). Nine RDTs were evaluated, including the Widal test. Point estimates for sensitivity and specificity were calculated using the Wilson method. Latent class analyses were performed using R to address the imperfect gold standard. A total of 531 serum samples were evaluated (264 blood culture positive; 267 blood culture negative). The sensitivity of RDTs varied widely (range, 0 to 78.8%), with the best overall performance shown by Enterocheck WB (72.7% sensitivity, 86.5% specificity). In latent class modeling, CTK IgG was found to have the highest sensitivity (79.1%), while the highest overall accuracy was observed with Enterocheck (73.8% sensitivity, 94.5% specificity). All commercially available Salmonella Typhi RDTs evaluated in the study had sensitivity and specificity values that fell below the required levels to be recommended for an accurate diagnosis. There were minimal differences in RDT performances between regions of endemicity. These findings highlight the clear need for new and more-accurate Salmonella Typhi tests.

Treatment of enteric fever (typhoid and paratyphoid fever) with cephalosporins.

Treatment of enteric fever (typhoid and paratyphoid fever) with cephalosporins.

Human brucellosis and fever of unknown origin

BackgroundHuman brucellosis has become one of the major public health problems in China, and increases atypical manifestations, such as fever of unknown origin (FUO), and misdiagnosis rates has complicated the diagnosis of brucellosis. To date, no relevant study on the relationship between brucellosis and FUO has been conducted.MethodsWe retrospectively reviewed the medical charts of 35 patients with confirmed human brucellosis and prospectively recorded their outcomes by telephone interview. The patients were admitted to the Second Affiliated Hospital of Nanchang University between January 01, 2013 and October 31, 2019. Patient data were collected from hospital medical records.ResultsThe percentage of males was significantly higher than that of female in FUO (78.95% vs. 21.05%, P < 0.05), and 80% of the patients had a clear history of exposure to cattle and sheep. Moreover, 19 (54%) cases were hospitalized with FUO, among which the patients with epidemiological histories were significantly more than those without (P < 0.05). The incidence of toxic hepatitis in FUO patients was higher than that in non-FUO patients (89% vs. 50%, P < 0.05). Meanwhile, the misdiagnosis rate was considerably higher in the FUO group than in the non-FUO group (100% vs. 63%; P < 0.05).ConclusionBrucellosis is predominantly FUO admission in a non-endemic area of China, accompanied by irregular fever and toxic hepatitis. Careful examination of the epidemiological history and timely improvement of blood and bone marrow cultures can facilitate early diagnosis and prevent misdiagnosis.

Preclinical Characterization of NGM936, a Novel Bispecific T Cell Engager Targeting ILT3 for the Treatment of Acute Myeloid Leukemia with Monocytic Differentiation

Acute myeloid leukemia (AML) with monocytic differentiation [M4 and M5 AML per the French-American-British (FAB) classification] accounts for 25-30% of all AML cases and has a particularly poor prognosis, with a <15% five-year overall survival rate and an increased risk of bone marrow and extramedullary relapse after stem cell transplant compared with other AML subtypes. The use of T cell engagers in AML has been limited by the lack of suitable target antigens with high specificity for AML cells and minimal expression on healthy bone marrow progenitors. Immunoglobulin-like transcript 3 (ILT3, also known as LILRB4) is a highly specific marker of AML with monocytic differentiation and is not expressed on non-monocytic blood cells or hematopoietic progenitor cells. This highly restricted expression profile makes ILT3 a promising target for monocytic AML, with the potential to enable effective elimination of AML cells with less toxicity than current therapies. Here, we report the pre-clinical characterization of NGM936, an ILT3-based T cell engager for the treatment of monocytic AML and other ILT3+ hematologic malignancies. NGM936 is a monovalent scFv-Fab bispecific on an effectorless human IgG1 backbone (LALA) with a knob-in-hole Fc design for heterodimeric assembly. NGM936 demonstrates sub-nM affinity towards ILT3 of human origin (KD = 0.2 nM at 25°C by surface plasmon resonance) and is not cross-reactive towards other LILRA/B family members. A panel of more than 30 ILT3 x CD3 engagers in various formats was generated and screened in assays to measure both T cell-dependent cytotoxicity and cytokine release. NGM936 was identified for its ability to potently induce T cell-dependent cytotoxicity (TDCC) against ILT3+ AML cells while inducing minimal cytokine release. In both whole blood cytokine release assays and in TDCC assays in which cytokine secretion was measured after target engagement, induction of TNF-α, IL-6, IFN-γ, and IL-2 by NGM936 was considerably lower than that induced by a vibecotamab biosimilar (CD123 x CD3). NGM936 induced potent cytotoxicity when both expanded and naïve T cells were used as effectors. Importantly, NGM936 efficiently ablated tumor cells with a range of ILT3 expression, from ~1500 copies/cell to ~40,000 copies/cell. In addition, NGM936 failed to induce T cell-dependent cytotoxicity against CD34+ hematopoietic stem cells or non-monocytic immune cells, consistent with the lack of ILT3 expression on these cell types. In ex vivo cultures of primary M5 AML bone marrow, NGM936 induced a dose-dependent depletion of AML cells and a concordant increase in T cell proliferation and activation. Finally, NGM936 induced a dose-dependent depletion of circulating tumor cells in a xenograft model in which irradiated, immunodeficient NSG mice were engrafted with human PBMCs and human ILT3+ AML cells. NGM936 thus represents a promising new treatment strategy for monocytic AML, with the potential to eliminate monocytic leukemia cells while minimizing the myelotoxicity associated with ablation of healthy bone marrow.

RF07 | PSUN350 Estradiol Effects on Polymorphonuclear Cell Production and Actions Contribute to Estrogen-mediated Lymphangioleiomyomatosis (LAM) Progression

Abstract Lymphangioleiomyomatosis (LAM) is a rare lung disease seen almost exclusively in female sexed individuals and characterized by slowly growing, metastatic smooth muscle cell-like adenomas that cause cyst formation in the lung parenchyma and irreversible loss of pulmonary function. Given the female specificity of disease manifestation, metastatic nature, and estrogen sensitivity of LAM cells, we previously proposed that LAM cells originate in the myometrium. Our subsequent reports showed that inactivation of TSC2 in the mouse uterus results in notable LAM features in the setting of primary myometrial tumors. Additionally, we established that estrogen is required to maintain LAM-like tumor progression in a uterine-specific Tsc2-knockout murine model. However, the observed estrogen sensitivity in vivo is more markedly pronounced than that of our estrogen receptor-positive TSC2-null cells when stimulated with estradiol in vitro, suggesting that estradiol may act elsewhere in vivo to promote LAM progression. Recent immunophenotyping of LAM-like TSC2-null uterine tumors revealed preferential increase in polymorphonuclear cell (PMNs) numbers of the tumor microenvironment; we also determined that PMNs are important regulators of tumor growth. Therefore, we hypothesize that, in addition to direct effects of estrogen on tumor cells, estrogen might also stimulate tumor growth by promoting PMN production in the bone marrow and actions in the tumor microenvironment. Here, we show that estrogen availability influences PMN mobilization in naïve and tumor-burdened mice. Using bone marrow cultures and CFC assay, we demonstrate that estradiol is a potent inducer of PMN production in chronic inflammatory conditions. Employing both pharmacologic agents and estrogen receptor (ER)-null bone marrow, we showed that ERα is necessary for promoting induction of PMN fate for myeloid progenitors. While we see that the migratory, invasive, and proliferative capacities of TSC2-null cell lines are not augmented when stimulated with E2 directly, experiments are underway to assess the extent to which estrogen promotes the pro-tumorigenic function of PMNs co-cultured with TSC2-null cell lines. Together these data provide insight into the robust effect of in vivo estrogen stimulation as estradiol may be a dual effector in LAM tumor progression and great target for anti-LAM therapeutic strategy. Presentation: Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

An improved method about culture and identification of primary rat bone marrow derived mesenchymal stem cells

目的: 改良原代大鼠骨髓间充质干细胞(BMSCs)的分离培养方法。方法: 基于“干细胞生态位”原理,采用全骨髓贴壁法结合骨片消化法分离培养原代大鼠BMSCs。通过细胞形态学观察、细胞表面标志物CD分子检测以及定向诱导分化实验对目的细胞进行鉴定。结果: 所培养的细胞形态为细长梭形,其融合后呈典型的“涡旋状”紧密排列,且细胞增殖迅速,原代培养5～6 d即可达到融合状态,按1∶3比例连续传代到第8代时,细胞形态仍基本保持不变;第4代细胞的间充质干细胞表面标志物CD90、CD29、CD73以及造血干细胞表面标志物CD45、CD34、CD11b/c的阳性表达率分别为89.0％、98.3％、64.2％、3.5％、5.6％、 24.7％;定向诱导分化实验表明目的细胞具有良好的成脂、成骨分化潜能。结论: 本研究基于“干细胞生态位”原理,成功建立了一种高效稳定的原代大鼠BMSCs分离培养方法。.

Isolating and targeting a highly active, stochastic dendritic cell subpopulation for improved immune responses.

Dendritic cell (DC) activation via pathogen-associated molecular patterns (PAMPs) is critical for antigen presentation and development of adaptive immune responses, but the stochastic distribution of DC responses to PAMP signaling, especially during the initial stages of immune activation, is poorly understood. In this study, we isolate a unique DC subpopulation via preferential phagocytosis of microparticles (MPs) and characterize this subpopulation of "first responders" (FRs). We present results that show these cells (1) can be isolated and studied via both increased accumulation of the micron-sized particles and combinations of cell surface markers, (2) show increased responses to PAMPs, (3) facilitate adaptive immune responses by providing the initial paracrine signaling, and (4) can be selectively targeted by vaccines to modulate both antibody and Tcell responses invivo. This study presents insights into a temporally controlled, distinctive cell population that influences downstream immune responses. Furthermore, it demonstrates potential for improving vaccine designs via FR targeting.

CT-296 Isolated Bone Marrow Infiltration by Streptococcus Pneumoniae: An Unusual Etiology of Fever of Unknown Origin

Fever of unknown origin (FUO) in adults is defined as a temperature >38.3°C lasting for more than 3 weeks with no obvious source despite appropriate investigation. The differential diagnoses are infections, malignancies, autoimmune conditions, and miscellaneous. To our knowledge, isolated bone marrow infiltration by Streptococcus pneumoniae without bacteremia has not been reported yet in the literature. We report the case of a 48-year-old female patient, previously healthy, who presented for persistent fever of one-week duration. Initially, she complained of a 39°C fever without other associated symptoms except for daily night sweats. A complete infectious workup, including a full-body CT scan and screening for fungal or bacterial etiologies, was negative. Additionally, both transthoracic and transesophageal echocardiograms eliminated any signs of endocarditis. Subsequently, over the next two weeks, a complete autoimmune workup to test for a possible underlying rheumatologic disease was done but was all negative. To complete the endless FUO workup and in view of high suspicion of a malignancy, the patient performed an (FDG) PET CT scan along with a bone marrow biopsy that were both negative for any signs of malignancy, thus excluding any lymphoproliferative disease. One month after persistent fever, pan-cultures were serially repeated and remained negative. After developing a grade I thrombocytopenia, bone marrow aspirate with bone marrow culture were performed: no signs of malignancy or infiltration were found on the medullogram, but surprisingly, and after 48 hours of incubation, the bone marrow cultures turned positive for multi-sensitive Streptococcus pneumonia. We treated the patient with intramuscular ceftriaxone for an empirical period of 2 weeks. After only 3 doses of ceftriaxone, the fever subsided and the night sweats started to decrease gradually. After receiving a total of 14 days of antibiotics, we only monitored the patient clinically, without repeating the bone marrow cultures. Clinicians must be aware of this rare and unusual etiology of FUO. Bone marrow studies are routinely performed to exclude any lymphoproliferative disorder. In this perspective, we could draw a bone marrow culture while performing the regular aspiration studies to exclude possible isolated bone marrow infiltration by bacterial microorganisms.