Splenic CD4 Research Articles

Rebalancing Immune Interactions within the Brain-Spleen Axis Mitigates Neuroinflammation in an Aging Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common cause of dementia worldwide, characterized by accumulation of amyloid-β protein and hyperphosphorylated tau protein in the brain. Neuroinflammation, resulting from chronic activation of brain-resident innate immune cells as well as enhanced peripheral leukocyte access across the blood–brain barrier, crucially affects AD progression. In this context, TNFSF10, a cytokine substantially expressed in the AD brain, has been shown to modulate both the innate and the adaptive branches of the immune response in AD-related neuroinflammation. In this study, we explored whether a TNFSF10-neutralizing treatment could represent a tool to re-balance the overall overshooting inflammatory response in a mouse model of AD. Specifically, 3xTg-AD mice were treated sub-chronically with an anti-TNFSF10 monoclonal antibody for three months, and were then sacrificed at 15 months. TNFSF10 neutralization reduced the expression of the inflammatory marker CD86, inversely related to levels of the anti-inflammatory marker CD206 in the brain of 3xTg-AD mice, suggesting a switch of microglia towards a neuroprotective phenotype. Similar results were observed in the splenic macrophage population. Moreover, flow cytometry revealed a significant decrease of CD4+CD25+FOXP3+ T regulatory cells as well as reduced number of CD11b+LY6Chigh proinflammatory monocytes in both the brain and the spleen of 3xTg-AD mice treated with anti-TNFSF10 monoclonal antibody. Finally, the treatment resulted in lower count of splenic CD4+ and CD8+ T cells expressing PD1. The data suggest that TNFSF10 system-targeted treatment effectively restrain overshooting central and peripheral inflammation by rebalancing the overall immune response, mitigating the progression of AD pathology. Graphical

High glucose/ChREBP-induced Hif-1α transcriptional activation in CD4+ T cells reduces the risk of diabetic kidney disease by inhibiting the Th1 response.

Diabetic kidney disease (DKD) features intrarenal inflammation, in which T cells play a part. Hypoxia-inducible factor-1α (HIF-1α), a key transcription factor regulating cellular responses to hypoxia, is reportedly involved in the course of inflammation. The role of HIF-1α in DKD has been investigated, but the conclusions are controversial so far. We report a previously unrecognised high glucose/carbohydrate response element binding protein (ChREBP)/Hif-1α transcription axis in CD4+ T cells. Lck-Cre+Hif1aloxp/loxp (Hif-1α-/-) mice were generated to explore the role of T cell HIF-1α in the pathogenesis of DKD. CD4+ T cells sorted from T cell-specific Hif-1α-ablated mice and wild-type mice were used for functional studies and transcriptional profiling. In this study, we used Lck-Cre transgenic mice to specifically disrupt Hif-1α in T cells and found that ablation of Hif-1α greatly accelerated the progression of DKD in a streptozocin-induced model of diabetes. Adoptive transfer of splenic CD4+ T cells from Hif-1α-/- mice rather than wild-type controls to diabetic mice elicited severe renal damage. Compared with wild-type controls, Hif-1α knockout markedly promoted IFN-γ secretion by CD4+ T cells in response to high glucose. Additional Ifn-γ ablation negated the effect of Hif-1α knockout on DKD progression. Mechanistically, the background Hif-1α mRNA synthesis rate in resting T cells was very low, but culture of T cells under high glucose led to significantly promoted Hif-1α expression, which was dependent on the transcription factor ChREBP. Consistent with results from Hif-1α-/- CD4+ T cells, adoptive transfer of Chrebp-/- CD4+ T cells to wild-type diabetic mice also elicited severe diabetic renal damage. By contrast, Chrebp-/-Ifn-γ-/- CD4+ T cells failed to show nephrotoxic effects. Examination of the Hif-1α promoter identified a ChREBP-binding sequence that mediated transcriptional upregulation of Hif-1α by high glucose. Our study reveals a previously unrecognised high glucose/ChREBP/Hif-1α transcription axis in CD4+ T cells, which serves as a self-protection mechanism against DKD progression via limiting T helper 1 response.

Abstract B004: TIGIT blockade synergizes with PD-1 blockade and radiation therapy to enhance antitumor T-cell responses in breast cancer

Abstract Background: The study aims to investigate the role of TIGIT in immunosuppressive environment and evaluates the potential of TIGIT blockade (αTIGIT) to improve antitumor immune responses. Methods: We analyzed public transcriptomic data to identify the expression patterns of TIGIT on T cells in breast cancer and its prognostic impact. In addition, a murine TNBC model was utilized to evaluate the effects of PD-1 blockade (αPD-1), local RT, and αTIGIT. T cells in tumors, tumor-draining lymph nodes (TdLNs), and the spleen were analyzed to assess the antitumor immune responses upon the treatments. Results: The analysis revealed that TIGIT is predominantly expressed on T cells within breast cancer, and the expression of TIGIT was associated with poor outcomes in TNBC patients. In the murine model, the combination of αPD-1 and RT increased TIGIT+CD226+CD8+ TILs, which are crucial for the efficacy of αTIGIT. Adding αTIGIT to αPD-1 and RT (αPD-1/RT) resulted in a synergistic antitumor effect, characterized by increased infiltration of CD8+ TILs in both irradiated and nonirradiated tumors. The triple combination therapy (TCT) also resulted in a less exhausted phenotype among CD8+ TILs and increased the proliferation of splenic CD8+ T cells. Moreover, αTIGIT significantly reduced Tregs in tumors, TdLNs, and the spleen when combined with αPD-1/RT. Conclusion: αTIGIT exhibits synergistic effects when added to αPD-1/RT by increasing the infiltration and activation of CD8+ TILs while reducing Tregs. The study suggests that αTIGIT could be an effective strategy to enhance the antitumor efficacy of αPD-1 and RT in TNBC. Citation Format: Seongmin Kim, Seung Hyuck Jeon, Yoomin Kim, Nawon Park, In Ah Kim. TIGIT blockade synergizes with PD-1 blockade and radiation therapy to enhance antitumor T-cell responses in breast cancer. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr B004.

The PPAR-α selective agonist WY14643 improves lupus nephritis via the downregulation of the RORγT/STAT3 signaling pathway in MRL/lpr mice.

Systemic lupus erythematosus (SLE) is a classic autoimmune disorder that mostly affects young women and involves various organs, such as the skin, joints, central nervous system, and kidneys. WY14643, a selective agonist of peroxisome proliferator-activated receptor-α, has previously shown anti-inflammatory effects in various disease models. However, its effects on lupus nephritis are yet to be explored. Therefore, the efficacy of WY14643 on renal biomarkers and lupus nephritis was assessed in MRL/lpr mice. Flow cytometry was used to examinethe effects of WY14643 on the expression of IL-17A, STAT3, RORγT, IL-21, IL-21R, IL-22, and TNF-α in splenic CD4+ T cells. We further investigated the impact of WY14643 on the mRNA expression of IL-17A, STAT3, RORγT, IL-21, IL-21R, IL-22, and TNF-α in kidney tissue via RT-PCR analysis. The administration of WY14643 effectively improved the symptoms of lupus nephritis in MRL/lpr mice. The administration of WY14643 decreased serum albumin, urine protein, serum creatinine, and blood urea nitrogen levels in MRL/lpr mice. WY14643 reduced the levels of inflammatory markers, including CD4+IL-17A+, CD4+STAT3+, CD4+RORγT+, CD4+IL-21+, CD4+IL-21R+, CD4+IL-22+, and CD4+TNF-α+, in the spleen cells of MRL/lpr mice. Additionally, we discovered that the administration of WY14643 resulted in the suppression of mRNA levels of IL-17A, STAT3, RORγT, IL-21, IL-22, and TNF-α. The current work shows that the suppression of inflammatory cells by WY14643 may effectively reduce autoimmune characteristics, such as renal inflammation, in lupus-prone MRL/lpr mice. Therefore, WY14643, being a specific PPAR-α agonist, shows significant potential as a novel therapeutic option for treatingnephritis associated with SLE, offering hope for future treatments in this challenging field.

Combined injection of pristane and Bacillus Calmette-Guerin Vaccine successfully establishes a lupus model with atherosclerosis.

Cardiovascular disease (CVD) induced by atherosclerosis (AS) is the main fatal complication of systemic lupus erythematosus (SLE). Establishing an appropriate animal model of SLE with AS is of great value for investigating the pathogenesis and therapeutic targets of SLE-CVD. In the present work, pristane was injected intraperitoneally into C57BL/6J mice to establish the SLE model and Bacillus Calmette-Guerin Vaccine (BCG) was injected intradermally one month later to enhance immunity and induce AS. Both pristane or pristane and BCG treated C57BL/6J mice exhibit a classical lupus-like phenotype which manifested as proteinuria and high levels of serum anti-ANA and anti-dsDNA autoantibodies, in conjunction with pathological changes in spleen and kidney, complement C3 deposition in the kidney, overactivation of T and B cells, a decreased proportion of splenic CD19+ B cells, and an increased frequency of CD19-CD138+ plasma cells, CD19+CD27+ memory B cells, CD3+CD4+ helper T (Th) cells, and CD3+CD4+CXCR5+PD-1+ T follicular helper cells. The combined pristane and BCG challenge aggravated AS in SLE mice, which had an enlarged thymus gland, an increased T cell proliferative vitality, an expanded Th cell pool, severe perivascular lymphocytes, and CD68+ macrophage infiltration, in addition to an intimal lipid deposition, and further elevation of Toll-like receptor 2 (TLR2), TLR4, and the transcription factor nuclear factor-κB (NF-κB) expression in kidney tissue and blood vessels when comparing with pristane or BCG injection alone. Pristane combined BCG challenge is able to establish a validated SLE-AS mouse model in C57BL/6J mice.

HDAC3 inhibitors induce drug resistance by promoting IL-17 A production by T cells

HDAC3 has been demonstrated to play a crucial role in the progression of various tumors and the differentiation and development of T cells. However, its impact on peripheral T cells in the development of murine lung cancer remains unclear. In this experiment, a subcutaneous lung tumor model was established in C57BL/6 mice, and tumor-bearing mice were treated with the specific inhibitor of HDAC3, RGFP966, at different doses to observe changes in tumor size. Additionally, a lung tumor model was established using hdac3fl/flcd4cre+/+ mice to investigate its mechanism. Mice injected with 10 mg/kg RGFP966 had the smallest tumor volume, while those injected with 30 mg/kg RGFP966 had the largest tumors. Flow cytometry analysis revealed that the expression of HDAC3 in splenic T cells was reduced in all groups of mice, while IFN-γ and IL-17 A were increased. Moreover, the expression of granzyme B and perforin in splenic CD8+ T cells was increased in all groups of mice. Compared to the use of 30 mg/kg RGFP966 alone, the combination with anti-IL-17 A mAb reduced the infiltration of Neutrophils and exhausted T cells in mouse tumors, thereby impeding tumor development. These findings demonstrate that the use of RGFP966 or T cell-specific loss of hdac3 promotes the expression of IL-17 A in splenic T cells, leading to tumor resistance and providing insights for clinical treatment.

The Pro-inflammatory Functions of Type 1 CD 8+ T Cells and Interleukin-17-producing Cluster of Differentiation 8+ T Cells are Exhausted by Cholesterol in Atherosclerosis.

CD8+ T cells have been found to accumulate in atherosclerotic plaques. However, the specific role of CD8+ T cell subsets in the development of atherosclerosis is still not fully understood. To investigate the presence and functions of type 1 CD8+ T (Tc1) cells and interleukin-17 (IL-17)-producing CD8+ T (Tc17) cells. Apolipoprotein E-deficient mice were fed a high-fat diet to induce atherosclerosis. Flow cytometry was used to identify and isolate aortic CD8+ T cell subsets, which were then cultured in vitro to assess their pro-inflammatory activities. The cholesterol content of the CD8+ T cell subsets was quantified. T-box expressed in T cells (T-bet)+ Tc1 cells and retinoic acid-related orphan receptor gamma t (RORγt)+ Tc17 cells were found in the atherosclerotic aorta. Aortic CD8+ T cells showed lower pro-inflammatory activity compared to splenic counterparts, with less interferon-gamma (IFN-γ) (P <0.01) and tumor necrosis factor-alpha (TNF-α) production (P <0.01). Surprisingly, aortic CD8+ T cells expressed little IL-17 and interleukin-21 (IL-21) despite the presence of Tc17 cells. Aortic Tc1 and Tc17 cells expressed high levels of 2B4 and programmed cell death protein 1 (PD-1). Furthermore, aortic Tc1 and Tc17 cells had higher cholesterol contents than splenic CD8+ T cells (P <0.05, respectively). Cholesterol treatment decreased IFN-γ expression in Tc1 cells (P <0.001) and reduced IL-17 expression in Tc17 cells (P <0.001). Additionally, cholesterol up-regulated 2B4 and PD-1 on Tc1 (P <0.001) and Tc17 cells (P <0.001). Aortic CD8+ T cells, particularly aortic Tc17 cells, are functionally exhausted in atherosclerosis, possibly due to the influence of cholesterol.

Deficiencies of Inducible Costimulator (ICOS) During Chronic Infection with Toxoplasma gondii Upregulate the CD28-Dependent Cytotoxicity of CD8+ T Cells and Their Effector Function Against Tissue Cysts of the Parasite.

We recently identified that the cerebral mRNA expression of inducible costimulator (ICOS) and its ligand, ICOSL, both significantly increase during the elimination of Toxoplasma gondii cysts from the brains of infected mice by the perforin-mediated cytotoxic activity of CD8+ T cells. In the present study, we examined the role of ICOS in activating the effector activity of CD8+ T cells in response to the presence of cysts in infected mice. Following the adoptive transfer of splenic CD8+ T cells from chronically infected ICOS-deficient (ICOS-/-) and wild-type (WT) mice to infected SCID mice, fewer CD8+ T cells were detected in the brains of the recipients of ICOS-/- CD8+ T cells than the recipients of WT CD8+ T cells. Interestingly, even with the lower migration rate of the ICOS-/- CD8+ T cells, those T cells eliminated T. gondii cysts more efficiently than WT CD8+ T cells did in the brains of the recipient mice. Consistently, the ICOS-/- CD8+ T cells secreted greater amounts of granzyme B in response to T. gondii antigens in vitro than WT CD8+ T cells did. We identified that CD8+ T cells of infected ICOS-/- mice express significantly greater levels of CD28 on their surface than CD8+ T cells of infected WT mice, and the relative expression of CD28 mRNA to CD8β mRNA levels in the brains of the recipients of those CD8+ T cells were strongly correlated with their relative expression levels of mRNA for T-bet transcription factors and perforin. Furthermore, blocking CD28 signaling using a combination of anti-CD80 and anti-CD86 antibodies eliminated the increased cytotoxic activity of the ICOS-/- CD8+ T cells in vitro. The present study uncovered notable compensatory interactions between ICOS and CD28, which protected the cytotoxic effector activity of CD8+ T cells against microbial infection in a murine model of chronic infection with T. gondii.

MHC class I upregulation contributes to the therapeutic response to radiotherapy in combination with anti-PD-L1/anti-TGF-β in squamous cell carcinomas with enhanced CD8 T cell memory-driven response

Radiation therapy (RT), a mainstay treatment for head and neck squamous cell carcinoma (HNSCC), kills cancer cells and modulates the tumor immune microenvironment. We sought to assess the effect of RT in combination with PD-L1/TGF-β dual blockade in squamous cell carcinomas (SCC) and analyze the underlying mechanisms. We transplanted mouse SCC cells derived from keratin-15 (K15) stem cells harboring KrasG12D/Smad4−/− mutations into syngeneic recipients and irradiated tumors followed by PD-L1/TGF-β dual blockade. We identified a responder line and a non-responder line to this combination therapy. Responder hosts eradicated SCCs by the combined therapy and rejected re-transplanted SCC cells 6 months post tumor eradication, which correlated with clonotype expansions of splenic CD8 T cells and effector memory gene expression identified by single cell sequencing of TCR and transcriptomes, respectively. Mechanistically, RT upregulated MHC-I (major histocompatibility complex I) and its transcriptional regulators including NLRC5, in SCCs of the responders but not non-responders. These data are consistent with the TCGA HNSCC database in which NLRC5 correlated to MHC-I genes and CD8 T cell gene expression. Functional contribution of MHC-I to PD-L1/TGF-β blockade response was confirmed by knocking out beta-2-microglobulin in responder cells that attenuated the response to the same therapy. Thus, the therapeutic effectiveness appeared to largely depend on cancer-cell MHC-I expression, triggering CD8 T cell effector memory-driven responses against tumor cell antigens. Identifying the differential RT response to MHC-I induction may serve as a predictive marker for stratifying patients that are most likely to benefit from this combination therapy.

Biofabricated zinc oxide nanoparticles mitigate acrylamide-induced immune toxicity and modulate immune-related genes and microRNA in rats.

This study evaluated the potential efficacy of eco-friendly biofabricated zinc oxide nanoparticles (GS-ZnONP) (10mg/kg b.wt) to reduce the impacts of long-term oral acrylamide (ALD) exposure (20mg/kg b.wt) on the blood cells, immune components, splenic oxidative status, and expression of CD20, CD3, CD4, CD8, TNF-α, caspase-3, microRNA-181a-5p, and microRNA-125-5p in rats in a 60-day experiment. The study findings revealed that GS-ZnONP significantly corrected the ALD-induced hematological alterations. Additionally, the ALD-induced increase in the serum C3, splenic ROS, CD4, CD8, and MDA and histological alterations were significantly repressed in the ALD + GS-ZnONP-treated rats. Instead, the depleted splenic antioxidants and Zn contents were markedly reestablished in the ALD + GS-ZnONP-treated group. Additionally, a significant upregulation of expression of splenic CD3, CD4, CD8,CD20, TNF-α, and caspase-3, but downregulation of microRNA-181a-5p and microRNA-125-5p was detected in the ALD-exposed group. Yet, the former deviations in the gene expressions were corrected in the ALD + GS-ZnONP-treated rats. Furthermore, GS-ZnONP treatment significantly minimized the increased caspase-3 and TNF-α immunoexpression in the splenic tissues of ALD-exposed rats. Conclusively, the study findings proved the efficacy of GS-ZnONP in rescuing ALD-induced disturbances in blood cell populations, immune function, splenic antioxidant status, and immune-related gene expression.

Protective efficacy of a recombinant adenovirus expressing novel dual F and HN proteins of bovine parainfluenza virus type 3

Bovine parainfluenza virus type 3 (BPIV3) is a viral respiratory pathogen that infects cattle and causes significant economic losses. We generated a recombinant adenovirus called rHAd5-F + HN by expressing the fusion (F) and hemagglutinin-neuraminidase (HN) glycoprotein of BPIV3 using the human adenovirus serotype 5 (rHAd5). We evaluated its effects on humoral and cellular immune responses in mice (n = 45) and calves (n = 9). Serum antibody responses were assessed by enzyme-linked immunosorbent assay (ELISA), hemagglutination inhibition (HI), and neutralising antibodies (NAb). After boosting immunity with rHAd5-F + HN, mice produced significantly higher levels of antibodies against the BPIV3 genotype A and genotype C strains. The production of antibodies exceeded those produced by adenoviruses rHAd5-F and rHAd5-HN, which express the F and HN glycoprotein, respectively. The percentages of splenic CD3+/CD8+T lymphocytes and IL-4+ cytokines in rHAd5-F + HN mice were considerably higher than those in the control group. Mice immunised with rHAd5-F + HN exhibited much lower viral loads in the lungs and tracheas compared to the control group. Additionally, the lungs of mice vaccinated with rHAd5-F + HN showed no notable histopathological changes. On the other hand, rHAd5-F + HN produced a humoral immune response in calves. Following the booster intramuscular injection with the rHAd5-F + HN, the serum antibody levels against BPIV3 genotype C strain were 1:20 452, 1:1024, and 1:426 in calves, as detected by ELISA, HI, and NAb, respectively. The HI and NAb levels against the BPIV3 genotype A strain were 1:213 and 1:85 in calves, respectively. These results indicate that rHAd5-F + HN effectively induced immunity against BPIV3 infection.

Probing Selenium-Deficient Chicken Spleen Th1/Th17 Differentiation Based on Selenoprotein W Targeting of PKM2/HIF1α.

Selenium regulates the differentiation and function of immune cells mainly through selenoproteins. Selenoprotein W (SelW) has been shown to mitigate inflammatory bowel disease in mice by modulating the differentiation of helper T (CD4+ T) cell. Previous studies by our team have underscored SelW's critical role in safeguarding chicken spleens and splenic lymphocytes against inflammatory injury. However, research examining SelW's involvement in regulating CD4+ T cell differentiation in avian spleens remains scarce. Therefore, the selenium-deficient chicken model was constructed in this study. It was found that the spleen of selenium-deficient chickens showed significant inflammatory damage, accompanied by decreased SelW expression, diminished antioxidant capacity, heightened glycolysis, and an elevated count of Th1/Th17 cells. To elucidate the specific mechanism of SelW regulating Th1/Th17 cell differentiation, this study used molecular docking technology, fluorescence colocalization, and co-immunoprecipitation and initially confirmed the targeting relationship between SelW and pyruvate kinase M2 (PKM2). Subsequently, an in vitro model of SelW overexpression, knockdown, and TEPP-46 (PKM2 tetramer activator) cotreatment of chicken primary splenic lymphocytes was replicated. Our findings revealed that selenium deficiency triggers oxidative stress and promotes PKM2 nuclear translocation via SelW downregulation, which stabilizes HIF1α transcription in the nucleus, enhancing glycolysis and skewing chicken splenic CD4+ T cells toward the Th1/Th17 phenotype. Our study, for the first time, demonstrates the existence of an interaction between SelW and PKM2 in poultry, emphasizing SelW's paramount significance in CD4+ T cell differentiation, providing fresh perspectives on the contributions of selenoproteins to T cell biology and immune processes.

Transient High Salt Intake Promotes T-Cell-Mediated Hypertensive Vascular Injury.

Dietary high salt (HS) intake has a strong impact on cardiovascular diseases. Here, we investigated the link between HS-aggravated immune responses and the development of hypertensive vascular disease. ApolipoproteinE-deficient mice were transiently treated with HS (1% NaCl) via drinking water for 2 weeks, followed by a washout period, and subsequent Ang II (angiotensin II) infusion (1000 ng/kg per min for 10 days) to induce abdominal aortic aneurysms/dissections and inflammation. While transient HS intake alone triggered nonpathologic infiltration of activated T cells into the aorta, subsequent Ang II infusion increased mortality and the incidence of abdominal aortic aneurysms/dissections and atherosclerosis compared with hypertensive control mice. There were no differences in blood pressure between both groups. In transient HS-treated hypertensive mice, the aortic injury was associated with increased inflammation, accumulation of neutrophils, monocytes, CD69+CD4+ T cells, as well as CD4+ and CD8+ memory T cells. Mechanistically, transient HS intake increased expression levels of aortic RORγt as well as splenic CD4+TH17 and CD8+TC1 T cells in Ang II-treated mice. Isolated aortas of untreated mice were incubated with supernatants of TH17, TH1, or TC1 cells polarized in vitro under HS or normal conditions which revealed that secreted factors of HS-differentiated TH17 and TC1 cells, but not TH1 cells accelerated endothelial dysfunction. Our data suggest that transient HS intake induces a subclinical T-cell-mediated aortic immune response, which is enhanced by Ang II. We propose a 2-hit model, in which HS acts as a predisposing factor to enhance hypertension-induced TH17 and TC1 polarization and aortic disease.

9343 Protection Against Type 1 Diabetes Development In Mice With 4E-BP2 Deletion

Abstract Disclosure: V. Pita Grisanti: None. F. Pecanha: None. R. Louzada: None. M. Blandino: None. C. Jaramillo: None. N. Arenas: None. A. Bayer: None. E. Bernal-Mizrachi: None. Type 1 diabetes is an autoimmune disease characterized by β-cell destruction promoted by autoreactive T cells that acquire an effector inflammatory phenotype. 4E-BP1/2 proteins are translational repressors and downstream targets of mTORC1, a key regulator of metabolism. mTORC1 signaling disruption is implicated in human diseases including diabetes. Activation of 4E-BP2/eIF4E pathway by 4E-BP2 deletion promotes translation initiation, which induces β-cell expansion and proliferation and is crucial for the regulation of adaptive immunity. However, the involvement of 4E-BP2 in type 1 diabetes development has not been explored. Therefore, this study aimed to determine the role of 4E-BP2/eIF4E signaling in type 1 diabetes prevention by regulation of β-cell survival and immune modulation. To investigate the role of 4E-BP2/eIF4E axis in diabetes pathogenesis, we used the non-obese diabetic (NOD) mouse model as a type 1 diabetes model, and generated mice with global deletion of 4E-BP2 in the NOD background (4E-BP2KONOD). We assessed type 1 diabetes development, glucose homeostasis, pancreas morphometry and immune responses in male and female 4E-BP2KONOD and control NOD mice. We found that 4E-BP2KONOD exhibited reduced diabetes incidence in male but not female mice. Reduction in diabetes incidence in 4E-BP2KONOD male mice was associated with comparable degree of insulitis and β-cell proliferation, and with preserved β-cell mass compared to the control NOD mice. Glucose-stimulated insulin secretion of the islets, assessed in vitro by static incubation, was significantly higher in the 4E-BP2KONOD compared to the NOD control. Autoimmune responses were also evaluated by assessment of insulitis and characterization of T cell compartments, which showed a decrease in splenic CD8+ cytotoxic T cells and an increase in pancreatic regulatory T cell (Treg) infiltration mainly by increased Treg survival in 4E-BP2KONOD mice compared to control NOD. Finally, adoptive transfer studies demonstrated that lymphocytes derived from male 4E-BP2KONOD mice were less diabetogenic than those derived from control NOD mice. In conclusion, this study showed that activation of 4E-BP2/eIF4E axis in 4E-BP2KONOD male mice protects against type 1 diabetes development by dampening autoimmune responses and preserving β-cell mass. Targeting 4E-BP2 may provide a potential treatment for type 1 diabetes. Presentation: 6/1/2024

8090 A Gut Commensal, Parabacteroides distasonis, and Molecular Mimicry in Type 1 Diabetes

Abstract Disclosure: A. Randall: None. Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by the destruction of pancreatic, insulin-producing beta cells by autoreactive T-cells. The trigger(s) of T1D are unclear and genetics alone cannot explain the recent increase in T1D incidence. The gut microbiome composition in T1D patients is altered and thought to play a key role in T1D pathogenesis. Most longitudinal studies have been descriptive. However, a direct cause-and-effect relationship hasn't been established yet. Insulin is a key autoantigen in T1D autoimmunity, and insulin B-chain amino acids 9-23 (insB:9-23) is an important, commonly recognized T-cell epitope. Molecular mimicry is an autoimmunity mechanism where host-like microbial proteins trigger autoimmune responses. We previously identified a peptide mimic of insB:9-23, amino acids 4-18 of hypoxanthine phosphoribosyl transferase (HPRT:4-18) of Parabacteroides distasonis (Girdhar et al., 2022). HPRT:4-18 stimulated insB:9-23-specific human and non-obese diabetic (NOD) mice T-cells. We hypothesize that P. distasonis HPRT:4-18 is required to accelerate diabetes via molecular mimicry of insB:9-23. By orally gavaging NOD mice (n=40 mice/group), we showed that P. distasonis accelerated diabetes onset. Next, we colonized NOD mice with another common gut commensal, Bacteroides fragilis, as a control, and did not observe any effect on islet infiltration. In addition, P. distasonis colonization increased infiltration of immune cells into the islets of germ-free NOD mice (n=6-8 mice/group), while the diabetes incidence experiment in mice is ongoing. P. distasonis-colonized mice had significantly more splenic CD8 and naïve T-cells, dendritic cells and macrophages but fewer FOXP3 cells (n=3-6 mice/group). To determine whether P. distasonis’s effect is specific to the pancreas, we checked intestinal barrier function and intestinal immune cell composition. Disruption of intestinal barrier function has been associated with diabetes. P. distasonis colonization did not alter gut permeability. Furthermore, P. distasonis did not increase intestinal inflammation. Among the intestinal intraepithelial lymphocytes (IELs), there were fewer naïve, central and effector T-cells and B-cells. The findings indicate that P. distasonis does not stimulate an unspecific immune response and its inflammatory effect is specific to the pancreas, supporting our initial hypothesis. Taken together, our results indicate that exposure to P. distasonis in the first years of life has the potential to stimulate molecular mimicry mechanism and cause T1D onset. Reference: Girdhar, K., Huang, Q., Chow, I. T., Vatanen, T., Brady, C., Raisingani, A., . . . Altindis, E. (2022). A gut microbial peptide and molecular mimicry in the pathogenesis of type 1 diabetes. Proc Natl Acad Sci U S A, 119(31), e2120028119. doi:10.1073/pnas.2120028119 Presentation: 6/2/2024

Therapeutic effects of S-allyl-L-cysteine in a mouse endometriosis model and its immunomodulatory effects via regulation of T cell subsets and cytokine expression.

Endometriosis is a female hormone-dependent gynecological disorder characterized by chronic inflammation. Therefore, the development of novel treatment strategies that can diminish the side effects of the long-term use of hormone-based drugs has been emphasized. S-Allyl-L-cysteine (SAC) is the major constituent of aged garlic extracts. Although the therapeutic effects resulting from the antioxidant properties of SAC have been extensively studied in inflammatory diseases, the therapeutic efficacy of SAC in endometriosis has not been described. In this study, we investigated the therapeutic potential of SAC for endometriosis using a mouse model. An endometriosis mouse model was surgically induced, and oral treatment with 30mg/kg SAC was administered daily for 28 days. The development of endometriotic lesions was assessed by histological analysis, and the expression profiles of adhesion-, apoptosis-, and inflammation-related genes were evaluated by PCR. Flow cytometric analysis of mouse spleen was conducted to assess changes in lymphocyte subpopulations. SAC treatment significantly inhibited endometriotic lesion growth. Transcriptional expression analysis revealed the antiadhesion and apoptosis-promoting effects of SAC. In particular, SAC showed an effective immune modulatory response by altering splenic CD4+ and CD8+ T cell subsets and inflammatory cytokine production in the spleen and endometriotic lesions. This study newly elucidates the inhibitory effects of SAC on the growth of endometriosis in a mouse model and describes its immunomodulatory effects.

Ultrafast Power Doppler Ultrasound Enables Longitudinal Tracking of Vascular Changes that Correlate with Immune Response After Radiotherapy.

While immunotherapy shows great promise in patients with triple negative breast cancer, many will not respond to treatment. Radiotherapy has the potential to prime the tumor-immune microenvironment for immunotherapy. However, predicting response is difficult due to tumor heterogeneity across patients, which necessitates personalized medicine strategies that incorporate tumor tracking into the therapeutic approach. Here, we investigated the use of ultrasound (US) imaging of the tumor vasculature to monitor the tumor response to treatment. We utilized ultrafast power doppler US to track the vascular response to radiotherapy over time. We used 4T1 (metastatic) and 67NR (non-metastatic) breast cancer models to determine if US measurements corroborate conventional immunostaining analysis of the tumor vasculature. To evaluate the effects of radiation, tumor volume and vascular index were calculated using US, and the correlation between vascular changes and immune cell infiltration was determined. US tumor measurements and the quantified vascular response to radiation were confirmed with caliper measurements and immunostaining, respectively, demonstrating a proof-of-principle method for non-invasive vascular monitoring. Additionally, we found significant infiltration of CD8 + T cells into irradiated tumors 10 days after radiation, which followed a sustained decline in vascular index and an increase in splenic CD8 + T cells that was first observed 1 day post-radiation. Our findings reveal that ultrafast power doppler US can evaluate changes in tumor vasculature that are indicative of shifts in the tumor-immune microenvironment. This work may lead to improved patient outcomes through observing and predicting response to therapy.

MARCH8 Mediates K27-Linked Polyubiquitination of IL-7 Receptor α to Negatively Regulate IL-7-Triggered T Cell Homeostasis.

IL-7 is a cytokine produced by stromal cells, which binds to IL-7Rα and plays an important role for homeostasis of T lymphocytes. Excessive activities of IL-7-triggered signaling pathways causes autoimmune diseases. How IL-7-triggered signaling and immune effects are regulated is not fully understood. In this study, we show that the membrane-associated RING-CH (MARCH) E3 ligase family member MARCH8 mediates K27-linked polyubiquitination of IL-7Rα, leading to its lysosomal degradation. Site-directed mutagenesis suggests that MARCH8 meditates polyubiquitination of IL-7Rα at K265/K266, and mutation of these residues renders IL-7Rα resistance to MARCH8-mediated polyubiquitination and degradation. MARCH8 deficiency increases IL-7-triggered activation of the downstream transcription factor STAT5 and transcriptional induction of the effector genes in human T lymphoma cells. MARCH8 deficiency also promotes IL-7-triggered T cell proliferation and splenic memory CD8+ T cell differentiation in mice. Our findings suggest that MARCH8 negatively regulates IL-7-triggered signaling by mediating K27-linked polyubiquitination and lysosomal degradation of IL-7Rα, which reveals a negative regulatory mechanism of IL-7-triggered T cell homeostasis.

Adenosine A2B receptor activation regulates the balance between T helper 17 cells and regulatory T cells, and inhibits regulatory T cells exhaustion in experimental autoimmune myositis.

Idiopathic inflammatory myopathy (IIM) is a systemic autoimmune disease characterized by skeletal muscle involvement. This study aimed to investigate the role of adenosine receptor signalling pathways in the development of experimental autoimmune myositis (EAM). An ecto-5'-nucleotidase (CD73) inhibitor, adenosine receptor agonists, a hypoxia-inducible factor-1α (HIF-1α) inhibitor or a vehicle were administered to control and EAM mice. Murine splenic CD4+ or regulatory T cells (Tregs) were isolated using magnetic beads and subsequently stimulated with an adenosine A2B receptor agonist, a HIF-1α inhibitor, or vehicle in vitro. In cross-sectional studies, we collected 64 serum samples (69% female, 49±9years), 63 peripheral blood samples (70% female, 50±11years), and 34 skeletal muscle samples (71% female, 63±6years) from patients with IIM. Additionally, 35 serum samples and 30 peripheral blood samples were obtained from age- and sex-matched healthy controls, and six quadriceps muscle samples were collected from patients with osteoarthritis to serve as the normal group. Patients with IIM exhibited increased CD73 [dermatomyositis (DM), polymyositis (PM): P<0.01; immune-mediated necrotizing myopathy (IMNM): P<0.0001] and adenosine deaminase (ADA) expression (DM: P<0.001; PM, IMNM: P<0.0001) in the skeletal muscles, and serum ADA levels [56.7 (95% CI: 53.7, 58.7) vs. 198.8 (95% CI: 186.2, 237.3) ng/μL, P<0.0001]. Intervention with a CD73 inhibitor exacerbated (P=0.0461), whereas adenosine receptor agonists (A1: P=0.0009; A2B: P<0.0001; A3: P=0.0001) and the HIF-1α inhibitor (P=0.0044) alleviated skeletal muscle injury in EAM mice. Elevated expression of programmed cell death protein-1 (PD1: P=0.0023) and T-cell immunoglobulin and mucin-domain containing-3 (TIM3: P<0.0001) in skeletal muscles of patients with IIM were correlated with creatine kinase levels (PD1, r=0.7072, P<0.0001; TIM3, r=0.4808, P=0.0046). PD1+CD4+ (r=0.3243, P=0.0115) and PD1+CD8+ (r=0.3959, P=0.0017) T cells were correlated with Myositis Disease Activity Assessment Visual Analogue Scale scores (muscle) in IIM. The exhausted Tregs were identified in the skeletal muscles of patients with IIM. Activation of the A2B adenosine receptor downregulated HIF-1α (protein or mRNA level, P<0.01), resulting in decreased T helper cell 17 (Th17) (13.58% vs. 5.43%, P=0.0201) and phosphorylated-signal transducer and activator of transcription 3 (p-STAT3)+ Th17 (16.32% vs. 6.73%, P=0.0029), decreased exhausted Tregs (PD1+ Tregs: 53.55% vs. 40.28%, P=0.0005; TIM3+ Tregs: 3.93% vs. 3.11%, P=0.0029), and increased Tregs (0.45% vs. 2.89%, P=0.0006) in EAM mice. The exhausted T cells may be pathogenic in IIM,andthe activation of adenosine A2B receptor signalling pathway can regulate Th17/Treg balance and inhibit Tregsexhaustion, thereby slowing EAM disease progression.

Cryoablation Does Not Significantly Contribute to Systemic Effector Immune Responses in a Poorly Immunogenic B16F10 Melanoma Model.

Cryoablation is a minimally invasive procedure implemented to destroy solid tumors. It also results in the release of tumor antigens into the systemic circulation. Preclinical studies using immunogenic tumor models have shown that cryoablation evokes antitumor immune responses. The mechanisms by which cryoablation impacts immune responses in poorly immunogenic tumors have not been sufficiently explored. We used a bilateral B16F10 melanoma model devoid of strong immunogenic antigens. Cryoablation-induced effector immune responses were investigated, also in combination with a peritumoral STING agonist and systemic anti-PD-1. Selective immune cell depletion, T-cell migration arrest, in vivo T-cell transplantation, and cryoablation versus surgical removal techniques were used to determine the contribution of cryoablation and immunotherapies to systemic antitumor effector immune responses. Treatment of a tumor with cryoablation + STING agonist + anti-PD-1 resulted in the rejection of unablated, contralateral tumors. Depletion studies demonstrated that tumor rejection is essentially dependent on CD8+ T cells. T-cell arrest in the lymph nodes had no effect on the rejection process. Splenic CD8+ T cells isolated from cryoablation-treated mice with B16F10 melanoma, upon transplantation into melanoma-bearing recipients, did not impact the recipient's tumor growth. Finally, comparison of cryoablation + STING agonist + anti-PD-1 versus surgery + STING agonist + anti-PD-1 in the bilateral tumor model showed no difference in the rejection of contralateral tumors. Cryoablation does not significantly contribute to systemic antitumor effector immune responses in a B16F10 melanoma model. Cryoablation primarily performs tumor debulking, and immunotherapy functions independently of cryoablation in eliciting antitumor effector immune responses.