The Tianzhu white yak, a globally rare species, holds immense value as a source for yak materials. While the Fas/FasL pathway is pivotal in granulosa cells apoptosis, its precise molecular workings remain enigmatic. This study endeavours to decipher the role of follicle-stimulating hormone (FSH) in suppressing ovarian granulosa cells (GC) apoptosis in the Tianzhu white yak. Utilizing advanced cell culture techniques, we employed the MTT method, flow cytometry, fluorescence labelling and RT-PCR to investigate the apoptotic effects of FSH on yak GCs. Our results reveal that FSH\'s inhibitory effect on GC apoptosis follows a normal distribution pattern, peaking at an FSH concentration of 100 ng/mL with an apoptosis inhibition rate of 89.31%. When serum was withdrawn, an FSH concentration of 2 × 106 ng/mL reduced apoptosis by 72.84%. Annexin V-FITC staining revealed membrane invaginations, bubble and protrusion formation on the cell surface, and alterations in membrane structure and cell morphology. Flow cytometry analysis further demonstrated that FSH administration prior to early granulosa cell apoptosis had a more profound effect than during gradual apoptosis, both showing a suppressive effect on early follicular granulosa cell apoptosis. A transcription-level analysis conducted 3 h prior to serum withdrawal, with the addition of 100 ng/mL FSH, revealed intricate regulations in the expression of Fas/FasL. Notably, we observed a gradual increase in FasL expression over time, yet the presence of FSH effectively down-regulated FasL expression to baseline levels, without notable changes in Fas expression. Immunocytochemical analysis further confirmed the presence of both Fas and FasL on the cell membrane, nucleus and cytoplasm, with varying intensities depending on the duration of FSH treatment. Our findings suggest that FSH may suppress the apoptotic pathway in follicular primarily by down-regulating FasL expression, indicating that Fas-regulated mitochondrial pathways play a more prominent role compared to death receptor pathways. This study offers a fresh perspective on the mechanism underlying follicular atresia in Tianzhu white yaks and lays a solid theoretical foundation for the expansion of this endangered species\' population.

The pathogenesis of ankylosing spondylitis (AS) remains unclear, and while recent studies have implicated necroptosis in various autoimmune diseases, an investigation of its relationship with AS has not been reported. In this study, we utilized the Gene Expression Omnibus database to compare gene expressions between AS patients and healthy controls, identifying 18 differentially expressed necroptosis-related genes (DENRGs), with 8 upregulated and 10 downregulated. Through the application of three machine learning algorithms-least absolute shrinkage and selection operation, support vector machine-recursive feature elimination and random forest-two hub genes, FASLG and TARDBP, were pinpointed. These genes demonstrated high specificity and sensitivity for AS diagnosis, as evidenced by receiver operating characteristic curve analysis. These findings were further supported by external datasets and cellular experiments, which confirmed the downregulation of FASLG and upregulation of TARDBP in AS patients. Immune cell infiltration analysis suggested that CD4+ T cells, CD8+ T cells, NK cells and neutrophils may be associated with the development of AS. Notably, in the group with high FASLG expression, there was a significant infiltration of CD8+ T cells, memory-activated CD4+ T cells and resting NK cells, with relatively less infiltration of memory-resting CD4+ T cells and neutrophils. Conversely, in the group with high TARDBP expression, there was enhanced infiltration of naïve CD4+ T cells and M0 macrophages, with a reduced presence of memory-resting CD4+ T cells. In summary, FASLG and TARDBP may contribute to AS pathogenesis by regulating the immune microenvironment and immune-related signalling pathways. These findings offer new insights into the molecular mechanisms of AS and suggest potential new targets for therapeutic strategies.

Regular assessment of disease activity in relapsing-remitting multiple sclerosis (RRMS) is required to optimize clinical outcomes. Biomarkers can be a valuable tool for measuring disease activity in multiple sclerosis (MS) if they reflect the pathological processes underlying MS pathogenicity. In this pilot study, we combined multiple biomarkers previously analyzed in RRMS patients into an MS disease activity (MSDA) score to evaluate their ability to predict relapses and treatment response to glatiramer acetate (GA). Response Gene to Complement 32 (RGC-32), FasL, IL-21, SIRT1, phosphorylated SIRT1 (p-SIRT1), and JNK1 p54 levels were used to generate cut-off values for each biomarker. Any value below the cutoff for RGC-32, FasL SIRT1, or p-SIRT1 or above the cutoff for IL-21 or JNK1 p54 was given a +1 value, indicating relapse or lack of response to GA. Any value above the cutoff value for RGC-32, FasL, SIRT1, p-SIRT1 or below that for IL-21 or JNK1 p54 was given a -1 value, indicating clinical stability or response to GA. An MSDA score above +1 indicated a relapse or lack of response to treatment. An MSDA score below -1 indicated clinical stability or response to treatment. Our results showed that the MSDA scores generated using either four or six biomarkers had a higher sensitivity and specificity and significantly correlated with the expanded disability status scale. Although these results suggest that the MSDA test can be useful for monitoring therapeutic response to biologic agents and assessing clinically challenging situations, the present findings need to be confirmed in larger studies.

OBJECTIVE: To investigate the effect of Porphyromonas gingivalis (Pg) infection on immune escape of oesophageal cancer cells and the role of YTHDF2 and Fas in this regulatory mechanism.
METHODS: We examined YTHDF2 and Fas protein expressions in esophageal squamous cell carcinoma (ESCC) tissues with and without Pg infection using immunohistochemistry and in Pg-infected KYSE150 cells using Western blotting. The interaction between YTHDF2 and Fas was investigated by co-immunoprecipitation (Co-IP). Pg-infected KYSE150 cells with lentivirus-mediated YTHDF2 knockdown were examined for changes in expression levels of YTHDF2, cathepsin B (CTSB), Fas and FasL proteins, and the effect of E64 (a cathepsin inhibitor) on these proteins were observed. After Pg infection and E64 treatment, KYSE150 cells were co-cultured with human peripheral blood mononuclear cells (PBMCs), and the expressions of T cell-related effector molecules were detected by flow cytometry.
RESULTS: ESCC tissues and cells with Pg infection showed significantly increased YTHDF2 expression and lowered Fas expression. The results of Co-IP demonstrated a direct interaction between YTHDF2 and Fas. In Pg-infected KYSE150 cells with YTHDF2 knockdown, the expression of CTSB was significantly reduced while Fas and FasL expressions were significantly increased. E64 treatment of KYSE150 cells significantly decreased the expression of CTSB without affecting YTHDF2 expression and obviously increased Fas and FasL expressions. Flow cytometry showed that in Pg-infected KYSE150 cells co-cultured with PBMCs, the expressions of Granzyme B and Ki67 were significantly decreased while PD-1 expression was significantly enhanced.
CONCLUSIONS: Pg infection YTHDF2-dependently regulates the expression of Fas to facilitate immune escape of esophageal cancer and thus promoting cancer progression, suggesting the key role of YTHDF2 in regulating immune escape of esophageal cancer.

The transmembrane death receptor Fas transduces apoptotic signals upon binding its ligand, FasL. Although Fas is highly expressed in cancer cells, insufficient cell surface Fas expression desensitizes cancer cells to Fas-induced apoptosis. Here, we show that the increase in Fas microaggregate formation on the plasma membrane in response to the inhibition of endocytosis sensitizes cancer cells to Fas-induced apoptosis. We used a clinically accessible Rho-kinase inhibitor, fasudil, that reduces endocytosis dynamics by increasing plasma membrane tension. In combination with exogenous soluble FasL (sFasL), fasudil promoted cancer cell apoptosis, but this collaborative effect was substantially weaker in nonmalignant cells. The combination of sFasL and fasudil prevented glioblastoma cell growth in embryonic stem cell-derived brain organoids and induced tumor regression in a xenograft mouse model. Our results demonstrate that sFasL has strong potential for apoptosis-directed cancer therapy when Fas microaggregate formation is augmented by mechano-inhibition of endocytosis.

The longevity of grafts remains a major challenge in allogeneic transplantation due to immune rejection. Systemic immunosuppression can impair graft function and can also cause severe adverse effects. Here, we report a local immuno-protective strategy to enhance post-transplant persistence of allografts using a mesenchymal stem cell membrane-derived vesicle (MMV)-crosslinked hydrogel (MMV-Gel). MMVs are engineered to upregulate expression of Fas ligand (FasL) and programmed death ligand 1 (PD-L1). The MMVs are retained within the hydrogel by crosslinking. The immuno-protective microenvironment of the hydrogel protects allografts by presenting FasL and PD-L1. The binding of these ligands to T effector cells, the dominant contributors to graft destruction and rejection, results in apoptosis of T effector cells and generation of regulatory T cells. We demonstrate that implantation with MMV-Gel prolongs the survival and function of grafts in mouse models of allogeneic pancreatic islet cells and skin transplantation.

The clinical application of doxorubicin (DOX) is mainly restricted by its serious side effects, poor drug delivery efficiency, and limited immunogenic death (ICD) effect. To improve DOX-based chemotherapy and ameliorate its adverse effects, we utilized 3LL cell-derived extracellular vesicles to encapsulate DOX and sodium nitroprusside (SNP) to obtain DOX/SNP@CM, which could effectively target the tumor site by harnessing the inherent homologous targeting property of tumor cell membranes. DOX performed its role on chemotherapy, and SNP successfully respond to the intracellular GSH to continuously generate nitric oxide (NO). The in situ-produced NO upregulated the Fas expression on the tumor cell surface, thereby sensitizing the Fas/FasL pathway-mediated tumor cell apoptosis of DOX. Furthermore, NO also boosted the intratumoral infiltration of cytotoxic T cells by promoted ICD effect towards tumor cells. Importantly, the anti-tumor immunity tightly cooperated with Fas/FasL mediated tumor cell apoptosis by NO-mediated manipulation on Fas/FasL interaction, collectively making DOX/SNP@CM exert significant tumor growth inhibition with low-dose DOX. Remarkably, DOX and SNP both are widely used clinical medicines, ensuring DOX/SNP@CM a potential opportunity for future practical applications.

Rationale: It has been emergingly recognized that apoptosis generates plenty of heterogeneous apoptotic vesicles (apoVs), which play a pivotal role in the maintenance of organ and tissue homeostasis. However, it is unknown whether apoVs influence postnatal ovarian folliculogenesis. Methods: Apoptotic pathway deficient mice including Fas mutant (Fasmut ) and Fas ligand mutant (FasLmut ) mice were used with apoV replenishment to evaluate the biological function of apoVs during ovarian folliculogenesis. Ovarian function was characterized by morphological analysis, biochemical examination and cellular assays. Mechanistical studies were assessed by combinations of transcriptomic and proteomic analysis as well as molecular assays. CYP17A1-Cre; Axin1fl /fl mice was established to verify the role of WNT signaling during ovarian folliculogenesis. Polycystic ovarian syndrome (PCOS) mice and 15-month-old mice were used with apoV replenishment to further validate the therapeutic effects of apoVs based on WNT signaling regulation. Results: We show that systemic administration of mesenchymal stem cell (MSC)-derived apoptotic vesicles (MSC-apoVs) can ameliorate impaired ovarian folliculogenesis, PCOS phenotype, and reduced birth rate in Fasmut and FasLmut mice. Mechanistically, transcriptome analysis results revealed that MSC-apoVs downregulated a number of aberrant gene expression in Fasmut mice, which were enriched by kyoto encyclopedia of genes and genomes (KEGG) pathway analysis in WNT signaling and sex hormone biosynthesis. Furthermore, we found that apoptotic deficiency resulted in aberrant WNT/β-catenin activation in theca and mural granulosa cells, leading to responsive action of dickkopf1 (DKK1) in the cumulus cell and oocyte zone, which downregulated WNT/β-catenin expression in oocytes and, therefore, impaired ovarian folliculogenesis via NPPC/cGMP/PDE3A/cAMP cascade. When WNT/β-catenin was specially activated in theca cells of CYP17A1-Cre; Axin1fl /fl mice, the same ovarian impairment phenotypes observed in apoptosis-deficient mice were established, confirming that aberrant activation of WNT/β-catenin in theca cells caused the impairment of ovarian folliculogenesis. We firstly revealed that apoVs delivered WNT membrane receptor inhibitor protein RNF43 to ovarian theca cells to balance follicle homeostasis through vesicle-cell membrane integration. Systemically infused RNF43-apoVs down-regulated aberrantly activated WNT/β-catenin signaling in theca cells, contributing to ovarian functional maintenance. Since aging mice have down-regulated expression of WNT/β-catenin in oocytes, we used MSC-apoVs to treat 15-month-old mice and found that MSC-apoVs effectively ameliorated the ovarian function and fertility capacity of these aging mice through rescuing WNT/β-catenin expression in oocytes. Conclusion: Our studies reveal a previously unknown association between apoVs and ovarian folliculogenesis and suggest an apoV-based therapeutic approach to improve oocyte function and birth rates in PCOS and aging.

BACKGROUND: Autoimmune lymphoproliferative syndrome (ALPS) is a rare primary immune disorder caused by defect of the extrinsic apoptotic pathway. The current diagnostic criteria combine clinical features and typical biomarkers but have not been the object of clear international consensus.
METHODS: We conducted a retrospective study on pediatric patients who were investigated for autoimmune cytopenia and/or lymphoproliferation at the CHU Sainte-Justine Hospital over 10 years. Patients were screened using the combination of TCRαβ+ CD4- CD8- \"double negative\" (DN) T cells and soluble plasmatic FAS ligand (sFASL).
RESULTS: Among the 398 tested patients, the median sFASL and DN T cells were 200 ng/mL and 1.8% of TCRαβ+ T cells, respectively. sFASL was highly correlated with vitamin B12 levels. We identified five patients diagnosed with ALPS for whose sFASL and vitamin B12 levels were the more discriminating biomarkers. While ALPS diagnostic criteria had high sensibility, their predictive value remained low.
CONCLUSIONS: sFASL level can efficiently discriminate patients with ALPS when using the appropriate thresholds. Our study highlights the need for an international consensus to redefine the place and threshold of biological biomarkers for ALPS diagnosis.

Idiopathic severe aplastic anemia (SAA) is a disease of bone marrow failure caused by T-cell-induced destruction of hematopoietic stem and progenitor cells (HSPCs), however the mechanism remains unclear. We performed single-cell RNA sequencing of PBMCs and BMMCs from SAA patients and healthy donors and identified a CD8+ T cell subset with a tissue residency phenotype (Trm) in bone marrow that exhibit high IFN-γ and FasL expression and have a higher ability to induce apoptosis in HSPCs in vitro through FasL expression. CD8+ Trm cells were induced by IL-15 presented by IL-15Rα on monocytes, especially CD16+ monocytes, which were increased in SAA patients. CD16+ monocytes contributed to IL-15-induced CD38+CXCR6+ pre-Trm differentiation into CD8+ Trm cells, which can be inhibited by the CD38 inhibitor 78c. Our results demonstrate that IL-15-induced CD8+ Trm cells are pathogenic cells that mediate HSPC destruction in SAA patients and are therapeutic targets for future treatments.