Understanding the relationship between inflammation, apoptosis, and diabetes osteoporosis: A bioinformatics approach and experimental verification.

Diabetes osteoporosis (DOP) is a chronic metabolic bone disease. This study aimed to identify potential biomarkers of DOP and explore their underlying mechanisms through bioinformatics methods and experimental verification. Bioinformatics methods were used to identify differentially expressed genes (DEGs) for DOP based on GEO data and the GeneCards database. GO and KEGG enrichment analyses were used to search the key pathways. The STRING website was used to construct a protein-protein interaction (PPI) network and identify key genes. Then, 50 mg/mL glucose was used to interveneosteoblasts (OBs).CCK-8 and Alizarin Red staining were used to investigate the proliferation and differentiation changes in OBs. Flowcytometry was used to investigate apoptosis. The membrane protein chip, WB, and RT-PCR were used to verify the expression of key targets or pathways about DOP. Forty-two common genes were screened between DOP-related targets and DEGs. GO and KEGG enrichment analysis showed that DOP was mainly associated with cytokine-cytokine receptor interactions, and apoptosis. PPI network analysis showed that TNF, IL1A, IL6, IL1B, IL2RA, Fas ligand (FASLG), and Fas cell surface death receptor (FAS) were key up-regulated genes in the occurrence of DOP. The experiment results show that 50 mg/mL glucose significantly inhibited OBs proliferation but presented an increase in apoptosis. Membrane protein chip, WB, and RT-PCR-verified a significantly active in the expression of TNF/FASLG/FAS pathway. High glucose activated the TNF-α/FAS/FASLG pathway and induced the inflammatory microenvironment and apoptosis, then impaired osteogenic differentiation of OBs. These may be an important mechanism for the occurrence and development of DOP.

Prognostic Value of Fas/Fas Ligand Expression on Circulating Tumor Cells (CTCs) and Immune Cells in the Peripheral Blood of Patients with Metastatic Breast Cancer.

The Fas/Fas ligand (FasL) system is a major apoptosis-regulating pathway with a key role in tumor immune surveillance and metastasis. The expression of Fas/FasL on mammary tumor tissues holds prognostic value for breast cancer (BC) patients. We herein assessed Fas/FasL expression on circulating tumor cells (CTCs) and matched peripheral blood mononuclear cells (PBMCs) from 98 patients with metastatic BC receiving first-line treatment. Fas+, FasL+, and Fas+/FasL+ CTCs were identified in 88.5%, 92.3%, and 84.6% of CTC-positive patients, respectively. In addition, Fas+/FasL+, Fas-/FasL+, and Fas-/FasL- PBMCs were identified in 70.3%, 24.2%, and 5.5% of patients, respectively. A reduced progression-free survival (PFS) was revealed among CTC-positive patients (median PFS: 9.5 versus 13.4 months; p = 0.004), and specifically among those harboring Fas+/FasL+ CTCs (median PFS: 9.5 vs. 13.4 months; p = 0.009). On the other hand, an increased overall survival (OS) was demonstrated among patients with Fas+/FasL+ PBMCs rather than those with Fas-/FasL+ and Fas-/FasL- PBMCs (median OS: 35.7 vs. 25.9 vs. 14.4 months, respectively; p = 0.008). These data provide for the first time evidence on Fas/FasL expression on CTCs and PBMCs with significant prognostic value for patients with metastatic BC, thus highlighting the role of the Fas/FasL system in the peripheral immune response and metastatic progression of BC.

Agent-Based Modeling of Virtual Tumors Reveals the Critical Influence of Microenvironmental Complexity on Immunotherapy Efficacy.

Since the introduction of the first immune checkpoint inhibitor (ICI), immunotherapy has changed the landscape of molecular therapeutics for cancers. However, ICIs do not work equally well on all cancers and for all patients. There has been a growing interest in using mathematical and computational models to optimize clinical responses. Ordinary differential equations (ODEs) have been widely used for mechanistic modeling in immuno-oncology and immunotherapy. They allow rapid simulations of temporal changes in the cellular and molecular populations involved. Nonetheless, ODEs cannot describe the spatial structure in the tumor microenvironment or quantify the influence of spatially-dependent characteristics of tumor-immune dynamics. For these reasons, agent-based models (ABMs) have gained popularity because they can model more detailed phenotypic and spatial heterogeneity that better reflect the complexity seen in vivo. In the context of anti-PD-1 ICIs, we compare treatment outcomes simulated from an ODE model and an ABM to show the importance of including spatial components in computational models of cancer immunotherapy. We consider tumor cells of high and low antigenicity and two distinct cytotoxic T lymphocyte (CTL) killing mechanisms. The preferred mechanism differs based on the antigenicity of tumor cells. Our ABM reveals varied phenotypic shifts within the tumor and spatial organization of tumor and CTLs despite similarities in key immune parameters, initial simulation conditions, and early temporal trajectories of the cell populations.

Evaluation of the Effect of Menopausal Status and BMI on Polymorphisms in Fas/Fas L and the Risk of Breast Cancer.

BACKGROUND: FAS and FAS ligand play an essential role in cell apoptosis. An identifying feature of malignant cells is the loss of FAS and increased FASL expression. A study analyzing the effects of menopausal status and body mass index (BMI) on functional polymorphisms of FAS-(1377G/A; rs2234767 & 670 A/G; rs1800682) and FASL (-844T/C; rs763110 & Ivs-2nt; rs5030772) in breast cancer evaluated these effects. PATIENTS AND METHODS: 316 blood samples were collected from breast cancer patients and healthy controls in this case/control study. RFLP-PCR was used after DNA extraction to determine genotypes. Age, BMI, menopausal status, smoking, and family history were also analyzed with genotypes. It was analyzed using SPSS software, X2 statistical tests, logistic regression, and Pearson's correlation. The study evaluated the role of indices and polymorphisms in breast cancer risk. RESULTS: While BMI and family history were significantly different, age, menopause status, and smoking were not. Examining the average BMI between menopausal and nonmenopausal people in the 2 groups showed a statistically significant difference between menopausal people (P <0.0001). As a result of 1377AA, 670GG, 844TT, and IVS-2ntGG, the risk of breast cancer increased by 1.83 times, 2.35 times, and 2.38 times respectively. In addition, mutant alleles increased disease risk significantly. The risk of disease increased considerably for postmenopausal females with certain genotypes (except 1377GA and 844CT genotypes) and high BMI. CONCLUSION: Having a high BMI during postmenopause increases your risk of breast cancer. In addition to menopause, BMI also influences disease progression. Different genotypes are needed to clarify this issue.

MicroRNA-216a-5p Alleviates Acute Kidney Injury of Mice via Suppressing FAS Ligand Expression.

INTRODUCTION: The aim of this present work was to investigate the mechanism of the microRNA (miR)-216a-5p/FASL axis in mice with acute kidney injury (AKI). METHODS: Mice kidney ischemia/reperfusion (I/R) injury was used as AKI models in this study. I/R mice were injected with miR-216a-5p- and FASL-related constructs to investigate potential mechanisms of kidney protection. Kidney function, inflammation, oxidative stress, and kidney cell apoptosis were assessed after 24 h of reperfusion. In vitro, the hypoxia-reoxygenation (H/R) model was used with kidney tubular epithelial cells (TECs) to mimic kidney I/R injury. H/R-treated TECs were transfected with miR-216a-5p- and FASL-related constructs to detect cell viability, inflammation, and oxidative stress. MiR-216a-5p and FASL expression levels in mouse kidney tissues and in H/R-treated TECs were detected. RESULTS: MiR-216a-5p was downregulated and FASL was upregulated in kidney tissues of I/R mice and H/R-treated TECs. Upregulating miR-216a-5p attenuated kidney cell apoptosis and the damage of kidney function, and reduced inflammatory factor levels and oxidative stress response in kidney tissues of I/R mice. Upregulating miR-216a-5p advanced cell viability and reduced inflammatory factor levels and oxidative stress response in H/R-treated TECs. Downregulation of FASL effectively reversed the influences of downregulation of miR-216a-5p on kidney injury in mice and kidney TEC survival. CONCLUSION: Our study reveals that miR-216a-5p reduces I/R-induced pathological kidney damage in AKI via suppressing FASL.

Caspase-8-mediated inflammation but not apoptosis drives death of retinal ganglion cells and loss of visual function in glaucomaa.

Background-: Glaucoma is a complex multifactorial disease where apoptosis and inflammation represent two key pathogenic mechanisms. However, the relative contribution of apoptosis versus inflammation in axon degeneration and death of retinal ganglion cells (RGCs) is not well understood. In glaucoma, caspase-8 is linked to RGC apoptosis, as well as glial activation and neuroinflammation. To uncouple these two pathways and determine the extent to which caspase-8-mediated inflammation and/or apoptosis contributes to the death of RGCs, we used the caspase-8 D387A mutant mouse (Casp8 DA/DA ) in which a point mutation in the auto-cleavage site blocks caspase-8-mediated apoptosis but does not block caspase-8-mediated inflammation. Methods-: Intracameral injection of magnetic microbeads was used to elevate the intraocular pressure (IOP) in wild-type, Fas deficient Faslpr, and Casp8 DA/DA mice. IOP was monitored by rebound tonometry. Two weeks post microbead injection, retinas were collected for microglia activation analysis. Five weeks post microbead injection, visual acuity and RGC function were assessed by optometer reflex (OMR) and pattern electroretinogram (pERG), respectively. Retina and optic nerves were processed for RGC and axon quantification. Two- and five-weeks post microbead injection, expression of the necrosis marker, RIPK3, was assessed by qPCR. Results-: Wild-type, Faslpr, and Casp8 DA/DA mice showed similar IOP elevation as compared to saline controls. A significant reduction in both visual acuity and pERG that correlated with a significant loss of RGCs and axons was observed in wild-type but not in Faslpr mice. The Casp8 DA/DA mice displayed a significant reduction in visual acuity and pERG amplitude and loss of RGCs and axons similar to that in wild-type mice. Immunostaining revealed equal numbers of activated microglia, double positive for P2ry12 and IB4, in the retinas from microbead-injected wild-type and Casp8 DA/DA mutant mice. qPCR analysis revealed no induction of RIPK3 in wild-type or Casp8 DA/DA mice at two- or five-weeks post microbead injection. Conclusions-: Our results demonstrate that caspase-8-mediated extrinsic apoptosis is not involved in the death of RGCs in the microbead-induced mouse model of glaucoma implicating caspase-8-mediated inflammation, but not apoptosis, as the driving force in glaucoma progression. Taken together, these results identify the caspase-8-mediated inflammatory pathway as a potential target for neuroprotection in glaucoma.

Survivin: A key apoptosis inhibitor in COVID-19 infection and its implication for treatment protocol.

While the relationship between cellular apoptosis and proliferation rates in COVID patients remains underexplored in existing literature, various viruses are known to impact these fundamental process to modulate response to infection. This paper aims to assess apoptosis and proliferation rates in individuals recently infected with Coronavirus, both before and after vaccination, comparing them with healthy controls. Peripheral blood cells from newly diagnosed COVID-19 patients revealed a significant increase in proliferation and apoptosis levels in fresh lymphocytes and granulocytes compared to healthy donors. Notably, as none of the patients were under corticosteroid therapy or cytotoxic drugs, the study underscores the critical role of white blood (WBC) apoptosis in viral pathogenesis, potentially contributing significantly to COVID-19's pathogenicity. Elevated levels of soluble Fas ligand (FaSL) and the pro-inflatmmatory cytokine IL-38 were identified in COVID-19 patients, indicating potential immune dysregulation. Furthermore, individual who received the vaccine or recovered from COVID-19 exhibited higher survivin rates, suggesting a protective role for survivin in migitating lung damage. These findings suggest the prospect of developing a strategy to prevent WBC apoptosis, offering potential benefits in averting lymphopenia associated with severe COVID-19 ouctomes.

FasL impacts Tgfb signaling in osteoblastic cells.

Fas ligand (FasL, CD178) belongs to classical apoptotic molecules, however, recent evidence expands the spectrum of FasL functions into non-apoptotic processes which also applies for the bone. Tgfb subfamily members (Tgfb1, Tgfb2, Tgfb3) represent major components in osteogenic pathways and extracellular matrix. Their possible association with FasL has not yet been investigated but can be postulated. To test such a hypothesis, FasL deficient (gld) calvaria-derived cells were examined with a focus on the expression of Tgfb receptor ligands. The qPCR analysis revealed significantly increased expression of Tgfb1, Tgfb2 and Tgfb3 in gld cells. To check the vice versa effect, the gld cells were stimulated by soluble FasL. As a consequence, a dramatic decrease in expression levels of all three ligands was observed. This phenomenon was also confirmed in IDG-SW3 (osteoblastic cells of endochondral origin). TFLink gateway identified Fosl2 as an exclusive candidate of FasL capable to impact expression of all three Tgfb ligands. However, Fosl2 siRNA did not cause any significant changes in expression of Tgfb ligands. Therefore, the upregulation of the three ligands is likely to occur separately. In this respect, we tested the only exclusive candidate transcription factor for Tgfb3, Prrx1. Additionally, an overlapping candidate for Tgfb1 and Tgfb2, Mef2c capable to modulate expression of sclerostin, was examined. Prrx1 as well as Mef2c were found upregulated in gld samples and their expression decreased after addition of FasL. The same effect of FasL treatment was observed in the IDG-SW3 model. Taken together, FasL deficiency causes an increase in the expression of Tgfb ligands and stimulation by FasL reduces Tgfb expression in osteoblastic cells. The candidates mediating the effect comprise Prrx1 for Tgfb3 and Mef2c for Tgfb1/2. These results indicate FasL as a novel cytokine interfering with Tgfb signaling and thus the complex osteogenic network. The emerging non-apoptotic functions of FasL in bone development and maintenance should also be considered in treatment strategies such as the anti-osteoporotic factor.

Fas Ligand enhances vessel maturation and inhibits vascular leakage associated with age-related macular degeneration.

Neovascular age-related macular degeneration (AMD), results from choroidal neovascularization (CNV), retinal edema and loss of photoreceptors. Previous studies suggested that Fas Ligand (FasL) on retinal pigment epithelial cells inhibited CNV by inducing apoptosis of infiltrating Fas+ vascular endothelial cells. However, induction of apoptosis depends on membrane-bound (mFasL) while the FasL cleavage product (sFasL) is neuroprotective. To better understand how FasL regulates the development of CNV, we used a mouse model of laser CNV to evaluate the development of CNV in mice with a FasL cleavage site mutation (ΔCS) and can only express the membrane-bound form of FasL. There was no significant difference in CNV size and area of vascular leakage in homozygous FasLΔCS/ΔCS mice when compared to wild type mice. Unexpectedly, heterozygous FasLΔCS/WT mice developed significantly less vascular leakage and showed accelerated neovessel maturation. However, CNV was not prevented in heterozygous FasLΔCS/WT mice if the Fas receptor was deleted in myeloid cells (FasLΔCS/+ Fasflox/flox CreLysM). Thus, FasL-mediated CNV inhibition depends on the extent of FasL cleavage, and on FasL engagement of Fas+ myeloid cells. Moreover, accelerated neovessel maturation prevents vascular leakage in AMD.

Platelets Induce Cell Apoptosis of Cardiac Cells via FasL after Acute Myocardial Infarction.

Acute myocardial infarction (AMI) is one of the leading causes of death worldwide. Cell apoptosis in the myocardium plays an important role in ischemia and reperfusion (I/R) injury, leading to cardiac damage and dysfunction. Platelets are major players in hemostasis and play a crucial role in vessel occlusion, inflammation, and cardiac remodeling after I/R. Here, we studied the impact of platelets on cell apoptosis in the myocardium using a close-chest mouse model of AMI. We found caspase-3-positive resident cardiac cells, while leukocytes were negative for caspase-3. Using two different mouse models of thrombocytopenia, we detected a significant reduction in caspase-3 positive cells in the infarct border zone after I/R injury. Further, we identified platelet FasL to induce cell apoptosis via the extrinsic pathway of Fas receptor activation of target cells. Mechanistically, hypoxia triggers platelet adhesion to FasR, suggesting that platelet-induced apoptosis is elevated after I/R. Platelet-specific FasL knock-out mice showed reduced Bax and Bcl2 expression, suggesting that platelets modulate the intrinsic and extrinsic pathways of apoptosis, leading to reduced infarct size after myocardial I/R injury. Thus, a new mechanism for how platelets contribute to tissue homeostasis after AMI was identified that should be validated in patients soon.

Dysregulated FGFR3 signaling alters the immune landscape in bladder cancer and presents therapeutic possibilities in an agent-based model.

Bladder cancer is an increasingly prevalent global disease that continues to cause morbidity and mortality despite recent advances in treatment. Immune checkpoint inhibitors (ICI) and fibroblast growth factor receptor (FGFR)-targeted therapeutics have had modest success in bladder cancer when used as monotherapy. Emerging data suggests that the combination of these two therapies could lead to improved clinical outcomes, but the optimal strategy for combining these agents remains uncertain. Mathematical models, specifically agent-based models (ABMs), have shown recent successes in uncovering the multiscale dynamics that shape the trajectory of cancer. They have enabled the optimization of treatment methods and the identification of novel therapeutic strategies. To assess the combined effects of anti-PD-1 and anti-FGFR3 small molecule inhibitors (SMI) on tumor growth and the immune response, we built an ABM that captures key facets of tumor heterogeneity and CD8+ T cell phenotypes, their spatial interactions, and their response to therapeutic pressures. Our model quantifies how tumor antigenicity and FGFR3 activating mutations impact disease trajectory and response to anti-PD-1 antibodies and anti-FGFR3 SMI. We find that even a small population of weakly antigenic tumor cells bearing an FGFR3 mutation can render the tumor resistant to combination therapy. However, highly antigenic tumors can overcome therapeutic resistance mediated by FGFR3 mutation. The optimal therapy depends on the strength of the FGFR3 signaling pathway. Under certain conditions, ICI alone is optimal; in others, ICI followed by anti-FGFR3 therapy is best. These results indicate the need to quantify FGFR3 signaling and the fitness advantage conferred on bladder cancer cells harboring this mutation. This ABM approach may enable rationally designed treatment plans to improve clinical outcomes.

Synthesis of N-Glycosylated Soluble Fas Ligand.

Controlled cell death is essential for the regulation of the immune system and plays a role in pathogen defense. It is often altered in pathogenic conditions such as cancer, viral infections and autoimmune diseases. The Fas receptor and its corresponding membrane-bound ligand (FasL) are part of the extrinsic apoptosis pathway activated in these cases. A soluble form of FasL (sFasL), produced by ectodomain shedding, displays a diverse but still elusive set of non-apoptotic functions and sometimes even serves as a pro-survival factor. To gather more knowledge about the characteristics of this protein and the impact N-glycosylations may have, access to homogeneous posttranslationally modified variants of sFasL is needed. Therefore, we developed a flexible strategy to obtain such homogeneously N-glycosylated variants of sFasL by applying chemical protein synthesis. This strategy can be flexibly combined with enzymatic methods to introduce more complex, site selective glycosylations.

Tissue-targeted and localized AAV5-DCN and AAV5-PEDF combination gene therapy abrogates corneal fibrosis and concurrent neovascularization in rabbit eyes in vivo.

PURPOSE: Corneal fibrosis and neovascularization (CNV) after ocular trauma impairs vision. This study tested therapeutic potential of tissue-targeted adeno-associated virus5 (AAV5) mediated decorin (DCN) and pigment epithelium-derived factor (PEDF) combination genes in vivo. METHODS: Corneal fibrosis and CNV were induced in New Zealand White rabbits via chemical trauma. Gene therapy in stroma was delivered 30-min after chemical-trauma via topical AAV5-DCN and AAV5-PEDF application using a cloning cylinder. Clinical eye examinations and multimodal imaging in live rabbits were performed periodically and corneal tissues were collected 9-day and 15-day post euthanasia. Histological, cellular, and molecular and apoptosis assays were used for efficacy, tolerability, and mechanistic studies. RESULTS: The AAV5-DCN and AAV5-PEDF combination gene therapy significantly reduced corneal fibrosis (p < 0.01 or p < 0.001) and CNV (p < 0.001) in therapy-given (chemical-trauma and AAV5-DCN + AAV5-PEDF) rabbit eyes compared to the no-therapy given eyes (chemical-trauma and AAV5-naked vector). Histopathological analyses demonstrated significantly reduced fibrotic α-smooth muscle actin and endothelial lectin expression in therapy-given corneas compared to no-therapy corneas on day-9 (p < 0.001) and day-15 (p < 0.001). Further, therapy-given corneas showed significantly increased Fas-ligand mRNA levels (p < 0.001) and apoptotic cell death in neovessels (p < 0.001) compared to no-therapy corneas. AAV5 delivered 2.69 × 107 copies of DCN and 2.31 × 107 copies of PEDF genes per µg of DNA. AAV5 vector and delivered DCN and PEDF genes found tolerable to the rabbit eyes and caused no significant toxicity to the cornea. CONCLUSION: The combination AAV5-DCN and AAV5-PEDF topical gene therapy effectively reduces corneal fibrosis and CNV with high tolerability in vivo in rabbits. Additional studies are warranted.

Inhibiting Endothelial Cell-Mediated T Lymphocyte Apoptosis with Integrin-Targeting Peptide-Drug Conjugate Filaments for Chemoimmunotherapy of Triple-Negative Breast Cancer.

Tumor-associated endothelial cells (TECs) limit antitumor immunity via inducing apoptosis of infiltrating T lymphocytes through a Fas ligand (FasL) mediated mechanism. Herein, this work creates a peptide-drug conjugate (PDC) by linking 7-ethyl-10-hydroxycamptothecin (SN38) to hydrophilic segments with either RGDR or HKD motif at their C-terminus through a glutathione-responsive linker. The PDCs spontaneously assemble into filaments in aqueous solution. The PDC filaments containing 1% of SN38-RGDR (SN38-HKD/RGDR) effectively target triple-negative breast cancer (TNBC) cells and TECs with upregulated expression of integrin, and induce immunogenic cell death (ICD) of tumor cells and FasL downregulation of TECs. SN38-HKD/RGDR increases infiltration, activity, and viability of CD8+ T cells, and thus inhibits the growth of primary tumors and pulmonary metastasis. This study highlights the synergistic modulation of cancerous cells and TECs with integrin-targeting PDC filaments as a promising strategy for TNBC chemoimmunotherapy.

Hei Xiaoyaosan Regulates Fas/FasL/Caspase-8/Caspase-3 Signaling Pathway to Inhibit Neuronal Apoptosis in AD Rats / 中国实验方剂学杂志

ObjectiveTo explore the effect and mechanism of Hei Xiaoyaosan in regulating the tumor necrosis factor receptor superfamily member 6 （Fas）/Fas ligand （FasL）/cysteine protease-8 （Caspase-8）/cysteine protease-3 （Caspase-3） signaling pathway to intervene in neuronal apoptosis and prevent Alzheimer's disease （AD）. MethodNinety SPF-grade SD male rats of 4 months old were selected and randomly grouped as follows： 10 rats in the blank group， 10 rats in the sham group （bilateral hippocampus injected with 1 μL normal saline）， and 70 rats in the modeling group ［bilater hippocampus injected with 1 μL amyloid-beta protein 1-42 （Aβ1-42） solution for the modeling of AD］. Fifty successfully modeled rats were selected and randomly assigned into model， donepezil hydrochloride （0.45 mg·kg-1）， and high-， medium-， and low-dose （15.30， 7.65， 3.82 g·kg-1） Hei Xiaoyaosan groups. Rats were administrated with corresponding agents by gavage once a day for 42 days. Terminal-deoxynucleoitidyl transferase-mediated nick end labeling （TUNEL） was employed to observe the apoptosis of neurons in the cortex and hippocampus， and immunohistochemistry （IHC） was used to detect the expression of B-cell lymphoma-2 （Bcl-2） and Bcl-2-associated X protein （Bax） in the hippocampus. Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR） was employed to determine the mRNA levels of Fas， FasL， and Fas-associated protein with death domain （Fadd）. Western blot was used to determine the protein levels of Fas， FasL， Fadd， Caspase-3， cleved Caspase-3， Caspase-8， and cleved Caspase-8. ResultCompared with the blank group and sham group， the model group showed increased apoptosis rate in the cortex and hippocampus （P<0.01）， elevated Bax level （P<0.01）， lowered Bcl-2 level （P<0.01）， up-regulated mRNA levels of Fas， FasL， and Fadd in the hippocampus （P<0.01）， and up-regulated protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.01）. Compared with the model group， donepezil hydrochloride and Hei Xiaoyaosan at high and medium doses decreased the apoptosis rate in the cortex and hippocampus （P<0.05， P<0.01）， lowered the Bax level （P<0.01）， elevated the Bcl-2 level （P<0.01）， and down-regulated the mRNA levels of Fas， FasL， and Fadd and the protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.05， P<0.01） in the hippocampus. Low-dose Hei Xiaoyaosan decreased the apoptosis rate in the cortex and hippocampus （P<0.05， P<0.01）， lowered the Bcl-2 level （P<0.01）， and down-regulated the mRNA levels of FasL and Fadd （P<0.05） and the protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.05） in the hippocampus. ConclusionHei Xiaoyaosan can protect neurons in the cortex and hippocampus of AD rats by inhibiting the apoptosis mediated by the Fas/FasL/Caspase-8/Caspase-3 signaling pathway.

Activation and Denitrosylation of Procaspase-3 in KA-induced Excitotoxicity.

BACKGROUND: It has been reported that activation of glutamate kainate receptor subunit 2 (GluK2) subunit-containing glutamate receptors and the following Fas ligand(FasL) up-regulation, caspase-3 activation, result in delayed apoptosis-like neuronal death in hippocampus CA1 subfield after cerebral ischemia and reperfusion. Nitric oxide-mediated S-nitrosylation might inhibit the procaspase activation, whereas denitrosylation might contribute to cleavage and activation of procaspases. OBJECTIVES: The study aimed to elucidate the molecular mechanisms underlying procaspase-3 denitrosylation and activation following kainic acid (KA)-induced excitotoxicity in rat hippocampus. METHODS: S-nitrosylation of procaspase-3 was detected by biotin-switch method. Activation of procaspase-3 was shown as cleavage of procaspase-3 detected by immunoblotting. FasL expression was detected by immunoblotting. Cresyl violets and TdT-mediated dUTP Nick-End Labeling (TUNEL) staining were used to detect apoptosis-like neuronal death in rat hippocampal CA1 and CA3 subfields. RESULTS: KA led to the activation of procaspase-3 in a dose- and time-dependent manner, and the activation was inhibited by KA receptor antagonist NS102. Procaspase-3 was denitrosylated at 3 h after kainic acid administration, and the denitrosylation was reversed by SNP and GSNO. FasL ASODNs inhibited the procaspase-3 denitrosylation and activation. Moreover, thioredoxin reductase (TrxR) inhibitor auranofin prevented the denitrosylation and activation of procaspase-3 in rat hippocampal CA1 and CA3 subfields. NS102, FasL AS-ODNs, and auranofin reversed the KAinduced apoptosis and cell death in hippocampal CA1 and CA3 subfields. CONCLUSIONS: KA led to denitrosylation and activation of procaspase-3 via FasL and TrxR. Inhibition of procaspase-3 denitrosylation by auranofin, SNP, and GSNO played protective effects against KA-induced apoptosis-like neuronal death in rat hippocampal CA1 and CA3 subfields. These investigations revealed that the procaspase-3 undergoes an initial denitrosylation process before becoming activated, providing valuable insights into the underlying mechanisms and possible treatment of excitotoxicity.

A novel Fas ligand plays an important role in cell apoptosis of Crassostrea hongkongensis: molecular cloning, expression profiles and functional identification of ChFasL.

Background: Apoptosis regulates normal development, homeostasis, immune tolerance and response to environmental stress by eliminating unwanted or diseased cells, and plays a key role in non-specific immunity of invertebrates. The exogenous pathway mediated by death receptors and death ligands is a very important pathway for cell apoptosis. Death ligands are mainly members of the tumour necrosis factor (TNF) family, of which FasL is an important member. The deep involvement of FasL in vertebrates cell apoptosis and immunity has been reported many times, but there is limited research on the FasL gene in shellfish, and its functional importance in oyster cell apoptosis and immunity remains unclear. Methods: The full length of ChFasL was identified and cloned based on the genome of Crassostrea hongkongensis. Quantitative PCR was used to detect the relative expression of ChFasL in different developmental stages and tissues, as well as the changes of relative expression in hemocytes after bacterial infection. The expression position of ChFasL in HEK293T cells was also located by subcellular localization, and the effect of increased recombinant protein content on the activity of reporter genes p53 and p21 was studied by dual-fluorescence reporter gene. Finally, the changes of apoptosis rate in hemocytes after ChFasL silencing was identified by RNA interference technology. Results: We identified a novel FasL gene from C. hongkongensis and named it ChFasL. We found that ChFasL has potential N-linked glycosylation site, a transmembrane domain and a TNF region, which was a typical characteristics of TNF family. ChFasL was expressed in all developmental stages of larvae and in all tissues of oysters. After stimulation by V. alginolyticus or S. haemolyticus, its relative expression in hemocytes increased significantly, suggesting that ChFasL was deeply engaged in the immune response process of C. hongkongensis to external microbial stimulation. The results of subcellular localization showed that ChFasL was mainly distributed in the cytoplasm of HEK293T cells. With the overexpression of the recombinant protein pcDNA3 1- ChFasL, the activity of p53 and p21 significantly increased, showing a positive regulatory effect. Moreover, after dsRNA successfully reduced the relative expression of ChFasL, the apoptosis rate of hemocytes was significantly lower than that the dsGFP group. Conclusion: These results comprehensively confirmed the important role of ChFasL in the apoptosis process of C. hongkongensis, which provided the basis and premise for the in-depth understanding of the immune function of apoptosis in molluscs, and also contributed to the research on the pathogenic death mechanism and disease resistance breeding of marine bivalves.

Involvement of Innate Immune System in the Pathogenesis of Sepsis-Associated Acute Kidney Injury.

Although experimental models have shown that the innate immune system is a main contributor to acute kidney injury (AKI), its involvement in human sepsis-associated AKI (SA-AKI) remains unclear. We retrospectively evaluated 19 patients with SA-AKI who were treated with continuous renal replacement therapy (CRRT). Serum cytokine, complement components, and the proportion and functions of innate immune cells, such as CD56+ T cells, CD56+ natural killer (NK) cells, and monocytes, were analyzed. There were no differences in the proportions of CD56+ T and NK cells between patients with SA-AKI and healthy controls. In patients with SA-AKI, fas ligand (FasL) expression in CD56+ T cells was significantly upregulated, and the proportion of perforin-positive CD56+ T cells tended to be higher than that in healthy controls. The positive rate of both FasL and perforin of CD56+ T cells was significantly higher than that of CD56- T cells, which include cytotoxic T cells. Antigen-presenting capacity and phagocytic activity of monocytes in patients with SA-AKI were significantly decreased compared to those of healthy controls and did not recover soon after the initiation of CRRT. CD56+ T cells are involved in the disease processes of human SA-AKI through effector molecules such as FasL or perforin.

Unsolved mystery of Fas: mononuclear cells may have trouble dying in patients with Sjögren's syndrome.

BACKGROUND: Patients with Sjögren's syndrome, like other patients with autoimmune disorders, display dysregulation in the function of their immune system. Fas and Fas Ligand (FasL) are among the dysregulated proteins. METHODS: We studied Fas and FasL on IL-2Rα+ cells and in serum of patients with Sjögren's syndrome (n = 16) and healthy individuals (n = 16); both from same ethnic and geographical background. We used flow cytometry and enzyme-linked immunosorbent for this purpose. We also measured the expression of Bcl-2 and Bax by reverse transcription quantitative real-time PCR (RT-qPCR) and percentage of apoptotic and dead cells using Annexin V and 7-AAD staining in lymphocytes. RESULTS: FasL was increased in patients' T and B cells while Fas was increased in patients' monocytes, T and B cells. No signs of increased apoptosis were found. sFas and sFasL in patients' serum were increased, although the increase in sFasL was not significant. We suspect an effect of non-steroidal anti-inflammatory therapy on B cells, explaining the decrease of the percentage Fas+ B cells found within our samples. In healthy individuals, there was a noticeable pattern in the expression of FasL which mutually correlated to populations of mononuclear cells; this correlation was absent in the patients with Sjögren's syndrome. CONCLUSIONS: Mononuclear cells expressing IL-2Rα+ had upregulated Fas in Sjögren's syndrome. However, the rate of apoptosis based on Annexin V staining and the Bcl-2/Bax expression was not observed in mononuclear cells. We suspect a functional role of abnormal levels of Fas and FasL which has not been cleared yet.

Novel Fas-TNFR chimeras that prevent Fas ligand-mediated kill and signal synergistically to enhance CAR T cell efficacy.

The hostile tumor microenvironment limits the efficacy of adoptive cell therapies. Activation of the Fas death receptor initiates apoptosis and disrupting these receptors could be key to increasing CAR T cell efficacy. We screened a library of Fas-TNFR proteins identifying several novel chimeras that not only prevented Fas ligand-mediated kill, but also enhanced CAR T cell efficacy by signaling synergistically with the CAR. Upon binding Fas ligand, Fas-CD40 activated the NF-κB pathway, inducing greatest proliferation and IFN-γ release out of all Fas-TNFRs tested. Fas-CD40 induced profound transcriptional modifications, particularly genes relating to the cell cycle, metabolism, and chemokine signaling. Co-expression of Fas-CD40 with either 4-1BB- or CD28-containing CARs increased in vitro efficacy by augmenting CAR T cell proliferation and cancer target cytotoxicity, and enhanced tumor killing and overall mouse survival in vivo. Functional activity of the Fas-TNFRs were dependent on the co-stimulatory domain within the CAR, highlighting crosstalk between signaling pathways. Furthermore, we show that a major source for Fas-TNFR activation derives from CAR T cells themselves via activation-induced Fas ligand upregulation, highlighting a universal role of Fas-TNFRs in augmenting CAR T cell responses. We have identified Fas-CD40 as the optimal chimera for overcoming Fas ligand-mediated kill and enhancing CAR T cell efficacy.