Fas-induced Apoptosis Research Articles

Recombinant Human Angiotensin-Converting Enzyme 2 and COVID-19 Acute Respiratory Distress Syndrome: A Theoretical or a Real Resource?

Coronavirus disease 2019 (COVID-19) is a respiratory tract infection caused by a newly emergent beta-coronavirus closely linked to SARS virus, characterized by interstitial lung infiltrate, whose intensive care unit related admission rate is of 5%. Its natural history can be complicated by mild to severe respiratory failure till the onset of a fearsome life-treatening acute respiratory distress syndrome (ARDS). Given the interaction with host ACE2 type II pneumocytes receptors, dysregulation of the renin-angiotensin system may serve a central role both in the onset and progression of lung injury [1,2]. The complex SARS-CoV-2 Spike (S) glycoprotein and ACE2 receptor primed by the cellular protease TMPRSS2 is a critical step for ectodomain virion entry by suppressing ACE2 activity and altering the ACE/ACE2 balance to a predominant ACE/AngII axis with a reduction of Ang(1-7)-Mas complex and subsequent vasoconstriction, cytokines-bradykinin inflammatory response, Fas-induced apoptosis, fibrogenesis and oxidative damage [3]. As reported by Liu et al [4], in a small monocentric case series including twelve patients, serum Ang II levels in COVID-19 patients were significantly higher than in non-infected individuals with a linear association with both viremia and lung severity injury. Since ACE2 exerts cytoprotective effects on pulmonary parenchyma by an antagonistic action of Ang II, we speculated about both direct (restorative of the renin angiotensin system) and indirect (chimeric receptor effect) therapeutic effects in the treatment of COVID-19 related ARDS. Khan A et al [5], in a double-blind two-part phase II trial comparing the effect of the administration of a recombinant form of human angiotensin-converting enzyme 2 (GSK2586881) in forty-six patients with acute respiratory distress syndrome, reported a significant reduction of Ang II levels after scalar infusion with a long standing 48-hours plateau phase. Moreover, surfactant protein D increased as far as interleukin-6 concentrations decreased. The authors reported no significant differences in either peak or plateau pressures between recombinant human angiotensin-converting enzyme 2 (rhACE2) and placebo group in the first 72 hours, but an equally increase at the end of the five-day observation period. No adverse haemodynamic effects were reported; however, hypernatremia, rush and dysphagia were noted. However, some concerns may rise dealing with enrollement process in the trial, such as the inclusion of only hemodynamically stable patients with recent diagnosis (within 48 hours) of respiratory distress without any reference to the radiological severity and extension of the pulmonary injury. This aspect could theoretically limit the adoption in COVID-19 patients for various reasons, such as the not negligible prevalence of concurrent related cardiomyopathies (17-23%) and the relative late onset of a full-blown ARDS (10-12 days from the onset of the first symptoms) [6]. A correct stratification and monitoring would therefore appear essential in order to envisage the adoption only in selected cases. In our opinion, further elements of reflection arise about the genetic susceptibility of enzymatic mechanisms, as ACE2 gene (Xp22; 39.98kb) exhibits a high degree of genetic polymorphisms [7], which would justify the co-presence of responder and non-responder patients. Finally, the last limit is reserved for therapeutic feasibility both in terms of effective doses required (low rhACE2 half-life) and clinical monitoring (delayed effects on ventilatory pressures). On the other hand, the adoption of a target therapy for COVID-19 ARDS is promising as it could ensure both an anti-inflammatory (like interleukin-inhibitors, such as Tocilizumab) and regenerative (restoration of surfactant homeostasis, prevention of post-injury fibrotic remodelling) effects. In conclusion, the development of target therapies acting on the renin-angiotensin system appear promising although theoretically limited only to selected patients. In order to extend indications, we believe it could be essential to establish early therapy in patients who meet ARDS criteria without concomitant hemodynamic instability. However, some concerns still claim debate about protocols as well as individual genetic sensitivity which could result into an unspecified estimation of non-responder cases. Finally, the cytoprotective and remodeling aspects that could theoretically be clinically associated with a reduced incidence of post-treatment sequelae, such as pulmonary fibrosis and chronic post-injury respiratory failure, is fascinating.

NUP210 and MicroRNA-22 Modulate Fas to Elicit HeLa Cell Cycle Arrest.

PurposeCervical cancer is one of the most fatal diseases among women in under-developed countries. To improve cervical cancer treatment, discovery of new targets is needed. In this study, we investigated the expression of NUP210, miR-22, and Fas in cervical cancer tissues and their functions in cell cycle regulation.Materials and MethodsWe detected and compared the expression levels of NUP210, miR-22, and Fas in cervical cancer tissues with paired normal tissues using immunohistochemistry, Western blot, and real-time quantitative polymerase chain reaction. NUP210 was knocked down in HeLa cells via lentivirus, followed by cell cycle and proliferation analysis. Using a luciferase reporter assay, we explored the link between miR-22 and NUP210. We overexpressed miR-22 in HeLa cells and analyzed cell cycle and proliferation function. We then overexpressed miR-22 in NUP210 knockdown cells to explore the connection between Fas and miR-22-NUP210 signaling.ResultsWe found that NUP210 was overexpressed in cervical cancer patients. Knocking down NUP210 restored cell apoptosis and proliferation. We confirmed miR-22 as a regulator of NUP210 and verified that miR-22 was inhibited in cervical cancer development. We also found that restoring miR-22 expression could induce cell apoptosis. Finally, we found that miR-22-regulated expression of NUP210 could alter Fas expression and, in turn, elicit cell cycle arrest and proliferation.ConclusionmiR-22 in cervical cancer is downregulated, resulting in NUP210 overexpression and inhibition of Fas-induced cell apoptosis.

Soluble FAS ligand is not required for pancreatic islet inflammation or beta-cell destruction in non-obese diabetic mice

CD8+ T cells play a central role in beta-cell destruction in type 1 diabetes. CD8+ T cells use two main effector pathways to kill target cells, perforin plus granzymes and FAS ligand (FASL). We and others have established that in non-obese diabetic (NOD) mice, perforin is the dominant effector molecule by which autoreactive CD8+ T cells kill beta cells. However, blocking FASL pharmacologically was shown to protect NOD mice from diabetes, indicating that FASL may have some role. FASL can engage with its receptor FAS on target cells either as membrane bound or soluble FASL. It has been shown that membrane-bound FASL is required to stimulate FAS-induced apoptosis in target cells, whereas excessive soluble FASL can induce NF-κB-dependent gene expression and inflammation. Because islet inflammation is a feature of autoimmune diabetes, we tested whether soluble FASL could be important in disease pathogenesis independent of its cell death function. We generated NOD mice deficient in soluble FASL, while maintaining expression of membrane-bound FASL due to a mutation in the FASL sequence required for cleavage by metalloproteinase. NOD mice lacking soluble FASL had normal numbers of lymphocytes in their spleen and thymus. Soluble FASL deficient NOD mice had similar islet inflammation as wild-type NOD mice and were not protected from diabetes. Our data indicate that soluble FASL is not required in development of autoimmune diabetes.

Role of prognostic biomarker decoy receptor 3 and immunomodulation in kidney diseases.

Decoy receptor 3 (DcR3), also known as tumor necrosis factor receptor superfamily member 6b (TNFRSF6B), was recently identified as a novel biomarker for predicting progression of kidney diseases with potential immune modulation. The purpose of this review is to discuss the current evidence related to DcR3 in kidney diseases and to compare the differences between human and animal studies both in vivo and in vitro. High serum DcR3 predicts the occurrence of peritonitis in patients receiving chronic peritoneal dialysis and is positively correlated with inflammatory markers such as interleukin-6, high-sensitivity C-reactive protein, and adhesion molecules in patients on maintenance hemodialysis (HD). Higher serum DcR3 levels not only independently predict cardiovascular and all-cause mortality in HD patients but also identify older adults on HD at risk of protein-energy wasting in combination with a low geriatric nutritional risk index. Recently, renal tubular epithelial cells (RTECs) expressing DcR3 have also been used to predict progression of chronic kidney disease. Expression of DcR3 was correlated with a 2-fold increase in serum creatinine or failure of kidney allograft. DcR3 could protect renal myofibroblasts against Fas-induced apoptosis and subsequently lead to renal fibrosis. Locally expressed DcR3 in the RTECs may suppress the FasL-Fas-mediated apoptosis of T cells, resulting in an accumulation of allo-reactive T cells. In addition to traditional biological functions, recombinant DcR3.Fc and cytomegalovirus promoter-driven human DcR3 plasmid are able to modulate the activation and differentiation of dendritic cells and macrophages via "non-decoy" action. Both progressive IgA nephropathy and autoimmune crescentic glomerulonephritis in mice can be suppressed after hydrodynamics-based gene delivery of DcR3 plasmid. DcR3-mediated effects in vitro could be surveyed via over-expressing DcR3 or addition of recombinant DcR3.Fc, and CD68-driven DcR3 transgenic mice are suitable for investigating systemic effect in vivo. Inhibition of DcR3 expression in human may be a promising approach for pathomechanism.

TNF-α-elicited miR-29b potentiates resistance to apoptosis in peripheral blood monocytes from patients with rheumatoid arthritis.

CD14-positive monocytes from patients with rheumatoid arthritis (RA) are more resistant to apoptosis, which promotes their persistence at the inflammatory site and thereby contributes crucially to immunopathology. We sought to elucidate one mechanism underlying this unique pathogenesis: resistance to apoptosis and the potential involvement of miR-29b in this process. CD14-positive peripheral blood monocytes (PBMs) from RA patients were observed to be resistant to spontaneous apoptosis compared to PBMs from healthy volunteers. Intriguingly, expression of miR-29b was significantly upregulated in PBMs from RA patients than those from healthy volunteers, and this upregulation was correlated with RA disease activity. Functionally, forced expression of the exogenous miR-29b in CD14-positive Ctrl PBMs conferred resistance to spontaneous apoptosis and Fas-induced death, thereafter enhancing the production of major proinflammatory cytokines in there cells. Following identification of the potential miR-29b target transcripts using bioinformatic algorithms, we showed that miR-29b could directly bind to the 3'-UTR of the high-mobility group box-containing protein 1 (HBP1) and inhibited its transcription in PBMs. Importantly, stable expression of the exogenous HBP1 in differentiated THP-1 monocytes effectively abolished miR-29b-elicited resistance to Fas-induced apoptosis. Finally, among patients with RA and good clinical responses to immunotherapy, expression levels of miR-29b were significantly compromised in those treated with infliximab (a TNF-α inhibitor) but not in those treated with tocilizumab (a humanized mAb against the IL-6 receptor), pointing to a potential association between miR-29b activation and TNF-α induction. The available data collectively suggest that TNF-α-elicited miR-29b potentiates resistance to apoptosis in PBMs from RA patients via inhibition of HBP1 signaling, and testing patients for miR-29b/HBP1 expression ratios may provide more accurate prognostic information and could influence the recommended course of immunotherapy.

Apoptotic signalling targets the post-endocytic sorting machinery of the death receptor Fas/CD95

Fas plays a major role in regulating ligand-induced apoptosis in many cell types. It is well known that several cancers demonstrate reduced cell surface levels of Fas and thus escape a potential control system via ligand-induced apoptosis, although underlying mechanisms are unclear. Here we report that the endosome associated trafficking regulator 1 (ENTR1), controls cell surface levels of Fas and Fas-mediated apoptotic signalling. ENTR1 regulates, via binding to the coiled coil domain protein Dysbindin, the delivery of Fas from endosomes to lysosomes thereby controlling termination of Fas signal transduction. We demonstrate that ENTR1 is cleaved during Fas-induced apoptosis in a caspase-dependent manner revealing an unexpected interplay of apoptotic signalling and regulation of endolysosomal trafficking resulting in a positive feedback signalling-loop. Our data provide insights into the molecular mechanism of Fas post-endocytic trafficking and signalling, opening possible explanations on how cancer cells regulate cell surface levels of death receptors.

Polypeptide-engineered DNA tetrahedrons for targeting treatment of colorectal cancer via apoptosis and autophagy

Smart delivery of therapeutic peptides that target cellular signaling pathways holds high specificity and great promise for cancer therapy. Here, DNA tetrahedrons (TDs) are designed to carry two therapeutic peptides-FAS peptide and FK-16 peptide. DNA TDs are designed with varied numbers and spatial placement of FAS peptides and FK-16 peptides, and tested for their anti-cancer efficacy. Trimerization of FAS receptors using TDs that are assembled with three FAS peptides enhances FAS-induced cell apoptosis. FK-16 peptides are conjugated to TDs via a peptide sequence sensitive to MMP-2/9 in tumor microenvironment. Therefore, FK-16 peptides are expected to detach from TDs once arrived the tumor microenvironment. A cell penetrating peptide (TAT) is also conjugated to the FK-16 peptide to facilitate its intracellular delivery, which increases the FK-16 peptide-induced cell apoptosis and autophagy. TD-3(TFM)3(FAS) (TFM: TAT + FK-16 + MMP-2/9) exhibits the highest HT-29 inhibition in vitro and in vivo among all therapies. In addition to the high anti-cancer efficacy, TD-3(TFM)3(FAS) shows a high specificity to HT-29 cells in vitro and in vivo. Low cell inhibition rates and cellular uptake are observed in normal cells. In sum, the multifunctional TD-3(TFM)3(FAS) provides a new platform for the smart delivery of anti-cancer peptides to achieve enhanced efficacy and high specificity.

PS1115 THE RELATIONSHIP BETWEEN THE PRETREATMENT PNH CLONE SIZE AND CLINICAL COURSE IN PATIENTS WITH BONE MARROW FAILURE SYNDROMES: INTERIM ANALYSIS OF JAPANESE MULTICENTER PROSPECTIVE STUDY

Background: Gaucher Disease (GD) is a congenital disorder secondary to GBA1 gene mutations that cause a defective function of the catabolic enzyme β-glucocerebrosidase (GBA) and a progressive accumulation of its substrate- glucocerebroside (GC) in various organs, in particular in mononuclear phagocite system. Bone infiltration, hepatosplenomegaly and cytopenia represent the most common features of the disease. Since clinical manifestation can be subdolous, in some cases, phenotype can overlap with Autoimmune Lymphoproliferative Sindrome (ALPS). Nonetheless, GD patients were also shown to have hyperinflammatory features- secondary to machrophages engorgement and actviation- and an aspecific impaiment involving B, T and NK cells. In addition, some patients also showed more specific ALPS-like immune-dyregulation features suggesting an underlying apoptosis defect. Aims: To evaluate specific ALPS-like immunological and serological pattern (Double Negative T-cells, TCR alfa/beta B220, B-memory cells, T-regs/HLA-DR ratio, IL-10, IL-18,) in a cohort patients with GD and to test apoptosis pathway function in those showing ALPS-like features. Methods: All patients were diagnosed with GD by enzyme assay on lymphocytes culture or fibroblasts and by characterization of pathogenetic variants of GBA1. Lymphocytes subsets and ALPS-related serum biomarkers (IL-10, IL-18, sFAS, Vit.B12) were analyzed in 41 GD patients followed-up at Istituto Giannina Gaslini. Furthermore, in those patients who showed an ALPS-like phenotype, apoptosis function was analyzed after FAS–induced stimulation of EBV-immortalized B-cells and Western blot analysis of CASP10, CASP8, and PARP proteins. Results: 10/41 (24%) patients showed an ALPS-like immunological pattern which was more frequent in naïve patients (p = 0.003) and in patients with an earlier onset of the diesease (p = 0.010). EBV-immortalized B-cells of 7 out of these 10 patients were further studied and all of them showed a defective FAS-induced apoptosis and caspases activation. Fig 1 shows apoptosis evalutation of the selected population.Summary/Conclusion: To the best of our knowledge, this study shows for the first time that untreated subjects with early-onset GD present an immune-dysregulation pattern secondary to a defect of apoptosis as seen in ALPS patients. These results suggest that diagnostic work-up of both diseases must take into consideration their clinical and biochemical overlap. Further studies are needed to evaluate the potential role of cell-membrane lipids impairment on FAS receptor structure as a cause of such defect.

Dysregulation of Mesenchymal Cell Survival Pathways in Severe Fibrotic Lung Disease: The Effect of Nintedanib Therapy.

Impaired apoptotic clearance of myofibroblasts can result in the continuous expansion of scar tissue during the persistent injury in the lung. However, the molecular and cellular mechanisms underlying the apoptotic clearance of multiple mesenchymal cells including fibrocytes, fibroblasts and myofibroblasts in severe fibrotic lung diseases such as idiopathic pulmonary fibrosis (IPF) remain largely unknown. We analyzed the apoptotic pathways activated in mesenchymal cells of IPF and in a mouse model of TGFα-induced pulmonary fibrosis. We found that fibrocytes and myofibroblasts in fibrotic lung lesions have acquired resistance to Fas-induced apoptosis, and an FDA-approved anti-fibrotic agent, nintedanib, effectively induced apoptotic cell death in both. In support, comparative gene expression analyses suggest that apoptosis-linked gene networks similarly dysregulated in both IPF and a mouse model of TGFα-induced pulmonary fibrosis. TGFα mice treated with nintedanib show increased active caspase 3-positive cells in fibrotic lesions and reduced fibroproliferation and collagen production. Further, the long-term nintedanib therapy attenuated fibrocyte accumulation, collagen deposition, and lung function decline during TGFα-induced pulmonary fibrosis. These results highlight the importance of inhibiting survival pathways and other pro-fibrotic processes in the various types of mesenchymal cells and suggest that the TGFα mouse model is relevant for testing of anti-fibrotic drugs either alone or in combination with nintedanib.

Formaldehyde induces the apoptosis of BMCs of BALB/c mice via the PTEN/PI3K/Akt signal transduction pathway.

The International Agency for Research on Cancer has classified formaldehyde (FA) as a leukemogen to humans in 2012; however, the underlying mechanism remains unclear. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor-suppressor gene and can negatively regulate the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signal transduction pathway, which is associated with cell proliferation, apoptosis and carcinogenesis. To determine the association between FA and the PTEN/PI3K/Akt signal transduction pathway, flow cytometry, reverse transcription-quantitative polymerase chain reaction, western blotting and immunohistochemical analysis were conducted. Bone marrow cells were obtained from BALB/c mice, divided into the control (untreated cells) and FA groups, which were treated with various doses of FA (50, 100 and 200 µmol/l). Following treatment with FA for 24 h, cell viability, the cell cycle, apoptosis, and the expression of PTEN, PI3K and Akt, as well as the protein expression of B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X (Bax), and Caspases-3 and −9 were examined. Furthermore, 10 µmol/PI3K inhibitor (LY294002) was applied to inhibit the PTEN/PI3K/Akt signal transduction pathway and 100 µmol/l FA was selected for treatment; alteration in the cell cycle were analyzed. The results demonstrated that FA could suppress cell viability, and downregulate PTEN and Bcl-2; the expression of PI3K, Akt, Bax, and Caspases-3 and −9 were upregulated. Additionally, FA was reported to induce cell cycle arrest at the G0/G1 phase and apoptosis. Following the application of LY294002 to inhibit the PTEN/PI3K/Akt signal transduction pathway, the numbers of cells arrested in the G0/G1 phase were significantly increased in the PI3K inhibitor group compared with the control (P<0.01); however, no significant change in the number of G0/G1 cells compared with FA group was observed (P>0.05). The results of the present study suggested that the PTEN/PI3K/Akt signal transduction pathway served an important role in the process of FA-induced apoptosis, which may be associated with regulating the cell cycle; thus, cell proliferation may be affected.

TIPE2 as a potential therapeutic target in chronic viral hepatitis

ABSTRACTIntroduction: Tumor necrosis factor-α-induced protein-8 like-2 (TIPE2) is a novel negative regulator of innate and adaptive immune responses by binding to caspase-8. The binding of TIPE2 and caspase-8 can inhibit the activity of activating protein-1(AP-1) and nuclear factor-κB (NF-κB), ultimately promoting Fas-induced apoptosis in immune cells. Therefore, TIPE2-caspase-8-NF-κB signaling might serve as a biomarker and a potential target for therapeutic intervention.Areas covered: This review summarizes the biological functions of TIPE2 in the regulation of immune homeostasis and the underlying mechanism by which TIPE2 is regulated in the human immune response. The molecular pathway of TIPE2-caspase-8 signaling in chronic infections of hepatitis B virus and hepatitis C virus is also explained.Expert opinion: Considering the essential role of TIPE2 in linking immunity and inflammation, this protein may be a promising therapeutic target in chronic viral hepatitis. However, studies are necessary to elucidate the molecular mechanism of TIPE2 in the immunogenesis of viral hepatitis and to develop potential interventions for breaking immune tolerance in chronic hepatitis B virus infection. Additional studies are required to understand how TIPE2 binds to caspase-8.

Overexpressed Hsp70 alleviated formaldehyde-induced apoptosis partly via PI3K/Akt signaling pathway in human bronchial epithelial cells.

Formaldehyde (FA) is a ubiquitous environmental pollutant, which can induce apoptosis in lung cell and is related to the pathogenesis of asthma, pneumonia, and chronic obstructive pulmonary disease. Heat shock protein 70 (Hsp70) is an ATP-dependent molecular chaperone and exhibits an anti-apoptosis ability in a variety of cells. Previous studies reported that the expression of Hsp70 was induced when organisms were exposed to FA. Whether Hsp70 plays a role in the FA-induced apoptosis and the involved cell signaling pathway remain largely unknown. In this study, human bronchial epithelial cells with overexpressed Hsp70 and the control were exposed to different concentrations of FA (0, 40, 80, and 160 μmol/L) for 24 hours. Apoptosis and the expression levels of PI3K, Akt, p-Akt, MEK, p-MEK, and GLI2 were detected by Annexin-APC/7AAD double-labeled flow cytometry and western blot. The results showed that overexpression of Hsp70 decreased the apoptosis induced by FA and alleviated the decline of PI3k and p-Akt significantly. Inhibitor (LY 294002, a specific inhibitor of PI3K-Akt) test result indicated that PI3K-Akt signaling pathway was involved in the inhibition of FA-induced apoptosis by Hsp70 overexpression and also active in the maintenance of GLI2 level. However, it also suggested that other signaling pathways activated by overexpressed Hsp70 participated in this process, which was needed to be elucidated in further research.

Fibroblast Growth Factor-1 Inhibition Enhances FAS-Induced Apoptosis in Mantle Cell Lymphoma Cells By Accelerated BIRC2/3 Degradation

Fibroblast growth factor-1 Inhibition Enhances FAS-Induced Apoptosis in Mantle Cell Lymphoma Cells by Accelerated BIRC2/3 Degradation.Neeraj Jain1, Tamer Khashab1, Natalie Willingham2, Felipe Samaniego1 and Lalit Sehgal21 Department of Lymphoma/Myeloma, UT MD Anderson Cancer center, Houston, TX 770542 Division of Hematology, Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USAIntroduction Mantle cell lymphoma (MCL) is an aggressive form of non-Hodgkin lymphoma that is characterized by the t(11:14)(q13:p32) translocation. MCL cells have altered cyclinD1 levels, impaired cell cycle regulation, DNA damage response, and likely defects in apoptosis signaling. Furthermore, up-regulated anti-apoptotic mediators such as the target of NF-κB BIRC2 and BIRC3 were correlated with decreased apoptosis signaling. Also many cancer cells and malignant tumors show a prevalent resistance to apoptosis induction by FAS. Thus, by understanding the underpinnings of apoptosis resistance, we will be in a better position to develop strategies that improve Fas-induced killing of lymphoma cells.Methods More detailed insight into MCL pathogenesis has been delayed until the recent development of a tissue culture system, using human mesenchymal stromal cells (hMSC), suitable for propagating primary MCL cells. Isolates of primary MCL cells were co-cultured with human mesenchymal stem cells (hMSCs) and the content of MCL-ICs was analyzed by flow-cytometry based on marker expression profile; CD34-CD3-CD45+CD19-. Cytokine array was used to identify the soluble factors enriched in the co-cultures and the expression of these factors was confirmed by RT-PCR analysis. The signaling pathways employed by the newly-identified factors were blocked in 3 MCL cell lines (JVM2, Mino, Z138) to confirm their essential role in survival of MCL cells and, more importantly, for MCL-ICs.Results Co-cultures of primary MCL isolates with hMSCs supported the growth of MCL cells for over 4 weeks with continued presence of MCL-ICs (CD34-CD3-CD45+CD19-) representing about 1% of MCL cells. We found that IL-6 produced by hMSCs triggered an FGF/FGFR autocrine loop in MCL-ICs. The extent of FGFR expression correlated tightly with expression of SOX11, a pathology related negative prognostic marker in MCL. MCL cell survival and growth was regulated via the FGFR-1 mediated BIRC2/3 axis. Blocking of this signaling pathway with FGFR-1 inhibitors consistently induced early degradation in BIRC2/3 levels and subsequently MCL cell death.Conclusion We established that propagation of primary MCL in co-cultures with hMSCs depends on activation of FGF/FGFR-1 autocrine loop that enhances BIRC2/3 protein expression and thus, supports survival of MCL cells. We identified the factors essential for survival of MCL and MCL-ICs that present new targets for improved MCL treatment strategies. This study reveals that inhibition of FGFR-1 signaling by specific inhibitor has a profound positive impact on extrinsic cell death signaling; it enhances FAS sensitivity by promoting processing of caspases through enhanced BIRC2/3 degradation. The capacity of FGFR-1 inhibition to target stability of BIRC2/3, underscores its potential for enhancing efficacy of conventional cancer therapies. DisclosuresSamaniego:ADC Therapeutics: Research Funding.

Hepatitis B Spliced Protein (HBSP) Suppresses Fas-Mediated Hepatocyte Apoptosis via Activation of PI3K/Akt Signaling.

Hepatitis B spliced protein (HBSP) is known to associate with viral persistence and pathogenesis; however, its biological and clinical significance remains poorly defined. Acquired resistance to Fas-mediated apoptosis is thought to be one of the major promotors for hepatitis B virus (HBV) chronicity and malignancy. The purpose of this study was to investigate whether HBSP could protect hepatocytes against Fas-initiated apoptosis. We showed here that HBSP mediated resistance of hepatoma cells or primary human hepatocytes (PHH) to agonistic anti-Fas antibody (CH11)- or FasL-induced apoptosis. Under Fas signaling stimulation, expression of HBSP inhibited Fas aggregation and prevented recruitment of the adaptor molecule Fas-associated death domain (FADD) and procaspase-8 (or FADD-like interleukin-1β-converting enzyme [FLICE]) into the death-inducing signaling complex (DISC) while increasing recruitment of cellular FLICE-inhibitory protein L (FLIPL) into the DISC. Those effects may be mediated through activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway as evidenced by increased cellular phosphatidylinositol (3,4,5)-trisphosphate (PIP3) content and PI3K activity and enhanced phosphorylation of mTORC2 and PDPK1 as well as Akt itself. Confirmedly, inhibition of PI3K by LY294002 reversed the effect of HBSP on Fas aggregation, FLIPL expression, and cellular apoptosis. These results indicate that HBSP functions to prevent hepatocytes from Fas-induced apoptosis by enhancing PI3K/Akt activity, which may contribute to the survival and persistence of infected hepatocytes during chronic infection.IMPORTANCE Our study revealed a previously unappreciated role of HBSP in Fas-mediated apoptosis. The antiapoptotic activity of HBSP is important for understanding hepatitis B virus pathogenesis. In particular, HBV variants associated with hepatoma carcinoma may downregulate apoptosis of hepatocytes through enhanced HBSP expression. Our study also found that Akt is centrally involved in Fas-induced hepatocyte apoptosis and revealed that interventions directed at inhibiting the activation or functional activity of Akt may be of therapeutic value in this process.

Fas receptor induces apoptosis of synovial bone and cartilage progenitor populations and promotes bone loss in antigen-induced arthritis.

Rheumatoid arthritis (RA) is an inflammatory joint disease that eventually leads to permanent bone and cartilage destruction. Fas has already been established as the regulator of inflammation in RA, but its role in bone formation under arthritic conditions is not completely defined. The aim of this study was to assess the effect of Fas inactivation on the bone damage during murine antigen-induced arthritis. Subchondral bone of wild-type (WT) and Fas-knockout (Fas-/-) mice was evaluated by histomorphometry and microcomputerized tomography. Proportions of synovial bone and cartilage progenitors were assessed by flow cytometry. Synovial bone and cartilage progenitors were purified by fluorescence-activated cell sorting and expression of Fas and Fas-induced apoptosis were analyzed in vitro. Results showed that Fas-/- mice developed attenuated arthritis characterized by preserved epiphyseal bone and cartilage. A proportion of the earliest CD200+ bone and cartilage progenitors was reduced in WT mice with arthritis and was unaltered in Fas-/- mice. During osteoblastic differentiation in vitro, CD200+ cells express the highest levels of Fas and are removed by Fas ligation. These results suggest that Fas-induced apoptosis of early CD200+ osteoprogenitor population represents potential mechanism underlying the impaired bone formation in arthritis, so their preservation may represent the bone-protective mechanism during arthritis.-Lazić Mosler, E., Lukač, N., Flegar, D., Fadljević, M., Radanović, I., Cvija, H., Kelava, T., Ivčević, S., Šućur, A., Markotić, A., Katavić, V., Marušić, A., Grčević, D., Kovačić, N. Fas receptor induces apoptosis of synovial bone and cartilage progenitor populations and promotes bone loss in antigen-induced arthritis.

Adult Hepatocytes Are Hedgehog-Responsive Cells in the Setting of Liver Injury: Evidence for Smoothened-Mediated Activation of NF-κB/Epidermal Growth Factor Receptor/Akt in Hepatocytes that Counteract Fas-Induced Apoptosis

Although hedgehog (Hh) signaling pathway is inactive in adult healthy liver, it becomes activated during acute and chronic liver injury and, thus, modulates the reparative process and disease progression. We developed a novel mouse model with liver-specific knockout of Smoothened (Smo LKO), and animals were subjected to Fas-induced liver injury invivo. Results showed that Smo deletion in hepatocytes enhances Fas-induced liver injury. Activation of Hh signaling in hepatocytes in the setting of Fas-induced injury was indicated by the fact that Jo2 treatment enhanced hepatic expression of Ptch1, Smo, and its downstream target Gli1 in control but not Smo LKO mice. Primary hepatocytes from control mice showed increased Hh signaling activation in response to Jo2 treatment invitro. On the other hand, the Smo KO hepatocytes were devoid of Hh activation and were more susceptible to Jo2-induced apoptosis. The levels of NF-κB and related signaling molecules, including epidermal growth factor receptor and Akt, were lower in Smo KO livers/hepatocytes than in control livers/hepatocytes. Accordingly, hydrodynamic gene delivery of active NK-κB prevented Jo2-induced liver injury in the Smo LKO mice. Our findings provide important evidence that adult hepatocytes become responsive to Hh signaling through up-regulation of Smo in the setting of Fas-induced liver injury and that such alteration leads to activation of NF-κB/epidermal growth factor receptor/Akt, which counteracts Fas-induced hepatocyte apoptosis.

Antioxidative CXXC Peptide Motif From Mesencephalic Astrocyte-Derived Neurotrophic Factor Antagonizes Programmed Cell Death.

Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a potent survival-promoting protein with neurorestorative effect for neurodegenerative diseases. Its mechanism of action, albeit poorly known, depends strongly on the CXXC motif (CKGC). Here we studied the survival-promoting properties of the CKGC tetrapeptide from MANF. In the Jurkat T lymphocytic cell line, CKGC potently inhibits death receptor Fas-induced apoptosis and mildly counteracts mitochondrial apoptosis and necroptosis. The peptide with serines instead of cysteines (SKGS) has no survival-promoting activity. The cytoprotective efficiency of the peptide against Fas-induced apoptosis is significantly improved by reduction of its cysteines by dithiotreitol, suggesting that it protects the cells via cysteine thiol groups, partially as an antioxidant. CKGC neutralizes the reactive oxygen species, maintains the mitochondrial membrane potential and prevents activation of the effector caspases in the Jurkat cells with activated Fas. The peptide does not require intracellular administration, as it is endocytosed and resides mainly in the Golgi. Finally, the peptide also potently promotes survival of cultured primary dopaminergic neurons.

STAT3 inhibition induces Bax-dependent apoptosis in liver tumor myeloid-derived suppressor cells.

Immunosuppressive myeloid-derived suppressor cells (MDSC) subvert antitumor immunity and limit the efficacy of chimeric antigen receptor T cells (CAR-T). Previously, we reported that the GM-CSF/JAK2/STAT3 axis drives liver-associated MDSC (L-MDSC) proliferation and blockade of this axis rescued antitumor immunity. We extended these findings in our murine liver metastasis (LM) model, by treating tumor-bearing mice with STAT3 inhibitors (STATTIC or BBI608) to further our understanding of how STAT3 drives L-MDSC suppressive function. STAT3 inhibition caused significant reduction of tumor burden as well as L-MDSC frequencies due to decrease in pSTAT3 levels. L-MDSC isolated from STATTIC or BBI608-treated mice had significantly reduced suppressive function. STAT3 inhibition of L-MDSC was associated with enhanced antitumor activity of CAR-T. Further investigation demonstrated activation of apoptotic signaling pathways in L-MDSC following STAT3 inhibition as evidenced by an upregulation of the pro-apoptotic proteins Bax, cleaved caspase-3, and downregulation of the anti-apoptotic protein Bcl-2. Accordingly, there was also a decrease of pro-survival markers, pErk and pAkt, and an increase in pro-death marker, Fas, with activation of downstream JNK and p38 MAPK. These findings represent a previously unrecognized link between STAT3 inhibition and Fas-induced apoptosis of MDSCs. Our findings suggest that inhibiting STAT3 has potential clinical application for enhancing the efficacy of CAR-T cells in LM through modulation of L-MDSC.

Stress of Strains: Inbred Mice in Liver Research.

Inbred mice are the most popular animals used for in vivo liver research. These mice are genetically defined, readily available, less expensive to maintain than larger animals, and enjoy a broad array of commercial reagents for scientific characterization. C57BL/6 mice are the most commonly used strain. However, other strains discussed, including BALB/c, C3H, A/J, and FVB/N, may be better suited to a particular disease model or line of investigation. Understanding the phenotypes of different inbred mouse strains facilitates informed decision making during experimental design. Model systems influenced by strain-dependent phenotype include tissue regeneration, drug-induced liver injury (DILI; e.g., acetaminophen), fibrosis (e.g., carbon tetrachloride, CCl₄), Fas-induced apoptosis, cholestasis, alcohol-induced liver disease and cirrhosis, nonalcoholic fatty liver disease and steatohepatitis (NAFLD/NASH), and hepatocellular carcinoma (HCC). Thoughtful consideration of the strengths and weaknesses of each inbred strain in a given model system will lead to more robust data and a clearer understanding of translational relevance to human liver disease.

Uncovering Cellular retinoic acid-binding protein 2 as a potential target for rheumatoid arthritis synovial hyperplasia

Rheumatoid arthritis (RA) is a systemic autoimmune disease including synovitis and synovial hyperplasia that contribute to joint destruction. Pivotal pathogenic mechanisms in this process are the dysregulated proliferation and apoptosis of fibroblast-like synoviocytes (FLS). Unfortunately, the mechanisms of FLS dysregulation are not completely elucidated. Here, we explored a new hypothesis based in the potent anti-proliferative and pro-apoptotic activity of retinoids in some types of cancer. Specifically, we investigated the role of retinoids and of the retinoic acid binding proteins, CRABP2 and FABP5, on the proliferation and apoptosis of FLS from RA by adding all-trans retinoic acid (ATRA) or silencing CRABP2 and FABP5. We showed an unconventional behaviour of RA FLS, which were relatively insensitive to ATRA. In effect, ATRA increased the resistance to apoptosis despite the high CRABP2/FABP5 ratio of RA FLS; and CRABP2 suppression sensitized RA FLS to Fas-induced apoptosis. This latter effect was associated with changes in expression of kinases, ASK1 up-regulation and ERK down-regulation, and increased phosphorylation of JNK. In addition, the potentiation of FLS apoptosis by CRABP2 silencing persisted in the presence of pro-inflammatory mediators, TNF e IL1β. Therefore, the results point to CRABP2 as a potential target to decrease synovial hyperplasia in RA.