Research progress in RIPK3 and its inhibitors / 中国药理学通报

Receptor-interacting serine/threonine-protein kinase 3(RIPK3),a member of the RIP kinase family,plays an important role in cell death,especially in necroptosis. In addition,RIPK3 is also involved in apoptosis and pyroptosis,suggesting that RIPK3 may be the intersection of multiple cell death and it possesses the potential to be a target for precise regulation of cell death. According to the kinase binding mode,current RIPK3 inhibitors can be classified into type ,type Ⅱ and other types. This review summarizes the research progress in the role of RIPK3 in cell death and its inhibitors,which is of great significance in seeking drugs for the treatment of injury-related diseases.

Effect of naringenin regulating RIP1-RIP3-MLKL signaling pathway on apoptosis of ovarian granulosa cells in rats with polycystic ovary syndrome / 中国药理学通报

Aim Based on the apoptotic pathway mediated by receptor interacting protein kinase(RIP)1-RIP3-mixed spectrum kinase domain like protein(MLKL), to explore the effects of naringenin on ovarian granulosa cell apoptosis in rats with polycystic ovary syndrome(PCOS). Methods SD rats were randomly assigned into normal control group, model group, naringenin group, RIP1 inhibitor(Nec-1)group, RIP1-RIP3-MLKL necrosis signal activator(Z-VAD-fmk)group, naringenin+Z-VAD-fmk group, 15 rats per group. ELISA method was performed to measure the levels of IL-1β and TNF-α in ovarian tissue. HE method was performed to observe the shape of the ovary. Granular cells were isolated from ovarian tissue, and flow cytometry was performed to measure apoptosis rate and necrosis rate. Immunohistochemistry was performed to measure the positive expression of p-RIP1 in ovarian tissue. Western blot was employed to detect the expression of RIP1-RIP3-MLKL pathway. Results RIP1 specific inhibitor Nec-1 and naringenin could block the phosphorylation and activation of RIP1, inhibit the RIP1-RIP3-MLKL signaling pathway, reduce the inflammation level in PCOS rats, and alleviate the necrosis and apoptosis of ovarian granulosa cells(P<0.05). Z-VAD-fmk could promote the activation of RIP1-RIP3-MLKL pathway, aggravate the apoptosis of ovarian granulosa cells, and partially weaken the anti-apoptosis effect of naringenin(P<0.05). Conclusions Naringenin may inhibit the apoptosis of ovarian granulosa cells in PCOS rats by blocking the activation of the necrotic apoptotic pathway mediated by RIP1-RIP3-MLKL.

Structure-based development of potent and selective type-II kinase inhibitors of RIPK1

Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) functions as a key regulator in inflammation and cell death and is involved in mediating a variety of inflammatory or degenerative diseases. A number of allosteric RIPK1 inhibitors (RIPK1i) have been developed, and some of them have already advanced into clinical evaluation. Recently, selective RIPK1i that interact with both the allosteric pocket and the ATP-binding site of RIPK1 have started to emerge. Here, we report the rational development of a new series of type-II RIPK1i based on the rediscovery of a reported but mechanistically atypical RIPK3i. We also describe the structure-guided lead optimization of a potent, selective, and orally bioavailable RIPK1i, 62, which exhibits extraordinary efficacies in mouse models of acute or chronic inflammatory diseases. Collectively, 62 provides a useful tool for evaluating RIPK1 in animal disease models and a promising lead for further drug development.

Resveratrol Prevents Vibrio vulnificus-Induced Sepsis by Attenuating Necroptosis / 生物医学与环境科学（英文）

OBJECTIVE@#This study investigated how the natural phytophenol and potent SIRT1 activator resveratrol (RSV) regulate necroptosis during Vibrio vulnificus (V. vulnificus)-induced sepsis and the potential mechanism.@*METHODS@#The effect of RSV on V. vulnificus cytolysin (VVC)-induced necroptosis was analyzed in vitro using CCK-8 and Western blot assays. Enzyme-linked immunosorbent assays and quantitative real-time polymerase chain reaction, western blot, and immunohistochemistry and survival analyses were performed to elucidate the effect and mechanism of RSV on necroptosis in a V. vulnificus-induced sepsis mouse model.@*RESULTS@#RSV relieved necroptosis induced by VVC in RAW264.7 and MLE12 cells. RSV also inhibited the inflammatory response, had a protective effect on histopathological changes, and reduced the expression level of the necroptosis indicator pMLKL in peritoneal macrophages, lung, spleen, and liver tissues of V. vulnificus-induced septic mice in vivo. Pretreatment with RSV downregulated the mRNA of the necroptosis indicator and protein expression in peritoneal macrophages and tissues of V. vulnificus-induced septic mice. RSV also improved the survival of V. vulnificus-induced septic mice.@*CONCLUSION@#Our findings collectively demonstrate that RSV prevented V. vulnificus-induced sepsis by attenuating necroptosis, highlighting its potency in the clinical management of V. vulnificus-induced sepsis.

Protective role and mechanism of human umbilical cord mesenchymal stem cell-derived exosome in renal ischemia-reperfusion injury / 器官移植

Objective To investigate the protective effect of human umbilical cord mesenchymal stem cell-derived exosome (hucMSC-Exo) on renal ischemia-reperfusion injury (IRI), and to clarify the critical role and regulating mechanism of transient receptor potential canonical (TRPC) 6/poly adenosine-diphosphate-ribose polymerase (PARP) 1 signaling pathway during this process. Methods The hucMSC-Exo was extracted by ultracentrifugation, and identified by transmission electron microscope (TEM), nanoparticle tracing analysis and Western blot. SD rats were randomly divided into the sham operation group (group S), sham operation+TRPC6 inhibitor SKF96365 group (group SS), renal IRI group (group IRI), exosome treatment group (group EXO) and exosome +TRPC6 inhibitor SKF96365 group (group ES), with 6 rats in each group. Serum creatinine and blood urea nitrogen levels were detected. Pathological changes of renal tissues were observed by hematoxylin-eosin (HE) staining and Paller score was calculated. The expression levels of key molecules of necroptosis in rat renal tissues, including receptor-interacting protein kinase (RIPK)1, RIPK3 and mixed-lineage kinase domain-like protein (MLKL), TRPC6 and PARP1, were detected by Western blot. Results Typical saucer-like structure was observed under TEM. Nanoparticle tracing analysis showed that the average diameter of the extracted substance was 125.9 nm. Western blot revealed that the surface markers of CD9, CD63 and CD81 were positively expressed, confirmed that the extracted substance was exosome. Compared with group S, the serum creatinine and blood urea nitrogen levels were up-regulated, the pathological damage of renal tissues was worsened, Paller score was elevated, the relative expression levels of TRPC6 and PARP1 proteins were down-regulated, and the relative expression levels of RIPK1, RIPK3 and MLKL proteins were up-regulated in group IRI (all P < 0.05). Compared with group IRI, the serum creatinine and blood urea nitrogen levels were down-regulated, the pathological damage of renal tissues was mitigated, Paller score was decreased, the relative expression levels of TRPC6 and PARP1 proteins were up-regulated, and the relative expression levels of RIPK1, RIPK3 and MLKL proteins were down-regulated in group EXO (all P < 0.05). Compared with group EXO, the serum creatinine and blood urea nitrogen levels were up-regulated, the pathological damage of renal tissues was aggravated, Paller score was increased, the relative expression levels of TRPC6 and PARP1 proteins were down-regulated, and the relative expression levels of RIPK1, RIPK3 and MLKL proteins were up-regulated in group ES (all P < 0.05). Conclusions hucMSC-Exo may alleviate the necroptosis induced by renal IRI in rat models, which is related to the activation of TRPC6/PARP1 signaling pathway.

Progress in study on the final executor of necroptosis MLKL and its inhibitors / 中南大学学报(医学版)

Necroptosis is one of the regulated cell death, which involves receptor interacting protein kinase (RIPK) 1/RIPK3/mixed lineage kinase domain like protein (MLKL) signaling pathway. Among them, MLKL is the final execution of necroptosis. The formation of RIPK1/RIPK3/MLKL necrosome induces the phosphorylated MLKL, and the activated MLKL penetrates into the membrane bilayer to form membrane pores, which damages the integrity of the membrane and leads to cell death. In addition to participating in necroptosis, MLKL is also closely related to other cell death, such as NETosis, pyroptosis, and autophagy. Therefore, MLKL is involved in the pathological processes of various diseases related to abnormal cell death pathways (such as cardiovascular diseases, neurodegenerative diseases and cancer), and may be a therapeutic target of multiple diseases. Understanding the role of MLKL in different cell death can lay a foundation for seeking various MLKL-related disease targets, and also guide the development and application of MLKL inhibitors.

PANoptosis： Molecular Mechanism of Action and Effects on Blinding Eye Diseases / 中山大学学报(医学科学版)

Previous studies focused on the unique regulatory mechanisms of different cell death pathways. However， recent studies highlight crosstalk and co-ordination between these pathways and initiate a new cell death process called PANoptosis （pyroptosis， apoptosis， necroptosis）. PANoptosis is an inflammatory programmed cell death pathway regulated by the PANoptosome complex with critical features of pyroptosis， and/or necroptosis but cannot be characterized by any of the death modes of pyroptosis， apoptosis or necroptosis alone. By activating the PANoptosis pathway， some triggers like bacterial， viral， and fungal infections can cause death of the host. This review explains the PANoptosis-related routes， regulators and their potential effects on blinding eye diseases.

Advances on mechanisms of regulated cell death in neurotoxicity of aluminum / 环境与职业医学

Aluminum is a light metal which is rich in the earth's crust and widely used. Recently, the adverse health effects of environmental and occupational aluminum exposure on human have attracted more and more attention. Aluminum exposure has toxic effects on the central nervous system and is believed to be closely related to the development and progression of Alzheimer's disease. The neurotoxic mechanism of aluminum is complex, especially the role of regulated cell death (RCD) in aluminum-induced neuronal death remains to be further studied. RCD refers to all modes of cell death regulated by multiple intracellular signal transduction pathways under physiological and pathological conditions, including apoptosis, necroptosis, autophagy, pyroptosis, and ferroptosis. This review summarized the morphological characteristics and mechanisms of each RCD mode in the process of aluminum-induced neuronal death, and discussed the relationship and transformation between different RCD modes, providing a new scientific basis for future studies on the treatment and intervention of neurotoxicity induced by aluminum exposure.

A preliminary study on the effect of arsenic exposure on necroptosis of mouse myocardial cells / 中华地方病学杂志

Objective:To study the effects of arsenic exposure on necroptosis pathway and inflammatory response of mouse myocardial cells.Methods:Sixty male C57BL/6J mice were randomly divided into control group (group C) and low, medium, and high dose arsenic exposure groups (groups L, M, H) based on body weight using a random number table method. Each group had 15 mice, and they drank 0.00, 0.15, 1.50, and 15.00 mg/L arsenic trioxide (As 2O 3) solution prepared with deionized water. The exposure period was 12 weeks. Hematoxylin-eosin (HE) staining and Masson trichrome staining of paraffin-embedded heart tissues were used to observe the histopathology changes of the heart. Transmission electron microscopy (TEM) was used to evaluate the ultrastructural changes of myocardial cells. The quantitative real-time PCR (qRT-PCR) was used to detect the mRNA expression of inflammatory genes [tumor necrosis factor (TNF)-α and interleukin(IL)-6] and the genes involved in necroptosis pathway [receptor-interacting protein (RIP) 1, RIP3 and mixed-lineage kinase domain-like protein (MLKL)]. Protein expressions of RIP1 and RIP3 in the heart were assessed by western blotting. Results:Histopathological examination results showed there were myocardial necrosis, inflammatory cells infiltration and fibroblasts hyperplasia and other changes in groups M and H. TEM analysis revealed marked ultrastructural changes in groups M and H, including fractured myofibril, fractured Z lines of sarcomere, and swollen mitochondria with fractured cristae. Compared with group C (1.00 ± 0.00), the mRNA expression of RIP1 in group H was significantly up-regulated (1.41 ± 0.06, P < 0.05); the mRNA expressions of RIP3 (1.29 ± 0.14, 1.56 ± 0.08), MLKL (1.23 ± 0.05, 1.36 ± 0.07), TNF-α (2.20 ± 0.10, 2.23 ± 0.18) and IL-6 (1.87 ± 0.16, 1.63 ± 0.15) were significantly up-regulated in groups M and H ( P < 0.05). The protein expressions of RIP1 (0.43 ± 0.04, 0.50 ± 0.04) and RIP3 (0.68 ± 0.02, 0.84 ± 0.05) in groups M and H were higher than those in group C (0.25 ± 0.01, 0.45 ± 0.04, P < 0.05). Conclusion:Subchronic arsenic exposure induces histopathological changes such as myocardial necrosis and fibrosis in mice, inducing necroptosis and inflammatory reactions in myocardial cells.

Effects and mechanisms of total flavones of Abelmoschus manihot in inhibiting podocyte necroptosis and renal fibrosis in diabetic kidney disease / 中国中药杂志

Previous studies have shown that high blood glucose-induced chronic microinflammation can cause inflammatory podocyte injury in patients with diabetic kidney disease(DKD). Therein, necroptosis is a new form of podocyte death that is closely associated with renal fibrosis(RF). To explore the effects and mechanisms in vivo of total flavones of Abelmoschus manihot(TFA), an extract from traditional Chinese herbal medicine Abelmoschus manihot for treating kidney diseases, on podocyte necroptosis and RF in DKD, and to further reveal its scientific connotation with multi-pathway and multi-target, the authors randomly divided all rats into four groups: a namely normal group, a model group, a TFA group and a rapamycin(RAP) group. After the modified DKD rat models were successfully established, four group rats were given double-distilled water, TFA suspension and RAP suspension, respectively by gavage every day. At the end of the 4th week of drug treatment, all rats were sacrificed, and the samples of their urine, blood and kidneys were collected. And then, the various indicators related to podocyte necroptosis and RF in the DKD model rats were observed, detected and analyzed, respectively. The results indicated that, general condition, body weight(BW), serum creatinine(Scr), urinary albumin(UAlb), and kidney hypertrophy index(KHI) in these modified DKD model rats were both improved by TFA and RAP. Indicators of RF, including glomerular histomorphological characteristics, fibronectin(FN) and collagen type Ⅰ(collagen Ⅰ) staining extent in glomeruli, as well as the protein expression levels of FN, collagen Ⅰ, transforming growth factor-β1(TGF-β1) and Smad2/3 in the kidneys were improved respectively by TFA and RAP. Podocyte damage, including foot process form and the protein expression levels of podocin and CD2AP in the kidneys was improved by TFA and RAP. In addition, tumor necrosis factor-α(TNF-α)-mediated podocyte necroptosis in the kidneys, including the morphological characteristics of podocyte necroptosis, the extent and levels of the protein expression of TNF-α and phosphorylated mixed lineage kinase domain like pseudokinase(p-MLKL) was improved respectively by TFA and RAP. Among them, RAP had the better effect on p-MLKL. More importantly, the activation of the receptor interacting serine/threonine protein kinase 1(RIPK1)/RIPK3/MLKL signaling axis in the kidneys, including the expression levels of its key signaling molecules, such as phosphorylated receptor interacting serine/threonine protein kinase 1(p-RIPK1), p-RIPK3, p-MLKL and cysteinyl aspartate specific proteinase-8(caspase-8) was improved respectively by TFA and RAP. Among them, the effect of TFA on p-RIPK1 was superior. On the whole, in this study, the authors demonstrated that TFA alleviates podocyte necroptosis and RF in DKD through inhibiting the activation of the TNF-α-mediated RIPK1/RIPK3/MLKL signaling axis in diabetic kidneys. The authors' findings provide new pharmacological evidence to reveal the scientific connotation of TFA in treating RF in DKD in more depth.

Progress of Different Programmed Cell Death Pathways in Kidney Cancer / 肿瘤防治研究

Programmed cell death (PCD) is a genetically determined, active and orderly cell death in the organism, and it affects the evolution of the organism, maintenance of its homeostasis, and development of several tissues and organs. The abnormal regulation of this process is closely related to various human diseases, including cancer. The identified pathways of PCD include apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis, which can be activated when cells are stimulated by various internal and external environmental factors. These pathways can induce cell death or maintain cell survival in kidney cancer cells under the regulation of various signaling molecules, thus affecting tumor progression or therapeutic efficacy. In this paper, the role of these PCD pathways in the development of kidney cancer was reviewed in light of recent research advances to provide new directions for the in-depth study of the pathogenesis of kidney cancer and the development of targeted antitumor drugs.

Polissacarídeos de Lentinula edodes suprimem a expressão de citocinas pró-inflamatórias e de colite em camundongos / Lentinula edodes polysaccharides suppressed pro-inflammatory cytokines expression and colitis in mice

ABSTRACT Background: Polysaccharides from edible mushrooms possess immunomodulatory, anti-inflammatory, and anti-tumor activities. Recent studies indicated that necroptosis plays a role in the pathogenesis of inflammatory diseases and mediates increased expression of inflammatory cytokines. Objective: Therefore, it is imperative to determine the impact of polysaccharide extract from Lentinula edodes (L. edodes) on inflammatory cytokines in experimental model of colitis in mice. Methods: Female C57BL/6 mice divided into three or four mice per group were used for this study. Polysaccharide sample was orally administered to mice prior to (7 days) and during colitis induction with 2.5% dextran sodium sulfate (7 days), followed by additional 3 days of administration. Changes in body weight and colon length were used as markers for colitis, and pro-inflammatory cytokines and tumor necrosis factor receptor 1 (TNFR1) expressions, as well as necroptosis were analyzed in the colon of colitis mice. Data obtained were analysed by Tukey-Kramer and two-tailed standard t tests. Results: The results indicated that the polysaccharide sample suppressed colitis in mice using effects on the body weight and colon length as markers. Also, it was demonstrated that necrostatin-1, a specific inhibitor of necroptosis, suppressed the expression of interleukin (IL)-8, a pro-inflammatory chemokine, in Caco-2 cells induced necroptosis induced by zVAD and TNF-α, an indication that necroptosis may be involved in the expression of pro-inflammatory cytokines. Moreover, the polysaccharide sample suppressed the expression of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, IL-6, IL-1β, and interferon (IFN)-γ in the colon of mice. Conclusion: These results suggested that the suppressive effects of the polysaccharide sample on inflammatory cytokines expression may contribute to its anti-colitis effect, and so may serve as a potent therapeutic agent against inflammatory bowel disease.

RESUMO Contexto: Polissacarídeos de cogumelos comestíveis possuem atividades imunomodulatórias, anti-inflamatórias e anti-tumorais. Estudos recentes indicaram que a necroptose desempenha um papel na patogênese de doenças inflamatórias e regula o aumento da expressão de citocinas inflamatórias. Objetivo: Torna-se imprescindível determinar o impacto do extrato de polissacarídeo de Lentinula edodes (L. edodes) em citocinas inflamatórias em modelo experimental de colite em camundongos. Métodos: Foram utilizados para este estudo os camundongos C57BL/6 femininos divididos em três ou quatro camundongos por grupo. A amostra de polissacarídeo foi administrada oralmente em camundongos antes (7 dias) e durante a indução de colite com sulfato de dextran sulfato de sódio (7 dias), seguido por 3 dias adicionais de administração. Alterações no peso corporal e comprimento do cólon foram utilizadas como marcadores para colite, e citocinas pró-inflamatórias e tumores receptor fator 1 (TNFR1), bem como necroptose foram analisadas no cólon de camundongos colite. Os dados obtidos foram analisados por testes Tukey-Kramer e testes padrão t de duas caudas. Resultados: Os resultados indicaram que a amostra de polissacarídeo suprimiu colite em camundongos usando efeitos sobre o peso corporal e o comprimento do cólon como marcadores. Além disso, foi demonstrado que a necrostatina-1, inibidora específica da necroptose, suprimiu a expres são de interleucina (IL)-8, uma quimiocina pró-inflamatória, em células caco-2 induzidas necroptose induzidas por zVAD e TNF-α, uma indicação de que a necroptose pode estar envolvida na expressão de citocinas pro-inflamatórias. Além disso, a amostra de polissacarídeo suprimiu a expressão de citocinas pró-inflamatórias, como o fator de necrose tumoral (TNF)-α, IL-6, IL-1β e interferon (IFN)-γ no cólon dos camundongos. Conclusão: Esses resultados sugeriram que os efeitos supressivos da amostra de polissacarídeo na expressão de citocinas inflamatórias podem contribuir para o seu efeito anti-colite, podendo, portanto, servir como um potente agente terapêutico contra doença inflamatória intestinal.

Research progress of phosphoglycerate mutase 5-mediated mitophagy and necroptosis / 中华危重病急救医学

Mitophagy is the selective degradation of damaged mitochondria, and it is of great significance to maintain the normal quantity and quality of mitochondria to ensure cell homeostasis and survival. Necroptosis is a type of programmed cell necrosis that can be induced by excessive mitophagy. Reactive oxygen species (ROS) are produced mainly by mitochondria and can damage mitochondria. Hyperoxic acute lung injury (HALI) is a serious complication of clinical oxygen therapy, and its pathogenesis is not clear. Existing studies have shown that mitophagy and necroptosis are involved in the occurrence of HALI. There are many mechanisms regulating mitophagy and necroptosis, including tumor necrosis factor-α (TNF-α), E3 ubiquitin protein ligase (PINK1/Parkin) protein pathway encoded by PTEN-induced kinase 1/PARK2 gene, phosphoglycerate mutase 5 (PGAM5), etc. PGAM5 has been proved to be a key factor linking mitophagy and necroptosis. Previous studies of our team found that the mechanism of microRNA-21-5p (miR-21-5p) alleviating HALI was related to its pGAM5-mediated inhibition of mitophagy, but the mechanism of PGAM5-mediated mitophagy and necroptosis remains unclear. Therefore, this paper reviews the targets of PGAM5-mediated mitophagy and necroptosis, in order to find clues of lung protection of pGAM5-mediated mitophagy and necroptosis in HALI, and provide theoretical basis for subsequent basic research.

Necroptosis in inflammatory bowel disease: A potential effective target / 中南大学学报(医学版)

The morbidity of inflammatory bowel diseases (IBD) is rising rapidly but no curative therapies to prevent its recurrence. Cell death is crucial to maintaining homeostasis. Necroptosis is a newly identified programmed cell death and its roles played in IBD need to be explored. Necroptosis is mediated by receptor interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL), which resulted in cell swelling, plasma membrane rupture, intracellular content leaking, and eventually cell death as well as the promotion of inflammation. Studies have found that inhibiting necroptosis alleviated IBD in animal models and IBD patients with an increased level of necroptosis in inflammatory tissues, indicating that necroptosis is related to the pathogenesis of IBD. However, due to the complexity in regulation of necroptosis and the involvement of multiple functions of relevant signaling molecules, the specific mechanism remains elusive. Necroptosis may play a vital regulatory role in the pathogenesis of IBD, which provides a new idea and method for further exploring the therapeutic target of IBD.

Progress in RIPK3-mediated necroptosis involved in myocardial ischemia-reperfusion injury / 中国药理学通报

Aim Timely re establishment of coronary blood How in patients with myocardial infarction is the cornerstone of their treatment; however, substantial amount of damage can oecur as a consequence of reperfusion.In recent years it has been found that receptor interacting protein kinase 3 ( RIPK3 ) contributes remarkably to myocardial ischemia-reperfusion injury (MIRI).RIPK3 can regulate necroptosis through RIPK1/RIPK3/MLKL and CaMKII, respectively, and participate in the MIRI process.This artiele reviews the researeh progress of RIPK3-mediated ne¬ croptosis involved in MIRI from endoplasmic reticulum stress, mitochondrial fragmentation disturbanee, cardiac microvascular dysfunction and inflammation, and focuses on whether RIPK3 can be used as a new target for anti-MIRI, so as to provide a new strategy and choice for improving the clinical treatment effect and prognosis of ischemic heart disease.

Berberine alleviates programmed necrosis of metabolic-associated fatty liver disease via activating Nrf2 pathway in mice / 中华肝脏病杂志

Objective: To investigate the effect of berberine on programmed necrosis of hepatocytes induced by metabolic-associated fatty liver disease (MAFLD) in mice and its related molecular mechanism. Methods: Twenty male C57BL/6N mice were randomly divided into four groups (n=5 in each group): control group (S), fatty liver group (H), berberine group(B), nuclear factor erythroid 2-related factor 2 inhibitor group (Nrf2), and all-trans-retinoic acid (ATRA) group (A). Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), triglycerides (TG), total cholesterol (TC), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) concentrations were detected at the end of week 12 to calculate fatty liver index (liver mass/body mass ratio). Liver tissue was stained with HE, Masson and Oil Red O, and SAF score was used to evaluate the degree of liver injury. The expression levels of hepatic programmed necrosis-related proteins, namely receptor-interacting protein kinase 3 (RIPK3), phosphorylated mixed series protease-like domain (p-MLKL) and Nrf2 were detected by Western blot method. One-way ANOVA was used for intragroup comparisons and LSD-t tests were used for intergroup comparisons. Results: Compared with S group, H group serum ALT, AST, LDH, TG, TC, TNF-α, IL-1β levels and fatty liver index were significantly increased. The liver tissue was filled with vacuolar-like changes and inflammatory cell infiltration. Numerous red lipid droplets were observed with oil red O staining. Collagen fiber hyperplasia was evident with Masson staining. SAF scores (6.60 ± 0.55 and 0.80 ± 0.45) were significantly increased. The expressions of RIPK3 and p-MLKL were up-regulated. Nrf2 level was relatively increased, and the differences were statistically significant (P < 0.05). Compared with H group, berberine intervention group liver biochemical indexes, lipid levels, pro-inflammatory mediator expression, fatty liver index, and SAF score were significantly reduced, and the expression of RIPK3 and p-MLKL were down-regulated, while Nrf2 levels were further increased, and the differences were statistically significant (P<0.05). Compared with B group, treatment with Nrf2 inhibitor had antagonized the protective effect of berberine on fatty liver. Serum ALT, AST, LDH, TG, TC and TNF-α, IL-1β levels, fatty liver index, and SAF scores were significantly increased and the expressions of RIPK3 and p-MLKL were relatively increased, and the differences were statistically significant (P < 0.05). Conclusion: Berberine can significantly improve the metabolic-associated fatty liver disease injury in mice, and its mechanism is related to activation of Nrf2 and inhibition of programmed necrosis of hepatocytes.

Experimental study on necroptosis of osteoblasts induced by fluoride / 中华地方病学杂志

Objective:To investigate whether the necroptosis pathway receptor interacting protein 1-receptor interacting protein 3-mixed lineage kinase domain-like protein (RIP1-RIP3-MLKL) is involved in fluoride-induced osteoblastic death.Methods:Human osteosarcoma cell line (Saos-2 cells) were cultured in vitro and divided into NC group, sodium fluoride (NaF) groups (5.0, 10.0, 20.0 and 40.0 mg/L NaF), necroptosis inhibitor Necrostatin-1 (Nec-1) group (50.0 μmol/L Nec-1) and NaF + Nec-1 groups (5.0, 10.0, 20.0 and 40.0 mg/L NaF + 50.0 μmol/L Nec-1). After cultured for 24 and 48 h, respectively, cell proliferation was determined via the CCK-8 method, and the activity of lactate dehydrogenase (LDH) was determined by chemical colorimetry. To further analyze the influence of NaF on RIP1-RIP3-MLKL pathway, Saos-2 cells were divided into NCⅡgroup and NaFⅡgroups (2.5, 5.0, 10.0, 20.0 and 40.0 mg/L NaF). After cultured for 24 and 48 h, respectively, the protein expression levels of RIP1, RIP3 and MLKL were determined by Western blotting. Results:The cell proliferation rates (%: 100.00 ± 0.59, 104.90 ± 0.44, 104.16 ± 0.41, 82.45 ± 1.91, 64.59 ± 1.83, 103.56 ± 0.41, 107.18 ± 0.87, 105.35 ± 1.28, 89.63 ± 1.20, 77.51 ± 1.30; 100.00 ± 0.33, 107.92 ± 0.44, 101.78 ± 1.06, 75.45 ± 0.39, 57.94 ± 1.17, 106.74 ± 0.21, 111.85 ± 0.21, 107.82 ± 0.68, 82.34 ± 0.56, 70.19 ± 0.99) among all groups were significantly different at both 24 and 48 h ( F = 77.13, 2 313.43, P < 0.05). Except the cell proliferation rate of the 10.0 mg/L NaF + Nec-1 group that was not significantly different with that of the 10.0 mg/L NaF group at 24 h ( P > 0.05), the cell proliferation rates of other NaF + Nec-1 groups were significantly higher than those of corresponding NaF groups at both 24 and 48 h ( P < 0.05). The proliferation rate was negatively correlated with fluoride concentration ( r24 h = - 0.976, r48 h = - 0.969, P < 0.001). The LDH activity in all concentrations of NaF groups was significantly higher than that in NC group and corresponding NaF + Nec-1 groups at both 24 and 48 h ( P < 0.05). The LDH activity was positively correlated with fluoride concentration ( r24 h = 0.985, r48 h = 0.988, P < 0.001). The protein expression levels of RIP1, RIP3 and MLKL of 5.0 mg/L NaFⅡ group at 24 h, RIP3 of 5.0 mg/L NaFⅡ group at 48 h, and RIP1, RIP3 and MLKL of 10.0, 20.0 and 40.0 mg/L NaFⅡ groups at both 24 and 48 h were higher than that in NCⅡ group ( P < 0.05). The protein expression levels of RIP1, RIP3 and MLKL were positively correlated with fluoride concentration ( r24 h-RIP1 = 0.881, r48 h-RIP1 = 0.952, r24 h-RIP3 = 0.867, r48 h-RIP3 = 0.938, r24 h-MLKL = 0.758, r48 h-MLKL = 0.907, P < 0.001). Conclusion:Fluoride can directly cause necroptosis of osteoblasts through the RIP1-RIP3-MLKL pathway, and the severity of cell damage is closely related to fluoride concentration, Nec-1 has partially reversed the effects of fluoride.

Inhibitory effect of necrostatin-1 on necroptosis of retinal ganglion cells in rats with acute ocular hypertension / 中华实验眼科杂志

Objective:To investigate the inhibitory effect of specific inhibitor of necroptosis necrostatin-1 (Nec-1) on necroptosis of retinal ganglion cells (RGCs) in rats with acute ocular hypertension.Methods:Twenty-four adult male Sprague Dawley rats were randomly divided into normal control group, model control group, Nec-1 treatment group and negative control group by random number table method, with 6 rats in each group.High intraocular pressure (IOP)-induced ischemia and reperfusion model was established through anterior chamber irrigation of 0.9% sodium chloride solution in left eyes of the rats, raising the IOP to 110 mmHg (1 mmHg=0.133 kPa) for 60 minutes.Nec-1 (4 mmol/L, 2 μl) or dimethyl sulfoxide (2 μl) was intravitreally injected immediately in Nec-1 treatment group and negative control group following modeling, respectively, according to grouping.No intervention was administered to the normal control group.Paraffin sections of rat retinas of the left eyes in different groups were prepared seven days after modeling.The retinal structure was observed by hematoxylin-eosin staining, and the expression levels of thymocyte antigen-1 (Thy-1) and glial fibrillary acidic protein (GFAP) were detected via immunohistochemical staining.All animal experiments were approved by an Ethics Committee of Tianjin Union Medical Center (No.2017 Quick audit C01).Results:Seven days after modeling, compared with normal control group, the retinal nerve fiber layer was thinner in model control group and negative control group, and the RGCs were arranged loosely, and cells in the inner nuclear layer were reduced and arranged disorderly, and cells in the outer nuclear layer were normal or enlarged.Compared with model control group and negative control group, the nerve fiber layer was thickened and the number of RGCs was significantly increased in Nec-1 treatment group.The number of Thy-1-positive RGCs was decreased in model control group, negative control group and Nec-1 treatment group than normal control group, and there were more Thy-1-positive RGCs in Nec-1 treatment group than model control group and negative control group.The integrated absorbance ( A) value of GFAP protein in normal control group, model control group, negative control group and Nec-1 treatment group was 47.209±15.311, 116.220±18.194, 116.382±19.020, 92.818±10.236, respectively, showing statistically significant differences among them ( F=24.675, P<0.001). The integrated A value of GFAP protein was significantly increased in model control group, negative control group and Nec-1 treatment group than normal control group, and the integrated A value of GFAP protein in Nec-1 treatment group was lower than that in model control group and negative control group, with statistically significant differences (all at P<0.05). Conclusions:Nec-1 can promote RGCs survival by inhibiting the necroptosis of RGCs in rats with acute intraocular hypertension.

Cellular FLICE-like inhibitory protein alleviates myocardial ischemia/reperfusion injury via inhibiting necroptosis / 中华急诊医学杂志

Objective:To explore the regulatory effect of cellular FLICE-like inhibitory protein (cFLIP) on myocardial ischemia-reperfusion injury based on the RIPK1/RIPK3/MLKL-mediated necroptosis pathway.Methods:The cardiomyocyte hypoxia/reoxygenation (H/R) model was constructed by hypoxia for 4 h/reoxygenation for 12 h, and the rat ischemia reperfusion (I/R) model was constructed by ligating the left anterior descending artery for 30 min and reperfusion for 3 h. CCK-8 method was used to detect the viability of cardiomyocytes in each group. DAPI/PI double staining was used to observe changes in necrosis rate of myocardial cell. STRING database was used to predict the protein interaction network of cFLIP. TTC staining was used to detect the area of myocardial infarction in each group of rats, and the protein expression of cFLIPL, cFLIPS, p-RIPK1, p-RIPK3 and p-MLKL were detected by Western blot.Results:In cardiomyocyte H/R injury and myocardial tissue I/R injury, the protein expressions of cFLIPL and cFLIPS were significantly down-regulated, while the levels of p-RIPK1, p-RIPK3 and p-MLKL were increased significantly. Up-regulating the protein expression of cFLIPL and cFLIPS could significantly reduce the damage of cardiomyocytes and the rate of cell necrosis induced by H/R, and decrease the area of myocardial infarction caused by I/R. STRING database results showed that cFLIP had direct protein interactions with RIPK1 and RIPK3. Overexpression of cFLIP in cardiomyocyte and myocardial tissue significantly inhibited H/R or I/R induced the phosphorylation levels of RIPK1, RIPK3 and MLKL.Conclusions:Overexpression of cFLIP can significantly inhibit the RIPK1/RIPK3/MLKL-mediated necroptosis, thereby reducing myocardial cell damage and decreasing the area of myocardial infarction.

Aging-elevated inflammation promotes DNMT3A R878H-driven clonal hematopoiesis

Aging-elevated DNMT3A R882H-driven clonal hematopoiesis (CH) is a risk factor for myeloid malignancies remission and overall survival. Although some studies were conducted to investigate this phenomenon, the exact mechanism is still under debate. In this study, we observed that DNMT3A R878H bone marrow cells (human allele: DNMT3A R882H) displayed enhanced reconstitution capacity in aged bone marrow milieu and upon inflammatory insult. DNMT3A R878H protects hematopoietic stem and progenitor cells from the damage induced by chronic inflammation, especially TNFα insults. Mechanistically, we identified that RIPK1-RIPK3-MLKL-mediated necroptosis signaling was compromised in R878H cells in response to proliferation stress and TNFα insults. Briefly, we elucidated the molecular mechanism driving DNMT3A R878H-based clonal hematopoiesis, which raises clinical value for treating DNMT3A R882H-driven clonal hematopoiesis and myeloid malignancies with aging.