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.
Humans ; Rats ; Animals ; Diabetic Nephropathies/drug therapy* ; Abelmoschus ; Flavones/pharmacology* ; Podocytes ; Tumor Necrosis Factor-alpha/metabolism* ; Necroptosis ; Receptor-Interacting Protein Serine-Threonine Kinases/metabolism* ; Fibrosis ; Threonine/pharmacology* ; Collagen/metabolism* ; Serine/pharmacology* ; Diabetes Mellitus/drug therapy*

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.
Protein Kinases/metabolism* ; Necroptosis/physiology* ; Receptor-Interacting Protein Serine-Threonine Kinases ; Signal Transduction ; Pyroptosis ; Apoptosis

OBJECTIVE: To explore the effect of transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) on toluene diisocyanate (TDI)-induced allergic airway inflammation in mice. METHODS: Thirty-two mice were randomly divided into AOO group, AOO+5Z-7-Oxozeaenol group, TDI group, and TDI+5Z-7-Oxozeaenol group. Another 32 mice were randomly divided into AOO group, TDI group, TDI +5Z-7-Oxozeaenol group, and TDI +5Z-7-Oxozeaenol + Necrostatin-1 group. TAK1 inhibitor (5Z-7-Oxozeaenol, 5 mg/kg) and/or RIPK1 inhibitor (Necrostatin-1, 5 mg/kg) were used before each challenge. Airway responsiveness, airway inflammation and airway remodeling were assessed after the treatments. We also examined the effect of TDI-human serum albumin (TDI-HSA) conjugate combined with TAK1 inhibitor on the viability of mouse mononuclear macrophages (RAW264.7) using CCK8 assay. The expressions of TAK1, mitogen-activated protein kinase (MAPK) and receptor interacting serine/threonine protease 1 (RIPK1) signal pathway in the treated cells were detected with Western blotting. The effects of RIPK1 inhibitor on the viability of RAW264.7 cells and airway inflammation of the mouse models of TDI-induced asthma were evaluated. RESULTS: TAK1 inhibitor aggravated TDI-induced airway inflammation, airway hyper responsiveness and airway remodeling in the mouse models (P < 0.05). Treatment with TAK1 inhibitor significantly decreased the viability of RAW264.7 cells, which was further decreased by co-treatment with TDI-HSA (P < 0.05). TAK1 inhibitor significantly decreased the level of TAK1 phosphorylation and activation of MAPK signal pathway induced by TDI-HSA (P < 0.05). Co-treatment with TAK1 inhibitor and TDI-HSA obviously increased the level of RIPK1 phosphorylation and caused persistent activation of caspase 8 (P < 0.05). RIPK1 inhibitor significantly inhibited the reduction of cell viability caused by TAK1 inhibitor and TDI-HSA (P < 0.05) and alleviated the aggravation of airway inflammation induced by TAK1 inhibitors in TDI-induced mouse models (P < 0.05). CONCLUSION Inhibition of TAK1 aggravates TDI-induced airway inflammation and hyperresponsiveness and may increase the death of macrophages by enhancing the activity of RIPK1 and causing persistent activation of caspase 8.
Animals ; Asthma/chemically induced* ; Inflammation ; Macrophages ; Mice ; Receptor-Interacting Protein Serine-Threonine Kinases ; Respiratory System ; Toluene 2,4-Diisocyanate/adverse effects*

To explore the effect and mechanism of Dahuang Zhechong Pills(DHZCP), a classical prescription, in improving testicular aging(TA) in vivo, the authors randomly divided 24 male rats into four groups: the normal, model, DHZCP and vitamin E(VE) groups. The TA rat model was established by continuous gavage of D-galactose(D-gal). During the experiment, the rats in the DHZCP and VE groups were given DHZCP suspension and VE suspension, respectively by gavage, while those in the normal and model groups were gavaged saline separately every day. After the co-administration of D-gal and various drugs for 60 days, all rats were sacrificed, and their blood and testis were collected. Further, various indexes related to TA and necroptosis of testicular cells in the model rats were examined and investigated, which included the aging phenotype, total testicular weight, testicular index, histopathological features of testis, number of spermatogenic cells, sex hormone level, expression characteristics of reactive oxygen species(ROS) in testis, expression levels and characteristics of cyclins in testis, and protein expression levels of the key molecules in receptor-interacting serine/threonine-protein kinase 1(RIPK1)/receptor-interacting serine/threonine-protein kinase 3(RIPK3)/mixed lineage kinase domain like pseudokinase(MLKL) signaling pathway in each group. The results showed that, for the TA model rats, both DHZCP and VE improved their aging phenotype, total testicular weight, testicular index, pathological features of testis, number of spermatogenic cells, serum testosterone and follicle stimulating hormone levels, expression characteristics of ROS and protein expression levels and characteristics of P21 and P53 in testis. In addition, DHZCP and VE improved the protein expression levels of the key molecules in RIPK1/RIPK3/MLKL signaling pathway in testis of the model rats. Specifically, DHZCP was better than VE in the improvement of RIPK3. In conclusion, in this study, the authors found that DHZCP, similar to VE, ameliorated D-gal-induced TA in model rats in vivo, and its mechanism was related to reducing necroptosis of testicular cells by inhibiting the activation of RIPK1/RIPK3/MLKL signaling pathway. This study provided preliminary pharmacological evidence for the development and application of classical prescriptions in the field of men's health.
Aging ; Animals ; Drugs, Chinese Herbal ; Male ; Necroptosis ; Protein Kinases/genetics* ; Rats ; Reactive Oxygen Species/metabolism* ; Receptor-Interacting Protein Serine-Threonine Kinases/pharmacology* ; Serine/pharmacology* ; Signal Transduction ; Testis ; Threonine/pharmacology*

OBJECTIVE: To investigate the expression and clinical significance of receptor interacting protein serine-threonine kinases 1 (RIPK1) in the nucleus pulposus of patients with lumbar disc herniation (LDH). METHODS: Nucleus pulposus tissue specimens of 40 patients with LDH patients underwent surgical treatment from January 2016 to January 2018 as the case group, and nucleus pulposus tissue specimens of 30 patients with lumbar spine fracture underwent surgical treatment at the same time as the control group. The expression of RIPK1 mRNA and protein of receptor interaction were detected by polymerase chain reaction (PCR) and Western blot, respectively. The expression of RIPK1 protein in the nucleus pulposus were detected by immunohistochemical staining. The concentrations of RIPK1 and tumor necrosis factor-α (TNF-α) in nucleus pulposus were detected by ELISA method. The relationship between the concentrations of RIPK1, TNF-α in nucleus pulposus and the Pearce grade of LDH patients was analyzed by one-way ANOVA. The correlation between RIPK1 and TNF-α was analyzed by Pearson. RESULTS: RIPK1 was weakly positively expressed in nucleus pulposus of control group, and RIPK1 protein was positively or strongly positively expressed in case group. The expression of RIPK1 mRNA in nucleus pulposus of case group was higher than that of control group ( CONCLUSION The expression levels of RIPK1 mRNA and protein in the intervertebral disc tissues of LDH patients are higher than those of normal intervertebral disc tissues, and increased with the increase of Pearce grade, which may be an important factor involved in LDH inflammatory disease.
Humans ; Intervertebral Disc/metabolism* ; Intervertebral Disc Degeneration ; Intervertebral Disc Displacement/genetics* ; Nucleus Pulposus ; Receptor-Interacting Protein Serine-Threonine Kinases/genetics* ; Tumor Necrosis Factor-alpha/metabolism*

There remains a significant gap in our quantitative understanding of crosstalk between apoptosis and necroptosis pathways. By employing the SWATH-MS technique, we quantified absolute amounts of up to thousands of proteins in dynamic assembling/de-assembling of TNF signaling complexes. Combining SWATH-MS-based network modeling and experimental validation, we found that when RIP1 level is below ~1000 molecules/cell (mpc), the cell solely undergoes TRADD-dependent apoptosis. When RIP1 is above ~1000 mpc, pro-caspase-8 and RIP3 are recruited to necrosome respectively with linear and nonlinear dependence on RIP1 amount, which well explains the co-occurrence of apoptosis and necroptosis and the paradoxical observations that RIP1 is required for necroptosis but its increase down-regulates necroptosis. Higher amount of RIP1 (>~46,000 mpc) suppresses apoptosis, leading to necroptosis alone. The relation between RIP1 level and occurrence of necroptosis or total cell death is biphasic. Our study provides a resource for encoding the complexity of TNF signaling and a quantitative picture how distinct dynamic interplay among proteins function as basis sets in signaling complexes, enabling RIP1 to play diverse roles in governing cell fate decisions.
Animals ; Apoptosis ; Caspase 8/metabolism* ; GTPase-Activating Proteins/metabolism* ; HEK293 Cells ; Humans ; Mice ; Mice, Knockout ; Necroptosis ; Receptor-Interacting Protein Serine-Threonine Kinases/metabolism*

The innate immune system is critical for clearing infection, and is tightly regulated to avert excessive tissue damage. Nod1/2-Rip2 signaling, which is essential for initiating the innate immune response to bacterial infection and ER stress, is subject to many regulatory mechanisms. In this study, we found that LRRK2, encoded by a gene implicated in Crohn's disease, leprosy and familial Parkinson's disease, modulates the strength of Nod1/2-Rip2 signaling by enhancing Rip2 phosphorylation. LRRK2 deficiency markedly reduces cytokine production in macrophages upon Nod2 activation by muramyl dipeptide (MDP), Nod1 activation by D-gamma-Glu-meso-diaminopimelic acid (iE-DAP) or ER stress. Our biochemical study shows that the presence of LRRK2 is necessary for optimal phosphorylation of Rip2 upon Nod2 activation. Therefore, this study reveals that LRRK2 is a new positive regulator of Rip2 and promotes inflammatory cytokine induction through the Nod1/2-Rip2 pathway.
Animals ; Cytokines ; genetics ; immunology ; HEK293 Cells ; Humans ; Immunity, Innate ; genetics ; Inflammation ; genetics ; immunology ; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 ; genetics ; immunology ; Mice ; Mice, Knockout ; Nod1 Signaling Adaptor Protein ; genetics ; immunology ; Nod2 Signaling Adaptor Protein ; genetics ; immunology ; Phosphorylation ; genetics ; immunology ; Receptor-Interacting Protein Serine-Threonine Kinase 2 ; genetics ; immunology ; Receptor-Interacting Protein Serine-Threonine Kinases ; genetics ; immunology ; Signal Transduction ; genetics ; immunology

The present study was aimed to investigate the role of necroptosis in the pathogenesis of acute respiratory distress syndrome (ARDS). The rat model of ARDS was induced by intravenous injection of oleic acid (OA), and observed for 4 h. The lung injury was evaluated by arterial blood gas, lung wet-dry weight ratio (W/D) and histological analyses. Simultaneously, bronchoalveolar lavage fluid (BALF) was collected for total and differential cell analysis and total protein determination. Tumor necrosis factor alpha (TNF-α) level in BALF was determined with a rat TNF-α ELISA kit. Expressions of receptor interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like protein (MLKL) in lung tissue were determined by Western blot and immunohistochemical staining. The interaction between RIPK1 and RIPK3 was explored by immunoprecipitation. The results showed that, compared with those in control group, total white blood cells count (WBC), polymorphonuclear percentage (PMN%), total protein concentration, TNF-α level in BALF, W/D, and the alveolar-arterial oxygen tension difference (P(A-a)O) in OA group were significantly increased at 4 h after OA injection. Western blot and immunostaining further showed remarkably increased expressions of RIPK1, RIPK3 and MLKL in lung tissue from OA group. Additionally, immunoprecipitation results indicated an enforced interaction between RIPK1 and RIPK3 in OA group. Collectively, the TNF-α level in BALF and the RIPK1-RIPK3-MLKL signaling pathway in lung tissue were found to be upregulated and activated with the process of ARDS. These findings implicate that RIPK1/RIPK3-mediated necroptosis plays a possible role in the pathogenesis of ARDS, which may provide a new idea to develop novel drugs for the therapy of ARDS.
Acute Disease ; Animals ; Bronchoalveolar Lavage Fluid ; Disease Models, Animal ; Lung Diseases ; Necrosis ; Oleic Acid ; Rats ; Receptor-Interacting Protein Serine-Threonine Kinases ; Respiration Disorders ; Signal Transduction ; Tumor Necrosis Factor-alpha

Recent years, the researchers have found a new type of cell death, referred to programmed necrosis or necroptosis, which involves the death receptor and the ligand binds and is initiated under the inhibition of apoptosis pathway. Programmed necrosis possesses the morphological features of typical necrosis accompanied by inflammation. The receptor interacting protein kinase 1/3(RIPK1/3) can be inhibited by the specific inhibitors, such as necrostatin-1. RIPK1/3 could regulate programmed necrosis and play a key role in the process. The significance of programmed necrosis in ischemia-reperfusion injury (IRI) has been attracted great attention at present. Simultaneously, a series of studies have found it also involves in the IRI of heart, kidney, brain and retina.
Apoptosis ; Humans ; Imidazoles ; Indoles ; Inflammation ; Necrosis ; Receptor-Interacting Protein Serine-Threonine Kinases ; Reperfusion Injury

To explore the antagonistic effect of gingerols against the inflammation induced by lectin from Pinellia ternata. In this study, ELISA method was used to determine the effect of different extracts from gingerols on the release of inflammatory factor TNF-α from macrophages induced by lectin from P. ternata. The fluorescence probe was used to determine the effect of gingerols on the changes in ROS of macrophages induced by lectin from P. ternata. The western-blot method was applied to study the effect of gingerols on the increase in expression of cell receptor interacting protein RIP3 in macrophages induced by lectin from P. ternata. The scanning electron microscope (SEM) was used to study the effect of gingerols on morphological changes in macrophages induced by lectin from P. ternata. According to the results, gingerols can significantly inhibit the release of inflammatory factor from macrophages induced by lectin from P. ternata, ROS overproduction and increase in RIP3 expression. SEM results showed that gingerols can inhibit the cytomorphosis and necrocytosis induced by lectin from P. ternata. Fresh ginger's detoxication may be related to gingerols' effects in inhibiing release of inflammatory factor, ROS overproduction and increase in RIP3 expression caused by macrophages induced by lectin from P. ternata, which are mainly inflammatory development.
Animals ; Catechols ; pharmacology ; Cells, Cultured ; Drug Antagonism ; Fatty Alcohols ; pharmacology ; Ginger ; chemistry ; Lectins ; toxicity ; Macrophages ; drug effects ; metabolism ; Male ; Mice ; Mice, Inbred ICR ; Pinellia ; chemistry ; toxicity ; Reactive Oxygen Species ; metabolism ; Receptor-Interacting Protein Serine-Threonine Kinases ; genetics ; metabolism ; Tumor Necrosis Factor-alpha ; genetics ; metabolism