STING deletion alleviates podocyte injury through suppressing inflammation by targeting NLRP3 in diabetic kidney disease

Inhibition of PKC-δ retards kidney fibrosis via inhibiting cGAS-STING signaling pathway in mice

Kidney fibrosis is considered to be the ultimate aggregation pathway of chronic kidney disease (CKD), but its underlying mechanism remains elusive. Protein kinase C-delta (PKC-δ) plays critical roles in the control of growth, differentiation, and apoptosis. In this study, we found that PKC-δ was highly upregulated in human biopsy samples and mouse kidneys with fibrosis. Rottlerin, a PKC-δ inhibitor, alleviated unilateral ureteral ligation (UUO)-induced kidney fibrosis, inflammation, VDAC1 expression, and cGAS-STING signaling pathway activation. Adeno-associated virus 9 (AAV9)-mediated VDAC1 silencing or VBIT-12, a VDAC1 inhibitor, attenuated renal injury, inflammation, and activation of cGAS-STING signaling pathway in UUO mouse model. Genetic and pharmacologic inhibition of STING relieved renal fibrosis and inflammation in UUO mice. In vitro, hypoxia resulted in PKC-δ phosphorylation, VDAC1 oligomerization, and activation of cGAS-STING signaling pathway in HK-2 cells. Inhibition of PKC-δ, VDAC1 or STING alleviated hypoxia-induced fibrotic and inflammatory responses in HK-2 cells, respectively. Mechanistically, PKC-δ activation induced mitochondrial membrane VDAC1 oligomerization via direct binding VDAC1, followed by the mitochondrial DNA (mtDNA) release into the cytoplasm, and subsequent activated cGAS-STING signaling pathway, which contributed to the inflammation leading to fibrosis. In conclusion, this study has indicated for the first time that PKC-δ is an important regulator in kidney fibrosis by promoting cGAS-STING signaling pathway which mediated by VDAC1. PKC-δ may be useful for treating renal fibrosis and subsequent CKD.

Comprehensive machine learning models for predicting therapeutic targets in type 2 diabetes utilizing molecular and biochemical features in rats

Introduction

With the increasing prevalence of type 2 diabetes mellitus (T2DM), there is an urgent need to discover effective therapeutic targets for this complex condition. Coding and non-coding RNAs, with traditional biochemical parameters, have shown promise as viable targets for therapy. Machine learning (ML) techniques have emerged as powerful tools for predicting drug responses.

Method

In this study, we developed an ML-based model to identify the most influential features for drug response in the treatment of type 2 diabetes using three medicinal plant-based drugs (Rosavin, Caffeic acid, and Isorhamnetin), and a probiotics drug (Z-biotic), at different doses. A hundred rats were randomly assigned to ten groups, including a normal group, a streptozotocin-induced diabetic group, and eight treated groups. Serum samples were collected for biochemical analysis, while liver tissues (L) and adipose tissues (A) underwent histopathological examination and molecular biomarker extraction using quantitative PCR. Utilizing five machine learning algorithms, we integrated 32 molecular features and 12 biochemical features to select the most predictive targets for each model and the combined model.

Results and discussion

Our results indicated that high doses of the selected drugs effectively mitigated liver inflammation, reduced insulin resistance, and improved lipid profiles and renal function biomarkers. The machine learning model identified 13 molecular features, 10 biochemical features, and 20 combined features with an accuracy of 80% and AUC (0.894, 0.93, and 0.896), respectively. This study presents an ML model that accurately identifies effective therapeutic targets implicated in the molecular pathways associated with T2DM pathogenesis.

The role and mechanism of NLRP3 in wasp venom-induced acute kidney injury

BACKGROUND

Inflammation and pyroptosis have crucial impacts on the development of acute kidney injury (AKI) and have been validated in a variety of existing AKI animal models. However, the mechanisms underlying wasp venom-induced AKI are still unclear. The involvement of nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) in some mouse models of AKI has been extensively documented, and its crucial function in controlling inflammation and pyroptosis has been highlighted. The objective of our study was to investigate the role and mechanism of NLRP3 in inflammation and pyroptosis associated with wasp venom-induced AKI.

METHODS

A mouse model of AKI induced by wasp venom pre-injected with an NLRP3 inhibitor was used to study the role and mechanism of NLRP3. To verify the importance of NLRP3, western blotting was performed to assess the expression of NLRP3, caspase-1 p20, and gasdermin D (GSDMD)-N. Additionally, quantitative real-time polymerase was used to determine the expression of NLRP3, caspase-1, and GSDMD. Furthermore, enzyme-linked immunosorbent assay was utilized to measure the levels of interleukin (IL)-1β and IL-18.

RESULTS

NLRP3 was found to be the downstream signal of the stimulator of interferon genes in the wasp sting venom-induced AKI model. The administration of wasp venom in mice significantly upregulated the expression of NLRP3, leading to renal dysfunction, inflammation, and pyroptosis. Treatment with an NLRP3 inhibitor reversed the renal damage induced by wasp venom and attenuated pathological injury, inflammatory response, and pyroptosis.

CONCLUSION

NLRP3 activation is associated with renal failure, inflammatory response and pyroptosis in the hyper early phase of wasp venom-induced AKI. The inhibition of NLRP3 significantly weakened this phenomenon. These findings could potentially offer a viable therapeutic approach for AKI triggered by wasp venom.

Non-Interferon-Dependent Role of STING Signaling in Pulmonary Hypertension

BACKGROUND

Patients with constitutive activation of DNA-sensing pathway through stimulator of IFN (interferon) genes (STING), such as those with STING-associated vasculopathy with onset in infancy, develop pulmonary hypertension (PH). However, the role of STING signaling in general PH patients is heretofore undescribed. Here, we seek to investigate the role of STING in PH development.

METHODS

STING expression in patient lung samples was examined. PH was induced in global STING-deficient mice and global type I IFN receptor 1-deficient mice using bleomycin or chronic hypoxia exposure. PH development was evaluated by right ventricular systolic pressure and Fulton index, with additional histological and flow cytometric analysis. VEGF (vascular endothelial growth factor) expression on murine immune cells was quantified and evaluated with multiplex and flow cytometry. Human myeloid-derived cells were differentiated from peripheral blood mononuclear cells and treated with either STING agonist or STING antagonist for evaluation of VEGF secretion.

RESULTS

Global STING deficiency protects mice from PH development, and STING-associated PH seems independent of type I IFN signaling. Furthermore, a role for STING-VEGF signaling pathway in PH development was demonstrated, with altered VEGF secretion in murine pulmonary infiltrated myeloid cells in a STING-dependent manner. In addition, pharmacological manipulation of STING in human myeloid-derived cells supports in vivo findings. Finally, a potential role of STING-VEGF-mediated apoptosis in disease development and progression was illustrated, providing a roadmap toward potential therapeutic applications.

CONCLUSIONS

Overall, these data provide concrete evidence of STING involvement in PH, establishing biological plausibility for STING-related therapies in PH treatment.

Stimulator of interferon genes promotes diabetic sarcopenia by targeting peroxisome proliferator activated receptors γ degradation and inhibiting fatty acid oxidation

BACKGROUND

Declined skeletal muscle mass and function are inevitable consequences of long-term diabetes and bring about many adverse events. Muscle fibre atrophy and interstitial fibrosis are major pathological manifestations of diabetic sarcopenia. Stimulator of interferon genes (STING) participates in various metabolic diseases. We aimed to explore whether and how STING regulates the above pathological manifestations of diabetic sarcopenia.

METHODS

Wild-type and STINGgt/gt C57BL/6J mice and C2C12 myotubes were used to study the role of STING in the regulation of diabetic sarcopenia and the underlying mechanisms.

RESULTS

STING was abnormally activated in diabetic muscles and in PA-treated myotubes (P < 0.01 for all parameters). The diabetic mice demonstrated decreased forelimb grip strength, lean mass, muscle weight and hanging impulse, which were improved by STING deficiency due to alleviated muscle fibre atrophy and interstitial fibrosis (P < 0.05 for all parameters). STING deficiency alleviated muscle fibre atrophy through the following mechanisms. Firstly, STING deficiency or inhibition increased the contents of pDRP1Ser616 , PINK1, Parkin and LC3-II, decreased p62 content, and increased the amount of mito-Keima fluorescent dots at 578 nm in diabetic state (P < 0.05 for all parameters), suggesting improved mitofission and mitophagy. Secondly, STING deficiency or inhibition increased the expression of pAKTSer473 and GLUT4 post-insulin change in diabetic state (P < 0.05 for all), indicating alleviated insulin resistance (IR). Mechanically, STING deficiency or inhibition increased peroxisome proliferator activated receptors γ (PPARγ) protein content by reducing the degradation of ubiquitinated PPARγ through the proteasome pathway and thus increased the expression of fatty acid oxidation (FAO)-related proteins in diabetic state (P < 0.05 for all parameters). Decreased expression of FAO-related proteins caused by PPARγ inhibition abolished the improvements in mitofission, mitophagy and IR achieved by STING inhibition in PA-treated myotubes and thus promoted muscle fibre atrophy (P < 0.05 for all parameters). STING deficiency alleviated interstitial fibrosis by decreasing TGFβ1 expression in diabetic state and TGFβ1 promoted the fibrogenic differentiation of fibro-adipogenic progenitors (P < 0.05 for all parameters). PPARγ inhibition abolished the effect of STING inhibition on reducing TGFβ1 content in PA-treated myotubes (P < 0.01).

CONCLUSIONS

STING deficiency exerted protective effects in diabetic sarcopenia by inhibiting the degradation of ubiquitinated PPARγ through the proteasome pathway and enhancing PPARγ-mediated FAO, which alleviated muscle fibre atrophy by promoting mitophagy and ameliorating IR, and alleviated interstitial fibrosis by reducing TGFβ1 production and suppressing the fibrogenic differentiation of fibro-adipogenic progenitors.

The intellectual base and global trends in inflammation of diabetic kidney disease: a bibliometric analysis

Diabetic kidney disease (DKD) is a severe complication of diabetes mellitus (DM). The literature on DKD inflammation research has experienced substantial growth. However, there is a lack of bibliometric analyses. This study aimed to examine the existing research on inflammation in DKD by analyzing articles published in the Web of Science Core Collection (WOSCC) over the past 30 years. We conducted a visualization analysis using several software, including CiteSpace and VOSviewer. We found that the literature on inflammation research in DKD has experienced substantial growth, indicating a rising interest in this developing area of study. In this field, Navarro-Gonzalez, JF is the most frequently cited author, Kidney International is the most frequently cited journal, China had the highest number of publications in the field of DKD inflammation, and Monash University emerged as the institution with the most published research. The research area on inflammation in DKD primarily centers around the investigation of 'Glycation end-products', 'chronic kidney disease', and 'diabetic nephropathy'. The emerging research trends in this field will focus on the 'Gut microbiota', 'NLRP3 inflammasome', 'autophagy', 'pyroptosis', 'sglt2 inhibitor', and 'therapeutic target'. Future research on DKD may focus on further exploring the inflammatory response, identifying specific therapeutic targets, studying biomarkers, investigating stem cell therapy and tissue engineering, and exploring gene therapy and gene editing. In summary, this study examines the main areas of study, frontiers, and trends in DKD inflammation, which have significant implications for future research.