Role of vitamin D/VDR nuclear translocation in down-regulation of NF-κB/NLRP3/caspase-1 axis in lupus nephritis

Identifying potential mechanism and targets for treatment of tertiary lymphoid structure in lupus nephritis based on bioinformatics analysis

BACKGROUND

Tertiary lymphoid structure (TLS) is an ectopic lymphoid structure that develops in non-lymphoid structures. Some studies have shown that the TLS formed in autoimmune diseases, such as lupus nephropathy (LN), can cause damage to normal tissues and continuous disease progression. Nevertheless, there is still a lack of efficient treatments for TLS in LN. Thus, the study aims to identify potential targets for therapy of TLS in LN.

METHODS

Mice datasets relative to TLS were obtained from Gene Expression Omnibus (GEO). The differentially expressed genes (DEGs) were identified from mice datasets. Then, the Genetic Ontological (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed. The Protein-Protein Interaction (PPI) network was constructed. Additionally, the hub genes were selected by Cytoscape and verified by human databases from GEO. The relationships between the immune cells with hub genes were explored. Finally, the two genes PSMB9 and STAT1 were validated in the kidney tissues of LN patients and mice.

RESULTS

443 DEGs and 178 DEGs relative to TLS were filtered from GSE160488 and GSE155405, respectively. The enrichment results of these genes mostly focused on inflammatory response, cytokine-cytokine receptor interaction, and immune system process. Six genes were recognized by Cytoscape. According to the validation of six genes in human databases, the two hub genes (PSMB9 and STAT1) were also significantly expressed in LN patients. Immune infiltration analysis of hub genes shows immune cells are significantly crucial in LN patients with TLS.

CONCLUSION

PSMB9 and STAT1 may be identified as possible targets for the treatment of TLS in LN. According to the analysis of the interaction between these genes and immune cells, the immune process mediated by these signature targets takes part in the advancement and formation of TLS.

Role of AhR-Hsp90-MDM2-mediated VDR ubiquitination in PM2.5-induced renal toxicity

BACKGROUND AND OBJECTIVES

The kidney is a primary target for the accumulation of particulate matter (PM2.5). This study aimed to investigate PM2.5-induced renal toxicity mechanisms, focusing on the aryl hydrocarbon receptor (AhR)-Hsp90-MDM2 axis and its impact on vitamin D receptor (VDR) ubiquitination.

METHODS

PM2.5's role in activating the AhR and its downstream pathways was investigated using in vitro and in vivo models. Renal damage and therapeutic effects in PM2.5-exposed and paricalcitol-treated mice were evaluated using weight measurements, histopathology, and scanning electron microscopy. AhR, Hsp90, and VDR localization and expression in renal cells were assessed using FISH and Western blot. Protein interactions were examined using co-immunoprecipitation. Differentially expressed gene (DEG) analysis of GEO datasets was used to identify related proteins and genes.

RESULTS

PM2.5 exposure caused significant renal damage in mice, including increased serum creatinine, albuminuria, and histopathological deterioration, which were alleviated by paricalcitol. PM2.5 induced the nuclear translocation of AhR and Hsp90 and reduced nuclear VDR expression; paricalcitol reversed these effects. Immunohistochemistry confirmed these findings. PM2.5 upregulated the NLRP3/caspase-1/IL-1β/IL-18 axis, which was reversed by paricalcitol treatment. Inhibition of Hsp90 increased nuclear VDR expression through MDM2 mediation. DEG analysis identified VDR-regulated genes; PM2.5 increased the mRNA levels of IL-6, IL-2, and CXCL8, which were downregulated by Hsp90 and MDM2 inhibitors, with VDR agonists further decreasing these levels.

CONCLUSION

This study reveals a novel mechanism of PM2.5-induced renal toxicity through the AhR-Hsp90-MDM2 axis, promoting VDR ubiquitination and degradation and increasing inflammation. These findings provide a foundation for future studies and lay the groundwork for developing targeted interventions to mitigate the public health impact of PM2.5 exposure.

Therapy Targeted to the NLRP3 Inflammasome in Chronic Kidney Disease

Background

The NLRP3 inflammasome is a cytoplasmic polymeric protein complex composed of the cytoplasmic sensor NLRP3, the apoptosis-related spot-like protein ASC, and the inflammatory protease caspase-1. NLRP3 activates and releases IL-1β through classical pathways, and IL-18 mediates inflammation and activates gasdermin-D protein to induce cellular pyroptosis. Numerous studies have also emphasized the non-classical pathway activated by the NLRP3 inflammasome in chronic kidney disease (CKD) and the inflammasome-independent function of NLRP3.

Summary

The NLRP3-targeting inflammasome and its associated pathways have thus been widely studied in models of CKD treatment, but no drug that targets NLRP3 has thus far been approved for the treatment of CKD.

Key Messages

We herein reviewed the current interventional methods for targeting the NLRP3 inflammasome in various CKD models, analyzed their underlying mechanisms of action, classified and compared them, and discussed the advantages and follow-up directions of various interventional methods. This review therefore provides novel ideas and a reference for the development of targeted NLRP3-inflammasome therapy in CKD.

Vitamin D and systemic lupus erythematosus: Causality and association with disease activity and therapeutics

The major role of bioactive vitamin 1,25-dihydroxyvitamin D3 (1,25(OH)2D or calcitriol) is to maintain the levels of calcium and phosphorus to achieve bone and mineral homeostasis. Dietary intake and adequate natural light exposure are the main contributors to normal vitamin D status. In addition to regulating metabolism, vitamin D exerts various immunomodulatory effects that regulate innate and adaptive immunity through immune effector cells such as monocytes, macrophages, T and B lymphocytes, and natural killer cells and nonimmune cells that express vitamin D receptors. Systemic lupus erythematosus (SLE) is an autoimmune disease with an unknown etiology, and the association between vitamin D and SLE remains incompletely understood. Given that the current treatment for SLE relies heavily on corticosteroids and that SLE patients tend to have low vitamin D status, vitamin D supplementation may help to reduce the dosage of corticosteroids and/or attenuate disease severity. In this review, we address the associations between vitamin D and several clinical aspects of SLE. In addition, the underlying immunomodulatory mechanisms accounting for the potential vitamin D-mediated therapeutic effects are discussed. Finally, several confounding factors in data interpretation and the execution of clinical trials and perspectives targeting vitamin D supplementation in patients with SLE are also addressed.

NLRP3 inflammasome and its role in autoimmune diseases: A promising therapeutic target

The NOD-like receptor protein 3 (NLRP3) inflammasome is a protein complex that regulates innate immune responses by activating caspase-1 and the inflammatory cytokines IL-1β and IL-18. Numerous studies have highlighted its crucial role in the pathogenesis and development of inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, autoimmune thyroid diseases, and other autoimmune diseases. Therefore, investigating the underlying mechanisms of NLRP3 in disease and targeted drug therapies holds clinical significance. This review summarizes the structure, assembly, and activation mechanisms of the NLRP3 inflammasome, focusing on its role and involvement in various autoimmune diseases. This review also identifies studies where the involvement of the NLRP3 inflammasome in the disease mechanism within the same disease appears contradictory, as well as differences in NLRP3-related gene polymorphisms among different ethnic groups. Additionally, the latest therapeutic advances in targeting the NLRP3 inflammasome for autoimmune diseases are outlined, and novel clinical perspectives are discussed. Conclusively, this review provides a consolidated source of information on the NLRP3 inflammasome and may guide future research efforts that have the potential to positively impact patient outcomes.

Huanglian Decoction treats Henoch-Schonlein purpura nephritis by inhibiting NF-κB/NLRP3 signaling pathway and reducing renal IgA deposition

Henoch-Schonlein purpura nephritis (HSPN) is a systemic vascular inflammatory disease. Huanglian Decoction (HLD) ameliorates renal injury in nephritis; however, the mechanism of action of HLD on HSPN has not been investigated. This study aimed to investigate the protective mechanism of HLD treatment in HSPN. The effects of HLD on HSPN biochemical indices, kidney injury and NF-κB/NLRP3 signaling pathway were analyzed by biochemical analysis, ELISA, HE and PAS staining, immunohistochemistry, immunofluorescence, and Western Blot. In addition, the effects of HLD on HSPN cells were analyzed. We found that HLD treatment significantly reduced renal tissue damage, decreased the levels of IL-17, IL-18, TNF-α, and IL-1β, and increased the levels of TP and ALB in HSPN mice. It also inhibited the deposition of IgA, IgG, and C3 in kidney tissues and significantly decreased the expression of IκBα, p-IκBα, NLRP3, caspase-1, and IL-1β in kidney tissues and cells. In addition, PMA treatment inhibited the above-mentioned effects of HLD. These results suggested that HLD attenuates renal injury, IgA deposition, and inflammation in HSPN mice and its mechanism of action may be related to the inhibition of the NF-κB/NLRP3 pathway.

Modulation of the vitamin D receptor by traditional Chinese medicines and bioactive compounds: potential therapeutic applications in VDR-dependent diseases

The Vitamin D receptor (VDR) is a crucial nuclear receptor that plays a vital role in various physiological functions. To a larger extent, the genomic effects of VDR maintain general wellbeing, and its modulation holds implications for multiple diseases. Current evidence regarding using vitamin D or its synthetic analogs to treat non-communicable diseases is insufficient, though observational studies suggest potential benefits. Traditional Chinese medicines (TCMs) and bioactive compounds derived from natural sources have garnered increasing attention. Interestingly, TCM formulae and TCM-derived bioactive compounds have shown promise in modulating VDR activities. This review explores the intriguing potential of TCM and bioactive compounds in modulating VDR activity. We first emphasize the latest information on the genetic expression, function, and structure of VDR, providing a comprehensive understanding of this crucial receptor. Following this, we review several TCM formulae and herbs known to influence VDR alongside the mechanisms underpinning their action. Similarly, we also discuss TCM-based bioactive compounds that target VDR, offering insights into their roles and modes of action.

Research Progress of Pyroptosis in Renal Diseases

Kidney diseases, particularly Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD), are identified as global public health issues affecting millions of individuals. In addition, the frequency of renal diseases in the population has increased dramatically and rapidly in recent years. Renal disorders have become a significant public health burden. The pathophysiology of renal diseases is significantly connected with renal cell death, including apoptosis, necrosis, necroptosis, ferroptosis, pyroptosis, and autophagy, as is now recognized. Unlike other forms of cell death, pyroptosis is a unique planned cell death (PCD). Scientists have proven that pyroptosis is crucial in developing various disorders, and this phenomenon is gaining increasing attention. It is considered a novel method of inflammatory cell death. Intriguingly, inflammation is among the most significant pathological characteristics of renal disease. This study investigates the effects of pyroptosis on Acute Kidney Injury (AKI), Chronic Kidney Disease (CKD), Diabetic Nephropathy (DN), Immunoglobulin A (IgA) Nephropathy, and Lupus Nephritis (LN) to identify novel therapeutic targets for kidney diseases.

New Potentiality of Bioactive Substances: Regulating the NLRP3 Inflammasome in Autoimmune Diseases

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is an essential component of the human innate immune system, and is closely associated with adaptive immunity. In most cases, the activation of the NLRP3 inflammasome requires priming and activating, which are influenced by various ion flux signals and regulated by various enzymes. Aberrant functions of intracellular NLRP3 inflammasomes promote the occurrence and development of autoimmune diseases, with the majority of studies currently focused on rheumatoid arthritis, systemic lupus erythematosus and systemic sclerosis. In recent years, a number of bioactive substances have shown new potentiality for regulating the NLRP3 inflammasome in autoimmune diseases. This review provides a concise overview of the composition, functions, and regulation of the NLRP3 inflammasome. Additionally, we focus on the newly discovered bioactive substances for regulating the NLRP3 inflammasome in autoimmune diseases in the past three years.

Vitamin D3 attenuates SARS-CoV-2 nucleocapsid protein-caused hyperinflammation by inactivating the NLRP3 inflammasome through the VDR-BRCC3 signaling pathway in vitro and in vivo

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-caused coronavirus disease 2019 (COVID-19) is a global crisis with no satisfactory therapies. Vitamin D3 (VD3) is considered a potential candidate for COVID-19 treatment; however, little information is available regarding the exact effects of VD3 on SARS-CoV-2 infection and the underlying mechanism. Herein, we confirmed that VD3 reduced SARS-CoV-2 nucleocapsid (N) protein-caused hyperinflammation in human bronchial epithelial (HBE) cells. Meanwhile, VD3 inhibited the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation in N protein-overexpressed HBE (HBE-N) cells. Notably, the inhibitors of caspase-1, NLRP3, and NLRP3 or caspase-1 small interference RNA (siRNA) enhanced VD3-induced NLRP3 inflammasome inactivation, with subsequent suppression of interleukin-6 (IL6) and IL1β release in HBE-N cells, which were abolished by the NLRP3 agonist. Moreover, VD3 increased NLRP3 ubiquitination (Ub-NLRP3) expression and the binding of the VDR with NLRP3, with decreased BRCA1/BRCA2-containing complex subunit 3 (BRCC3) expression and NLRP3-BRCC3 association. VD3-induced Ub-NLRP3 expression, NLRP3 inflammasome inactivation, and hyperinflammation inhibition were improved by the BRCC3 inhibitor or BRCC3 siRNA, which were attenuated by the vitamin D receptor (VDR) antagonist or VDR siRNA in HBE-N cells. Finally, the results of the in vivo study in AAV-Lung-enhanced green fluorescent protein-N-infected lungs were consistent with the findings of the in vitro experiment. In conclusion, VD3 attenuated N protein-caused hyperinflammation by inactivating the NLRP3 inflammasome partially through the VDR-BRCC3 signaling pathway.

MiR-874-5p targets VDR/NLRP3 to reduce intestinal pyroptosis and improve intestinal barrier damage in sepsis

BACKGROUND

Vitamin D receptor (VDR) is associated with intestinal barrier damage in sepsis. However, the mechanism of action of miR-874-5p/VDR/NLRP3 axis in disease has not been clearly explained. Therefore, the main content of this study is to explore the mechanism of this axis in intestinal barrier damage in sepsis.

METHODS

In order to confirm the progress of miR-874-5p regulation of VDR/NLRP3 pathway and its involvement in intestinal barrier damage in sepsis, a series of molecular biology and cell biology methods were carried out in this study. These include the establishment of cecal ligation puncture model, Western blot, RT-qPCR, hematoxylin and eosin staining, double luciferase reporting method, Fluorescence in situ hybridization, immunohistochemistry, and enzyme-linked immunosorption assay.

RESULTS

The expression level of miR-874-5p was higher and that of VDR was lower in sepsis. miR-874-5p was negatively correlated with VDR. Inhibition of miR-874-5p expression increased the expression of VDR, decreased the expression of NLRP3, reduced caspase-1 activation and IL-1β secretion, reduced pyroptosis and inflammatory response, and thus protected the intestinal barrier damage in sepsis, all of which were reversed by the downregulation of VDR.

CONCLUSIONS

This study suggested that down-regulation of miR-874-5p or up-regulation of VDR could reduce intestinal barrier damage in sepsis, which may provide potential biomarkers and therapeutic targets for intestinal barrier damage in sepsis.

Comparison of Vitamin D and Resveratrol Performances in COVID-19

Over the last few years, we have experienced the infection generated by severe respiratory syndrome coronavirus 2 (SARS-CoV-2) often resulting in an exaggerated immune reaction and systemic inflammation. The preferred treatments against SARS-CoV-2 were those that mitigated immunological/inflammatory dysfunction. A variety of observational epidemiological studies have reported that vitamin D deficiency is often a crucial factor in many inflammatory diseases and autoimmune diseases, as well as the susceptibility to contract infectious diseases, including acute respiratory infections. Similarly, resveratrol regulates immunity, modifying the gene expression and the release of proinflammatory cytokines in the immune cells. Therefore, it plays an immunomodulatory role that can be beneficial in the prevention and development of non-communicable diseases associated with inflammation. Since both vitamin D and resveratrol also act as immunomodulators in inflammatory pathologies, many studies have paid particular attention to an integrated treatment of either vitamin D or resveratrol in the immune reaction against SARS-CoV-2 infections. This article offers a critical evaluation of published clinical trials that have examined the use of vitamin D or resveratrol as adjuncts in COVID-19 management. Furthermore, we aimed to compare the anti-inflammatory and antioxidant properties linked to the modulation of the immune system, along with antiviral properties of both vitamin D and resveratrol.

Vitamin D and COVID-19: Narrative Review after 3 Years of Pandemic

Active vitamin D [1,25(OH)₂D₃-calcitriol] is a secosteroid hormone whose receptor is expressed on all cells of the immune system. Vitamin D has a global anti-inflammatory effect and its role in the management of a SARS-CoV-2 infection has been investigated since the beginning of the COVID-19 pandemic. In this narrative review, the laboratory and clinical results of a vitamin D supplementation have been collected from both open-label and blinded randomized clinical trials. The results are generally in favor of the utility of maintaining the serum concentrations of calcifediol [25(OH)D₃] at around 40 ng/mL and of the absolute usefulness of its supplementation in subjects with deficient serum levels. However, two very recent large-scale studies (one open-label, one placebo-controlled) have called into question the contribution of vitamin D to clinical practice in the era of COVID-19 vaccinations. The precise role of a vitamin D supplementation in the anti-COVID-19 armamentarium requires further investigations in light of the breakthrough which has been achieved with mass vaccinations.

Inhibition of the NLRP3/caspase-1 signaling cascades ameliorates ketamine-induced renal injury and pyroptosis in neonatal rats

Ketamine is a widely-used anesthetic in the field of pediatrics and obstetrics. Multiple studies have revealed that ketamine causes neurotoxicity in developing animals. However, further studies are needed to determine whether clinical doses of ketamine (20 mg/kg) are able to cause kidney damage in developing animals. Herein, we investigated the effects of continuous ketamine exposure on kidney injury and pyroptosis in seven-day-old rats. Serum renal function indicators, renal histopathological analysis, pyroptosis, as well as oxidative stress indicators, were tested. Additionally, the NLRP3 inhibitor MCC950 and the Caspase-1 inhibitor VX765 were used to evaluate the role of the NLRP3/Caspase-1 axis in ketamine-induced kidney injury among developing rats. Our findings indicate that ketamine exposure causes renal histopathological injury, increased the levels of blood urea nitrogen (BUN) and creatinine (Cre), and led to upregulation in the levels of pyroptosis. Furthermore, we found that ketamine induced an increase in levels of reactive oxygen species (ROS) and malonaldehyde (MDA), as well as a decrease in the content of glutathione (GSH) and catalase (CAT) in the kidneys of neonatal rats. Moreover, targeting NLRP3 and caspase-1 with MCC950 or VX765 improved pyroptosis and reduced renal damage after continuous ketamine exposure. In conclusion, this study suggested that continued exposure to ketamine caused kidney damage among neonatal rats and that the NLRP3/Caspase-1 axis-related pyroptosis may be involved in this process.

Calcipotriol attenuates liver fibrosis through the inhibition of vitamin D receptor-mediated NF-κB signaling pathway

Liver fibrosis is an inevitable stage in the development of chronic liver disease to cirrhosis. Nonetheless, the interventional treatment and achieving control over the disease at this stage can substantially reduce the incidence of liver cirrhosis. To demonstrate these aspects, liver pathological sections of 18 patients with chronic liver disease are collected for research according to the degree of fibrosis. Further, the expressions of related proteins in each group are studied by the Western blot method. The cell proliferation and apoptosis are detected by CKK-8 and flow cytometry analyses. Further, a rat model with carbon tetrachloride (CCl₄)-induced liver fibrosis is employed to verify the effect and mechanism of VDR on the process of liver fibrosis in vivo. The expression of VDR in liver tissues of patients with liver fibrosis is negatively correlated with α-smooth muscle actin (α-SMA), Col-1, and liver fibrosis stages. Moreover, the tumor necrosis factor (TNF)-α stimulation could increase the proliferation of LX-2, up-regulate the expression of α-SMA, Col-1, NF-κB, p-IκBα, p-IKKβ, p-p65m, and some fibrosis factors, as well as down-regulate the expressions of VDR and matrix metalloproteinase-1 (MMP-1). Considering the protective actions of VDR, calcipotriol, a VDR agonist, effectively reduced the degree of liver fibrosis in a rat model of liver fibrosis by inhibiting the deposition of extracellular (ECM) and activation of hepatic stellate cells (HSCs), which is negatively correlated with the degree of liver fibrosis. Together, these shreds of evidence demonstrated that the calcipotriol showed great potential in effectively attenuating liver fibrosis.

Diet and Hygiene in Modulating Autoimmunity During the Pandemic Era

The immune system is an efficiently toned machinery that discriminates between friends and foes for achieving both host defense and homeostasis. Deviation of immune recognition from foreign to self and/or long-lasting inflammatory responses results in the breakdown of tolerance. Meanwhile, educating the immune system and developing immunological memory are crucial for mounting defensive immune responses while protecting against autoimmunity. Still to elucidate is how diverse environmental factors could shape autoimmunity. The emergence of a world pandemic such as SARS-CoV-2 (COVID-19) not only threatens the more vulnerable individuals including those with autoimmune conditions but also promotes an unprecedented shift in people's dietary approaches while urging for extraordinary hygiene measures that likely contribute to the development or exacerbation of autoimmunity. Thus, there is an urgent need to understand how environmental factors modulate systemic autoimmunity to better mitigate the incidence and or severity of COVID-19 among the more vulnerable populations. Here, we discuss the effects of diet (macronutrients and micronutrients) and hygiene (the use of disinfectants) on autoimmunity with a focus on systemic lupus erythematosus.