Hedgehog-induced ZFYVE21 promotes chronic vascular inflammation by activating NLRP3 inflammasomes in T cells

Dissecting shared genetic architecture between depression and body mass index

BACKGROUND

A growing body of evidence supports the comorbidity between depression (DEP) and obesity, yet the genetic mechanisms underlying this association remain unclear. Our study explored the shared genetic architecture and causal associations of DEP with BMI.

METHODS

We investigated the multigene overlap and genetic correlation between DEP (N > 1.3 million) and BMI (N = 806,834) based on genome-wide association studies (GWAS) and using the bivariate causal mixture model and linkage disequilibrium score regression (LDSC). The causal association was explored by bi-directional Mendelian randomization (MR). Common risk loci were identified through cross-trait meta-analyses. Stratified LDSC and multi-marker gene annotation analyses were applied to investigate single-nucleotide polymorphisms enrichment across tissue types, cell types, and functional categories. Finally, we explored shared functional genes by Summary Data-Based Mendelian Randomization (SMR) and further detected differential expression genes (DEG) in brain tissues of individuals with depression and obesity.

RESULTS

We found a positive genetic correlation between DEP and BMI (rg = 0.19, P = 4.07 × 10-26), which was more evident in local genomic regions. Cross-trait meta-analyses identified 16 shared genetic loci, 5 of which were newly identified, and they had influence on both diseases in the same direction. MR analysis showed a bidirectional causal association between DEP and BMI, with comparable effect sizes estimated in both directions. Combined with gene expression information, we found that genetic correlations between DEP and BMI were enriched in 6 brain regions, predominantly in the nucleus accumbens and anterior cingulate cortex. Moreover, 6 specific cell types and 23 functional genes were found to have an impact on both DEP and BMI across the brain regions. Of which, NEGR1 was identified as the most significant functional gene and associated with DEP and BMI at the genome-wide significance level (P < 5 × 10-8). Compared with healthy controls, the expression levels of NEGR1 gene were significant lower in brain tissues of individuals with depression and obesity.

CONCLUSIONS

Our study reveals shared genetic basis underpinnings between DEP and BMI, including genetic correlations and common genes. These insights offer novel opportunities and avenues for future research into their comorbidities.

Aging kidneys reveal underlying mechanisms of endothelial dysfunction

Jiang et al. show that zinc finger FYVE-type containing 21, a Rab5 effector in glomerular endothelial cells is involved in the maintenance of glomerular filtration barrier homeostasis through the stabilization of activated endothelial nitric oxide synthase on subcellular vesicles. The study demonstrates that zinc finger FYVE-type containing 21 could modulate the levels of caveolin-1 in glomerular endothelial cells using vesicle-based trafficking, thereby supporting endothelial nitric oxide synthase activity. The authors provide evidence that decreased zinc finger FYVE-type containing 21 expression in glomerular endothelial cells could play a role in aging-related glomerular filtration barrier dysfunction.

Contribution of genetic variants in the development of familial premature coronary artery disease in a cohort of cardiac patients

Coronary artery disease (CAD), the most prevalent cardiovascular disease, is the leading cause of death worldwide. Heritable factors play a significant role in the pathogenesis of CAD. It has been proposed that approximately one-third of patients with CAD have a positive family history, and individuals with such history are at ~1.5-fold increased risk of CAD in their lifespans. Accordingly, the long-recognized familial clustering of CAD is a strong risk factor for this disease. Our study aimed to identify candidate genetic variants contributing to CAD by studying a cohort of 60 large Iranian families with at least two members in different generations afflicted with premature CAD (PCAD), defined as established disease at ≤45 years in men and ≤55 years in women. Exome sequencing was performed for a subset of the affected individuals, followed by prioritization and Sanger sequencing of candidate variants in all available family members. Subsequently, apparently healthy carriers of potential risk variants underwent coronary computed tomography angiography (CCTA), followed by co-segregation analysis of the combined data. Putative causal variants were identified in seven genes, ABCG8, CD36, CYP27A1, PIK3C2G, RASSF9, RYR2, and ZFYVE21, co-segregating with familial PCAD in seven unrelated families. Among these, PIK3C2G, RASSF9, and ZFYVE21 are novel candidate CAD susceptibility genes. Our findings indicate that rare variants in genes identified in this study are involved in CAD development.

Increasing CB2 Receptor Activity after Early Life Stress Prevents Depressive Behavior in Female Rats

Early adversity, the loss of the inhibitory GABAergic interneuron parvalbumin, and elevated neuroinflammation are associated with depression. Individuals with a maltreatment history initiate medicinal cannabis use earlier in life than non-maltreated individuals, suggesting self-medication. Female rats underwent maternal separation (MS) between 2 and 20 days of age to model early adversity or served as colony controls. The prelimbic cortex and behavior were examined to determine whether MS alters the cannabinoid receptor 2 (CB2), which has anti-inflammatory properties. A reduction in the CB2-associated regulatory enzyme MARCH7 leading to increased NLRP3 was observed with Western immunoblots in MS females. Immunohistochemistry with stereology quantified numbers of parvalbumin-immunoreactive cells and CB2 at 25, 40, and 100 days of age, revealing that the CB2 receptor associated with PV neurons initially increases at P25 and subsequently decreases by P40 in MS animals, with no change in controls. Confocal and triple-label microscopy suggest colocalization of these CB2 receptors to microglia wrapped around the parvalbumin neuron. Depressive-like behavior in MS animals was elevated at P40 and reduced with the CB2 agonist HU-308 or a CB2-overexpressing lentivirus microinjected into the prelimbic cortex. These results suggest that increasing CB2 expression by P40 in the prelimbic cortex prevents depressive behavior in MS female rats.

Comprehensive analysis of necroptosis-related genes in renal ischemia-reperfusion injury

Background

Oxidative stress is the primary cause of ischemia-reperfusion injury (IRI) in kidney transplantation, leading to delayed graft function (DGF) and implications on patient health. Necroptosis is believed to play a role in renal IRI. This research presents a comprehensive analysis of necroptosis-related genes and their functional implications in the context of IRI in renal transplantation.

Methods

The necroptosis-related differentially expressed genes (NR-DEGs) were identified using gene expression data from pre- and post-reperfusion renal biopsies, and consensus clustering analysis was performed to distinguish necroptosis-related clusters. A predictive model for DGF was developed based on the NR-DEGs and patients were divided into high- and low-risk groups. We investigated the differences in functional enrichment and immune infiltration between different clusters and risk groups and further validated them in single-cell RNA-sequencing (scRNA-seq) data. Finally, we verified the expression changes of NR-DEGs in an IRI mouse model.

Results

Five NR-DEGs were identified and were involved in various biological processes. The renal samples were further stratified into two necroptosis-related clusters (C1 and C2) showing different occurrences of DGF. The predictive model had a reliable performance in identifying patients at higher risk of DGF with the area under the curve as 0.798. Additionally, immune infiltration analysis indicated more abundant proinflammatory cells in the high-risk group, which was also found in C2 cluster with more DGF patients. Validation of NR-DEG in scRNA-seq data further supported their involvement in immune cells. Lastly, the mouse model validated the up-regulation of NR-DEGs after IR and indicated the correlations with kidney function markers.

Conclusions

Our research provides valuable insights into the identification and functional characterization of NR-DEGs in the context of renal transplantation and sheds light on their involvement in immune responses and the progression of IRI and DGF.

Hedgehog costimulation during ischemia-reperfusion injury potentiates cytokine and homing responses of CD4+ T cells

Introduction

Ischemia reperfusion injury (IRI) confers worsened outcomes and is an increasing clinical problem in solid organ transplantation. Previously, we identified a "PtchHi" T-cell subset that selectively received costimulatory signals from endothelial cell-derived Hedgehog (Hh) morphogens to mediate IRI-induced vascular inflammation.

Methods

Here, we used multi-omics approaches and developed a humanized mouse model to resolve functional and migratory heterogeneity within the PtchHi population.

Results

Hh-mediated costimulation induced oligoclonal and polyclonal expansion of clones within the PtchHi population, and we visualized three distinct subsets within inflamed, IRI-treated human skin xenografts exhibiting polyfunctional cytokine responses. One of these PtchHi subsets displayed features resembling recently described T peripheral helper cells, including elaboration of IFN-y and IL-21, expression of ICOS and PD-1, and upregulation of positioning molecules conferring recruitment and retention within peripheral but not lymphoid tissues. PtchHi T cells selectively homed to IRI-treated human skin xenografts to cause accelerated allograft loss, and Hh signaling was sufficient for this process to occur.

Discussion

Our studies define functional heterogeneity among a PtchHi T-cell population implicated in IRI.

Hedgehog signalling in allograft vasculopathy: a new therapeutic target?

Allograft vasculopathy (AV) leads to chronic rejection of organ transplants, but its causes are obscure. New research from the Jane-Wit laboratory showed that Sonic Hedgehog (SHH) signalling from damaged graft endothelium drives vasculopathy by promoting proinflammatory cytokine production and NLRP3-inflammasome activation in alloreactive CD4+PTCH1hiPD-1hiT memory cells, offering new diagnostic and therapeutic strategies.

A ZFYVE21-Rubicon-RNF34 signaling complex promotes endosome-associated inflammasome activity in endothelial cells

Internalization of complement membrane attack complexes (MACs) assembles NLRP3 inflammasomes in endothelial cells (EC) and promotes IL-β-mediated tissue inflammation. Informed by proteomics analyses of FACS-sorted inflammasomes, we identify a protein complex modulating inflammasome activity on endosomes. ZFVYE21, a Rab5 effector, partners with Rubicon and RNF34, forming a "ZRR" complex that is stabilized in a Rab5- and ZFYVE21-dependent manner on early endosomes. There, Rubicon competitively disrupts inhibitory associations between caspase-1 and its pseudosubstrate, Flightless I (FliI), while RNF34 ubiquitinylates and degradatively removes FliI from the signaling endosome. The concerted actions of the ZRR complex increase pools of endosome-associated caspase-1 available for activation. The ZRR complex is assembled in human tissues, its associated signaling responses occur in three mouse models in vivo, and the ZRR complex promotes inflammation in a skin model of chronic rejection. The ZRR signaling complex reflects a potential therapeutic target for attenuating inflammasome-mediated tissue injury.