Progressive peritoneal fibrosis affects patients receiving peritoneal dialysis (PD) and has no reliable treatment. The mechanisms that initiate and sustain peritoneal fibrosis remain incompletely elucidated. To overcome these problems, we developed a strategy that prevents peritoneal fibrosis by suppressing PD-stimulated mesothelial-to-mesenchymal transition (MMT). We evaluated single-cell transcriptomes of mesothelial cells obtained from normal peritoneal biopsy and effluent from PD-treated patients. In cells undergoing MMT, we found cellular heterogeneity and intermediate transition states associated with up-regulation of enzymes involved in glycolysis. The expression of glycolytic enzymes was correlated with the development of MMT. Using gene expression profiling and metabolomics analyses, we confirmed that PD fluid induces metabolic reprogramming, characterized as hyperglycolysis, in mouse peritoneum. We found that transforming growth factor β1 (TGF-β1) can substitute for PD fluid to stimulate hyperglycolysis, suppressing mitochondrial respiration in mesothelial cells. Blockade of hyperglycolysis with 2-deoxyglucose (2-DG) inhibited TGF-β1–induced profibrotic cellular phenotype and peritoneal fibrosis in mice. We developed a triad of adeno-associated viruses that overexpressed microRNA-26a and microRNA-200a while inhibiting microRNA-21a to target hyperglycolysis and fibrotic signaling. Intraperitoneal injection of the viral triad inhibited the development of peritoneal fibrosis induced by PD fluid in mice. We conclude that hyperglycolysis is responsible for MMT and peritoneal fibrogenesis, and this aberrant metabolic state can be corrected by modulating microRNAs in the peritoneum. These results could provide a therapeutic strategy to combat peritoneal fibrosis.

BackgroundChronic kidney disease (CKD) is commonly associated with cachexia, a condition that causes skeletal muscle wasting and an unfavourable prognosis. Although mechanisms leading to cachexia have been intensively studied, the advance of biological knowledges and technologies encourages us to make progress in understanding the pathogenesis of this disorder. Long noncoding RNAs (lncRNAs) are defined as >200 nucleotides RNAs but lack the protein‐coding potential. LncRNAs are involved in the pathogenesis of many diseases, but whether they functionally involve in muscle protein loss has not been investigated.MethodsWe performed lncRNA array and identified an lncRNA, which we named Atrolnc‐1, remarkably elevated in atrophying muscles from mice with cachexia. We examined how overexpression or knockdown of Atrolnc‐1 could influence muscle protein synthesis and degradation. We also examined whether inhibition of Atrolnc‐1 ameliorates muscle wasting in mice with CKD.ResultsWe documented that Atrolnc‐1 expression is continuously increased in muscles of mice with fasting (5.4 fold), cancer (2.0 fold), or CKD (5.1 fold). We found that depressed insulin signalling stimulates the transcription factor C/EBP‐α binding to the promoter of Atrolnc‐1 and promotes the expression of Atrolnc‐1. In cultured C2C12 myotubes, overexpression of Atrolnc‐1 increases protein degradation (0.45±0.03 vs. 0.64±0.02, *p<0.05); Atrolnc‐1 knockdown significantly reduces the rate of protein degradation stimulated by serum depletion (0.61±0.03 vs. 0.47±0.02, *p<0.05). Using mass spectrometry and a lncRNA pull‐down assay, we identified that Atrolnc‐1 interacts with A20 binding inhibitor of NF‐κB‐1 (ABIN‐1). The interaction impairs function, resulting in enhanced NF‐κB activity plus MuRF‐1 transcription. This response is counteracted by CRISPR/dCas9 mediated overexpression. In muscles from normal mice, overexpression of Atrolnc‐1 stimulates a 2.7‐fold increase in MuRF‐1 expression leading to myofibers atrophy. In contrast, Atrolnc‐1 knockdown attenuates muscle wasting by 42% in mice with CKD via suppression of NF‐κB activity and MuRF‐1 expression.ConclusionsOur findings provide evidence that lncRNAs initiates the pathophysiological process of muscle wasting. The interaction between Atrolnc‐1 and NF‐κB signalling modulates muscle mass and proteolysis in CKD and perhaps other catabolic conditions.

Activation-induced cytidine deaminase (AID) initiates class-switch recombination and somatic hypermutation (SHM) in antibody genes. Protein expression and activity are tightly controlled by various mechanisms. However, it remains unknown whether a signal from the extracellular environment directly affects the AID activity in the nucleus where it works. Here, we demonstrated that a deubiquitinase USP10, which specifically stabilizes nuclear AID protein, can translocate into the nucleus after AKT-mediated phosphorylation at its T674 within the NLS domain. Interestingly, the signals from BCR and TLR1/2 synergistically promoted this phosphorylation. The deficiency of USP10 in B cells significantly decreased AID protein levels, subsequently reducing neutralizing antibody production after immunization with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or human immunodeficiency virus type 1 (HIV-1) nanoparticle vaccines. Collectively, we demonstrated that USP10 functions as an integrator for both BCR and TLR signals and directly regulates nuclear AID activity. Its manipulation could be used for the development of vaccines and adjuvants.