Single-cell RNA sequencing reveals the transcriptomic landscape of kidneys in patients with ischemic acute kidney injury

Background:Ischemic acute kidney injury(AKI)is a common syndrome associated with considerable mortality and healthcare costs.Up to now,the underlying pathogenesis of ischemic AKI remains incompletely understood,and specific strategies for early diagnosis and treatment of ischemic AKI are still lacking.Here,this study aimed to define the transcriptomic landscape of AKI patients through single-cell RNA sequencing(scRNA-seq)analysis in kidneys.Methods:In this study,scRNA-seq technology was applied to kidneys from two ischemic AKI patients,and three human public scRNA-seq datasets were collected as controls.Differentially expressed genes(DEGs)and cell clusters of kidneys were determined.Gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analysis,as well as the ligand-receptor interaction between cells,were performed.We also validated several DEGs expression in kidneys from human ischemic AKI and ischemia/reperfusion(I/R)injury induced AKI mice through immunohistochemistry staining.Results:15 distinct cell clusters were determined in kidney from subjects of ischemic AKI and control.The injured proximal tubules(PT)displayed a proapoptotic and proinflammatory phenotype.PT cells of ischemic AKI had up-regulation of novel pro-apoptotic genes including USP47,RASSF4,EBAG9,IER3,SASH1,SEPTIN7,and NUB1,which have not been reported in ischemic AKI previously.Several hub genes were validated in kidneys from human AKI and renal I/R injury mice,respectively.Furthermore,PT highly expressed DEGs enriched in endoplasmic reticulum stress,autophagy,and retinoic acid-inducible gene I(RIG-I)signaling.DEGs overexpressed in other tubular cells were primarily enriched in nucleotide-binding and oligomerization domain(NOD)-like receptor signaling,estrogen signaling,interleukin(IL)-12 signaling,and IL-17 signaling.Overexpressed genes in kidney-resident immune cells including macrophages,natural killer T(NKT)cells,monocytes,and dendritic cells were associated with leukocyte activation,chemotaxis,cell adhesion,and complement activation.In addition,the ligand-receptor interactions analysis revealed prominent communications between macrophages and monocytes with other cells in the process of ischemic AKI.Conclusion:Together,this study reveals distinct cell-specific transcriptomic atlas of kidney in ischemic AKI patients,altered signaling pathways,and potential cell-cell crosstalk in the development of AKI.These data reveal new insights into the pathogenesis and potential therapeutic strategies in ischemic AKI.

Application of regional citrate anticoagulation in patients at high risk of bleeding during intermittent hemodialysis:a prospective multicenter randomized controlled trial

Objective:Safe and effective anticoagulation is essential for hemodialysis patients who are at high risk of bleeding.The purpose of this trial is to evaluate the effectiveness and safety of two-stage regional citrate anticoagulation(RCA)combined with sequential anticoagulation and standard calcium-containing dialysate in intermittent hemodialysis(IHD)treatment.Methods:Patients at high risk of bleeding who underwent IHD from September 2019 to May 2021 were prospectively enrolled in 13 blood purification centers of nephrology departments,and were randomly divided into RCA group and saline flushing group.In the RCA group,0.04 g/mL sodium citrate was infused from the start of the dialysis line during blood draining and at the venous expansion chamber.The sodium citrate was stopped after 3 h of dialysis,which was changed to sequential dialysis without anticoagulant.The hazard ratios for coagulation were according to baseline.Results:A total of 159 patients and 208 sessions were enrolled,including RCA group(80 patients,110 sessions)and saline flushing group(79 patients,98 sessions).The incidence of severe coagulation events of extracorporeal circulation in the RCA group was significantly lower than that in the saline flushing group(3.64%vs.20.41%,P<0.001).The survival time of the filter pipeline in the RCA group was significantly longer than that in the saline flushing group((238.34±9.33)min vs.(221.73±34.10)min,P<0.001).The urea clearance index(Kt/V)in the RCA group was similar to that in the saline flushing group with no statistically significant difference(1.12±0.34 vs.1.08±0.34,P=0.41).Conclusions:Compared with saline flushing,the two-stage RCA combined with a sequential anticoagulation strategy significantly reduced extracorporeal circulation clotting events and prolonged the dialysis time without serious adverse events.

Clinico-biological characteristics and treatment of hepatitis B virus-related mixed cryoglobulinemia

To the Editor:Cryoglobulinemia is a disease characterized by cryoglobulins in serum that precipitate under in vitro conditions<37°C and redissolve on rewarming.It is divided into three types:Type I,where the cryoglobulin is composed of monoclonal IgG or IgM,and rarely IgA or free immunoglobulin(Ig)light chains;Type II,where the cryoglobulin is made of monoclonal IgM with rheumatoid factor(RF)activity and polyclonal IgG;and Type III,where the cryoglobulin is composed of polyclonal IgM with RF activity and polyclonal IgG.[1]Types II and III are mixed cryoglobulinemia(MC).MC could be related to several infectious diseases,like hepatitis C and B.It mainly presents as cryoglobulinemic vasculitis,[2]including fatigue,purpura,arthralgia,myalgia,peripheral neuropathy,and even severe organ damage,like glomerulonephritis.However,cryoglobulinemic vasculitis involving the gastrointestinal tract and heart is rare.Besides,neurological,ocular,and rhino-otological symptoms of hyperviscosity syndrome are also hardly seen in MC.Here,we report one hepatitis B virus(HBV)-related MC case and analyze 41 cases in literature.We have analyzed these 42 HBV-related MC cases to clarify their clinico-biological characteristics and treatment.