湊口 俊

Abstract Pancreatic stellate cells (PSCs) are stromal cells in the pancreas that play an important role in pancreatic pathology. In chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC), PSCs are known to get activated to form myofibroblasts or cancer‐associated fibroblasts (CAFs) that promote stromal fibroinflammatory reactions. However, previous studies on PSCs were mainly based on the findings obtained using ex vivo expanded PSCs, with few studies that addressed the significance of in situ tissue‐resident PSCs using animal models. Their contributions to fibrotic reactions in CP and PDAC are also lesser‐known. These limitations in our understanding of PSC biology have been attributed to the lack of specific molecular markers of PSCs. Herein, we established Meflin (Islr), a glycosylphosphatidylinositol‐anchored membrane protein, as a PSC‐specific marker in both mouse and human by using human pancreatic tissue samples and Meflin reporter mice. Meflin‐positive (Meflin⁺) cells contain lipid droplets and express the conventional PSC marker Desmin in normal mouse pancreas, with some cells also positive for Gli1, the marker of pancreatic tissue‐resident fibroblasts. Three‐dimensional analysis of the cleared pancreas of Meflin reporter mice showed that Meflin⁺ PSCs have long and thin cytoplasmic protrusions, and are localised on the abluminal side of vessels in the normal pancreas. Lineage tracing experiments revealed that Meflin⁺ PSCs constitute one of the origins of fibroblasts and CAFs in CP and PDAC, respectively. In these diseases, Meflin⁺ PSC‐derived fibroblasts showed a distinctive morphology and distribution from Meflin⁺ PSCs in the normal pancreas. Furthermore, we showed that the genetic depletion of Meflin⁺ PSCs accelerated fibrosis and attenuated epithelial regeneration and stromal R‐spondin 3 expression, thereby implying that Meflin⁺ PSCs and their lineage cells may support tissue recovery and Wnt/R‐spondin signalling after pancreatic injury and PDAC development. Together, these data indicate that Meflin may be a marker specific to tissue‐resident PSCs and useful for studying their biology in both health and disease. © 2023 The Pathological Society of Great Britain and Ireland.

Abstract Adipose-derived mesenchymal stem cells (ASCs) have shown therapeutic potentials against refractory diseases. However, the detailed therapeutic mechanisms remain unclear. Here, we report the therapeutic actions of human ASCs in nephritis, focusing on cellular dynamics and multi-organ networks. Intravenously-administered ASCs accumulated in spleen but not kidneys. Nevertheless, ASCs increased M2 macrophages and Tregs in kidneys and drove strong renoprotection. Splenectomy abolished these therapeutic effects. ASC-derived extracellular vesicles (EVs) were transferred to M2 macrophages, which entered the bloodstream from spleen. EVs induced the transcriptomic signatures of hyperpolarization and PGE2 stimulation in M2 macrophages and ameliorated glomerulonephritis. ASCs, ASC-derived EVs, and EV-transferred M2 macrophages enhanced Treg induction. These findings suggest that EV transfer from spleen-accumulated ASCs to M2 macrophages and subsequent modulation of renal immune-environment underlie the renoprotective effects of ASCs. Our results provide insights into the therapeutic actions of ASCs, focusing on EV-mediated modulation of macrophages and the spleen-kidney immune network.

Abstract Perivascular mesenchymal cells (PMCs), which include pericytes, give rise to myofibroblasts that contribute to chronic kidney disease progression. Several PMC markers have been identified; however, PMC heterogeneity and functions are not fully understood. Here, we describe a novel subset of renal PMCs that express Meflin, a glycosylphosphatidylinositol-anchored protein that was recently identified as a marker of fibroblasts essential for cardiac tissue repair. Tracing the lineage of Meflin⁺ PMCs, which are found in perivascular and periglomerular areas and exhibit renin-producing potential, showed that they detach from the vasculature and proliferate under disease conditions. Although the contribution of Meflin⁺ PMCs to conventional α-SMA⁺ myofibroblasts is low, they give rise to fibroblasts with heterogeneous α-SMA expression patterns. Genetic ablation of Meflin⁺ PMCs in a renal fibrosis mouse model revealed their essential role in collagen production. Consistent with this, human biopsy samples showed that progressive renal diseases exhibit high Meflin expression. Furthermore, Meflin overexpression in kidney fibroblasts promoted bone morphogenetic protein 7 signals and suppressed myofibroblastic differentiation, implicating the roles of Meflin in suppressing tissue fibrosis. These findings demonstrate that Meflin marks a PMC subset that is functionally distinct from classic pericytes and myofibroblasts, highlighting the importance of elucidating PMC heterogeneity.

Objectives We aimed to examine the validity of the quick Sequential Organ Failure Assessment (qSOFA) score for mortality and bacteraemia risk assessment in Japanese haemodialysis patients. Design This is a retrospective multicentre cohort study. Setting The six participating hospitals are tertiary-care institutions that receive patients on an emergency basis and provide primary, secondary and tertiary care. The other participating hospital is a secondary-care institution that receives patients on an emergency basis and provides both primary and secondary care. Participants This study included haemodialysis outpatients admitted for bacteraemia suspicion, who had blood drawn for cultures within 48 hours of their initial admission. Primary and secondary outcome measures The primary outcome measure was overall in-hospital mortality. Secondary outcomes included 28-day in-hospital mortality and the incidence of bacteraemia diagnosed based on blood culture findings. The discrimination, calibration and test performance of the qSOFA score were assessed. Missing data were handled using multiple imputation. Results Among the 507 haemodialysis patients admitted with bacteraemia suspicion between August 2011 and July 2013, the overall in-hospital mortality was 14.6% (74/507), the 28-day in-hospital mortality was 11.1% (56/507) and the incidence of bacteraemia, defined as a positive blood culture, was 13.4% (68/507). For predicting in-hospital mortality among haemodialysis patients, the area under the receiver operating characteristic curve was 0.61 (95% CI 0.56–0.67) for a qSOFA score ≥2. The Hosmer-Lemeshow χ²statistics for the qSOFA score as a predictor of overall and 28-day in-hospital mortality were 5.72 (p=0.02) and 7.40 (p<0.01), respectively. Conclusion On external validation, the qSOFA score exhibited low diagnostic accuracy and miscalibration for in-hospital mortality and bacteraemia among haemodialysis patients.

Abstract Multiple studies have shown that Staphylococcus aureus bacteremia (SAB) has been a major cause of death in hemodialysis patients. We examined whether SAB is a risk for mortality among chronic hemodialysis patients in Japan where the standard vascular access is arteriovenous fistula (AVF). This was a multicenter, retrospective study of maintenance hemodialysis patients with bloodstream infection (BSI) from 2011 to 2013 at tertiary care centers in Japan. The endpoint was hospital mortality. Our cohort contained 32 SAB cases (14 MRSA and 18 MSSA) and 42 non‐SAB cases. Hospital mortality was higher among SAB cases than non‐SAB cases (46.9% vs. 23.8%, P = 0.038). In patients with BSI, SAB was significantly associated with hospital mortality after adjustment for potential confounders, including type of vascular access (OR 3.26). S. aureus was the leading cause of BSI and hospital mortality among this cohort. Therefore, initial empiric treatment should cover for S. aureus.