Macrophage-derived extracellular vesicles regulate concanavalin A-induced hepatitis by suppressing macrophage cytokine production.

Acute liver failure is a clinical syndrome of severe hepatic dysfunction. Immune cells play an important role in acute liver failure. In recent years, the immunoregulatory function of extracellular vesicles (EVs) has been reported; therefore, it is inferred that EVs play a role in immune-mediated hepatitis. In this study, we investigated the immunoregulatory function of EVs in concanavalin A (Con A)-induced hepatitis. The mouse model was prepared by a single intravenous administration of 15 mg/kg Con A, in which there was a significant increase in the serum EVs number. In an in vitro study, the number of secreted EVs was also significantly increased in Con A-treated RAW264.7 cells, a mouse macrophage cell line, but not in Hepa1-6 cells, a mouse hepatoma cell line. In an in vitro EVs treatment study, EVs from Con A-treated mouse serum and Con A-treated RAW264.7 cells suppressed inflammatory cytokine production in Con A-stimulated RAW264.7 cells. miRNA sequencing analysis showed that the expression of mmu-miR-122-5p and mmu-miR-148a-3p was commonly increased in these EVs and EVs-treated cells. The pathways enriched in the predicted miRNA target genes included inflammatory response pathways. The mRNA levels of the target genes in these pathways (mitogen-activated protein kinase, phosphoinositide 3-kinase/Akt and Rho/Rho-associated coiled-coil containing protein kinase pathways) were decreased in the EVs-treated cells. In an in vivo RNA interference study, the knockdown of liver RAB27A, an EVs secretion regulator, significantly exacerbated Con A-induced hepatitis. These data suggest that macrophage-derived EVs play an important role in Con A-induced hepatitis through immunoregulation.

Cholesterol-binding protein TSPO2 coordinates maturation and proliferation of terminally differentiating erythroblasts.

TSPO2 (translocator protein 2) is a transmembrane protein specifically expressed in late erythroblasts and has been postulated to mediate intracellular redistribution of cholesterol. We identified TSPO2 as the causative gene for the HK (high-K+) trait with immature red cell phenotypes in dogs and investigated the effects of the TSPO2 defects on erythropoiesis in HK dogs with the TSPO2 mutation and Tspo2 knockout (Tspo2-/-) mouse models. Bone marrow-derived erythroblasts from HK dogs showed increased binucleated and apoptotic cells at various stages of maturation and shed large nuclei with incomplete condensation when cultured in the presence of erythropoietin, indicating impaired maturation and cytokinesis. The canine TSPO2 induces cholesterol accumulation in the endoplasmic reticulum and could thereby regulate cholesterol availability by changing intracellular cholesterol distribution in erythroblasts. Tspo2-/- mice consistently showed impaired cytokinesis with increased binucleated erythroblasts, resulting in compensated anemia, and their red cell membranes had increased Na,K-ATPase, resembling the HK phenotype in dogs. Tspo2-deficient mouse embryonic stem cell-derived erythroid progenitor (MEDEP) cells exhibited similar morphological defects associated with a cell-cycle arrest at the G2/M phase, resulting in decreased cell proliferation and had a depletion in intracellular unesterified and esterified cholesterol. When the terminal maturation was induced, Tspo2-/- MEDEP cells showed delays in hemoglobinization; maturation-associated phenotypic changes in CD44, CD71, and TER119 expression; and cell-cycle progression. Taken together, these findings imply that TSPO2 is essential for coordination of maturation and proliferation of erythroblasts during normal erythropoiesis.

Exploration of small RNA biomarkers for testicular injury in the serum exosomes of rats.

Testicular injury is often observed in drug development. Serum hormones are usually used as noninvasive biomarkers for testicular injury; however, their sensitivities are low. Therefore, it is difficult to monitor testicular injury in drug development. In recent years, molecules in body fluid exosomes have attracted attention as biomarkers for diseases. In this study, small RNAs in serum exosomes were analyzed to identify noninvasive biomarkers of testicular injury in rats, which are often used in preclinical drug development. The rat models of testicular injury were prepared by a single oral administration of 2000 mg/kg ethylene glycol monomethyl ether, in which spermatocyte degeneration and Sertoli cell vacuolation were observed, or 400 mg/kg carbendazim, in which Sertoli cell vacuolation and seminiferous tubule dilation were observed. Serum exosomal small RNA-seq analysis of these models was performed. The analysis identified 3 small RNAs that fluctuated in common between the models, and miR-423-5p and miR-128-3p were selected as candidate markers. For evaluating these candidate markers in other testicular injury models, the models were prepared by a single oral administration of 60 mg/kg 1,3-dinitrobenzene or 500 mg/kg nitrofurazone, and spermatocyte degeneration and Sertoli cell vacuolation were observed. In qPCR analysis, these exosomal miRNAs were upregulated in all models except for the 1,3-dinitrobenzene model, in which severe hemolysis was observed. By contrast, these miRNAs in whole serum extracts did not significantly change in any of the models. In conclusion, we identified miR-423-5p and miR-128-3p in serum exosomes as noninvasive biomarkers for testicular injury in rats.

Analysis of a Skeletal Muscle Injury and Drug Interactions in Lovastatin- and Fenofibrate-Coadministered Dogs.

Because dogs are widely used in drug development as nonrodent experimental animals, using a dog model for drug-induced adverse reactions is considered to be relevant for an evaluation and investigation of a mechanism and a biomarker of clinical drug-induced adverse reactions. Skeletal muscle injury occurs by various drugs, including statins and fibrates, during drug development. However, there is almost no report of a dog model for drug-induced skeletal muscle injury. In the present study, we induced skeletal muscle injury in dogs by oral coadministration of lovastatin (LV) and fenofibrate (FF) for 4 weeks. Increases in plasma levels of creatine phosphokinase, myoglobin, miR-1, and miR-133a and degeneration/necrosis of myofibers in skeletal muscles but not in the heart were observed in LV- and FF-coadministered dogs. Plasma levels of lovastatin lactone and lovastatin acid were higher in LV- and FF-coadministered dogs than LV-administered dogs. Taken together, FF coadministration is considered to affect LV metabolism and result in skeletal muscle injury.