Probes for INS

Chronic kidney disease (CKD) is characterized by persistent abnormalities in kidney function, accompanied by structural changes. Interstitial fibrosis, characterized by the accumulation of extracellular matrix (ECM) proteins, is frequently detected during CKD development. Given the multiple underlying causes of CKD, numerous animal models have been developed to advance our understanding of human nephropathy. Herein, we compared two reliable toxin-induced mouse kidney fibrosis models in terms of fibrosis and inflammation. Administration of folic acid (250 mg/kg, intraperitoneal injection) or an adenine diet (0.25 % for three weeks) afforded similar effects on kidney function, as detected by increased serum nitrogen levels. In addition, the kidneys exhibited a similar extent of tubule dilation and kidney damage. The degree of fibrosis was compared using various biological methods. Although both models developed a significant fibrotic phenotype, the adenine diet-fed model showed a marginally higher increase in fibrosis than the folic acid model, as reflected by increased kidney ECM gene and protein levels. We further compared inflammatory responses in the kidneys. Interestingly, pro-inflammatory responses, including cytokine expression and immune cell infiltration, were significantly increased in adenine diet-fed kidneys. Furthermore, collagen expression was identified in the macrophage-infiltrated region, implying the importance of inflammation in fibrogenesis. Collectively, we observed that the adenine diet-fed kidney fibrosis model presented a higher inflammatory response with increased fibrosis when compared with the folic acid-induced kidney fibrosis model, indicating the importance of the inflammatory response in fibrosis development.

The source of new hepatocytes in the uninjured liver has remained an open question. By lineage tracing using the Wnt-responsive gene Axin2 in mice, we identify a population of proliferating and self-renewing cells adjacent to the central vein in the liver lobule. These pericentral cells express the early liver progenitor marker Tbx3, are diploid, and thereby differ from mature hepatocytes, which are mostly polyploid. The descendants of pericentral cells differentiate into Tbx3-negative, polyploid hepatocytes, and can replace all hepatocytes along the liver lobule during homeostatic renewal. Adjacent central vein endothelial cells provide Wnt signals that maintain the pericentral cells, thereby constituting the niche. Thus, we identify a cell population in the liver that subserves homeostatic hepatocyte renewal, characterize its anatomical niche, and identify molecular signals that regulate its activity.

A high-fat diet (HFD) is a major risk factor for chronic kidney disease. Although HFD promotes renal injury, characterized by increased inflammation and oxidative stress leading to fibrosis, the underlying mechanism remains elusive. Here, we investigated the role and mechanism of protease-activating receptor 2 (PAR2) activation during HFD-induced renal injury in C57/BL6 mice. HFD for 16 weeks resulted in kidney injury, manifested by increased blood levels of blood urea nitrogen, increased levels of oxidative stress with inflammation, and structural changes in the kidney tubules. HFD-fed kidneys showed elevated PAR2 expression level in the tubular epithelial region. To elucidate the role of PAR2, PAR2 knockout mice and their littermates were administered HFD. PAR2 deficient kidneys showed reduced extent of renal injury. PAR2 deficient kidneys showed significantly decreased levels of inflammatory gene expression and macrophage infiltration, followed by reduced accumulation of extracellular matrix proteins. Using NRK52E kidney epithelial cells, we further elucidated the mechanism and role of PAR2 activation during renal injury. Palmitate treatment increased PAR2 expression level in NRK52E cells and scavenging of oxidative stress blocked PAR2 expression. Under palmitate-treated conditions, PAR2 agonist-induced NF-κB activation level was higher with increased chemokine expression level in the cells. These changes were attenuated by the depletion of oxidative stress. Taken together, our results suggest that HFD-induced PAR2 activation is associated with increased levels of renal oxidative stress, inflammatory response, and fibrosis.

Ischemic cardiomyopathy (ICM) is the leading cause of heart failure worldwide, yet the cellular and molecular signature of this disease is largely unclear. Using single-nucleus RNA sequencing (snRNA-seq) and integrated computational analyses, we profile the transcriptomes of over 99,000 human cardiac nuclei from the non-infarct region of the left ventricle of 7 ICM transplant recipients and 8 non-failing (NF) controls. We find the cellular composition of the ischemic heart is significantly altered, with decreased cardiomyocytes and increased proportions of lymphatic, angiogenic, and arterial endothelial cells in patients with ICM. We show that there is increased LAMININ signaling from endothelial cells to other cell types in ICM compared with NF. Finally, we find that the transcriptional changes that occur in ICM are similar to those in hypertrophic and dilated cardiomyopathies and that the mining of these combined datasets can identify druggable genes that could be used to target end-stage heart failure.