A systemic inflammatory response leads to widespread organ dysfunction, such as kidney dysfunction. Plasminogen activator inhibitor-1 (PAI-1) is involved in the pathogenesis of inflammatory kidney ...injury; however, the regulatory mechanism of PAI-1 in injured kidneys remains unclear. PAI-1 is induced by interleukin (IL)-6 in patients with sepsis. In addition, the stabilization of IL-6 is regulated by the adenine–thymine-rich interactive domain-containing protein 5a (Arid5a). Therefore, the aim of the present study was to examine the involvement of Arid5a/IL-6/PAI-1 signaling in lipopolysaccharide (LPS)-induced inflammatory kidney injury. LPS treatment to C57BL/6J mice upregulated Pai-1 mRNA in the kidneys. Enzyme-linked immunosorbent assay (ELISA) revealed that PAI-1 expression was induced in the culture supernatants of LPS-treated human umbilical vein endothelial cells, but not in those of LPS-treated human kidney 2 (HK-2) cells, a tubular cell line. Combined with single-cell analysis, endothelial cells were found to be responsible for PAI-1 elevation in LPS-treated kidneys. Administration of TM5441, a PAI-1 inhibitor, reduced the urinary albumin/creatinine ratio, concomitant with downregulation of Il-6 and Arid5a mRNA expressions. IL-6 treatment in LPS model mice further upregulated Pai-1 mRNA expression compared with LPS alone, accompanied by renal impairment. Furthermore, the expression of Il-6 and Pai-1 mRNA was lower in Arid5a knockout mice than in wild-type mice after LPS treatment. Taken together, the vicious cycle of Arid5a/IL-6/PAI-1 signaling is involved in LPS-induced kidney injury.
Prevention of kidney fibrosis is an essential requisite for effective therapy in preventing chronic kidney disease (CKD). Here, we identify Old astrocyte specifically induced substance (OASIS)/cAMP ...responsive element‐binding protein 3‐like 1 (CREB3l1), a CREB/ATF family transcription factor, as a candidate profibrotic gene that drives the final common pathological step along the fibrotic pathway in CKD. Although microarray data from diseased patient kidneys and fibrotic mouse model kidneys both exhibit OASIS/Creb3l1 upregulation, the pathophysiological roles of OASIS in CKD remains unknown. Immunohistochemistry revealed that OASIS protein was overexpressed in human fibrotic kidney compared with normal kidney. Moreover, OASIS was upregulated in murine fibrotic kidneys, following unilateral ureteral obstruction (UUO), resulting in an increase in the number of OASIS‐expressing pathological myofibroblasts. In vitro assays revealed exogenous TGF‐β1 increased OASIS expression coincident with fibroblast‐to‐myofibroblast transition and OASIS contributed to TGF‐β1–mediated myofibroblast migration and increased proliferation. Significantly, in vivo kidney fibrosis induced via UUO or ischemia/reperfusion injury was ameliorated by systemic genetic knockout of OASIS, accompanied by reduced myofibroblast proliferation. Microarrays revealed that the transmembrane glycoprotein Bone marrow stromal antigen 2 (Bst2) expression was reduced in OASIS knockout myofibroblasts. Interestingly, a systemic anti‐Bst2 blocking antibody approach attenuated kidney fibrosis in normal mice but not in OASIS knockout mice after UUO, signifying Bst2 functions downstream of OASIS. Finally, myofibroblast‐restricted OASIS conditional knockouts resulted in resistance to kidney fibrosis. Taken together, OASIS in myofibroblasts promotes kidney fibrosis, at least in part, via increased Bst2 expression. Thus, we have identified and demonstrated that OASIS signaling is a novel regulator of kidney fibrosis.
Abstract
Podocyte injury is involved in the onset and progression of various kidney diseases. We previously demonstrated that the transcription factor, old astrocyte specifically induced substance ...(OASIS) in myofibroblasts, contributes to kidney fibrosis, as a novel role of OASIS in the kidneys. Importantly, we found that OASIS is also expressed in podocytes; however, the pathophysiological significance of OASIS in podocytes remains unknown. Upon lipopolysaccharide (LPS) treatment, there is an increase in OASIS in murine podocytes. Enhanced serum creatinine levels and tubular injury, but not albuminuria and podocyte injury, are attenuated upon podocyte-restricted OASIS knockout in LPS-treated mice, as well as diabetic mice. The protective effects of podocyte-specific OASIS deficiency on tubular injury are mediated by protein kinase C iota (PRKCI/PKCι), which is negatively regulated by OASIS in podocytes. Furthermore, podocyte-restricted OASIS transgenic mice show tubular injury and tubulointerstitial fibrosis, with severe albuminuria and podocyte degeneration. Finally, there is an increase in OASIS-positive podocytes in the glomeruli of patients with minimal change nephrotic syndrome and diabetic nephropathy. Taken together, OASIS in podocytes contributes to podocyte and/or tubular injury, in part through decreased PRKCI. The induction of OASIS in podocytes is a critical event for the disturbance of kidney homeostasis.
Tumor suppressor protein p53 plays crucial roles in the onset of heart failure. p53 activation results in cardiac dysfunction, at least partially by suppressing angiogenesis. Though p53 has been ...reported to reduce VEGF production by inhibiting hypoxia‐inducible factor, the anti‐angiogenic property of p53 remains to be fully elucidated in cardiomyocytes. To explore the molecular signals downstream of p53 that regulate vascular function, especially under normoxic conditions, DNA microarray was performed using p53‐overexpressing rat neonatal cardiomyocytes. Among genes induced by more than 2‐fold, we focused on CXCL10, an anti‐angiogenic chemokine. Real‐time PCR revealed that p53 upregulated the CXCL10 expression as well as p21, a well‐known downstream target of p53. Since p53 is known to be activated by doxorubicin (Doxo), we examined the effects of Doxo on the expression of CXCL10 and found that Doxo enhanced the CXCL10 expression, accompanied by p53 induction. Importantly, Doxo‐induced CXCL10 was abrogated by siRNA knockdown of p53, indicating that p53 activation is necessary for Doxo‐induced CXCL10. Next, we examined the effect of hypoxic condition on p53‐mediated induction of CXCL10. Interestingly, CXCL10 was induced by hypoxia and its induction was potentiated by the overexpression of p53. Finally, the conditioned media from cultured cardiomyocytes expressing p53 decreased the tube formation of endothelial cells compared with control, analyzed by angiogenesis assay. However, the inhibition of CXCR3, the receptor of CXCL10, restored the tube formation. These data indicate that CXCL10 is a novel anti‐angiogenic factor downstream of p53 in cardiomyocytes and could contribute to the suppression of vascular function by p53.
The conditioned media from p53‐expressing cardiomyocytes decreased the tube formation of Rat Aortic Endothelial Cells. The blockade of CXCR3, a receptor of CXCL10, restored the angiogenic activity of the conditioned media from p53‐expressing cardiomyocytes.
The number of patients with chronic kidney disease (CKD) is increasing worldwide. When kidneys are exposed to severe injury, tubular cell death occurs and kidney fibrosis progresses by activating ...fibroblasts and myofibroblasts (referred to as (myo)fibroblasts), leading to CKD; however, the pathological and molecular mechanisms underlying CKD, including kidney fibrosis, remain obscure. In the present study, we focused on a transcription factor PBX/Knotted Homeobox 2 (PKNOX2) in kidney fibrosis. The transcript and protein expression of PKNOX2 was upregulated in fibrotic kidneys after unilateral ureteral obstruction (UUO). Importantly, immunofluorescence microscopic analysis revealed that the number of PKNOX2-expressing myofibroblasts was increased, whereas the expression of PKNOX2 was decreased in proximal tubular epithelial cells after UUO. In (myo)fibroblasts, PKNOX2 was induced by TGF-β1. Knockdown of PKNOX2 using shRNA lentiviral system reduced the viability of (myo)fibroblasts either in the presence or absence of TGF-β1, accompanied by increased apoptosis. Moreover, PKNOX2 knockdown decreased TGF-β1-induced migration of myofibroblasts and differentiation of fibroblasts into myofibroblasts. Significantly, knockdown of PKNOX2 also decreased the viability and increased apoptosis of tubular epithelial cells. Collectively, PKNOX2 regulates the function of (myo)fibroblasts and the viability of proximal tubular epithelial cells in progression of kidney fibrosis.
•Myofibroblasts expressing PKNOX2 were increased in fibrotic kidneys.•PKNOX2 expression in tubular epithelial cells was downregulated in fibrotic kidneys.•TGF-β1 induced PKNOX2 expression in (myo)fibroblasts.•PKNOX2 is necessary for the function and viability of myofibroblasts.•PKNOX2 knockdown induced cell death in tubular epithelial cells.
Coronavirus disease 2019 (COVID-19) induces respiratory dysfunction as well as kidney injury. Although the kidney is considered a target organ of severe acute respiratory syndrome coronavirus 2 ...(SARS-CoV-2) and affected by the COVID-19-induced cytokine storm, the mechanisms of renal reaction in SARS-CoV-2 infection are unknown. In this study, a murine COVID-19 model was induced by nasal infection with mouse-adapted SARS-CoV-2 (MA10). MA10 infection induced body weight loss along with lung inflammation in mice 4 days after infection. Serum creatinine levels and the urinary albumin/creatinine ratio increased on
after MA10 infection. Measurement of the urinary neutrophil gelatinase-associated lipocalin/creatinine ratio and hematoxylin and eosin staining revealed tubular damage in MA10-infected murine kidneys, indicating kidney injury in the murine COVID-19 model. Interferon (IFN)-γ and interleukin-6 upregulation in the sera of MA10-infected mice, along with the absence of MA10 in the kidneys, implied that the kidneys were affected by the MA10 infection-induced cytokine storm rather than by direct MA10 infection of the kidneys. RNA-sequencing analysis revealed that antiviral genes, such as the IFN/Janus kinase (JAK) pathway, were upregulated in MA10-infected kidneys. Upon administration of the JAK inhibitor baricitinib on
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after MA10 infection, an antiviral pathway was suppressed, and MA10 was detected more frequently in the kidneys. Notably, JAK inhibition upregulated the hypoxia response and exaggerated kidney injury. These results suggest that endogenous antiviral activity protects against SARS-CoV-2-induced kidney injury in the early phase of infection, providing valuable insights into the pathogenesis of COVID-19-associated nephropathy.
Patients frequently present with acute kidney injury or abnormal urinary findings after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Here, we investigated how the kidneys respond during SARS-CoV-2 infection using a murine coronavirus disease 2019 (COVID-19) model and showed that Janus kinase-mediated endogenous antiviral activity protects against kidney injury in the early phase of SARS-CoV-2 infection. These findings provide valuable insights into the renal pathophysiology of COVID-19.
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