Kidney vascular congestion exacerbates acute kidney injury in mice.

Heart failure is frequently accompanied by kidney failure and co-incidence of these organ failures worsens the mortality in patients with heart failure. Recent clinical observations revealed that increased kidney venous pressure, rather than decreased cardiac output, causes the deterioration of kidney function in patients with heart failure. However, the underlying pathophysiology is unknown. Here, we found that decreased blood flow velocity in peritubular capillaries by kidney congestion and upregulation of endothelial nuclear factor-κB (NF-κB) signaling synergistically exacerbate kidney injury. We generated a novel mouse model with unilateral kidney congestion by constriction of the inferior vena cava between kidney veins. Intravital imaging highlighted the notable dilatation of peritubular capillaries and decreased kidney blood flow velocity in the congestive kidney. Damage after ischemia reperfusion injury was exacerbated in the congestive kidney and accumulation of polymorphonuclear leukocytes within peritubular capillaries was noted at the acute phase after injury. Similar results were obtained in vitro, in which polymorphonuclear leukocytes adhesion on activated endothelial cells was decreased in flow velocity-dependent manner but cancelled by inhibition of NF-κB signaling. Pharmacological inhibition of NF-κB for the mice subjected by both kidney congestion and ischemia reperfusion injury ameliorated the accumulation of polymorphonuclear leukocytes and subsequent exacerbation of kidney injury. Thus, our study demonstrates the importance of decreased blood flow velocity accompanying activated NF-κB signaling in aggravation of kidney injury. Hence, inhibition of NF-κB signaling may be a therapeutic candidate for the vicious cycle between heart and kidney failure with increased kidney venous pressure.

Intratubular epithelial-mesenchymal transition and tubular atrophy after kidney injury in mice.

Tubular atrophy is a common pathological feature of kidney fibrosis. Although fibroblasts play a predominant role in tissue fibrosis, the role of repairing tubular epithelia in tubular atrophy is unclear. We demonstrated the essential role of focal adhesion kinase (FAK)-mediated intratubular epithelial-mesenchymal transition (EMT) in the pathogenesis of tubular atrophy after severe ischemia-reperfusion injury (IRI). Actively proliferating tubular epithelia undergoing intratubular EMT were noted in the acute phase of severe IRI, resulting in tubular atrophy in the chronic phase, reflecting failed tubular repair. Furthermore, FAK was phosphorylated in the tubular epithelia in the acute phase of severe IRI, and its inhibition ameliorated both tubular atrophy and interstitial fibrosis in the chronic phase after injury. In vivo clonal analysis of single-labeled proximal tubular epithelial cells after IRI using proximal tubule reporter mice revealed substantial clonal expansion after IRI, reflecting active epithelial proliferation during repair. The majority of these proliferating epithelia were located in atrophic and nonfunctional tubules, and FAK inhibition was sufficient to prevent tubular atrophy. In vitro, transforming growth factor-ß induced FAK phosphorylation and an EMT phenotype, which was also prevented by FAK inhibition. In an in vitro tubular epithelia gel contraction assay, transforming growth factor-ß treatment accelerated gel contraction, which was suppressed by FAK inhibition. In conclusion, injury-induced intratubular EMT is closely related to tubular atrophy in a FAK-dependent manner.

IgA nephropathy in a patient receiving infliximab for generalized pustular psoriasis.

BACKGROUND: IgA nephropathy is the most common glomerulonephritis. Secondary IgA nephropathy complicated with systemic diseases, including psoriasis, is also often reported. Generalized pustular psoriasis is a form of psoriasis characterized by sterile pustules on reddened skin and fever. Infliximab, one of the first-line therapies for severe psoriasis, has also been reported to cause systemic vasculitis and IgA nephropathy. We herein report a case of IgA nephropathy activated during infliximab treatment for generalized pustular psoriasis. CASE PRESENTATION: A 28-year-old woman presented with episodic gross hematuria, increasing proteinuria, and renal dysfunction. She had been receiving anti-TNFα therapy with infliximab because of generalized pustular psoriasis for 3 years, but her skin symptoms worsened following withdrawal during pregnancy. After delivery, her skin symptoms improved with the resumption of infliximab, but clinical signs suggested glomerulonephritis, and renal biopsy showed active IgA nephropathy. Infliximab was discontinued, and the combination of corticosteroids, tonsillectomy, and secukinumab, an IL-17A inhibitor, improved both the skin symptoms and the glomerulonephritis. CONCLUSIONS: In our case, the activity of IgA nephropathy was exacerbated by anti-TNFα therapy but was improved by the combination of corticosteroids, tonsillectomy, and an IL-17A inhibitor against the original disease. Autoimmune diseases may underlie the development of secondary IgA nephropathy associated with anti-TNFα therapy, and so further studies are needed to better understand the association between molecular-targeted drugs and IgA nephropathy.

Lower blood pressure and risk of cisplatin nephrotoxicity: a retrospective cohort study.

BACKGROUND: The pathophysiological mechanisms of cisplatin nephrotoxicity include the reduction of renal blood flow, as well as tubular epithelial cell toxicity. The objective of this study was to investigate the influence of lower blood pressure and decreased food intake on the incidence of cisplatin nephrotoxicity. METHODS: We conducted a retrospective cohort study at a university hospital between 2011 and 2012. We identified hospitalized adult patients with head and neck cancer, esophageal cancer, or gastric cancer, who received intravenous cisplatin administration. The primary outcome was the incidence of cisplatin nephrotoxicity defined as the increase in serum creatinine after cisplatin administration more than 1.5 times from baseline. RESULTS: The study participants included 182 patients, in whom we observed a total of 442 cycles of cisplatin chemotherapy. The incidence of cisplatin nephrotoxicity was observed in 41 of 182 cycles with initial administration. Multivariate logistic regression analysis showed that systolic blood pressure was independently associated with cisplatin nephrotoxicity (adjusted odds ratio 0.75, 95% confidence interval 0.57 to 0.95 for each 10 mmHg). The use of renin-angiotensin system (RAS) inhibitors was also associated with cisplatin nephrotoxicity (3.39, 1.30 to 8.93). Among quartiles of systolic blood pressure in all cycles of chemotherapy, the incidence of nephrotoxicity in the lower blood pressure group was significantly higher than that in the higher blood pressure group for patients taking non-solid food (P = 0.037), while there was no significant difference for patients taking solid food (P = 0.67). CONCLUSIONS: Lower blood pressure and the use of RAS inhibitors were associated with the incidence of cisplatin nephrotoxicity, and lower blood pressure had a greater influence on nephrotoxicity in patients who could not take solid food. Discontinuation of antihypertensive medication including RAS inhibitors before cisplatin chemotherapy should be considered, which may be beneficial for patients with lower blood pressure.

Kidney-specific Sonoporation-mediated Gene Transfer.

Sonoporation can deliver agents to target local organs by systemic administration, while decreasing the associated risk of adverse effects. Sonoporation has been used for a variety of materials and in a variety of organs. Herein, we demonstrated that local sonoporation to the kidney can offer highly efficient transfer of oligonucleotides, which were systemically administrated to the tubular epithelium with high specificity. Ultrasonic wave irradiation to the kidney collapsed the microbubbles and transiently affected the glomerular filtration barrier and increased glomerular permeability. Oligonucleotides were passed through the barrier all at once and were absorbed throughout the tubular epithelium. Tumor necrosis factor alpha (TNFα), which plays a central role in renal ischemia-reperfusion injury, was targeted using small interfering RNA (siRNA) with renal sonoporation in a murine model. The reduction of TNFα expression after single gene transfer significantly inhibited the expression of kidney injury markers, suggesting that systemic administration of siRNA under temporary and local sonoporation could be applicable in the clinical setting of ischemic acute kidney injury.

Steroid-resistant nephrotic syndrome as the initial presentation of nail-patella syndrome: a case of a de novo LMX1B mutation.

BACKGROUND: Nail-patella syndrome (NPS) is an autosomal dominant disorder caused by mutations in the LMX1B gene and is characterized by nail dysplasia, skeletal abnormalities, and nephropathy. We herein report a case of steroid-resistant nephrotic syndrome (SRNS) prior to overt orthopedic symptoms in a patient with NPS. CASE PRESENTATION: A 24-year-old woman presented to our hospital with knee pain. She had poorly developed nails, hypoplastic patellas, dislocation of the elbows, and iliac horns in the pelvis. At the age of 7, she developed nephrotic syndrome and was diagnosed with primary focal segmental glomerulosclerosis by renal biopsy. She received long-term corticosteroid therapy with no obvious response. Her clinical course and orthopedic manifestations indicated NPS, and a genetic analysis showed a de novo mutation in the LMX1B gene (c.819 + 1G > A). Nephropathy in this case was considered to be associated with NPS. Therefore, we discontinued corticosteroids without the exacerbation of nephrotic syndrome. CONCLUSIONS: Patients with NPS may develop nephrotic syndrome prior to overt orthopedic symptoms and only show non-specific findings in renal biopsy at an early stage of NPS nephropathy. Hereditary nephrotic syndrome, often presenting as childhood-onset SRNS, may also be difficult to diagnose in patients with the following conditions: renal symptoms prior to overt extrarenal symptoms, de novo mutations, and non-specific findings in renal biopsy. Therefore, in the management of SRNS in children, we need to reconsider the possibility of hereditary diseases such as NPS even without a family history.

Differentiated kidney epithelial cells repair injured proximal tubule.

Whether kidney proximal tubule harbors a scattered population of epithelial stem cells is a major unsolved question. Lineage-tracing studies, histologic characterization, and ex vivo functional analysis results conflict. To address this controversy, we analyzed the lineage and clonal behavior of fully differentiated proximal tubule epithelial cells after injury. A CreER(T2) cassette was knocked into the sodium-dependent inorganic phosphate transporter SLC34a1 locus, which is expressed only in differentiated proximal tubule. Tamoxifen-dependent recombination was absolutely specific to proximal tubule. Clonal analysis after injury and repair showed that the bulk of labeled cells proliferate after injury with increased clone size after severe compared with mild injury. Injury to labeled proximal tubule epithelia induced expression of CD24, CD133, vimentin, and kidney-injury molecule-1, markers of putative epithelial stem cells in the human kidney. Similar results were observed in cultured proximal tubules, in which labeled clones proliferated and expressed dedifferentiation and injury markers. When mice with completely labeled kidneys were subject to injury and repair there was no dilution of fate marker despite substantial proliferation, indicating that unlabeled progenitors do not contribute to kidney repair. During nephrogenesis and early kidney growth, single proximal tubule clones expanded, suggesting that differentiated cells also contribute to tubule elongation. These findings provide no evidence for an intratubular stem-cell population, but rather indicate that terminally differentiated epithelia reexpress apparent stem-cell markers during injury-induced dedifferentiation and repair.

Paracrine Wnt1 Drives Interstitial Fibrosis without Inflammation by Tubulointerstitial Cross-Talk.

AKI with incomplete epithelial repair is a major contributor to CKD characterized by tubulointerstitial fibrosis. Injury-induced epithelial secretion of profibrotic factors is hypothesized to underlie this link, but the identity of these factors and whether epithelial injury is required remain undefined. We previously showed that activation of the canonical Wnt signaling pathway in interstitial pericytes cell autonomously drives myofibroblast activation in vivo. Here, we show that inhibition of canonical Wnt signaling also substantially prevented TGFß-dependent myofibroblast activation in vitro. To investigate whether Wnt ligand derived from proximal tubule is sufficient for renal fibrogenesis, we generated a novel mouse strain with inducible proximal tubule Wnt1 secretion. Adult mice were treated with vehicle or tamoxifen and euthanized at 12 or 24 weeks postinjection. Compared with vehicle-treated controls, kidneys with tamoxifen-induced Wnt1 expression from proximal tubules displayed interstitial myofibroblast activation and proliferation and increased matrix protein production. PDGF receptor ß-positive myofibroblasts isolated from these kidneys exhibited increased canonical Wnt target gene expression compared with controls. Notably, fibrotic kidneys had no evidence of inflammatory cytokine expression, leukocyte infiltration, or epithelial injury, despite the close histologic correlation of each with CKD. These results provide the first example of noninflammatory renal fibrosis. The fact that epithelial-derived Wnt ligand is sufficient to drive interstitial fibrosis provides strong support for the maladaptive repair hypothesis in the AKI to CKD transition.

Who regenerates the kidney tubule?

The kidney possesses profound regenerative potential and in some cases can recover completely 'restitutio at integrum' following an acute kidney injury (AKI). Emerging evidence strongly suggests that sometimes repair is incomplete, however, and, in this situation, an episode of AKI leads to future chronic kidney disease (CKD). Understanding the tubular response after AKI will shed light on the relationship between incomplete repair and future risk of CKD. The first repair phase after AKI is characterized by robust proliferation of epithelial cells in the proximal tubule. The exact source of these proliferating cells has been a source of controversy for the last decade. While nearly everyone now agrees that reparative cells arise within the proximal tubule, there is disagreement about whether all surviving cells possess an equivalent repair capacity through dedifferentiation, or alternatively whether a pre-existing intratubular stem cell population [so-called scattered tubular cells (STC)] is responsible for repair. This review will summarize the evidence on both sides of this issue and will discuss very recent genetic fate-tracing data that strongly points against the existence of intratubular stem cells but rather indicates that terminally differentiated proximal tubule epithelial cells undergo dedifferentiation upon injury to replace lost neighboring tubular epithelial cells through proliferative self-duplication. This new evidence includes data clearly indicating that STC are not committed tubular stem cells but instead represent individual dedifferentiated tubular epithelial cells that transiently express putative stem cell markers.

Controversies on the origin of proliferating epithelial cells after kidney injury.

The kidney possesses the capacity to repair after an acute insult, even one that causes complete organ failure. This regenerative response is characterized by robust proliferation of epithelial cells, principally those located in the proximal tubule. Because defining the origin of these reparative cells has important consequences for stem cell and regenerative approaches to treating kidney injury, this area has been the subject of intense investigation and debate. While progress has been made in narrowing the possible origin of these cells to an intratubular source, there has been no consensus between the possibility of a pre-existing intratubular stem or progenitor cell versus the possibility that fully differentiated epithelial cells re-enter the cell cycle after injury and generate new proximal tubule cells through self-duplication. This review will summarize the evidence on both sides of this active controversy and provide support for the notion that no pre-existing proximal tubule stem cell population exists, but rather all differentiated proximal tubule epithelia have the capacity to proliferate during repair by a mechanism of dedifferentiation and self-duplication.

Aversion to a High Salt Taste is Disturbed in Patients With CKD.

Introduction: A reduced salt intake is a vital lifestyle modification in the management of hypertension. Initiatives aimed at decreasing the intake of salt are based on the preference by humans for a salt taste. Salt intake behavior appears to be affected by the balance between attraction to a low salt taste and aversion to a high salt taste. However, aversion to a high salt taste has not yet been quantitively investigated in both healthy individuals and patients with chronic kidney disease (CKD). Methods: Assessments of gustatory and aversion thresholds for salt, bitter, sour, and sweet tastes were performed using a stimulant-impregnated test strip in healthy subjects and patients with CKD. Results: In a pilot taste test of 125 healthy subjects, the number of participants with an aversive reaction increased at higher salt concentrations. The threshold for normal taste perception was arbitrarily defined as 10% NaCl, with 47.2% of healthy subjects displaying an aversive reaction. In taste tests performed by 70 patients with CKD, 10% were unable to recognize a salt taste, even at the highest concentration (20% NaCl), suggesting a significant impairment in taste perception in patients with CKD. Only 15.7% of patients with CKD exhibited a normal aversion to NaCl, whereas 78.6% showed the complete loss of aversion to salt. Conclusion: The present results confirmed the anticipated aversive response to a high salt taste in humans and demonstrated its impairment in patients with CKD, implying that patients with CKD have reduced resistance to a high salt intake.

The importance of proinflammatory failed-repair tubular epithelia as a predictor of diabetic kidney disease progression.

The immense public health burden of diabetic kidney disease (DKD) has led to an increase in research on the pathophysiology of advanced DKD. The present study focused on the significance of proinflammatory vascular cell adhesion molecule 1 (VCAM1)+ tubules in DKD progression. A retrospective cohort study of DKD patients showed that the percentage of VCAM1+ tubules in kidney samples was correlated with poor renal outcomes. We established an advanced DKD model by partial resection of the kidneys of db/db mice and demonstrated that it closely resembled the human advanced DKD phenotype, with tissue hypoxia, tubular DNA damage, tissue inflammation, and high tubular VCAM1 expression. Luseogliflozin ameliorated tissue hypoxia and proinflammatory responses, including VCAM1+ expression, in tubules. These findings suggest the potential of tubular VCAM1 as a histological marker for poor DKD outcomes. SGLT2 inhibitors may attenuate tissue hypoxia and subsequent tissue inflammation in advanced DKD, thereby ameliorating tubular injury.

Clinical characteristics of silent myocardial ischemia diagnosed with adenosine stress 99mTc-tetrofosmin myocardial scintigraphy in Japanese patients with acute cerebral infarction.

It is well known that silent myocardial ischemia (SMI) often complicates patients with cerebral infarction and that stroke patients often die of ischemic heart disease. Therefore, it is considered important to treat myocardial ischemia in stroke patients. This study investigated SMI complicating Japanese patients with fresh stroke, using (99m)Tc-tetrofosmin myocardial scintigraphy with pharmacologic stress testing to elucidate their clinical manifestations. This study included 41 patients (26 men, mean age 76.0 ± 10.7 years) with acute cerebral infarction and no history of coronary artery disease. All patients underwent (99m)Tc-tetrofosmin myocardial scintigraphy with intravenous administration of adenosine to diagnose SMI. Of the 41 patients, myocardial ischemia was confirmed in 17 patients (41.5%). Atherosclerotic etiology was the major cause of stroke in the ischemia(+) group and embolic origin was the major cause in the ischemia(-) group. Patients with myocardial ischemia had a higher incidence of diabetes mellitus (52.9 vs 20.8%; P = 0.0323) and more than two conventional cardiovascular risk factors (64.7 vs 25.0%; P = 0.0110) compared with the nonischemic patients. Infarction subtype of atherosclerotic origin was an independent positive predictor of asymptomatic myocardial ischemia in patients with stroke. These findings indicate that the prevalence of asymptomatic myocardial ischemia is relatively high, especially in patients with stroke of atherosclerotic origin. Therefore, it is beneficial for us to narrow the target population who are at the highest risk when screening for SMI in Japanese patients with acute cerebral infarction.

Klotho is associated with VEGF receptor-2 and the transient receptor potential canonical-1 Ca2+ channel to maintain endothelial integrity.

Klotho is a circulating protein, and Klotho deficiency disturbs endothelial integrity, but the molecular mechanism is not fully clarified. We report that vascular endothelium in Klotho-deficient mice showed hyperpermeability with increased apoptosis and down-regulation of vascular endothelial (VE)-cadherin because of an increase in VEGF-mediated internal calcium concentration ([Ca(2+)]i) influx and hyperactivation of Ca(2+)-dependent proteases. Immunohistochemical analysis, the pull-down assay using Klotho-fixed agarose, and FRET confocal imaging confirmed that Klotho protein binds directly to VEGF receptor 2 (VEGFR-2) and endothelial, transient-receptor potential canonical Ca(2+) channel 1 (TRPC-1) and strengthens the association to promote their cointernalization. An in vitro mutagenesis study revealed that the second hydrolase domain of Klotho interacts with sixth and seventh Ig domains of VEGFR-2 and the third extracellular loop of TRPC-1. In Klotho-deficient endothelial cells, VEGF-mediated internalization of the VEGFR-2/TRPC-1 complex was impaired, and surface TRPC-1 expression increased 2.2-fold; these effects were reversed by supplementation of Klotho protein. VEGF-mediated elevation of [Ca(2+)]i was sustained at higher levels in an extracellular Ca(2+)-dependent manner, and normalization of TRCP-1 expression restored the abnormal [Ca(2+)]i handling. These findings provide evidence that Klotho protein is associated with VEGFR-2/TRPC-1 in causing cointernalization, thus regulating TRPC-1-mediated Ca(2+) entry to maintain endothelial integrity.

Percutaneous transluminal renal angioplasty remarkably improved severe hypertension and renal function in a patient with renal artery stenosis and postrenal kidney failure.

A 69-year-old man was admitted to our hospital with severe hypertension and rapidly worsening renal function. He presented with a 10-year history of chronic renal failure caused by bilateral ureteral obstruction due to retroperitoneal fibrosis. Magnetic resonance angiography and Doppler ultrasonography suggested severe right renal artery stenosis (RAS). Renal angiography revealed 99% stenosis at the ostium of the right renal artery. We performed percutaneous transluminal renal angioplasty (PTRA) with the support of intravascular ultrasound to decrease the amount of contrast agent needed. In addition, to prevent distal atheroembolism, a distal protection device was used. The procedure was completed without any adverse effects. After PTRA, renal function and blood pressure improved remarkably and remained stable for one year. PTRA for RAS remains controversial, especially in patients with renal insufficiency. Use of new devices should be considered to decrease catheterization-related adverse effects.

Streptozotocin induces renal proximal tubular injury through p53 signaling activation.

Streptozotocin (STZ), an anti-cancer drug that is primarily used to treat neuroendocrine tumors (NETs) in clinical settings, is incorporated into pancreatic ß-cells or proximal tubular epithelial cells through the glucose transporter, GLUT2. However, its cytotoxic effects on kidney cells have been underestimated and the underlying mechanisms remain unclear. We herein demonstrated that DNA damage and subsequent p53 signaling were responsible for the development of STZ-induced tubular epithelial injury. We detected tubular epithelial DNA damage in NET patients treated with STZ. Unbiased transcriptomics of STZ-treated tubular epithelial cells in vitro showed the activation of the p53 signaling pathway. STZ induced DNA damage and activated p53 signaling in vivo in a dose-dependent manner, resulting in reduced membrane transporters. The pharmacological inhibition of p53 and sodium-glucose transporter 2 (SGLT2) mitigated STZ-induced epithelial injury. However, the cytotoxic effects of STZ on pancreatic ß-cells were preserved in SGLT2 inhibitor-treated mice. The present results demonstrate the proximal tubular-specific cytotoxicity of STZ and the underlying mechanisms in vivo. Since the cytotoxic effects of STZ against ß-cells were not impaired by dapagliflozin, pretreatment with an SGLT2 inhibitor has potential as a preventative remedy for kidney injury in NET patients treated with STZ.

The kinase Pyk2 is involved in renal fibrosis by means of mechanical stretch-induced growth factor expression in renal tubules.

Unilateral ureteral obstruction is a well-established experimental model of progressive renal fibrosis. We tested whether mechanical stretch and subsequent renal tubular distension might lead to renal fibrosis by first studying renal tubular epithelial cells in culture. We found that mechanical stretch induced reactive oxygen species that in turn activated the cytoplasmic proline-rich tyrosine kinase-2 (Pyk2). This kinase is abundantly expressed in tubular epithelial cells where it is activated by several stimuli. Using mice with deletion of Pyk2 we found that the expression of transforming growth factor-ß1 induced by mechanical stretch in renal tubular epithelial cells was significantly reduced. The expression of connective tissue growth factor was also reduced in the Pyk2(-/-) mice. We also found that expression of connective tissue growth factor was independent of transforming growth factor-ß1, but dependent on the Rho-associated coiled-coil forming protein kinase pathway. Thus, Pyk2 may be an important initiating factor in renal fibrosis and might be a new therapeutic target for ameliorating renal fibrosis.

Intravenous administration of human Muse cells recovers blood flow in a mouse model of hindlimb ischemia.

Cell-based therapies hold great promise for the treatment of peripheral arterial disease (PAD), especially in patients presenting with severe limb ischemia, although the optimal strategy remains to be explored. In this study, we evaluated the therapeutic effect of intravenous administration of human Muse cells, a unique subpopulation of mesenchymal stem cells (MSC), using a mouse model of hindlimb ischemia (HLI) without an immunosuppressant. Compared with the phosphate buffered saline (PBS) or non-Muse MSC groups, the Muse group showed significantly higher laser doppler blood flow in the ischemic limb at days 7 and 14 after HLI. Increased microvascular density [percent area of CD31(+) cells] and reduced interstitial fibrosis in the ischemic limb muscle were also observed in the Muse group. mCherry-expressing Muse cells were found in the ischemic border zone and expressed CD31 but did not in the non-ischemic limb. Muse cells produced higher amounts of vascular endothelial growth factor (VEGF) than non-Muse cells under normoxic and hypoxic conditions in vitro. In the ischemic muscle, tissue VEGF concentration and angiogenesis-related genes such as Vegfa, Angpt1, Pdgfb, and Igf1 were significantly higher in the Muse group than in the other two groups. In addition, the proportion of M2 macrophages to total macrophages and the ratio of anti-inflammatory-related genes such as IL-10, Arg1, and CD206 per iNOS were significantly higher in the Muse group than in the other two groups. In summary, Muse cells exert pleiotropic effects in a mouse model of HLI, and therefore may provide a novel therapeutic approach for the treatment of PAD patients with severe limb ischemia.

Nephritis-associated plasmin receptor (NAPlr)-positive glomerulonephritis in a case of ANCA-negative small vessel vasculitis.

A 75-year-old man with fever was diagnosed with alveolar hemorrhage. Antineutrophil cytoplasmic antibodies for myeloperoxidase and proteinase 3 were absent. He received corticosteroid therapy, which immediately improved his symptoms and chest radiological findings. After the discontinuation of corticosteroids, fever and general fatigue relapsed, and renal function deteriorated with hematuria and proteinuria. A nerve conduction study revealed mononeuritis multiplex. Renal biopsy demonstrated focal necrotizing crescentic glomerulonephritis with endocapillary proliferative lesions, immunofluorescence C3 deposits, and electron-microscopic subepithelial hump-like deposits. Nephritis-associated plasmin receptor (NAPlr) and plasmin activity, biomarkers of infection-related glomerulonephritis, were positive in glomeruli. Although pathological findings suggested infection-related glomerulonephritis (IRGN), clinical manifestations, such as alveolar hemorrhage and mononeuritis multiplex, suggested systemic small vessel vasculitis. After corticosteroid therapy, systemic symptoms disappeared, and the gradual amelioration of hematuria and proteinuria was observed. Based on the clinical symptoms for which steroid therapy was effective, the patient was considered to have systemic small vessel vasculitis, the etiology of which may have been associated with infection.