Precision engineered peptide targeting leukocyte extracellular traps mitigate acute kidney injury in Crush syndrome.

Crush syndrome induced by skeletal muscle compression causes fatal rhabdomyolysis-induced acute kidney injury (RIAKI) that requires intensive care, including hemodialysis. However, access to crucial medical supplies is highly limited while treating earthquake victims trapped under fallen buildings, lowering their chances of survival. Developing a compact, portable, and simple treatment method for RIAKI remains an important challenge. Based on our previous finding that RIAKI depends on leukocyte extracellular traps (ETs), we aimed to develop a novel medium-molecular-weight peptide to provide clinical treatment of Crush syndrome. We conducted a structure-activity relationship study to develop a new therapeutic peptide. Using human peripheral polymorphonuclear neutrophils, we identified a 12-amino acid peptide sequence (FK-12) that strongly inhibited neutrophil extracellular trap (NET) release in vitro and further modified it by alanine scanning to construct multiple peptide analogs that were screened for their NET inhibition ability. The clinical applicability and renal-protective effects of these analogs were evaluated in vivo using the rhabdomyolysis-induced AKI mouse model. One candidate drug [M10Hse(Me)], wherein the sulfur of Met10 is substituted by oxygen, exhibited excellent renal-protective effects and completely inhibited fatality in the RIAKI mouse model. Furthermore, we observed that both therapeutic and prophylactic administration of M10Hse(Me) markedly protected the renal function during the acute and chronic phases of RIAKI. In conclusion, we developed a novel medium-molecular-weight peptide that could potentially treat patients with rhabdomyolysis and protect their renal function, thereby increasing the survival rate of victims affected by Crush syndrome.

Inhibitory effect of aspirin on inflammation-induced lung metastasis of cancer cells associated with neutrophil infiltration.

PURPOSE: Systematic inflammation has been reported to contribute to cancer progression through various mechanisms; however, the exact mechanism is still the subject of research. In this study, we evaluated the influence of systematic inflammation on lung metastasis, using a murine abdominal sepsis model, and assessed its relationship with pneumonia after curative esophagectomy in patients with esophageal cancer. METHODS: We used a murine abdominal sepsis model given highly metastatic osteosarcoma, to reveal the mechanism of systematic inflammation and its potential for lung metastasis. The therapeutic effect of aspirin (ASA) in preventing distant metastasis was also investigated. Subsequently, we analyzed, retrospectively, the relationship between pneumonia and lung metastasis after esophagectomy in patients who underwent esophagectomy at Keio University between January, 2007 and October, 2020. RESULTS: Abdominal sepsis provoked lung injury in the acute phase. ASA inhibited the recruitment of neutrophils triggered by the lung injury, and it also suppressed lung metastasis. Our retrospective study revealed that lung metastasis was more frequent in patients with postoperative pneumonia. CONCLUSIONS: Postoperative acute lung injury is associated with a higher risk of lung metastasis. ASA may be a potential preoperative treatment for inhibiting lung metastasis by preventing the recruitment of neutrophils.

Longitudinal monitoring of circulating immune cell phenotypes in anti-neutrophil cytoplasmic antibody-associated vasculitis.

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) is a necrotizing multiorgan autoimmune disease that affects small- to medium-sized blood vessels. Despite the improvements in treatments, half of the patients with AAV still experience disease relapses. In this review, we focus on peripheral leukocyte properties and phenotypes in patients with AAV. In particular, we explore longitudinal changes in circulating immune cell phenotypes during the active phase of the disease and treatment. The numbers and phenotypes of leukocytes in peripheral blood were differs between AAV and healthy controls, AAV in active versus inactive phase, AAV in treatment responders versus non-responders, and AAV with and without severe infection. Therefore, biomarkers detected in peripheral blood immune cells may be useful for longitudinal monitoring of disease activity in AAV.

A novel I551F variant of the Na+/HCO3- cotransporter NBCe1-A shows reduced cell surface expression, resulting in diminished transport activity.

Homozygous mutations in SLC4A4, which encodes the electrogenic Na+/[Formula: see text] cotransporter (NBCe1), cause proximal renal tubular acidosis associated with extrarenal symptoms. Although 17` mutated sites in SLC4A4 have thus far been identified among patients with proximal renal tubular acidosis, the physiological significance of other nonsynonymous single-nucleotide variants (SNVs) remains largely undetermined. Here, we investigated the functional properties of SNVs in NBCe1. From the National Center for Biotechnology Information dbSNP database, we identified 13 SNVs that have not previously been characterized in the highly conserved, transmembrane domains of NBCe1-A. Immunocytochemical analysis revealed that the I551F variant was present predominantly in the cytoplasm in human embryonic kidney (HEK)-293 cells, whereas all other SNVs did not show as dramatic a change in subcellular distribution. Western blot analysis in HEK-293 cells demonstrated that the I551F variant showed impaired glycosylation and a 69% reduction in cell surface levels. To determine the role of I551 in more detail, we examined the significance of various artificial mutants in both nonpolarized HEK-293 cells and polarized Madin-Darby canine kidney cells, which indicated that only I551F substitution resulted in cytoplasmic retention. Moreover, functional analysis using Xenopus oocytes demonstrated that the I551F variant had a significantly reduced activity corresponding to 39% of that of the wild-type, whereas any other SNVs and artificial I551 mutants did not show significant changes in activity. Finally, immunofluorescence experiments in HEK-293 cells indicated that the I551F variant retained wild-type NBCe1-A in the cytoplasm. These data demonstrate that the I551F variant of NBCe1-A shows impaired transport activity predominantly through cytoplasmic retention and suggest that the variant can have a dominant negative effect by forming complexes with wild-type NBCe1-A.NEW & NOTEWORTHY Electrogenic Na+/[Formula: see text] cotransporter 1-A (NBCe1-A) in the proximal tubule regulates the acid/base balance and fluid volume homeostasis. From the National Center for Biotechnology Information dbSNP database, we identified the I551F variant of NBCe1-A, which showed reduced glycosylation, cell surface expression, and transport activity. We also found that the I551F variant can exert a dominant negative effect on wild-type NBCe1-A, suggesting its physiological significance.

Group A Streptococcus establishes pharynx infection by degrading the deoxyribonucleic acid of neutrophil extracellular traps.

Group A Streptococcus (GAS) secretes deoxyribonucleases and evades neutrophil extracellular killing by degrading neutrophil extracellular traps (NETs). However, limited information is currently available on the interaction between GAS and NETs in the pathogenicity of GAS pharyngitis. In this study, we modified a mouse model of GAS pharyngitis and revealed an essential role for DNase in this model. After intranasal infection, the nasal mucosa was markedly damaged near the nasal cavity, at which GAS was surrounded by neutrophils. When neutrophils were depleted from mice, GAS colonization and damage to the nasal mucosa were significantly decreased. Furthermore, mice infected with deoxyribonuclease knockout GAS mutants (∆spd, ∆endA, and ∆sdaD2) survived significantly better than those infected with wild-type GAS. In addition, the supernatants of digested NETs enhanced GAS-induced cell death in vitro. Collectively, these results indicate that NET degradation products may contribute to the establishment of pharyngeal infection caused by GAS.

Expanding Phenotype of Nephronophthisis-Related Ciliopathy: an Elderly Patient with Homozygous RPGRIP1L Mutation.

Nephronophthisis-related ciliopathies (NPHP-RC) are autosomal recessive disorders characterized by renal corticomedullary cysts with the extrarenal symptoms. Typically, patients with NPHP-RC reach end-stage kidney disease (ESKD) before the age of 30 years. We herein report a Japanese woman with NPHP-RC who had unusually delayed progression to ESKD after 6 decades. She exhibited liver dysfunction at the age of 23 years. She also showed mild renal dysfunction at the age of 43 years. Ultrasonography revealed bilateral multiple renal cysts with loss of corticomedullary differentiation. Her liver and renal functions gradually deteriorated. She was diagnosed with liver fibrosis as a result of biopsy, and initiated the maintenance hemodiafiltration therapy for ESKD at the age of 61 years. Because of a unique combination of multiple renal cysts and liver fibrosis, ciliopathy was suspected and medical exome analysis was performed. A novel homozygous missense mutation was identified in RPGRIP1L (c.1810G>A p.Glu604Lys), a causative gene for NPHP-RC. To the best of our knowledge, this patient is the oldest one who progressed to ESKD in NPHP-RC. Our case illustrates that NPHP-RC should be included in the differential diagnosis of the patient with corticomedullary polycystic kidneys accompanied by the extrarenal organ involvements, even if the patient is elderly.

Risk Factors for Relapse of Antineutrophil Cytoplasmic Antibody-associated Vasculitis in Japan: A Nationwide, Prospective Cohort Study.

OBJECTIVE: The aim was to elucidate the prognosis and risk factors associated with relapse during longterm remission maintenance therapy for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). METHODS: Patients with newly diagnosed AAV (n = 156) were registered in the Remission Induction Therapy in Japanese patients with ANCA-associated Vasculitides (RemIT-JAV) study, and among them, 83 patients who achieved remission were enrolled and followed up for 24 additional months in our nationwide, prospective cohort study (Co-RemIT-JAV; registration number UMIN 000006373). Patterns of maintenance therapy, effectiveness, and safety were evaluated from months 25 to 48 after the RemIT-JAV. The primary outcome measure was the rate of relapse. Secondary outcome measures included overall and renal survival, risk factors associated with relapse, and incidence rates of serious infections. RESULTS: The patients comprised 35 men and 48 women aged 65.3 ± 12.6 years. Between months 25 and 48, the survival rate was 95% (79/83). Causes of death included 1 thyroid cancer, 1 infection, and 2 unknown reasons. Four patients had developed endstage renal disease (ESRD) by Month 24; 1 developed ESRD beyond Month 25. The relapse rate was 24% (20/83) from months 25 to 48. Multivariable analysis revealed that oral prednisolone ≤ 2.5 mg/day at Month 24 was a significant risk factor for relapse between months 25 and 48 (HR = 3.1, 95% CI 1.1-8.5). CONCLUSION: One-quarter of patients with AAV relapsed during maintenance therapy, and relapse was associated with the dose of oral prednisolone 24 months after the initiation of remission induction therapy in Japan.

Macrophage extracellular trap formation promoted by platelet activation is a key mediator of rhabdomyolysis-induced acute kidney injury.

Rhabdomyolysis is a serious syndrome caused by skeletal muscle injury and the subsequent release of breakdown products from damaged muscle cells into systemic circulation. The muscle damage most often results from strenuous exercise, muscle hypoxia, medications, or drug abuse and can lead to life-threatening complications, such as acute kidney injury (AKI). Rhabdomyolysis and the AKI complication can also occur during crush syndrome, an emergency condition that commonly occurs in victims of natural disasters, such as earthquakes, and man-made disasters, such as wars and terrorism. Myoglobin released from damaged muscle is believed to trigger renal dysfunction in this form of AKI. Recently, macrophages were implicated in the disease pathogenesis of rhabdomyolysis-induced AKI, but the precise molecular mechanism remains unclear. In the present study, we show that macrophages released extracellular traps (ETs) comprising DNA fibers and granule proteins in a mouse model of rhabdomyolysis. Heme-activated platelets released from necrotic muscle cells during rhabdomyolysis enhanced the production of macrophage extracellular traps (METs) through increasing intracellular reactive oxygen species generation and histone citrullination. Here we report, for the first time to our knowledge, this unanticipated role for METs and platelets as a sensor of myoglobin-derived heme in rhabdomyolysis-induced AKI. This previously unknown mechanism might be targeted for treatment of the disease. Finally, we found a new therapeutic tool for prevention of AKI after rhabdomyolysis, which might rescue some sufferers of this pathology.

Omega-3 Polyunsaturated Fatty Acids for the Treatment of IgA Nephropathy.

IgA nephropathy is a common disease that causes end-stage renal failure and requires renal replacement therapy. The main purpose of therapeutic intervention in this disease is not limited to improvement of prognosis and prevention of transition to end-stage renal failure, but also prevention of the occurrence of cardiovascular lesions, which increases risk in patients with chronic kidney disease. Steroids and immunosuppressants have been widely used as remission induction therapies; however, the balance between their therapeutic benefits and detrimental side-effects are controversial. In this regard, it is critical to identify alternative therapies which would provide holistic life-long benefits. Currently, the potential of ω-3 fatty acids as anti-inflammatory and inflammation-convergent drugs-especially the remarkable progress of the multifunctional ω-3 polyunsaturated fatty acids (PUFAs)-has garnered attention. In this section, we outline the background and current status of ω-3 PUFA-based treatment in IgA nephropathy.

Effects of calcineurin inhibitors on sodium excretion in recipients of allogeneic hematopoietic stem cell transplantation.

Calcineurin inhibitors (CIs) such as cyclosporine A (CSA) and tacrolimus often cause renal dysfunction, resulting in increased serum creatinine, hyperkalemia, and hyperuricemia. However, the effects of CIs on sodium excretion have not been fully elucidated. We retrospectively evaluated the effects of CI administration on sodium excretion in recipients of allogeneic hematopoietic stem cell transplantation (HSCT). Fifty consecutive recipients each of allogeneic HSCT receiving either CSA or tacrolimus (100 patients in total) with available data for weekly fractional excretion of sodium (FENa) for a 4-week period after transplantation were enrolled in this retrospective analysis. No significant differences in patient characteristics were observed between CSA and tacrolimus groups except for the type of donor. FENa was significantly higher at the 3rd (1.25 ± 0.80) and 4th weeks (1.53 ± 1.06) after transplantation as compared with that at the 1st week (0.93 ± 0.51; P < 0.01, P < 0.001, respectively) in the tacrolimus group, but not at any time point in the CSA group. In addition, FENa was significantly higher in the tacrolimus group than the CSA group at the 4th week (1.53 ± 1.06 vs. 1.13 ± 0.80; P < 0.05). These results suggest that tacrolimus increases sodium excretion after allogeneic HSCT, and that this effect is minimal with CSA.

Lactoferrin Suppresses Neutrophil Extracellular Traps Release in Inflammation.

Neutrophils are central players in the innate immune system. They generate neutrophil extracellular traps (NETs), which protect against invading pathogens but are also associated with the development of autoimmune and/or inflammatory diseases and thrombosis. Here, we report that lactoferrin, one of the components of NETs, translocated from the cytoplasm to the plasma membrane and markedly suppressed NETs release. Furthermore, exogenous lactoferrin shrunk the chromatin fibers found in released NETs, without affecting the generation of oxygen radicals, but this failed after chemical removal of the positive charge of lactoferrin, suggesting that charge-charge interactions between lactoferrin and NETs were required for this function. In a model of immune complex-induced NET formation in vivo, intravenous lactoferrin injection markedly reduced the extent of NET formation. These observations suggest that lactoferrin serves as an intrinsic inhibitor of NETs release into the circulation. Thus, lactoferrin may represent a therapeutic lead for controlling NETs release in autoimmune and/or inflammatory diseases.

Aspirin and Eicosapentaenoic Acid May Arrest Progressive IgA Nephropathy: A Potential Alternative to Immunosuppression.

Immunoglobulin (Ig) A nephropathy is a prevalent form of primary glomerulonephritis, which leads to end-stage renal failure in a significant proportion of patients. Immunotherapy, including steroid use, is widely used to induce disease remission; however, it can cause serious side effects. We herein report 3 cases of progressive IgA nephropathy and their successful treatment with a combination of aspirin and eicosapentaenoic acid (EPA) without the use of steroids. The precise mechanism responsible for the combination therapy is still unknown; however, aspirin may potentiate the production of anti-inflammatory lipid mediators derived from EPA. Further clinical trials are required to substantiate this treatment regimen.

Diabetes Induces Aberrant DNA Methylation in the Proximal Tubules of the Kidney.

Epigenetic mechanisms may underlie the progression of diabetic kidney disease. Because the kidney is a heterogeneous organ with different cell types, we investigated DNA methylation status of the kidney in a cell type-specific manner. We first identified genes specifically demethylated in the normal proximal tubules obtained from control db/m mice, and next delineated the candidate disease-modifying genes bearing aberrant DNA methylation induced by diabetes using db/db mice. Genes involved in glucose metabolism, including Sglt2, Pck1, and G6pc, were selectively hypomethylated in the proximal tubules in control mice. Hnf4a, a transcription factor regulating transporters for reabsorption, was also selectively demethylated. In diabetic mice, aberrant hypomethylation of Agt, Abcc4, Cyp4a10, Glut5, and Met and hypermethylation of Kif20b, Cldn18, and Slco1a1 were observed. Time-dependent demethylation of Agt, a marker of diabetic kidney disease, was accompanied by histone modification changes. Furthermore, inhibition of DNA methyltransferase or histone deacetylase increased Agt mRNA in cultured human proximal tubular cells. Aberrant DNA methylation and concomitant changes in histone modifications and mRNA expression in the diabetic kidney were resistant to antidiabetic treatment with pioglitazone. These results suggest that an epigenetic switch involving aberrant DNA methylation causes persistent mRNA expression of select genes that may lead to phenotype changes of the proximal tubules in diabetic kidney disease.

Immunomodulation with eicosapentaenoic acid supports the treatment of autoimmune small-vessel vasculitis.

Small-vessel vasculitis is a life-threatening autoimmune disease that is frequently associated with anti-neutrophil cytoplasmic antibodies (ANCAs). Conventional immunotherapy including steroids and cyclophosphamide can cause serious adverse events, limiting the efficacy and safety of treatment. Eicosapentaenoic acid (EPA), a key component of fish oil, is an omega-3 polyunsaturated fatty acid widely known to be cardioprotective and beneficial for vascular function. We report two elderly patients with systemic ANCA-associated vasculitis (AAV) in whom the administration of EPA in concert with steroids safely induced and maintained remission, without the use of additioal immunosuppressants. To explore the mechanisms by which EPA enhances the treatment of AAV, we employed SCG/Kj mice as a spontaneous murine model of AAV. Dietary enrichment with EPA significantly delayed the onset of crescentic glomerulonephritis and prolonged the overall survival. EPA-derived anti-inflammatory lipid mediators and their precursors were present in the kidney, plasma, spleen, and lungs in the EPA-treated mice. Furthermore, a decrease in ANCA production and CD4/CD8-double negative T cells, and an increase in Foxp3(+) regulatory T cells in the lymph nodes of the kidney were observed in the EPA-treated mice. These clinical and experimental observations suggest that EPA can safely support and augment conventional therapy for treating autoimmune small-vessel vasculitis.

Classification and characteristics of Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis in a nationwide, prospective, inception cohort study.

INTRODUCTION: We investigated the clinical and serological features of patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in Japan using data from a nationwide, prospective, inception cohort study. METHODS: In total, 156 Japanese patients with newly diagnosed AAV were classified according to the European Medicines Agency (EMEA) algorithm with exploratory surrogate markers for AAV-related non-granulomatous pulmonary lesions, predefined as alveolar haemorrhage and interstitial lung disease (ILD), and their clinical and serological features were evaluated. RESULTS: Using the EMEA algorithm, we identified 14 patients (9.0%) with eosinophilic granulomatosis with polyangiitis (EGPA), 33 (21.2%) with granulomatosis with polyangiitis (GPA), 78 (50.0%) with microscopic polyangiitis and renal-limited vasculitis (MPA/RLV), and 31 (19.9%) with unclassifiable vasculitis. The average ages of patients with EGPA (male/female, 5/9), GPA (12/21), and MPA/RLV (35/43) and unclassifiable (9/22) were 58.0, 63.6, 71.1, and 70.6 years, respectively. Myeloperoxidase (MPO)-ANCA and proteinase-3 ANCA positivity was 50.0% and 0% for EGPA, 54.6% and 45.5% for GPA, 97.4% and 2.6% for MPA/RLV, and 93.5% and 3.2% for unclassifiable, respectively. According to the Birmingham Vasculitis Activity Score (BVAS), cutaneous (71.4%) and nervous system (92.9%) manifestations were prominent in EGPA and ear, nose, and throat manifestations (84.9%) and chest manifestations (66.7%) in GPA. Renal manifestations developed frequently in MPA/RLV (91.0%) and GPA (63.6%). The average serum creatinine levels were 0.71 mg/dL for EGPA, 1.51 mg/dL for GPA, 2.46 mg/dL for MPA/RLV, and 0.69 mg/dL for unclassifiable. The percentages of patients with ILD were 14.3% for EGPA, 9.0% for GPA, 47.4% for MPA/RLV, and 61.3% for unclassifiable. Patients with ILD (n = 61) had significantly lower BVAS (P = 0.019) with fewer ear, nose, and throat and cardiovascular manifestations than patients without ILD (n = 95). CONCLUSIONS: MPO-ANCA-positive MPA/RLV is the most common form of AAV in Japanese patients, and one-half of patients with GPA were positive for MPO-ANCA. ILD is an important clinical manifestation in Japanese patients with AAV. Unclassifiable vasculitis with MPO-ANCA positivity and ILD may represent a novel variant of MPA. TRIAL REGISTRATION: The University Hospital Medical Information Network Clinical Trials Registry: UMIN000001648. Registered 28 February 2009.

Successful treatment of acute kidney injury in patients with idiopathic nephrotic syndrome using human atrial natriuretic Peptide.

The acute onset of idiopathic nephrotic syndrome (NS) is often accompanied by acute kidney injury, which can lead to congestive heart failure and lung edema. In this report, we present two cases of NS-induced acute kidney injury successfully treated with a low dose of carperitide, a human atrial natriuretic peptide. In combination with standard diuretic therapy and immunotherapy, carperitide retained the renal function and spared the need for renal replacement therapy, including hemodialysis. Although further investigation in clinical trials is required to validate these findings, carperitide may be useful for maintaining the renal function in cases of NS-induced acute kidney injury.

Basic helix-loop-helix transcriptional factor MyoR regulates BMP-7 in acute kidney injury.

MyoR was originally identified as a transcriptional repressor in embryonic skeletal muscle precursors, but its function in adult kidney has not been clarified. In this study, we tried to clarify the functional role of MyoR using MyoR(-/-) mice. Cisplatin induced a significantly higher degree of severe renal dysfunction, tubular injury, and mortality in MyoR(-/-) mice than in wild-type mice. The injection of cisplatin significantly increased the number of apoptotic cells in the kidney tissues of MyoR(-/-) mice, compared with that in wild-type mice. To clarify the mechanism of severe cisplatin-induced damage and apoptosis in MyoR(-/-) mice, we focused on the p53 signaling pathway and bone morphogenic protein-7 (BMP-7). Treatment with cisplatin significantly activated p53 signaling in cultured renal proximal tubular epithelial cells (RTECs) in both wild-type and MyoR(-/-) mice, but no significant difference between the groups was observed. The injection of cisplatin significantly increased the expression of BMP-7 in the kidney tissues of wild-type mice, but no increase was observed in the MyoR(-/-) mice. Treatment with cisplatin significantly increased the expression of BMP-7 in cultured RTECs from wild-type mice but not in those from MyoR(-/-) mice. Moreover, treatment with recombinant BMP-7 rescued the cisplatin-induced apoptosis in RTECs from MyoR(-/-) mice. Taken together, our results demonstrate a new protective role of MyoR in adult kidneys that acts through the regulation of BMP-7.

The role of NF-κB signaling in the maintenance of pluripotency of human induced pluripotent stem cells.

NF-κB signaling plays an essential role in maintaining the undifferentiated state of embryonic stem (ES) cells. However, opposing roles of NF-κB have been reported in mouse and human ES cells, and the role of NF-κB in human induced pluripotent stem (iPS) cells has not yet been clarified. Here, we report the role of NF-κB signaling in maintaining the undifferentiated state of human iPS cells. Compared with differentiated cells, undifferentiated human iPS cells showed an augmentation of NF-κB activity. During differentiation induced by the removal of feeder cells and FGF2, we observed a reduction in NF-κB activity, the expression of the undifferentiation markers Oct3/4 and Nanog, and the up-regulation of the differentiated markers WT-1 and Pax-2. The specific knockdown of NF-κB signaling using p65 siRNA also reduced the expression of Oct3/4 and Nanog and up-regulated WT-1 and Pax-2 but did not change the ES-like colony formation. Our results show that the augmentation of NF-κB signaling maintains the undifferentiated state of human iPS and suggest the importance of this signaling pathway in maintenance of human iPS cells.