坪井 直毅

Objective: The complement cascade, especially the alternative pathway of complement, has been shown in basic research to be associated with anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV). We aimed to elucidate relationships between serum complement components and clinical characteristics in AAV. Method: In a nationwide prospective cohort study (RemIT-JAV-RPGN), we measured the serum levels of C1q, C2, C3, C3b/iC3b, C4, C4b, C5, C5a, C9, factor B, factor D, factor H, factor I, mannose-binding lectin, and properdin in 52 patients with microscopic polyangiitis (MPA) and 39 patients with granulomatosis with polyangiitis (GPA). Results: The properdin level of MPA and GPA was significantly lower than that of healthy donors. The properdin level was negatively correlated with the Birmingham Vasculitis Activity Score (BVAS) (ρ = −0.2148, p = 0.0409). The factor D level at 6 months was significantly positively correlated with the Vasculitis Damage Index (VDI) at 6, 12, and 24 months (ρ = 0.4207, 0.4132, and 0.3115, respectively). Patients with a higher ratio of C5a to C5 had higher neutrophil percentage and serum immunoglobulin G levels, and significantly lower creatinine levels. Cluster analysis divided the MPA and GPA patients into three subgroups. A principal component (PC) analysis aggregated 15 types of complements into alternative pathway-related PC 1 and complement classical pathway and common pathway-related PC 2. Conclusions: The serum levels of properdin and factor D were correlated with the BVAS and the VDI in MPA and GPA, respectively. Our analyses suggested the pathological heterogeneity of MPA and GPA from the aspect of complement components.

AIM: Some reports claim that intravenous iron supplements reduce serum phosphate levels in patients with chronic kidney disease (CKD), including those on dialysis. However, whether divalent oral iron supplements influence serum phosphate levels in patients with CKD remains unclear; thus, this study aimed to address this topic. MATERIALS AND METHODS: The study database was derived from the Aichi Cohort Study of Prognosis in Patients Newly Initiated into Dialysis (AICOPP), which is a multicenter, prospective, cohort study. Patients were classified into two groups: those who received iron orally (iron group, n = 255) from pre-dialysis to dialysis initiation and those who did not receive iron supplements (no-iron group, n = 1,261). Moreover, patients were classified into two groups (255 patients in each) by propensity score (PS) matching. We compared serum phosphate level at dialysis initiation and all-cause mortality. Multivariate regression analysis was used to extract factors contributing to serum phosphate level at dialysis initiation through a stepwise method. RESULTS: Serum phosphate levels at dialysis initiation were significantly lower in the iron group (all cohort, 6.0 ± 1.6 vs. 6.4 ± 1.9 mg/dL, p = 0.001; PS-matched cohort, 6.0 ± 1.6 vs. 6.5 ± 1.7 mg/dL, p = 0.001). Multivariate regression analysis revealed that oral iron supplementation was significantly correlated to serum phosphate level (p = 0.023). There were no significant differences in all-cause mortality after dialysis initiation. CONCLUSION: This study showed that oral ferrous citrate or ferrous sulfate use during predialysis was associated with differences in serum phosphate level at dialysis initiation.

High fructose intake has been known to induce metabolic syndrome in laboratory animals and humans. Although fructose intake enhances sodium reabsorption and elevates blood pressure, role of fructose metabolism in this process has not been studied. Here we show that by ketohexokinase - the primary enzyme of fructose - is involved in regulation of renal sodium reabsorption and blood pressure via activation of the sodium hydrogen exchanger in renal proximal tubular cells. First, wild-type and ketohexokinase knockout mice (Male, C57BL/6) were fed fructose water or tap water with or without a high salt diet. Only wild type mice fed the combination of fructose water and high salt diet displayed increased systolic blood pressure and decreased urinary sodium excretion. In contrast, ketohexokinase knockout mice were protected. Second, urinary sodium excretion after intraperitoneal saline administration was reduced with the decreased phosphorylation of sodium hydrogen exchanger 3 in fructose-fed WT; these changes were not observed in the ketohexokinase knockout mice, however. Third, knockdown of ketohexokinase attenuated fructose-mediated increases of NHE activity with decreased cAMP levels in porcine renal proximal tubular cells (LLC-PK1). In conclusion, fructose metabolism by ketohexokinase increases sodium hydrogen exchanger activity in renal proximal tubular cells via decreased intracellular cAMP level, resulting in increased renal sodium reabsorption and blood pressure in mice.

Hypertension is common in patients with chronic kidney disease. Whether blood pressure management before dialysis initiation influences prognosis during maintenance dialysis remains unclear. Hence, we surveyed the status of antihypertensive drug use in incident dialysis patients. Moreover, we examined the association between antihypertensive drug use patterns at the time of dialysis initiation and mortality. We used a database derived from the multicenter prospective Aichi Cohort Study of Prognosis in Patients Newly Initiated into Dialysis, which included 1520 incident dialysis patients in Aichi prefecture, Japan. The baseline in the present study was set as the time of dialysis initiation. We examined antihypertensive drug prescription patterns at baseline, as well as the association between use of antihypertensive drugs and mortality after dialysis initiation. Among all participants, 1440 were taking at least one antihypertensive drug. The rate of calcium channel blocker (CCB) use was highest, accounting for 74.3%. CCB use was significantly associated with lower all-cause and cardiovascular-related mortality (hazard ratio [HR]: 0.62 and 0.57, 95% confidence interval [CI]: 0.46-0.85 and [0.35-0.91], respectively). Compared with no use of either drug, combination therapy with a renin angiotensin system blocker (RASB) and CCB was significantly associated with lower mortality (HR: 0.51, 95% CI: 0.34-0.76). The present study demonstrated that antihypertensive drugs were used in 95% of incident dialysis patients. In addition, use of a CCB and combination therapy with a CCB and RASB at the time of dialysis initiation was associated with lower mortality during maintenance dialysis.

Cell-free and concentrated ascites reinfusion therapy (CART) by internal filtration pressure method (internal method) and external filtration pressure method (external method) using the same cancerous ascites was performed. The rate of rise in circuit pressure and recovered components were compared between the two methods. The factors related to circuit pressure rise were also researched. In both methods, circuit pressure rose in 50% of cases. The recovery rates of IgG, IgA, IgM, and haptoglobin were significantly higher for the internal method than for the external method, whereas the recovery rate of α1 -antitrypsin was significantly lower in the internal method than in the external method. The levels of IL-6, haptoglobin, α1 -antitrypsin, and fibrinogen/fibrindegradation products (FDP) in the original ascites were significantly higher in the group wherein circuit pressure rose than in that without circuit pressure rise. These proteins might be related to the rise in circuit pressure.

OBJECTIVE: The lung is one of the organs possibly involved in microscopic polyangiitis (MPA), and myeloperoxidase (MPO) antineutrophil cytoplasmic antibody (ANCA) is commonly found in patients with MPA. The aim of this study was to assess pulmonary lesions in Japanese patients with MPA. SUBJECTS AND METHODS: This prospective study was based on 144 patients with MPA who were enrolled in the Remission Induction Therapy in Japanese Patients With ANCA-Associated Vasculitis and Rapidly Progressive Glomerulonephritis Study and who underwent chest high-resolution CT (HRCT) imaging at the time of diagnosis during 2011-2014. We reviewed the electronic case report forms of patients with MPA who did and did not have interstitial pneumonia (IP), and the clinical features and laboratory findings of these groups were compared. RESULTS: Abnormal HRCT findings were noted in 134 of the 144 patients (93%). Chest HRCT findings included ground-glass opacity (n = 72; 50%), reticulation (n = 69; 48%), traction bronchiectasis (n = 57; 42%), honeycombing (n = 44; 31%), and emphysema (n = 32; 22%). IP was diagnosed radiologically in 74 patients (51%), 38% of whom had the usual IP (UIP) pattern. Ground-glass opacity, reticulation, traction bronchiectasis, honeycombing, and interlobular septal thickening were frequent in patients with IP (p < 0.05). Patients with MPA with the UIP or possible UIP pattern also had minor findings, such as bronchial wall thickening, consolidation, increased attenuation around honeycombing, and traction bronchiectasis. CONCLUSION: IP (51%) was most commonly observed in Japanese patients with MPA, and 38% of these patients exhibited a UIP pattern. Increased attenuation around honeycombing or traction bronchiectasis was also found.

BACKGROUND: Few studies have focused on the association between history of ischemic stroke at predialysis stage and mortality after dialysis initiation. OBJECTIVE: To examine whether history of stroke in incident dialysis patients is associated with mortality, including all-cause and cardiovascular (CV)-related mortality. METHODS: The study database was derived from the Aichi Cohort Study of Prognosis in Patients Newly Initiated into Dialysis, a multicenter, prospective, cohort analysis. We classified patients into 2 groups according to their history of ischemic stroke and compared their outcomes. Propensity scores (PSs) represented the probability of being assigned to a group with or without a history of ischemic stroke. We defined the following outcomes: all-cause mortality; CV-related mortality; non-CV-related mortality; infection-related mortality; and stroke event after dialysis initiation. Factors contributing to the outcomes were examined using stepwise multivariate Cox proportional hazards analysis. RESULTS: All-cause mortality was significantly higher in the ischemic stroke group (log-rank test p < 0.001). All-cause, non-CV-related, and infection-related mortality and stroke event after dialysis initiation were significantly higher in the ischemic stroke group after PS matching (log-rank test: p < 0.001, <0.001, 0.002, and 0.002, respectively). History of ischemic stroke was associated with all-cause mortality in univariate analysis (hazard ratio [HR] 1.85, 95% CI 1.44-2.37). History of ischemic stroke before dialysis initiation was associated with all-cause mortality in multivariate analysis (HR 1.39, 95% CI 1.05-1.85). CONCLUSION: The present study revealed that history of ischemic stroke before dialysis initiation was associated with all-cause, non-CV-related, and infection-related mortality and stroke event after dialysis initiation during maintenance dialysis.

Some variables including age, comorbidity of diabetes, and so on at dialysis initiation are associated with patient prognosis. Cardiovascular (CV) events are a major cause of death, and adequate models that predict prognosis in dialysis patients are warranted. Therefore, we created models using some variables at dialysis initiation. We used a database of 1,520 consecutive dialysis patients (median age, 70 years; 492 women [32.4%]) from a multicenter prospective cohort study. We established the primary endpoint as a composite of the incidence of first CV events or all-cause death. A multivariable Cox proportional hazard regression model was used to construct a model. We considered a complex and a simple model. We used area under the receiver operating characteristic curve (AUROC) to assess and compare the predictive performances of the prediction models and evaluated the improvement in discrimination using the complex model versus the simple model using net reclassification improvement (NRI). We then assessed integrated discrimination improvement (IDI) to evaluate improvements in average sensitivity and specificity. Of 392 deaths, 152 were CV-related. Totally, 506 CV events occurred during the follow-up period (median 1,285 days). Finally, 692 patients reached the primary endpoint. Baseline data were set at dialysis initiation. AUROC for the primary endpoint was 0.737 (95% confidence interval [CI], 0.712-0.761) in the simple model and 0.765 (95% CI, 0.741-0.788) in the complex model. There were significant intergroup differences in NRI (0.44; 95% CI, 0.34-0.53; p < 0.001) and IDI (0.02; 95% CI, 0.02-0.03; p < 0.001). We prepared a Shiny R application for each model to automatically calculate the predicted occurrence probability (https://statacademy.shinyapps.io/App_inaguma_20190717/). The complex model made more accurate predictions than the simple model. However, the intergroup difference was not significant. Hence, the simple model was more useful than the complex model. The tool was useful in a real-world clinical setting because it required only routinely available variables. Moreover, we emphasized that the tool could predict the incidence of CV events or all-cause mortality for individual patients. In the future, we must confirm its external validity in other prospective cohorts.

Objective: Ketohexokinase (KHK), a primary enzyme in fructose metabolism, has two isoforms, namely, KHK-A and KHK-C. Previously, we reported that renal injury was reduced in streptozotocin-induced diabetic mice which lacked both isoforms. Although both isoforms express in kidney, it has not been elucidated whether each isoform plays distinct roles in the development of diabetic kidney disease (DKD). The aim of the study is to elucidate the role of KHK-A for DKD progression. Materials and Methods: Diabetes was induced by five consecutive daily intraperitoneal injections of streptozotocin (50 mg/kg) in C57BL/6J wild-type mice, mice lacking KHK-A alone (KHK-A KO), and mice lacking both KHK-A and KHK-C (KHK-A/C KO). At 35 weeks, renal injury, inflammation, hypoxia, and oxidative stress were examined. Metabolomic analysis including polyol pathway, fructose metabolism, glycolysis, TCA (tricarboxylic acid) cycle, and NAD (nicotinamide adenine dinucleotide) metabolism in kidney and urine was done. Results: Diabetic KHK-A KO mice developed severe renal injury compared to diabetic wild-type mice, and this was associated with further increases of intrarenal fructose, dihydroxyacetone phosphate (DHAP), TCA cycle intermediate levels, and severe inflammation. In contrast, renal injury was prevented in diabetic KHK-A/C KO mice compared to both wild-type and KHK-A KO diabetic mice. Further, diabetic KHK-A KO mice contained decreased renal NAD+ level with the increase of renal hypoxia-inducible factor 1-alpha expression despite having increased renal nicotinamide (NAM) level. Conclusion: These results suggest that KHK-C might play a deleterious role in DKD progression through endogenous fructose metabolism, and that KHK-A plays a unique protective role against the development of DKD.

Background In patients with adult minimal change disease (MCD), proteinuria relapse is a problem to solve. However, the optimal relapse treatment regimen remains unclear regarding steroid dose. We described the treatment pattern of adult MCD patients and evaluated the appropriate steroid dose for relapse treatment. Methods This retrospective multicenter cohort study included 192 patients with adult biopsy-proven MCD from 14 hospitals in Japan. The prescription pattern of immunosuppressive drugs in relapse was reviewed. To assess the association between steroid dose used for relapse and subsequent outcomes, data of patients with tapered prednisolone (PSL) dosage to &lt 10 mg/day before the first relapse in whom the dose was subsequently increased to 10 mg/day were extracted and assigned to the High-PSL or Low-PSL groups, based on the median dose of 20 mg/day. Multivariate Cox proportional hazard model and propensity score analysis with multiple imputations were conducted to compare their clinical course. Results During a median observation period of 37.6 months, 186/192 (96.9%) patients achieved complete remission (CR) and 100 (52.1%) relapsed. The median urinary protein level at the first relapse was 3.12 g/gCr or g/day. The proportion of non-steroidal immunosuppressant use increased with relapses cyclosporine was the most common. No significant differences were found in the second relapse, frequent relapses, or adverse events between High-PSL (n = 34) and Low-PSL (n = 36) groups. A multivariate Cox proportional hazard model revealed that the hazard ratios adjusted with propensity score for the second relapse were 0.94 (High-PSL vs. Low-PSL 95% confidence interval, 0.42–2.10 P = 0.88) and 0.82 (PSL dose per 10 mg/day 95% confidence interval, 0.58–1.16 P = 0.25). Conclusions Among patients in CR with PSL dose &lt 10 mg/day, higher steroid dose (PSL &gt 20 mg/day) was not associated with favorable outcomes after the first relapse as compared to lower dose (10–20 mg/day).

Background: Mycophenolate mofetil (MMF) is recommended as a first-line immunosuppressant to treat lupus nephritis (LN). Prognosis and therapeutic response in LN are known to vary depending on race. We investigated the benefits of MMF and therapeutic drug monitoring (TDM) in the treatment of Japanese LN patients. Methods: In this retrospective cohort study, a total of 20 patients with LN who started MMF treatment were included. Clinical data were collected regularly after MMF administration. We evaluated complete remission (CR) rate as the primary outcome. Predictors of CR were identified using univariate and multivariate analyses. In the research of TDM, the correlation with the area under the curve (AUC) was analyzed at MMF dose, single-point value, treatment response, and adverse events. Results: Overall, 70% of cases showed CR both flare-ups and refractory cases had favorable results. Cases of LN with nephrotic syndrome (NS) or class III/IV + V showed a significantly lower CR rate (p &lt 0.005). The ratio of maintaining CR after MMF therapy was as high as 85.7%. In multivariate analysis, NS was an independent negative predictor of CR (HR 0.09, 95% confidence interval 0.01–0.81 p = 0.03). The relationship between AUC and MMF dose was low, and AUC correlated with trough level (r = 0.73). AUC tended to be high in the treatment responder (p = 0.09), but did not correlate with adverse events of infection (p = 0.92). Conclusion: MMF is a beneficial treatment option for Japanese LN patients, and further investigation on TDM-based therapy is needed.

Extracellular histones induce lethal thrombosis by promoting platelet aggregation, neutrophil migration, and cell injuries. Heparin, which has negative charges, can bind to extracellular histones however, heparin strongly inhibits the activation of coagulation. Since chondroitin sulfate (CS) shows less effect on the coagulation system than heparin does, CS has the potential to become an effective drug for lethal thrombosis with high risk of bleeding. To elucidate the therapeutic mechanisms of CS in lethal thrombosis, we investigated the interaction between CS and extracellular histones. Mouse vascular endothelial cells were incubated with histones in the presence of heparin or CS, and the expression of caspase-3/7 was measured. The interactions between histones and heparin or CS were measured by surface plasmon resonance analysis. Vascular permeability, platelet counts, liver and renal functions, and coagulation times were evaluated in an in vivo assay. The apoptosis induced by histones was inhibited by treatment with heparin or CS. Heparin and CS showed strong binding to histones and inhibited vascular hyperpermeability. The platelet counts as well as liver and renal functions were not decreased by the treatment with heparin or CS. Moreover, CS showed less effect on the coagulation system than heparin did. These results suggested that CS can be a novel agent for lethal thrombosis with the risk for hemorrhage. Since vascular endothelial cell injuries occur at an early stage of lethal thrombosis, administration of CS might be a useful approach.

Background: Patients with late referral and positive history of volume overload may have a poor prognosis after initiating dialysis due to insufficient and/or inadequate management of complications of renal failure and the lack of better dialysis preparation. Little is known about the influence of the relationship between history of volume overload and late referral on prognosis. Methods: We analyzed 1475 patients who had initiated dialysis for the first time from October 2011 to September 2013. late referral was defined as referral to a nephrologist &lt 3 months before dialysis initiation. The major outcomes were all-cause death and deaths due to cardiovascular diseases (CVD). The impact of late referral and history of volume overload on all-cause mortality was assessed by Cox proportional hazards models. Results: Among 1475 patients, the mean patient age was 67.5 years. During the median follow-up of 2.2 years, 260 deaths occurred 99 were due to CVD. Cox proportional hazards models demonstrated that late referral (adjusted hazard ratio [HR], 1.35 95% confidence interval [CI], 1.00-1.82) and history of volume overload (adjusted HR, 1.39 95% CI, 1.06-1.81) were risk factors for all-cause mortality. Furthermore, late referral coexisting was associated with a history of volume overload increased mortality (adjusted HR, 2.10 95% CI, 1.39-3.16 versus absence of late referral without history of volume overload) after adjusting for age, sex, diabetes, atherosclerotic disease, and laboratory values. Conclusions: Both late referral and history of volume overload were associated with increased risks of all-cause mortality. Trial registration: University Hospital Medical Information Network (UMIN000007096). Registered 18 January 2012, retrospectively registered. https://upload.umin.ac.jp/cgi-open-bin/ctr-e/ctr-view.cgi?recptno=R000008349.

The Oxford Classification is utilized globally, but has not been fully validated. In this study, we conducted a comparative analysis between the Oxford Classification and Japanese Histologic Classification (JHC) to predict renal outcome in Japanese patients with IgA nephropathy (IgAN). A retrospective cohort study including 86 adult IgAN patients was conducted. The Oxford Classification and the JHC were evaluated by 7 independent specialists. The JHC, MEST score in the Oxford Classification, and crescents were analyzed in association with renal outcome, defined as a 50% increase in serum creatinine. In multivariate analysis without the JHC, only the T score was significantly associated with renal outcome. While, a significant association was revealed only in the JHC on multivariate analysis with JHC. The JHC and T score in the Oxford Classification were associated with renal outcome among Japanese patients with IgAN. Superiority of the JHC as a predictive index should be validated with larger study population and cohort studies in different ethnicities.

Background Proteinuria is a powerful prognostic factor for end-stage renal disease in IgA nephropathy (IgAN) patients. However, it is not known whether proteinuria exacerbations are related to seasonal changes. Methods We retrospectively enrolled consecutive patients diagnosed with IgAN by kidney biopsy at our hospital between 2002 and 2014. Proteinuria remission was defined as urinary protein&lt;0.3 g/gCr in two consecutive outpatient urinalyses and exacerbation as urinary protein &gt;= 0.75 g/gCr. Four seasons were defined: spring (March-May), summer (June-August), autumn (September-November), and winter (December-February). We performed a multivariate analysis to identify factors associated with the second remission following a proteinuria exacerbation. Results We analyzed 116 patients. Proteinuria remission and exacerbation occurred in 77, and 43 patients, respectively. The incidence of proteinuria exacerbation was significantly higher in autumn and winter than in spring and summer (p = 0.040). The cumulative second remission rate was significantly higher in patients with autumn and winter proteinuria exacerbation than in patients with spring and summer exacerbations (p = 0.0091). In multivariate analyses, exacerbation onset in autumn and winter (hazard ratio [HR], 3.51; 95% confidence interval [Cl], 1.41-8.74) and intensive therapy (HR, 2.26; 95% Cl, 1.05-4.88) were significantly associated with a second proteinuria remission. Conclusion In IgAN patients in proteinuria remission, proteinuria exacerbation frequently occurred in autumn and winter. Exacerbations occurring in autumn and winter tended to remit early.

Background Malaria is an important tropical disease and has remained a serious health problem in many countries. One of the critical complications of malarial infection is renal injury, such as acute renal failure and chronic glomerulopathy. Few animal models of nephropathy related to malarial infection have been reported. Therefore, we developed and investigated a novel malarial nephropathy model in mice infected by murine malaria parasites. Methods NC mice and C57BL/6J mice were infected with Ttwo different murine malaria parasites, Plasmodium (P.) chabaudi AS and P. yoelii 17X. After the infection, renal pathology and blood and urinary biochemistry were analyzed. Results NC mice infected by the murine malaria parasite P. chabaudi AS, but not P. yoelii 17X, developed mesangial proliferative glomerulonephritis with endothelial damage, and decreased serum albumin concentration and increased proteinuria. These pathological changes were accompanied by deposition of immunoglobulin G and complement component 3, mainly in the mesangium until day 4 and in the mesangium and glomerular capillaries from day 8. On day 21, renal pathology developed to focal segmental sclerosis according to light microscopy. In C57BL/6J mice, renal injuries were not observed from either parasite infection. Conclusion The clinical and pathological features of P. chabaudi AS infection in NC mice might be similar to quartan malarial nephropathy resulting from human malaria parasite P. malariae infection. The NC mouse model might therefore be useful in analyzing the underlying mechanisms and developing therapeutic approaches to malaria-related nephropathy.

Background: Microscopic polyangiitis (MPA), which is classified as an anti-neutrophil cytoplasmic antibody (ANCA)associated small vessel vasculitis, is one of the most frequent primary vasculitides in Japan. We earlier nominated 16 genes (IRF7, IFIT1, IFIT5, OASL, CLC, GBP-1, PSMB9, HERC5, CCR1, CD36, MS4A4A, BIRC4BP, PLSCR1, DEFA1/DEFA3, DEFA4, and COL9A2) as predictors of response to remission induction therapy against MPA. The aim of this study is to determine the accuracy of prediction using these 16 predictors. Methods: Thirty-nine MPA patients were selected randomly and retrospectively from the Japanese nationwide RemIT-JAV-RPGN cohort and enrolled in this study. Remission induction therapy was conducted according to the Guidelines of Treatment for ANCA-Associated Vasculitis published by the Ministry of Health, Labour, and Welfare of Japan. Response to remission induction therapy was predicted by profiling the altered expressions of the 16 predictors between the period before and 1 week after the beginning of treatment. Remission is defined as the absence of clinical manifestations of active vasculitis (Birmingham Vasculitis Activity Score 2003: 0 or 1 point). Persistent remission for 18 months is regarded as a "good response," whereas no remission or relapse after remission is regarded as a "poor response." Results: "Poor" and "good" responses were predicted in 7 and 32 patients, respectively. Five out of 7 patients with "poor" prediction and 1 out of 32 patients with "good" prediction experienced relapse after remission. One out of 7 patients with "poor" prediction was not conducted to remission. Accordingly, the sensitivity and specificity to predict poor response was 85.7% (6/7) and 96.9% (31/32), respectively. Conclusions: Response to remission induction therapy can be predicted by monitoring the altered expressions of the 16 predictors in the peripheral blood at an early point of treatment in MPA patients.

Activated T cells play crucial roles in the pathogenesis of autoimmune diseases, including Lupus nephritis (LN). The activation of calcineurin/nuclear factor of activated T cells (NFAT) and STAT4 signaling is essential for T cells to perform various effector functions. Here, we identified the growth factor midkine (MK; gene name, Mdk) as a novel regulator in the pathogenesis of 2,6,10,14-tetramethylpentadecane-induced LN via activation of NFAT and IL-12/STAT4 signaling. Wild-type (MdK+/+) mice showed more severe glomerular injury than MK-deficient (Mdk(-/-)) mice, as demonstrated by mesangial hypercellularity and matrix expansion, and glomerular capillary loops with immune-complex deposition. Compared with Mdk(-/-) mice, the frequency of splenic CD69(+) T cells and T helper (Th) 1 cells, but not of regulatory T cells, was augmented in Mdk(+/+) mice in proportion to LN disease activity, and was accompanied by skewed cytokine production. MK expression was also enhanced in activated CD4(+) T cells in vivo and in vitro. MK induced activated CD4(+) T cells expressing CD69 through nuclear activation of NFAT transcription and selectively increased in vitro differentiation of naive CD4(+) T cells into Th1 cells by promoting IL-12/STAT4 signaling. These results suggest that MK serves an indispensable role in the NFAT-regulated activation of CD4(+) T cells and Th1 cell differentiation, eventually leading to the exacerbation of LN.

Extracellular histones promote platelet aggregation and thrombosis; this is followed by induction of coagulation disorder, which results in exhaustion of coagulation factors. Complement component 5 (C5) is known to be associated with platelet aggregation and coagulation system activation. To date, the pathological mechanism underlying liver injury has remained unclear. Here, we investigated whether C5 promotes liver injury associated with histone-induced lethal thrombosis. C5-sufficient and C5-deficient mice received single tail vein injections of purified, unfractionated histones obtained from calf thymus (45-75 mu g/g). Subsequently, the mice were monitored for survival for up to 72 h. Based on the survival data, the 45 mu g/g dose was used for analysis of blood cell count, liver function, blood coagulation ability, and promotion of platelet aggregation and platelet/leukocyte aggregate (PLA) production by extracellular histones. C5-deficient mice were protected from lethal thrombosis and had milder thrombocytopenia, consumptive coagulopathy, and liver injury with embolism and lower PLA production than C5-sufficient mice. These results indicate that C5 is associated with coagulation disorders, PLA production, and embolism-induced liver injury. In conclusion, C5 promotes liver injury associated with histone-induced lethal thrombosis.

To date, a recognized treatment for refractory membranous nephropathy (MN) has not been established. Recently, several reports have indicated the efficacy of rituximab as a novel treatment option. However, only a few published accounts exist of rituximab therapy for idiopathic MN (IMN) in the Asian population. We present the cases of three IMN patients who were treated with single-dose rituximab after they showed no response to conventional therapies, including corticosteroids, cyclosporine, cyclophosphamide, mizoribine, and mycophenolate mofetil. Although one case showed no response, a complete or incomplete remission was achieved in the other two cases. Rituximab may therefore be a beneficial treatment option for IMN.

Background. In addition to classically activated macrophages that have effector roles in tissue injury, alternatively activated M2 macrophages are involved in the resolution of inflammation in animal models of kidney disease. To clarify the clinical relevance of macrophage phenotypes in human glomerular diseases, we evaluated the renal accumulation of macrophages and plasma and urine levels of CD163, an M2 marker, in lupus nephritis (LN) patients. Methods. Kidney biopsies and plasma and urine samples were obtained from LN patients who underwent renal biopsy between 2008 and 2012. CD163(+), CD68(+) and CD204(+) cells were counted in paraffin-embedded and frozen sections. LN histological activity was evaluated semiquantitatively using the biopsy activity index. Plasma and urinary soluble CD163 (sCD163) concentrations were also measured and evaluated for their significance as potential LN biomarkers. Results. Immunohistological analysis of glomeruli from LN patients revealed that &gt;60% of CD68(+) macrophages had merged with CD163(+) cells. The increased number of glomerular CD163(+) macrophages was correlated with LN severity, as determined by the biopsy active index (r = 0.635). Urinary (u-) sCD163 level was strongly correlated with glomerular CD163(+) cell counts and histological disease score as well as urinary monocyte chemoattractant protein 1 levels (r = 0.638 and 0.592, respectively). Furthermore, the u-sCD163 level was higher in patients with active LN than in those with other diseases. Conclusions. Glomerular CD163(+) macrophages are the predominant phenotype in the kidneys of lupus patients. These findings indicate that the u-sCD163 level can serve as a biomarker for macrophage-dependent glomerular inflammation in human LN.

Macrophages are multifunctional immune cells that may either drive or modulate disease pathogenesis, depending on the activated phenotype. In this study, we investigated the protective effects of CD206(+) M2 macrophages against nephrotoxic serum nephritis in mice. We found that these immunosuppressive macrophages, derived from bone marrow and stimulated with IL-4/IL-13 [CD206(+) M2 bone marrow-derived macrophages (M2BMMs)], protected against renal injury, decreased proteinuria, and diminished the infiltration of CD68(+) macrophages, neutrophils, and T cells into glomerular tissue. Comparable therapeutic results were obtained with CD206(+) M2 cells derived from induced pluripotent stem cells. Notably, CD206(+) M2BMMs, which retained an M2 signature, could elicit a switch of M1 to M2 phenotype in co-cultured macrophages. Moreover, these cells were found to induce the production of regulatory T cells in the spleen and renal draining lymph node. Accordingly, mRNA expression of the T helper 1 cytokines tumor necrosis factor-alpha, interferon-beta, interferon-gamma, and IL-12 was significantly reduced in kidneys from mice treated with CD206+ M2BMMs. Taken together, the data suggest that CD206(+) M2 may have therapeutic potential against antibody-mediated glomerular injury and presents its therapeutic value for the treatment of crescentic nephritis in humans.