Porphyromonas gingivalis infection in the oral cavity is associated with elevated galactose-deficient IgA1 and increased nephritis severity in IgA nephropathy.

BACKGROUND: The relationship between the major periodontal bacteria, Porphyromonas gingivalis, and the pathogenesis of IgA nephropathy (IgAN)-particularly with respect to galactose-deficient IgA1 (Gd-IgA1)-has not been fully elucidated. METHODS: Saliva samples from 30 IgAN patients and 44 patients with chronic kidney disease (CKD) were subjected to analysis of P. gingivalis status via polymerase chain reaction using a set of P. gingivalis-specific primers. The associations between P. gingivalis presence and clinical parameters, including plasma Gd-IgA1, were analyzed in each group. RESULTS: Compared with the CKD group, the IgAN group demonstrated significantly higher plasma Gd-IgA1 levels (p < 0.05). Compared with the P. gingivalis-negative subgroup, the P. gingivalis-positive subgroup exhibited significantly higher plasma Gd-IgA1 levels in both IgAN and CKD patients (p < 0.05). Additionally, among IgAN patients, the P. gingivalis-positive subgroup displayed significantly higher plasma Gd-IgA1 and urine protein levels, compared with the P. gingivalis-negative subgroup (p < 0.05). With respect to renal biopsy findings, the frequencies of segmental glomerulosclerosis and tubular atrophy/interstitial fibrosis were significantly greater in the P. gingivalis-positive subgroup than in the P. gingivalis-negative subgroup, according to the Oxford classification of IgAN (p < 0.05). CONCLUSION: Our findings suggest an association between the presence of P. gingivalis in the oral cavity and the pathogenesis of IgAN, mediated by increased levels of Gd-IgA1.

Cigarette smoking and progression of kidney dysfunction: a longitudinal cohort study.

INTRODUCTION: Cigarette smoking is one of the most important life-modifiable risk factors for CVD events. The effect on CKD progression caused by smoking remained uncertain, while the effect on CVD had been established. METHOD: The study population included participants from the specific health check and specific health guidance, an annual health check-up for all inhabitants of Japan who were aged between 40 and 74 years. 149,260 subjects (male, 37.1%; female, 62.9%) were included in this analysis. RESULTS: The relationship between smoking status along with new-onset proteinuria and eGFR deterioration more than 15 mL/min/1.73 m2 was examined. Median observation periods were 1427 days [738, 1813] in males and 1437 days [729, 1816] in females. In male participants, the strongest factor upon kidney dysfunction was new-onset proteinuria (1.41 [1.31 1.51], P < 0.001). The second strongest factor on kidney deterioration was smoking (1.24 [1.16 1.31], P < 0.001). In female participants, strongest factor upon kidney dysfunction was smoking (1.27 [1.16-1.39], P < 0.001). The second strongest factor on kidney deterioration was new-onset proteinuria (1.26 [1.17 1.36], P < 0.001). To reveal the relationship of effects from new-onset proteinuria and smoking on the kidney function, the participants were divided into four groups with and without new-onset proteinuria and smoking. The group with both proteinuria and smoking had significantly worst renal prognosis (P for trend < 0.001). CONCLUSION: Large longitudinal observation study revealed smoking has an evil effect on the progression of CKD. This evil effect could be observed in CKD patients with proteinuria as well as in general population without new-onset proteinuria.

Distribution of periodontopathic bacterial species between saliva and tonsils.

Periodontopathic bacteria cause an inflammatory disease localized in the periodontal tissue and are associated with various conditions in other body parts. The distribution of periodontopathic bacterial species in the tonsils is unknown, even though the tonsils are located close to the oral cavity, and inflammation of the tonsils causes various systemic diseases. We detected the major periodontopathic bacterial species residing in saliva and tonsil specimens from 25 subjects undergoing tonsillectomy. Nine of the ten major periodontopathic bacterial species were detected by polymerase chain reaction of tonsil specimens, among which Campylobacter rectus was the most common (80.0%), followed by Porphyromonas gingivalis (36.0%). The other seven types of periodontopathic bacterial species were distributed with 0% to 25.0% abundance in the tonsil specimens. C. rectus had a high detection rate in tonsil specimens (> 75.0%), regardless of whether it was detected in the corresponding saliva specimens. However, the detection rate for P. gingivalis in tonsil specimens was significantly higher in subjects with P. gingivalis-positive saliva (77.8%) than in those with P. gingivalis-negative saliva (6.3%; P < 0.001). Furthermore, 75.0% of P. gingivalis in tonsil specimens did not have the known fimA gene that encodes the 41-kDa filamentous appendage protein FimA, which is expressed on the cell surface of the bacteria. Our results suggest that certain periodontopathic bacterial species are detected in the tonsils either independently of or depending on their distribution in the oral cavity and may be involved in tonsil-related diseases.

Title IgA Nephropathy and Oral Bacterial Species Related to Dental Caries and Periodontitis.

A relationship between IgA nephropathy (IgAN) and bacterial infection has been suspected. As IgAN is a chronic disease, bacteria that could cause chronic infection in oral areas might be pathogenetic bacteria candidates. Oral bacterial species related to dental caries and periodontitis should be candidates because these bacteria are well known to be pathogenic in chronic dental disease. Recently, several reports have indicated that collagen-binding protein (cnm)-(+) Streptococcs mutans is relate to the incidence of IgAN and the progression of IgAN. Among periodontal bacteria, Treponema denticola, Porphyromonas gingivalis and Campylobacte rectus were found to be related to the incidence of IgAN. These bacteria can cause IgAN-like histological findings in animal models. While the connection between oral bacterial infection, such as infection with S. mutans and periodontal bacteria, and the incidence of IgAN remains unclear, these bacterial infections might cause aberrantly glycosylated IgA1 in nasopharynx-associated lymphoid tissue, which has been reported to cause IgA deposition in mesangial areas in glomeruli, probably through the alteration of microRNAs related to the expression of glycosylation enzymes. The roles of other factors related to the incidence and progression of IgA, such as genes and cigarette smoking, can also be explained from the perspective of the relationship between these factors and oral bacteria. This review summarizes the relationship between IgAN and oral bacteria, such as cnm-(+) S. mutans and periodontal bacteria.

Relationship between IgA Nephropathy and Porphyromonas gingivalis; Red Complex of Periodontopathic Bacterial Species.

IgA nephropathy (IgAN) has been considered to have a relationship with infection in the tonsil, because IgAN patients often manifest macro hematuria just after tonsillitis. In terms of oral-area infection, the red complex of periodontal bacteria (Porphyromonas gingivalis (P. gingivalis), Treponema denticol (T. denticola) and Tannerella forsythia (T. forsythia)) is important, but the relationship between these bacteria and IgAN remains unknown. In this study, the prevalence of the red complex of periodontal bacteria in tonsil was compared between IgAN and tonsillitis patients. The pathogenicity of IgAN induced by P. gingivalis was confirmed by the mice model treated with this bacterium. The prevalence of P. gingivalis and T. forsythia in IgAN patients was significantly higher than that in tonsillitis patients (p < 0.001 and p < 0.05, respectively). A total of 92% of tonsillitis patients were free from red complex bacteria, while only 48% of IgAN patients had any of these bacteria. Nasal administration of P. gingivalis in mice caused mesangial proliferation (p < 0.05 at days 28a nd 42; p < 0.01 at days 14 and 56) and IgA deposition (p < 0.001 at day 42 and 56 after administration). Scanning-electron-microscopic observation revealed that a high-density Electron-Dense Deposit was widely distributed in the mesangial region in the mice kidneys treated with P. gingivalis. These findings suggest that P. gingivalis is involved in the pathogenesis of IgAN.

Intravenous administration of Streptococcus mutans induces IgA nephropathy-like lesions.

BACKGROUND: IgA nephropathy (IgAN) is one of the most frequently occurring types of chronic glomerulonephritis. Previous analyses have revealed that a major pathogen of dental caries, Streptococcus mutans [which expresses collagen-binding protein (Cnm) on its surface], is involved in the pathogenesis of IgAN. METHODS: Cnm-positive S. mutans isolated from a patient with IgAN was intravenously administered to specific pathogen-free Sprague-Dawley rats to evaluate their kidney conditions. RESULTS: The urinary protein level of the S. mutans group reached a plateau at 30 days, with increased numbers of mesangial cells and an increased mesangial matrix. The numbers of rats with IgA-positive and/or C3-positive glomeruli were significantly greater in the S. mutans group than in the control group at 45 days (P < 0.05). Electron microscopy analyses revealed electron-dense depositions in the mesangial area among rats in the S. mutans group. There were significantly more CD68-positive cells (macrophages) in the glomeruli of the S. mutans group than in the glomeruli of the control group during the late phase (P < 0.05), similar to the findings in patients with IgAN. CONCLUSION: Our results suggested that intravenous administration of Cnm-positive S. mutans caused transient induction of IgAN-like lesions in rats.

Efficacy of corticosteroid therapy for IgA nephropathy patients stratified by kidney function and proteinuria.

BACKGROUND: Steroid therapy is one of the important therapies for IgA nephropathy (IgAN), but the features of the IgAN patients who have the benefit from this therapy remained unclear. METHODS: This retrospective observational study, using data of 874 patients with IgAN analyzed the proteinuria and kidney function of IgAN patients who had beneficial effect by steroid therapy. Two advantages of the present study were a large cohort and a long observational period. RESULTS: Corticosteroid therapy had ameliorated the kidney prognosis [incident rate ratio (IRR) 0.57 (95%CI 0.34-0.92), P = 0.029]. Because of interaction between kidney function and use of corticosteroid (P = 0.047), stratification analysis by kidney function revealed that prognosis of kidney function in IgAN patients whose eGFR was less than 60 ml/min/1.73m2 was ameliorated by corticosteroid therapy [IRR 0.50 (95%CI 0.26-0.97), P = 0.015); while, there was no change of kidney prognosis in IgAN patients whose eGFR was above 60 ml/min/1.73 m2. To make the target of corticosteroid therapy for IgAN patients more clear, IgAN patients, whose eGFR were less than 60 ml/min/1.73 m2, were stratified by proteinuria (1 g/day). In IgAN patients whose eGFR were under 60 ml/min/1.73 m2 and whose proteinuria were over 1.0 g/day, corticosteroid therapy seemed to ameliorate kidney function [IRR 0.39 (95%CI 0.19-0.86), P < 0.05]; while, there was obviously no change by corticosteroid therapy in IgAN patients whose eGFR were less than 60 ml/min/1.73 m2 and whose proteinuria were less than 1.0 g/day. CONCLUSION: Our results suggested that steroid therapy was especially effective for IgAN patients whose eGFR was less than 60 ml/min/1.73 m2 and whose proteinuria was more than 1.0 g/day.

Imbalance of coagulation and fibrinolysis can predict vascular access failure in patients on hemodialysis after vascular access intervention.

OBJECTIVE: For patients with end-stage renal disease on hemodialysis, the durability of vascular access (VA) is still far from optimal, and access survival after intervention for access failure is an important aspect. Procoagulant status is a leading cause of access failure. Coagulation-fibrinolysis imbalance can occur in hemodialyzed patients, but the influence of the imbalance has not been fully elucidated. METHODS: We prospectively examined coagulation-fibrinolysis balance to assess the risk of access failure after the intervention of revascularization in a cohort of 462 hemodialysis patients. Thrombin-antithrombin complex (TAT) and plasmin-α2-plasmin inhibitor complex (PIC) are markers for coagulation and fibrinolysis. Median follow-up was 243 days. The end point was clinical access failure: revascularization or access revision. The survival curve for VA patency was assessed using the Kaplan-Meier method and compared using the log-rank test. Cox proportional hazards regression models that allowed adjustment for baseline differences in age, sex, dialysis vintage, diabetes mellitus, and various factors (quantity of blood flow, prothrombin time-international normalized ratio, fibrin degradation products, C-reactive protein, interleukin-6, tumor necrosis factor-α, and pentraxin-3) were used. RESULTS: The 162 patients who reached an end point had smaller access flow volume and smaller percentage of arteriovenous fistula and higher TAT/PIC ratio. Kaplan-Meier analysis indicated that the patients with elevated TAT/PIC ratio showed poorer outcome (P < .001). On Cox regression modeling, elevated TAT/PIC was an independent risk factor for access failure (hazard ratio, 1.58; P = .03). CONCLUSIONS: Our results suggest that coagulation-fibrinolysis imbalance is a significant risk factor for access failure and may predict VA failure in hemodialyzed patients after access intervention.

Inhibition of the Mammalian Target of Rapamycin May Augment the Increase in Soluble Klotho Levels in Renal Transplantation Recipients.

BACKGROUND/AIMS: α-Klotho is mainly expressed in the kidneys, and its soluble form can prevent vascular calcifications. Inhibition of the mammalian target of rapamycin (mTOR) upregulates Klotho. We assessed serial changes in the levels of soluble Klotho (sKlotho) in recipients before and after renal transplantation and investigated the effects of an mTOR inhibitor. METHODS: Serum sKlotho levels were measured in 36 recipients before and 1 year after transplantation and compared between those taking everolimus and those not taking everolimus. RESULTS: sKlotho levels were higher after transplantation than before transplantation (369.3 vs. 211.8 pg/mL). After transplantation, sKlotho levels were significantly higher in recipients taking everolimus than in those not taking everolimus (536.7 vs. 332.4 pg/mL). CONCLUSION: Our results suggest that mTOR inhibition may augment the increase in sKlotho levels in transplant recipients. Further studies are needed to examine whether mTOR inhibitors suppress the development of vascular complications via upregulation of Klotho expression in renal transplant recipients.

Oral Versus Intravenous Iron Supplementation for the Treatment of Iron Deficiency Anemia in Patients on Maintenance Hemodialysis-Effect on Fibroblast Growth Factor-23 Metabolism.

OBJECTIVE: Iron administration affects serum levels of intact (I-) fibroblast growth factor-23 (FGF23) and its cleavage product C-terminal (C-) FGF23 in iron-deficient patients on maintenance hemodialysis (MHD). The objective of this study was to compare the effect of oral or intravenous iron administration on serum levels of I-FGF23 and C-FGF23 in iron-deficient patients on MHD. DESIGN AND METHODS: A prospective randomized study. SUBJECTS: Participants on MHD with severe iron deficiency (n = 61). INTERVENTION: Participants were randomized to receive oral iron (50 mg of sodium ferrous citrate daily; oral group, n = 29) or intravenous iron (40 mg of saccharated ferric oxide weekly; IV group, n = 32). MAIN OUTCOME MEASURE: Changes in I-FGF23 and C-FGF23 after 10 weeks of treatment. RESULTS: Iron supplementation significantly increased hemoglobin, mean corpuscular volume, ferritin, and transferrin saturation rate, and decreased erythropoiesis-stimulating agent dose and erythropoiesis-stimulating agent resistance index value. Serum phosphate, calcium, and intact parathyroid hormone levels did not change significantly during the study. I-FGF23 levels increased significantly in the IV group and did not change in the oral group, whereas C-FGF23 levels were significantly reduced in both groups. Serum interleukin-6 and tumor necrosis factor-α levels were increased in both groups. Multiple regression analysis indicated the relationship between iron or erythropoiesis and FGF23 metabolism. CONCLUSION: Iron administration to patients on MHD with severe iron deficiency decreased C-FGF23 levels, whereas intravenous iron increased I-FGF23 levels though oral iron did not. If the target of chronic kidney disease-mineral and bone disorder therapy is reducing I-FGF23 levels, we suggest the use of oral iron.

CD16+CD56+ cells are a potential culprit for hematuria in IgA nephropathy.

BACKGROUND: Hematuria is the first manifestation of urinary abnormality in immunoglobulin A nephropathy (IgAN). Hematuria has recently been reported as a risk factor for deterioration of renal function; however, its cause remains unknown. METHODS: We analyzed the surface marker of peripheral blood mononuclear cells before and immediately after tonsillectomy in IgAN patients and controls (chronic tonsillitis or tonsillar hypertrophy) by flow cytometry and investigated the association with hematuria. To prove our hypothesis that NK cells induce hematuria, we administered IL-12, activator of NK cells, to HIGA mice. In addition, we transferred cultured NK cells to nude rats and transferred the CD16(+)CD56(+) cells, including NK cells, that are derived from the peripheral blood of IgAN patients immediately after tonsillectomy to nude rats to assess the hematuria level and renal histology of the recipients. We also performed cytotoxicity assays against glomerular endothelial cells by NK cells. RESULTS: We found that IgAN patients who showed rapid deterioration of hematuria after tonsillectomy also displayed a significant increase in CD16(+)CD56(+) cells in the peripheral blood immediately after tonsillectomy. Exogenous administration of IL-12 to HIGA mice induced hematuria. Adoptive transfer of either cells of an NK cell line, or of CD16(+)CD56(+) cells derived from IgAN patients, into nude rats induced hematuria in the recipients. In vitro analysis showed that NK cells exert cytotoxic activity toward human glomerular endothelial cells in a dose-dependent manner. CONCLUSIONS: CD16(+)CD56(+) cells seem to be responsible for hematuria in IgAN.

Current topics in therapeutic plasmapheresis.

Therapeutic plasmapheresis has been used for intractable diseases that cannot be cured by conventional drug therapy. Currently, the use of therapeutic plasmapheresis has been approved for 27 diseases by Japan's National Health Insurance system and is mainly categorized into three modalities: plasma exchange (PE), double-filtration plasmapheresis (DFPP), and plasma adsorption (PA). Plasma separators and/or fractionators are essential for the therapy. PE is performed for two purposes: removal of pathogenic antigens or substances in the plasma fraction and supplementation of essential factors, such as albumin and coagulation factors. PE can be used for thrombotic microangiopathy and acute hepatic failure. DFPP can be performed for selective removal of macromolecules while avoiding the use of substitution fluid (i.e., albumin or fresh frozen plasma). DFPP has now been used for conditions involving relatively larger plasma molecules, including hyperviscosity syndrome and ABO-incompatible kidney transplantation. PA can specifically remove pathogenic agents, such as low-density lipoprotein or autoantibodies, in the IgG fractions by the adsorption column and does not require substitution fluids. PA has now been used for a wide variety of neurological diseases, including chronic inflammatory demyelinating polyneuropathy. This review describes the characteristics of each modality, seeking to improve the efficacy and specificity of removal of the target substance.

An association between serum γ-glutamyltransferase and proteinuria in drinkers and non-drinkers: a Japanese nationwide cross-sectional survey.

BACKGROUND: The association between alcohol consumption and chronic kidney disease (CKD), characterized by reduced glomerular filtration rate and proteinuria, is controversial. Recent studies suggest that serum γ-glutamyltransferase (GGT) level, a conventional marker of excessive alcohol consumption, predicts the CKD incidence. Little information is available on the difference in the clinical impact of alcohol consumption and GGT on proteinuria. METHODS: The present cross-sectional survey included 332,296 Japanese people aged ≥40 years in 2008. To examine the associations of GGT and alcohol consumption with proteinuria, 134,600 men and 197,696 women were classified into 20 categories based on GGT quartiles and alcohol consumption categories, and their prevalence rate ratios (PRR) of proteinuria defined as ≥1+ of dipstick urinary protein were calculated after adjusting for clinically relevant factors. RESULTS: Prevalence of proteinuria was 7.5 and 3.7 % in men and women, respectively. In both gender an association between alcohol consumption and proteinuria was in a J-shaped fashion with the lowest PRR of mild drinkers with ≤19 g/day of ethanol consumption, whereas an association between serum GGT level and proteinuria was linear. Compared with rare drinkers in the lowest GGT quartile, the subjects in higher GGT quartiles had a higher probability of proteinuria, irrespective of alcohol consumption. An optimal cutoff level of serum GGT was 43.6 and 23.2 IU/L in men and women, respectively. CONCLUSIONS: The subjects with higher serum GGT level had a higher probability of proteinuria, regardless of alcohol consumption, suggesting that GGT has a clinically greater impact on CKD than alcohol consumption.

Factors contributing to subjective well-being and supporting successful aging among rural Japanese community-dwelling older adults: A cross-sectional and longitudinal study.

AIM: We aimed to identify the factors contributing to subjective well-being in community-dwelling older adults in rural Japan. This study explored the relationship among physical and mental health, socioeconomic status, and activity levels with regard to the subjective well-being of older adults. METHODS: In the Frail Elderly in the Sasayama-Tamba Area study, a cohort investigation of independent older adults in a rural Japanese community, 541 of 844 participants completed a 2-year follow-up survey. Subjective well-being was assessed as a binary based on three factors - "happiness," "satisfaction with life" and "meaning in life" - using a subset of the World Health Organization's Quality of Life questionnaire. The improvement group transitioned from not having subjective well-being during the baseline survey to having subjective well-being during the follow-up survey. Furthermore, we used multivariable log-Poisson regression models to calculate the prevalence ratios of subjective well-being. RESULTS: The cross-sectional study showed that sleep satisfaction, health services access satisfaction and having a higher-level functional capacity were positively associated with having "happiness" and "satisfaction with life." Furthermore, being aged ≥ 80 years and having financial leeway were positively associated with having "meaning in life." The longitudinal study showed that having a higher-level functional capacity was positively associated with improving "happiness" and "satisfaction with life." Being female was positively associated with improving "happiness" and "meaning in life," and health services access satisfaction and alcohol drinking were positively associated with improving "satisfaction with life" and "meaning in life," respectively. CONCLUSIONS: These findings offer promising avenues for enhancing the subjective well-being of older adults. Geriatr Gerontol Int 2024; 24: 311-319.

Retention of fetuin-A in renal tubular lumen protects the kidney from nephrocalcinosis in rats.

The serum glycoprotein fetuin-A is an important inhibitor of extraosseous calcification. The importance of fetuin-A has been confirmed in fetuin-A null mice, which develop widespread extraosseous calcification including the kidney. However, the mechanism how fetuin-A protects kidneys from nephrocalcinosis remains uncertain. Here, we demonstrate that intratubular fetuin-A plays a role in the prevention of nephrocalcinosis in the proximal tubules. Although normal rat kidney did not express mRNA for fetuin-A, we found punctate immunohistochemical staining of fetuin-A mainly in the S1 segment of the proximal tubules. The staining pattern suggested that fetuin-A passed through the slit diaphragm, traveled in the proximal tubular lumen, and was introduced into proximal tubular cells by megalin-mediated endocytosis. To test this hypothesis, we inhibited the function of megalin by intravenous injection of histidine-tagged soluble receptor-associated protein (His-sRAP), a megalin inhibitor. His-sRAP injection diminished fetuin-A staining in the proximal tubules and led to urinary excretion of fetuin-A. We further analyzed the role of fetuin-A in nephrocalcinosis. Continuous injection of parathyroid hormone (PTH) 1-34 induced nephrocalcinosis mainly in the proximal tubules in rats. His-sRAP retained fetuin-A in renal tubular lumen and thereby protected the kidneys of PTH-treated rats from calcification. Our findings suggest that tubular luminal fetuin-A works as a natural inhibitor against calcification in the proximal tubules under PTH-loaded condition.

Age and prediction of remission and relapse of proteinuria and corticosteroid-related adverse events in adult-onset minimal-change disease: a retrospective cohort study.

BACKGROUND: In adult-onset minimal-change disease (MCD) the predictors of remission and relapse of proteinuria and corticosteroid-related adverse events remain unknown. METHODS: The multicenter retrospective cohort study, the STudy of Outcomes and Practice patterns of Minimal-Change Disease (STOP-MCD), included 142 adult-onset MCD patients in 5 nephrology centers in Japan. Primary outcomes were first remission of proteinuria defined by urinary protein (UP) <0.3 g/day, UP/creatinine ratio (UPCR) <0.3, and/or negative/trace by dipstick test and first relapse of proteinuria defined by UP ≥1.0 g/day, UPCR ≥1.0, and/or dipstick test ≥1+ followed by immunosuppressive therapy. Secondary outcomes were corticosteroid-related adverse events. RESULTS: During the median 3.6 (interquartile range, 2.0-6.9) years of the entire observational period, 136 (95.8 %) and 79 (58.1 %) patients developed at least 1 remission and 1 recurrence within a median of 15 (10-34) days and 0.90 (0.55-1.57) years, respectively. Compared with younger patients aged 15-29 years at kidney biopsy, elderly patients aged ≥60 years developed remission significantly later [hazard ratio 0.53 (95 % confidence interval 0.32-0.88)], while older patients aged ≥45 years were at a significantly lower risk of relapse [45-59 years, 0.46 (0.22-0.96); 60-83 years, 0.39 (0.21-0.74)]. However, older patients were significantly more vulnerable to severe infection, diabetes, and cataract as compared with younger patients. CONCLUSION: Younger patients had a higher risk of relapse while older patients had a lower risk of relapse but a higher risk of corticosteroid-related adverse events.

The mitochondrial protein frataxin is downregulated in hemodialysis patients.

BACKGROUND: The mitochondrial protein frataxin regulates iron metabolism for heme and iron sulfur cluster synthesis in the mitochondria and could be associated with the regulation of oxidative stress. To clarify the expression of frataxin and its association with uremia, we evaluated the mRNA and protein levels of frataxin in the polymorphonuclear leukocytes (PMNLs) of patients on hemodialysis (HD). METHODS: Uremic patients on HD (n = 18) and healthy control subjects (n = 18) were investigated. PMNLs were isolated by differential centrifugation. The mRNA levels of frataxin in isolated leukocytes were quantified by TaqMan real-time polymerase chain reaction. Frataxin protein expression in the cell lysate was evaluated using SDS-polyacrylamide gel electrophoresis and Western blotting. RESULTS: The frataxin/glyceraldehyde-3-phosphate dehydrogenase mRNA ratio in PMNLs from uremic patients was significantly lower than that in control subjects. Frataxin protein expression in uremic patients was also significantly lower than that in controls. Multiple regression analysis showed that frataxin mRNA levels were independently associated with the serum levels of both the oxidative stress marker malondialdehyde and the proinflammatory cytokine tumor necrosis factor-α. CONCLUSION: The downregulation of frataxin seems to be linked with uremic status, which is usually associated with chronic inflammation and the acceleration of oxidative stress. Mitochondrial iron regulation may play a role in several comorbidities and in the poor prognosis in uremic patients. Further investigation is needed to elucidate whether reduced frataxin levels are linked to the pathological status of uremic patients and whether uremic substances affect frataxin expression.

A Dose-Dependent Association between Alcohol Consumption and Incidence of Proteinuria and Low Glomerular Filtration Rate: A Systematic Review and Meta-Analysis of Cohort Studies.

Previous cohort studies have reported conflicting associations between alcohol consumption and chronic kidney disease, characterized by proteinuria and low glomerular filtration rate (GFR). This systematic review, which included 14,634,940 participants from 11 cohort studies, assessed a dose-dependent association of alcohol consumption and incidence of proteinuria and low estimated GFR (eGFR) of <60 mL/min/1.73 m2. Compared with non-drinkers, the incidence of proteinuria was lower in drinkers with alcohol consumption of ≤12.0 g/day (relative risk 0.87 [95% confidence interval 0.83, 0.92]), but higher in drinkers with alcohol consumption of 36.1-60.0 g/day (1.09 [1.03, 1.15]), suggesting a J-shaped association between alcohol consumption and the incidence of proteinuria. Incidence of low eGFR was lower in drinkers with alcohol consumption of ≤12.0 and 12.1-36.0 than in non-drinkers (≤12.0, 12.1-36.0, and 36.1-60.0 g/day: 0.93 [0.90, 0.95], 0.82 [0.78, 0.86], and 0.89 [0.77, 1.03], respectively), suggesting that drinkers were at lower risk of low eGFR. In conclusion, compared with non-drinkers, mild drinkers were at lower risk of proteinuria and low eGFR, whereas heavy drinkers had a higher risk of proteinuria but a lower risk of low eGFR. The clinical impact of high alcohol consumption should be assessed in well-designed studies.

Simultaneous Presence of Campylobacter rectus and Cnm-Positive Streptococcus mutans in the Oral Cavity Is Associated with Renal Dysfunction in IgA Nephropathy Patients: 5-Year Follow-Up Analysis.

BACKGROUND: The simultaneous presence of Streptococcus mutans expressing the Cnm protein encoded by cnm (i.e., cnm-positive S. mutans) and Campylobacter rectus in the oral cavity has been associated with proteinuria in patients with IgA nephropathy (IgAN). OBJECTIVES: The present study evaluated the relationship between renal function and oral bacteria in patients with IgAN over 5 years of follow-up. METHODS: The presence of C. rectus and cnm-positive S. mutans in saliva samples of 117 patients with IgAN was initially evaluated by polymerase chain reaction. Patients were then divided into four groups according to the results of C. rectus and cnm-positive S. mutans detection: group A: C. rectus (-), cnm-positive S. mutans (-); group B: C. rectus (+), cnm-positive S. mutans (-); group C: C. rectus (-), cnm-positive S. mutans (+); and group D: C. rectus (+), cnm-positive S. mutans (+). Clinical characteristics were prospectively followed for 5 years. RESULTS: Serum creatinine levels were significantly higher in group D than in group A over 5 years of follow-up. Additionally, the proportion of patients with an estimated glomerular filtration rate <45 mL/min increased over time; it was significantly greater in group D than in group A over 5 years of follow-up. CONCLUSION: These results suggest that the simultaneous presence of C. rectus and cnm-positive S. mutans in the oral cavity is associated with renal dysfunction in IgAN patients.

Utility of ultrasonography for predicting indications for tolvaptan in patients with autosomal dominant polycystic kidney disease.

PURPOSE: Tolvaptan is the first approved treatment for autosomal dominant polycystic kidney disease (ADPKD) that targets a mechanism directly contributing to the development and growth of renal cysts. We investigated the ability of ultrasonography to predict total kidney volume (TKV) of 750 mL or more, which is an indication for tolvaptan therapy in patients with ADPKD. METHODS: A total of 46 patients with ADPKD were evaluated. The most statistically appropriate measurement based on ultrasonography for predicting TKV determined by computed tomography (CT) was assessed. RESULTS: TKV determined by CT was 796.8 (508.8-1,560.3) mL. The median length, anteroposterior distance, and mediolateral distance determined using ultrasonography were 15.7 cm, 7.6 cm, and 7.6 cm in the left kidney, and 13.4 cm, 6.9 cm, and 7.2 cm in the right kidney, respectively. Multivariate regression analysis showed that total kidney length (left and right) [variance inflation factor (VIF), 9.349] and total mediolateral distance (left and right) (VIF, 3.988) were independently associated with TKV. The correlation (r) between the logarithm of TKV determined by CT and total mediolateral distance determined using ultrasonography was 0.915 (p < 0.001). The linear regression equation was log (total kidney volume) = 1.833 + 0.075 × total mediolateral distance (left and right) based on ultrasonography. The area under the receiver operating characteristic curve for total mediolateral distance determined using ultrasonography to predict TKV of 750 mL or more was 0.989. Using the total mediolateral distance cut-off value of 14.2 cm, the sensitivity and specificity were 96.0% and 100.0%, respectively. CONCLUSION: Total mediolateral distance determined using ultrasonography can predict TKV in patients with ADPKD.