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.

[Mitochondrial Dysfunction and Oligomer Formation in Neurodegenerative Diseases].

Mitochondrial respiratory chain complexes are responsible for the oxidative phosphorylation system, and the association of these complexes is called a supercomplex. Since the formation of supercomplexes en- hances energy production and reduces electron leakage, the destabilization of supercomplexes may increase oxidative stress and mitochondrial dysfunction in the presence of aging and neurodegenerative disease. Both blue native polyacrylamide gel electrophoresis (BN-PAGE) and high-resolution clear native (hrCN) - PAGE are effective to examine supercomplex formation. Since the sensitivity of the in-gel enzyme activity assay of hrCN-PAGE is higher than that of BN-PAGE, we used hrCN-PAGE and two-dimensional hrCN/ SDS-PAGE to examine supercomplex formation in human mononuclear leukocytes, and compared them in relation to the sex and age group. We also applied the results to the analysis of soluble oligomer formation in neurodegenerative disease. Herein, we introduce the possibility of applying a clinical laboratory test for neurodegenerative diseases. [Review].

Transglutaminase 2 accelerates neuroinflammation in amyotrophic lateral sclerosis through interaction with misfolded superoxide dismutase 1.

Although the aberrant assembly of mutant superoxide dismutase 1 (mSOD1) is implicated in the pathogenesis of familial amyotrophic lateral sclerosis (ALS), the molecular basis of superoxide dismutase 1 (SOD1) oligomerization remains undetermined. We investigated the roles of transglutaminase 2 (TG2), an endogenous cross-linker in mSOD1-linked ALS. TG2 interacted preferentially with mSOD1 and promoted its oligomerization in transfected cells. Purified TG2 directly oligomerized recombinant mutant SOD1 and the apo-form of the wild-type SOD1 proteins in a calcium-dependent manner, indicating that misfolded SOD1 is a substrate of TG2. Moreover, the non-cell-autonomous effect of extracellular TG2 on the neuroinflammation was suggested, since the TG2-mediated soluble SOD1 oligomers induced tumor necrosis factor-α, interleukin-1ß, and nitric oxide in microglial BV2 cells. TG2 was up-regulated in the spinal cord of pre-symptomatic G93A SOD1 transgenic mice and in the hypoglossal nuclei of mice suffering nerve ligation. Furthermore, inhibition of spinal TG2 by cystamine significantly delayed the progression and reduced SOD1 oligomers and microglial activation. These results indicate a novel role of TG2 in SOD1 oligomer-mediated neuroinflammation, as well as in the involvement in the intracellular aggregation of misfolded SOD1 in ALS.

Supercomplex formation of mitochondrial respiratory chain complexes in leukocytes from patients with neurodegenerative diseases.

With population aging, cognitive impairments and movement disorders due to neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD) and dementia with Lewy bodies (DLB), are increasingly considered as key social issues. Clinically, it has remained challenging to diagnose them before the onset of symptoms because of difficulty to observe the progressive loss of neurons in the brain. Therefore, with exploratory research into biomarkers, a number of candidates have previously been proposed, such as activities of mitochondrial respiratory chain complexes in blood in AD and PD. In this study, we focused on the formation of mitochondrial respiratory chain supercomplexes (SCs) because the formation of SC itself modulates the activity of each complex. Here we investigated the SC formation in leukocytes from patients with AD, PD and DLB. Our results showed that SCs were well formed in AD and PD compared with controls, while poorly formed in DLB. We highlighted that the disruption of the SC formation correlated with the progression of PD and DLB. Taking our findings together, we propose that pronounced SC formation would already have occurred before the onset of AD, PD and DLB and, with the progression of neurodegeneration, the SC formation would gradually be disrupted.

C-terminal truncation is a prominent post-translational modification of human erythrocyte α-synuclein.

α-Synuclein (α-Syn) is a protein related to synucleinopathies with high expression in the central nervous system and erythrocytes which are a major source of peripheral α-Syn. Recent reports have suggested the presence of α-Syn within extracellular vesicles (EVs) derived from erythrocytes, potentially contributing to the pathogenesis of synucleinopathies. While Lewy bodies, intracellular inclusions containing aggregated α-Syn, are prominently observed within the brain, their occurrence in peripheral neurons implies the dissemination of synucleinopathy pathology throughout the body via the propagation of α-Syn. In this study, we found erythrocytes and circulating EVs obtained from plasma contained α-Syn, which was separated into four major forms using high-resolution clear native-PAGE and isoelectric focusing. Notably, erythrocyte α-Syn was classified into full-length and C-terminal truncated forms, with truncation observed between Y133 and Q134 as determined by LC-MS/MS analysis. Our finding revealed that C-terminally truncated α-Syn, which was previously reported to exist solely within the brain, was also present in erythrocytes and circulating EVs obtained from plasma.

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 case of tacrolimus plus intensive LCAP therapy combination for refractory ulcerative colitis].

A 30-year-old woman was referred to our hospital with recurrent refractory ulcerative colitis. She also suffered from avascular necrosis of the left femoral head caused by steroid use. We had expected that tacrolimus would contribute to remission, but effects remained insufficient even after 16 days of treatment. Intensive leukocytapheresis (LCAP) therapy was added to tacrolimus therapy, and this combination achieved remission. Tacrolimus plus intensive LCAP combination therapy appears useful in treating refractory ulcerative colitis.

Post-translational modification of lysine residues in erythrocyte α-synuclein.

α-Synuclein is a protein linked to various synuclein-associated diseases ('synucleinopathies'), including Parkinson's disease, dementia with Lewy Bodies and multiple system atrophy, and is highly expressed in the central nervous system and in erythrocytes. Moreover, α-synuclein-containing erythrocyte-derived extracellular vesicles may be involved in the pathogenesis of synucleinopathies and their progression across the blood-brain barrier. Several post-translational modifications of α-synuclein have been reported in brain inclusions, including S129 phosphorylation, but fewer have been found in erythrocytes. In this study, we analysed the post-translational modifications of erythrocyte α-synuclein using liquid chromatography-mass spectrometry. We found that all lysine residues in the α-synuclein protein could be modified by acetylation, glycation, ubiquitination or SUMOylation but that phosphorylation, nitration and acylation were uncommon minor post-translational modifications in erythrocytes. Since the post-translational modification of lysine residues has been implicated in both membrane association and protein clearance, our findings provide new insight into how synucleinopathies may progress and suggest possible therapeutic strategies designed to target α-synuclein.

High levels of tumor necrosis factor-α downregulate antimicrobial iron transport protein, Nramp1, in chronic hemodialysis patients: a key factor for infection risk.

BACKGROUND/AIMS: The susceptibility of patients on maintenance hemodialysis (MHD) to infections is a major cause of mortality and morbidity. Natural resistance-associated macrophage protein 1 (Nramp1) regulates intracellular pathogen proliferation, and its mRNA expression is highest in polymorphonuclear leukocytes (PMNLs). The purpose of this study was to determine the level of Nramp1 in PMNLs from MHD patients and the factors affecting its expression. METHODS: Twenty MHD patients and 24 healthy volunteers (controls) were recruited. Relative quantitative PCR was used to measure Nramp1 mRNA, and protein levels were semiquantified by means of real-time PCR and Western blot analysis or immunohistochemistry. The effect of tumor necrosis factor-α (TNF-α) or interleukin-6 (IL-6) on Nramp1 expression in PMNLs from controls was also examined. RESULTS: Nramp1 mRNA and protein levels were substantially lower in PMNLs from MHD than control subjects. Serum TNF-α levels were significantly higher in the MHD group and were inversely correlated with Nramp1 mRNA levels. The addition of TNF-α to PMNLs from control subjects decreased mRNA and protein levels of Nramp1. IL-6 did not alter Nramp1 mRNA or protein expression. CONCLUSION: We found that Nramp1 was downregulated in the PMNLs of MHD patients, which constitute the first defense barrier against bacterial challenges. High levels of TNF-α may be associated with the downregulation of Nramp1. Our findings indicate that the susceptibility to infection observed in MHD patients could be partly due to the impairment of the intracellular handling of iron and the donation of more iron to the bacteria.

Risk factors of proteinuria and potentially protective effect of renin-angiotensin system inhibitors in patients with renal cell carcinoma receiving axitinib.

PURPOSE: Patients receiving vascular endothelial growth factor-tyrosine kinase inhibitors are at a risk of developing proteinuria. Renin-angiotensin system (RAS) inhibitors exert renoprotective effects and might reduce proteinuria risk in these patients. We investigated the risk factors for and protective effect of RAS inhibitors against proteinuria in patients with renal cell carcinoma (RCC) receiving axitinib. METHODS: We retrospectively reviewed the medical records of patients with RCC receiving axitinib at Kobe City Medical Center General Hospital between September 2012 and October 2020. Patients with proteinuria ≥ 2+ at baseline were excluded. The patients were categorized into RAS inhibitor user, non-RAS inhibitor user, and non-user groups. The severity of proteinuria was graded based on the Common Terminology Criteria for Adverse Events, version 5.0. A multivariate Cox proportional hazards model was employed to identify the risk factors for developing grade ≥ 2 proteinuria. RESULTS: Among 42 patients, 28 received antihypertensive drugs at baseline. Among these, 17 and 11 patients were in the RAS inhibitor and non-RAS inhibitor user groups, respectively. Twenty-three patients (54.8%) developed grade ≥ 2 proteinuria. The multivariate analysis revealed that the non-RAS inhibitor user group (P = 0.001) and patients with pre-existing grade 1 proteinuria (P = 0.022) were significantly associated with the development of grade ≥ 2 proteinuria, whereas the RAS inhibitor user group was not significantly associated with it. CONCLUSION: In patients with RCC receiving axitinib, pre-existing proteinuria and non-RAS inhibitor use were significantly associated with grade ≥ 2 proteinuria development. Our preliminary data should be confirmed by further studies.

Capability of airline jets as an observation platform for noctilucent clouds at middle latitudes.

The exact occurrence frequency of noctilucent clouds (NLCs) in middle latitudes is significant information because it is thought to be sensitive to long-term atmospheric change. We conducted NLC observation from airline jets in the Northern Hemisphere during the summer 2019 to evaluate the effectiveness of NLC observation from airborne platforms. By cooperating with the Japanese airline All Nippon Airways (ANA), imaging observations of NLCs were conducted on 13 flights from Jun 8 to Jul 12. As a result of careful analysis, 8 of these 13 flights were found to successfully detect NLCs from middle latitudes (lower than 55° N) during their cruising phase. Based on the results of these test observations, it is shown that an airline jet is a powerful tool to continuously monitor the occurrence frequency of NLCs at midlatitudes which is generally difficult with a polar orbiting satellite due to sparse sampling in both temporal and spatial domain. The advantages and merits of NLC observation from jets over satellite observation from a point of view of imaging geometry are also presented.

Helicobacter pylori VacA reduces the cellular expression of STAT3 and pro-survival Bcl-2 family proteins, Bcl-2 and Bcl-XL, leading to apoptosis in gastric epithelial cells.

BACKGROUND: Helicobacter pylori vacuolating cytotoxin, VacA, stimulates apoptosis via a mitochondria-dependent pathway. VacA induces apoptosis via activation of the pro-apoptotic B-cell lymphoma (Bcl)-2 family proteins, Bcl-2-associated X protein (Bax) and Bcl-2 homologous antagonist/killer (Bak), while the implication of such pro-survival Bcl-2 family members as Bcl-2 and Bcl-XL in the VacA-induced apoptosis remains unknown. Signal transduction and activator of transcription 3 (STAT3) is a pivotal transcription factor that upregulates Bcl-2 and Bcl-XL. AIMS: This study was conducted to elicit the implication of STAT3 and pro-survival Bcl-2 and Bcl-XL in the intrinsic apoptosis. METHODS: Immunoblot and reverse transcriptase real-time polymerase chain reaction (RT-PCR) were employed to assess the cellular expression of STAT3, Bcl-2, and Bcl-XL in response to purified VacA in gastric adenocarcinoma cell lines. VacA-induced apoptosis was quantitated morphologically following knockdown by each specific small interfering RNA (siRNA) or in the presence of pharmacological inhibitors. RESULTS: VacA reduced STAT3, Bcl-2, and Bcl-XL expression in a dose-dependent manner. Knockdown of STAT3, Bcl-2, and Bcl-XL by siRNA induced apoptosis to a similar extent in the case of sufficient VacA inoculation. The VacA-mediated reduction of STAT3 expression was independent of cellular vacuolization, since a vacuolar-type ATPase inhibitor, bafilomycin A1, did not inhibit VacA-induced reduction of STAT3, Bcl-2, and Bcl-XL expression. Instead, a c-JUN NH2-terminal kinase (JNK) inhibitor, SP600125, restored the VacA-induced reduction of STAT3 expression to the basal level. CONCLUSIONS: VacA-induced apoptosis may be, in part, implicated in the reduction of STAT3 linking to the downregulation of Bcl-2 and Bcl-XL, in association with JNK activity.

Use of in-gel peroxidase assay for cytochrome c to visualize mitochondrial complexes III and IV.

The in-gel activity assay (IGA) is a powerful technique that uses enzymatic activity and compares intensities of detected bands in mitochondrial respiratory chain supercomplexes, and it is applicable to eukaryotic organisms. However, no IGA has been established for complex III because of the difficulty of access by ubiquinol, a substrate for complex III. Herein, we demonstrate that cytochrome c (Cyt c) showed peroxidase activity on IGA as a component of complexes III and IV. We used pre-incubation with sodium dodecyl sulfate (SDS) before IGA to loosen complexes in the gel after high-resolution clear native polyacrylamide gel electrophoresis (hrCN-PAGE), a refinement of blue native PAGE. The signals of IGA based on peroxidase activity were obtained using enhanced chemiluminescence solution. Then, the gel was directly used in western blotting or hrCN/SDS two-dimensional PAGE. Our findings indicate that IGA for Cyt c reflected the indirect activity of complexes III and IV.

Pneumatosis intestinalis in ulcerative colitis.

BACKGROUND: UC patients are considered to be at risk for pneumatosis intestinalis (PI). CASE REPORT: A 50-year-old man who had been treated with prednisolone for left-sided ulcerative colitis (UC) underwent follow-up colonoscopy. In addition to active colitis in the left colon, some cystic lesions were found in the unaffected ascending colon. Endoscopic ultrasonography and computed tomography confirmed the presence of intramural air, consistent with PI. Since corticosteroid use might contribute to the development of PI, the patient was successfully treated with leukocytapheresis. At the last follow-up colonoscopy the UC was still in remission and the pneumatic cysts were resolving. CONCLUSIONS: It is important to determine the clinical significance of PI in each patient to ensure appropriate therapy.

Degradation rate of DNA scaffolds and bone regeneration.

Scaffolds implanted into bone defect sites must achieve optimal biodegradation rates while appropriately filling the void as new bone formation progresses. We recently developed a unique biomaterial consisting of salmon deoxyribose nucleic acid (DNA) and protamine, which can be used as an osteoconductive scaffold for tissue engineering. The aim of the present study was to elucidate how the degradation rate of the scaffold affects bone regeneration. We examined the relationships between the degradation rate of salmon DNA scaffolds and new bone formation using a rat skin flank subcutaneous model and rat calvarial defect model. The degradation rates of the scaffolds were proportional to the durations of pretreatment with ultraviolet (UV) light irradiation. The biodegradation rates of the scaffolds were also dependent on the duration of UV irradiation, as tested a subcutaneous tissue implantation. Scaffolds irradiated with UV light for 0.5 h maintained gradual biodegradation of phosphate compared with scaffolds irradiated for 0 or 3 h. In the calvarial defect model, we found that new bone formation was higher in rats treated with scaffolds irradiated with UV light for 0.5 h compared with those irradiated with UV light for 0 or 3.0 h. The present results suggest that bioengineering of scaffolds for biodegradation is important to regenerate bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 122-128, 2019.

Interleukin 8 and 1beta and RANTES levels in esophageal mucosa predict recurrence of endoscopy-negative gastroesophageal reflux disease.

BACKGROUND/AIMS: Endoscopy-negative gastroesophageal reflux disease (ENRD), an incipient GERD phenotype without mucosal breaks, is a chronic relapsing condition with an impact on quality of life. Proinflammatory cytokines and chemokines play a role in the pathogenesis of various conditions including GERD. METHODOLOGY: This study investigated the relationship between interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), regulated on activation normal T-cell expressed and presumably secreted (RANTES) and IL-1beta levels in esophageal mucosa and recurrence of the reflux symptom in 22 patients with ENRD. RESULTS: Based on analysis using Cox's proportional hazard regression model, significantly positive association was observed between the mucosal levels of cytokines (IL-8 and -1beta and RANTES) and ENRD recurrence. Otherwise, parameters including age, gender, body mass index, smoking habits, alcohol intake, hiatal hernia and Helicobacter pylori status were not significantly related to relapse of the symptom. CONCLUSIONS: Enhanced production of such cytokines as IL-8 and -1beta and RANTES in esophageal mucosa can be potential predictors for ENRD recurrence.

Glutamine Deprivation Enhances Acetyl-CoA Carboxylase Inhibitor-induced Death of Human Pancreatic Cancer Cells.

BACKGROUND/AIM: Acetyl-CoA carboxylase (ACC) is a rate-limiting enzyme in fatty acid synthesis. In this study, we investigated the effect of ACC inhibition on survival of pancreatic cancer cells. MATERIAL AND METHODS: AsPC-1, BxPC-3 and PANC-1 were used as human pancreatic cancer cell lines. 5-(etradecyloxy)-2-furoic acid (TOFA) and bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl) ethyl sulfide (BPTES) were used as inhibitors of ACC and glutaminase (GLS) respectively. Apoptotic and live cells were distinguished by annexin-V staining. The activity of caspase-3 was evaluated by measuring the fluorescence intensity of the degradation product of the substrate, N-acetyl-Asp-Glu-Val-Asp-7-amido-4-trifluoromethylcoumarin. RESULTS: TOFA increased the number of annexin V-positive cells and enhanced caspase-3 activity in AsPC-1 and BxPC-3, but not in PANC-1 cells. The number of PANC-1 cells increased after 48 h in Earle's balanced salt solution. Interestingly, proliferation of PANC-1 cells was drastically suppressed by glutamine deprivation, but not by inhibition of glycolysis. BPTES also induced cell death to the same extent as glutamine deprivation. In addition, TOFA induced cell death of PANC-1 cells, both in the presence of BPTES and with glutamine deprivation, suggesting that inhibition of glutaminolysis causes cell death and enhances the effect of TOFA in PANC-1 cells. CONCLUSION: These findings suggest that glutaminolysis is important for the survival of pancreatic cancer cells showing tolerance to nutrient starvation such as PANC-1 cells, and use of a combination of inhibitors of ACC and GLS may be a new strategy for treatment of pancreatic cancer.

Putative denitrosylase activity of Cu,Zn-superoxide dismutase.

The Cu,Zn-superoxide dismutase (SOD1) has been reported to exert an S-nitrosylated glutathione (GSNO) denitrosylase activity that was augmented by a familial amyotrophic lateral sclerosis (FALS)-associated mutation in this enzyme. This putative enzymatic activity as well as the spontaneous decomposition of GSNO has been reexamined. The spontaneous decomposition of GSNO exhibited several peculiarities, such as a lag phase followed by an accelerating rate plus a marked dependence on GSNO concentration, suggestive of autocatalysis, and a greater rate in polypropylene than in glass vessels. Dimedone caused a rapid increase in absorbance likely due to reaction with GSNO, followed by a slower increase possibly due to reaction with an intermediate such as glutathione sulfenic acid. SOD1 weakly increased the rate of decomposition of GSNO, but did so only when GSH was present; and FALS-associated mutant forms of SOD1 were not more active in this regard than was the wild type. Decomposed GSNO, when added to fresh GSNO, hastened its decomposition, in accord with autocatalysis, and when added to GSH, generated GSNO in accord with the presence of nitrite. A mechanism is proposed that is in accord with these observations.

Enoxacin with UVA Irradiation Induces Apoptosis in the AsPC1 Human Pancreatic Cancer Cell Line Through ROS Generation.

Pancreatic cancer is one of the deadliest human cancers. In the current study, we investigated the possibility of a new treatment strategy using a combination of the new fluoroquinolone, enoxacin, and mild ultraviolet A (UVA) irradiation. Enoxacin with UVA irradiation increased the number of annexin V-positive (apoptotic) pancreatic cancer cells in time- and concentration-dependent manners, whereas alone neither had these effects. In addition, enoxacin with UVA irradiation induced cleavage of poly (ADP-ribose) polymerase in AsPC1 human pancreatic cancer cells. Moreover, the singlet oxygen scavengers, histidine and sodium azide, and the hydroxyl radical scavenger, mannitol, significantly suppressed apoptosis induced by enoxacin and UVA irradiation, respectively. These results suggest that UVA irradiation activates enoxacin, after which activated enoxacin induces apoptosis of AsPC1 cells through generation of reactive oxygen species. Therefore, the combination of enoxacin with mild UVA irradiation may be a useful method for treating pancreatic cancer.

The association of alcohol and smoking with CKD in a Japanese nationwide cross-sectional survey.

Chronic kidney disease (CKD) is characterized by a reduced glomerular filtration rate (GFR) and proteinuria. Modifiable lifestyle factors such as smoking and alcohol contribute to CKD. Recent cohort studies have shown that moderate alcohol consumption attenuates the decline of the GFR and smoking has been previously shown to be associated with CKD. However, the association of smoking and alcohol consumption on CKD is not entirely clear. To examine whether there is evidence to assume that smoking is an effective modifier of the association between CKD and alcohol consumption, we conducted a cross-sectional study of a population of people who presented for a health checkup under a program that targets the insured population aged ≧40 years using data from the Specific Health Check and Guidance in Japan between April 2008 and March 2009. Of the 506 807 participants aged ⩾40 years, 292 013 (57.6%) were included in the present analysis. Outcomes were kidney dysfunction, as an eGFR of <60 ml/min/1.73 m2, and proteinuria. In nonsmokers, drinking a small amount was associated with a lower prevalence of proteinuria, but in smokers, the association between alcohol and proteinuria was not observed. The analysis regarding eGFR <60 ml/min/1.73 m2 revealed that in both smokers and nonsmokers, alcohol consumption was inversely associated with the risk of CKD. Mild to moderate alcohol consumption might be associated with a lower risk of CKD (proteinuria and eGFR), especially among nonsmokers, because smoking might have modified the potential benefits of alcohol to prevent CKD.