Nicotine signaling and progression of chronic kidney disease in smokers

EHR-Based Risk Prediction for Kidney Cancer

BACKGROUND AND OBJECTIVES

The U.S. Preventive Services Task Force (USPSTF) does not currently recommend routine screening for kidney cancer, even though approximately 14 390 people are expected to die from this disease in the United States in 2024. Individualized risk-based kidney cancer screening offers the potential to effectively detect cancer at an early stage and avoid unnecessarily screening the rest of the population who are at low risk. This study proposes electronic health records (EHR) risk evaluation for kidney cancer by examining a comprehensive set of medical history including diagnoses, comorbidities, viruses, and rare diseases.

METHODS

The relevant medical history for predicting kidney cancer occurrence was identified from the analysis of All of Us data in three steps. First, a Systematized Nomenclature of Medicine (SNOMED) code binary indicator variable in EHR was set for the presence of kidney cancer. Second, the relationship between this binary indicator of cancer and all prior health conditions was examined using the Strong Rule for Feature Elimination and Least Absolute Shrinkage and Selection Operator logistic regression methods of variable selection. Third, the accuracy of the model was reported using cross-validated McFadden's R2 and Area under the Receiver Operating Characteristic curve (AROC) values.

RESULTS

The analysis identified 133 out of an initial set of 25 683 clinical diagnoses (represented by SNOMED codes) that were predictive of kidney cancer. The model achieved a cross-validated McFadden's R2 of 0.195 and an AROC of 0.799. Most of the identified codes are consistent with the known risk factors for kidney cancer.

CONCLUSIONS

It is possible to accurately predict the risk of kidney cancer from medical history using this method. Additional studies to establish high-dimensional predictive risk factors are needed to see if EHR personalized risk prediction can lead to cost-effective cancer screening and eventually better clinical outcomes.

Hydroxycotinine exhibits a stronger association with chronic kidney disease in smokers when compared to cotinine: Evidence from NHANES 2013-2018

INTRODUCTION

Smoking is a recognized risk factor for chronic kidney disease (CKD), and cotinine and hydroxycotinine are tobacco metabolites that can be used to quantify smoking. This study evaluated their relationship with CKD in smokers.

METHODS

This secondary dataset analysis is based on National Health and Nutrition Examination Survey (NHANES) data from 2013 to 2018. A cross-sectional examination of a subsample of 2930 adult smokers aged ≥20 years was conducted to investigate the relationship between serum cotinine and its metabolite, hydroxycotinine, and CKD. Linear regression, multivariable-adjusted logistic regression, restrictive cubic splines, and subgroup analysis were utilized.

RESULTS

Serum cotinine and hydroxycotinine levels were significantly elevated in CKD patients compared to the non-CKD population (230.00 vs 212.00 ng/mL, p=0.02 for cotinine; 97.30 vs 74.70 ng/mL, p<0.001 for hydroxycotinine). In multivariable-adjusted logistic regression models, cotinine (≥316 ng/mL) showed a positive association solely with renal insufficiency (adjusted odds ratio, AOR=1.53; 95% CI: 1.07-2.17). In contrast, hydroxycotinine (≥124 ng/mL) was independently associated with three CKD indices: CKD diagnosis (AOR=1.61; 95% CI: 1.06-2.43), renal insufficiency (AOR=2.07; 95% CI: 1.33-3.23), and albuminuria (or proteinuria) (AOR=1.61; 95% CI: 1.06-2.43). Restricted cubic spline analyses revealed nonlinear dose-response relationships: hydroxycotinine exhibited broader negative associations with both eGFR and uACR (p<0.001), while cotinine showed threshold-dependent correlations with CKD risk (positive <180 ng/mL, attenuated above). Subgroup analyses further indicated that hydroxycotinine consistently correlated with CKD across demographics (e.g. males, age <60 years, obesity), whereas cotinine's associations were more limited, with no significant interaction effects observed (p for interaction >0.05).

CONCLUSIONS

Elevated serum concentrations of cotinine and hydroxycotinine are positively associated with low glomerular filtration rate, albuminuria, and CKD in smokers, with hydroxycotinine demonstrating a stronger correlation. Smoking is established as a heightened risk factor for CKD, thus avoidance or reduction of smoking is strongly recommended.

Estimated glucose processing rates and the association of chronic kidney disease and proteinuria in non-diabetic adults

The study, which was based on NHANES data (1999-2018), included 21,234 nondiabetic individuals aged 20 years and older to investigate the associations between the estimated glucose disposal rate (eGDR) and the risk of chronic kidney disease (CKD) and proteinuria. CKD was defined as an estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m2, and proteinuria was defined as a urinary albumin-to-creatinine ratio (UACR) exceeding 30 mg/g. The results demonstrated a significant inverse association between eGDR levels and the risks of CKD and proteinuria. After adjusting for potential confounders, the association between eGDR and CKD showed that, compared with those for Q1, the adjusted odds ratios (ORs) for Q2, Q3, and Q4 were 0.82 (95% CI: 0.61-1.11), 0.62 (95% CI: 0.39-0.98), and 0.55 (95% CI: 0.28-1.05), respectively. For the relationship between eGDR and proteinuria, the adjusted ORs for Q2, Q3, and Q4 were 0.54 (95% CI: 0.42-0.69), 0.41 (95% CI: 0.27-0.62), and 0.65 (95% CI: 0.43-0.98), respectively. Moreover, each standard deviation increase in eGDR was associated with a 9% reduction in CKD risk (OR: 0.91, 95% CI: 0.85-0.98) and a 13% reduction in proteinuria risk (OR: 0.87, 95% CI: 0.82-0.93). Further adjustments via restricted cubic spline (RCS) regression analysis revealed a significant nonlinear relationship between eGDR and CKD and a U-shaped relationship between eGDR and proteinuria. A lower risk of proteinuria was observed when eGDR levels were between 8.70 and 9.91. These findings, combined with those of previous studies, suggest that eGDR may serve as a potential alternative metric for insulin resistance (IR). In nondiabetic individuals, the eGDR was significantly associated with the risk of CKD and proteinuria, with a notable nonlinear pattern in these relationships.

Acid Sphingomyelinase and Ceramide Signaling Pathway Mediates Nicotine-Induced NLRP3 Inflammasome Activation and Podocyte Injury

Background: Recent studies have shown that Nlrp3 inflammasome activation is importantly involved in podocyte dysfunction induced by nicotine. The present study was designed to test whether acid sphingomyelinase (Asm) and ceramide signaling play a role in mediating nicotine-induced Nlrp3 inflammasome activation and subsequent podocyte damage. Methods and Results: Nicotine treatment significantly increased the Asm expression and ceramide production compared to control cells. However, prior treatment with amitriptyline, an Asm inhibitor significantly attenuated the nicotine-induced Asm expression and ceramide production. Confocal microscopic and biochemical analyses showed that nicotine treatment increased the colocalization of NLRP3 with Asc, Nlrp3 vs. caspase-1, IL-1β production, caspase-1 activity, and desmin expression in podocytes compared to control cells. Pretreatment with amitriptyline abolished the nicotine-induced colocalization of NLRP3 with Asc, Nlrp3 with caspase-1, IL-1β production, caspase-1 activity and desmin expression. Immunofluorescence analyses showed that nicotine treatment significantly decreased the podocin expression compared to control cells. However, prior treatment with amitriptyline attenuated the nicotine-induced podocin reduction. In addition, nicotine treatment significantly increased the cell permeability, O2 production, and apoptosis compared to control cells. However, prior treatment with amitriptyline significantly attenuated the nicotine-induced cell permeability, O2 production and apoptosis in podocytes. Conclusions: Asm is one of the important mediators of nicotine-induced inflammasome activation and podocyte injury. Asm may be a therapeutic target for the treatment or prevention of glomerulosclerosis associated with smoking.

Serum hydroxycotinine was associated with chronic kidney disease (CKD): a cross-sectional study based on NHANES

OBJECTIVE

Smoking has been suggested as a modifiable and cardiovascular risk factor for chronic kidney disease (CKD). Although long-term smoking has been associated with CKD, the potential relationship between its metabolite hydroxycotinine and CKD has not been clarified.

METHODS

A total of 8,544 participants aged 20 years and above from the National Health and Nutrition Examination Survey (NHANES) 2017 - March 2020 were enrolled in our study. CKD was defined by estimated glomerular filtration rate (eGFR) < 60 mL/(min*1.73 m2). Serum hydroxycotinine was measured by an isotope-dilution high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometric (ID HPLC-APCI MS/MS) method with a lower limit of detections (LLOD) at 0.015 ng/mL. The non-linear relationship was explored with restricted cubic splines (RCS). Pearson's correlation coefficient and a multivariate logistic regression model were used for correlation analysis.

RESULTS

Serum hydroxycotinine and eGFR were negatively correlated in both non-CKD group (r= -0.05, p < 0.001) and CKD group (r= -0.04, p < 0.001). After serum hydoxycotinine dichotominzed with LLOD, serum hydroxycotinine ≥ 0.015 ng/mL was negatively correlated with eGFR not only in non-CKD group (r = -0.05, p < 0.001) but also in CKD group (r = -0.09, p < 0.001). After adjusting for comprehensive confounders, results from the multivariate logistic regression analysis showed that participants with serum hydroxycotinine ≥ 0.015 ng/mL had increased odds of CKD (OR = 1.505, p < 0.001).

CONCLUSIONS

Serum hydroxycotinine might be positively associated with CKD. Further study is warranted to find the right concentration of hydroxycotinine to measure the CKD.

Sex differences in the risk of excessive daytime sleepiness in mild and moderate ischaemic stroke patients: a retrospective database study

BACKGROUND

Excessive daytime sleepiness (EDS) is a common complication of stroke that has a detrimental effect on patients' daily life and functional recovery. The clinical characteristics and risk factors for poststroke EDS may differ between males and females.

METHODS

A retrospective study based on hospital medical records was conducted on patients with a diagnosis of stroke who participated in polysomnographic monitoring at the Affiliated Hospital of Yangzhou University from February 2022 to May 2024. Baseline data, laboratory test data, polysomnographic data, and related scale scores were retrospectively collected. The Epworth Sleepiness Scale (ESS) score was used to assess EDS after stroke. Binary logistic regression was used to determine the risk factors for daytime sleepiness. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. Statistical analysis was performed via IBM SPSS 26.0.

RESULTS

ESS scores were higher in males than in females, whereas females had higher Pittsburgh Sleep Quality Index (PSQI) scores and Hospital Anxiety and Depression Scale (HADS) scores. Male sex and higher depression scores were risk factors for EDS; among male patients, higher anxiety scores were a risk factor for EDS, whereas smoking was a protective factor. Depression, a higher arousal index and a reduced proportion of N3 sleep periods were risk factors for EDS in females.

CONCLUSIONS

The characteristics and influencing factors of EDS differ between the sexes in patients with mild and moderate ischaemic stroke. Our study may provide evidence and guidance for clinical diagnosis and treatment. Interventional studies are needed to assess the impact of treating these risk factors in the future.

Cardiometabolic traits mediating the effect of education on the risk of DKD and CKD: a Mendelian randomization study

Background

Both diabetic kidney disease (DKD) and chronic kidney disease (CKD) are more prevalent among individuals with lower levels of education in observational studies. To quantify the mediation effect of recognized cardiometabolic traits, we obtain causal estimates between education and DKD as well as CKD.

Materials and methods

We assessed the causal effect of education on DKD and CKD, separately estimated the causal effect of 26 cardiometabolic traits on DKD and CKD, and finally calculated the mediating effects and mediating proportions of each using two-step, two-sample multivariable Mendelian randomization (MVMR). Furthermore, the genetic association between exposure, mediators, and outcomes was investigated using linkage disequilibrium score (LDSC) regression analysis. Expression quantitative trait loci (eQTL) were retrieved from the Genotype-Tissue Expression Project (GTEx) v8 to serve as genetic instrumental variables. Transcriptome-wide association studies (TWAS), Bayesian colocalization analysis, and Summary-data-based Mendelian Randomization (SMR) analysis were performed to explore underlying susceptibility genes between education, mediators, and kidney diseases.

Results

Higher education with a genetically predicted 1-SD (4.2 years) was linked to a 48.64% decreased risk of DKD and a 29.08% decreased risk of CKD. After extensive evaluation of 26 cardiometabolic traits, 7 and 6 causal mediators were identified as mediating the effects of education on DKD and CKD, respectively. The largest mediating factor between education and DKD was BMI, which was followed by WHR, T2D, fasting insulin, SBP, fasting glucose, and DBP. In contrast, candidate mediators in the education-to-CKD pathway included BMI, followed by cigarettes smoked per day, WHR, SBP, T2D, and DBP. MR analysis revealed that TP53INP1 was found to be a shared susceptibility gene for cardiometabolic traits and DKD, while L3MBTL3 was found to be a shared susceptibility gene for cardiometabolic traits and CKD.

Conclusion

Our findings provide solid evidence that education has a causally protective effect on the development of DKD and CKD. We additionally reveal significant directions for intervention on cardiometabolic traits that mitigate the negative effects of educational inequities on the onset of DKD and CKD. Our work demonstrates a shared genetic basis between education, cardiometabolic traits, and kidney diseases. Future research aiming at lowering kidney risk may benefit from these findings.

Dexpanthenol protects against nicotine-induced kidney injury by reducing oxidative stress and apoptosis through activation of the AKT/Nrf2/HO-1 pathway

Dexpanthenol (DEX), a subtype of vitamin B5, plays an important role in anabolic reactions, cellular energy and regeneration in the body. Nicotine has been shown to induce kidney damage through the mechanisms of oxidative stress and apoptosis. The purpose of this study was to investigate the potential protective effects of DEX against nicotine-induced kidney damage through modulation of the AKT/Nrf2/HO-1 signaling pathway. Male rats were intraperitoneally administered with 0.5 mg/kg/day nicotine and/or 500 mg/kg/day DEX for 8 weeks. Following administration, renal function tests were conducted on serum samples, and histopathological examinations and analysis of oxidative stress markers and antioxidant enzymes were performed on tissue samples. Protein levels of Akt, Nrf-2, HO-1, Bcl-xL, and Caspase-9 were also evaluated. Nicotine administration resulted in decreased protein levels of p-Akt, Nrf-2, HO-1, and Bcl-xL and increased Caspase-9 protein levels. In addition, nicotine administration caused an increase in MDA, TOS, and OSI levels and a decrease in GSH, GSH-Px, GST, CAT, SOD, and TAS levels. Additionally, BUN and Creatinine levels increased after nicotine administration. DEX administration positively regulated these parameters and brought them closer to control levels. Nicotine-induced kidney injury caused apoptosis and oxidative stress through Caspase-9 activation. DEX effectively prevented nicotine-induced kidney damage by increasing intracellular antioxidant levels and regulating apoptosis through Bcl-xL activation. These findings suggest that DEX has potential as a protective agent against nicotine-induced kidney damage.

Smokeless tobacco consumption and its association with risk factors of chronic kidney disease in rural and peri-urban Bangladesh

INTRODUCTION

Compared to smoking, which has major consequences in chronic kidney disease (CKD) initiation and progression, smokeless tobacco (SLT) consumption is considered to have fewer health consequences. We investigated the prevalence of SLT consumption and its association with risk factors of CKD in a rural and peri-urban Bangladeshi population.

METHODS

Using random sampling we recruited 872 adults in 2020, from the Mirzapur Demographic Surveillance System of Bangladesh, who had resided in the area for at least five years. Interviews using a semi-structured questionnaire, physical examination and anthropometric measurements were done, followed by blood and urine testing. The blood and urine tests were repeated in selected participants after three months as per the CKD Epidemiology Collaboration equation.

RESULTS

The prevalence of SLT consumption was 29%. Being aged ≥46 years (OR=7.10; 95% CI: 4.79-10.94), female (OR=1.64; 95% CI: 1.21-2.22), housewife (OR=1.82; 95% CI: 1.35-2.45), farmer (OR=1.71; 95% CI: 1.06-2.76), widow (OR=3.40; 95% CI: 2.24-5.17), and having no formal schooling (OR=4.91; 95% CI: 3.59-6.72), family income of <$100/month (OR=1.66; 95% CI: 1.13-2.43), sleeping duration <7 hours per day (OR=2.33; 95% CI: 1.70-3.19), were associated with a significantly higher odds of SLT consumption. However, being aged 31-45 years (OR=0.25; 95% CI: 0.16-0.38) had significantly lower odds of being an SLT consumer. Among the diseases investigated, undernutrition (OR=1.63; 95% CI: 1.15-2.33), hypertension (OR=1.52; 95% CI: 1.13-2.05), anemia (OR=1.94; 95% CI: 1.39-2.71) and CKD (OR=1.62; 95% CI: 1.15-2.27) were significantly associated with SLT consumption. In the multivariable analysis, being aged 31-45 years (AOR=3.06; 95% CI: 1.91-4.90), ≥46 years (AOR=15.69; 95% CI: 4.64-53.09) and having no formal schooling (AOR=2.47; 95% CI: 1.72-3.55) were found to have a significant association with being an SLT consumer.

CONCLUSIONS

SLT consumption is associated with most of the established risk factors of CKD within the studied population.

Novel Approaches in Chronic Renal Failure without Renal Replacement Therapy: A Review

Chronic kidney disease (CKD) is characterized by renal parenchymal damage leading to a reduction in the glomerular filtration rate. The inflammatory response plays a pivotal role in the tissue damage contributing to renal failure. Current therapeutic options encompass dietary control, mineral salt regulation, and management of blood pressure, blood glucose, and fatty acid levels. However, they do not effectively halt the progression of renal damage. This review critically examines novel therapeutic avenues aimed at ameliorating inflammation, mitigating extracellular matrix accumulation, and fostering renal tissue regeneration in the context of CKD. Understanding the mechanisms sustaining a proinflammatory and profibrotic state may offer the potential for targeted pharmacological interventions. This, in turn, could pave the way for combination therapies capable of reversing renal damage in CKD. The non-replacement phase of CKD currently faces a dearth of efficacious therapeutic options. Future directions encompass exploring vaptans as diuretics to inhibit water absorption, investigating antifibrotic agents, antioxidants, and exploring regenerative treatment modalities, such as stem cell therapy and novel probiotics. Moreover, this review identifies pharmaceutical agents capable of mitigating renal parenchymal damage attributed to CKD, targeting molecular-level signaling pathways (TGF-β, Smad, and Nrf2) that predominate in the inflammatory processes of renal fibrogenic cells.

Smoking enhanced the expression of c-kit in chromophobe renal cell carcinoma

INTRODUCTION

Smoking is an important risk factor for inducing renal cell carcinoma (RCC), but its specific mechanism affecting the development of RCC remains to be elucidated. Chromophobe RCC (ChRCC) is a subtype of RCC. Many studies have shown smoking is closely associated with RCC occurrence and c-kit plays a critical role in the progression of RCC, however, few studies focus on ChRCC. This study investigated the molecular mechanism between smoking and the c-kit pathway in ChRCC.

METHODS

Differentially expressed genes (DEGs) were obtained from The Cancer Genome Atlas (TCGA) in ChRCC and the expression of KIT in ChRCC was analyzed through the TCGA database combined with Gene Expression Omnibus (GEO) and oncomine databases. Moreover, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses and Protein Protein Interaction (PPI) network analysis were performed to explore the function of KIT and correlated DEGs as well as its co-expression genes in ChRCC. Finally, ChRCC patient samples were used to verify the effect of smoking on the c-kit expression.

RESULTS

The results showed that KIT is one of the DEGs and plays a vital role in ChRCC tumorigenesis. Interestingly, the expression of c-kit in cancer tissues of 27 smoking patients was significantly higher than that of 25 non-smoking patients (p<0.05), which suggests smoking might enhance the expression of c-kit in ChRCC patients.

CONCLUSIONS

Our results demonstrate that smoking might play a pivotal role in the ChRCC tumorigenesis via a pathway related to c-kit, and provided new insight into the relationship between smoking and the c-kit pathway in ChRCC.

Anemia and Hypoxia Impact on Chronic Kidney Disease Onset and Progression: Review and Updates

Chronic kidney disease (CKD) is caused by hypoxia in the renal tissue, leading to inflammation and increased migration of pathogenic cells. Studies showed that leukocytes directly sense hypoxia and respond by initiating gene transcription, encoding the 2-integrin adhesion molecules. Moreover, other mechanisms participate in hypoxia, including anemia. CKD-associated anemia is common, which induces and worsens hypoxia, contributing to CKD progression. Anemia correction can slow CKD progression, but it should be cautiously approached. In this comprehensive review, the underlying pathophysiology mechanisms and the impact of renal tissue hypoxia and anemia in CKD onset and progression will be reviewed and discussed in detail. Searching for the latest updates in PubMed Central, Medline, PubMed database, Google Scholar, and Google search engines were conducted for original studies, including cross-sectional studies, cohort studies, clinical trials, and review articles using different keywords, phrases, and texts such as "CKD progression, anemia in CKD, CKD, anemia effect on CKD progression, anemia effect on CKD progression, and hypoxia and CKD progression". Kidney tissue hypoxia and anemia have an impact on CKD onset and progression. Hypoxia causes nephron cell death, enhancing fibrosis by increasing interstitium protein deposition, inflammatory cell activation, and apoptosis. Severe anemia correction improves life quality and may delay CKD progression. Detection and avoidance of the risk factors of hypoxia prevent recurrent acute kidney injury (AKI) and reduce the CKD rate. A better understanding of kidney hypoxia would prevent AKI and CKD and lead to new therapeutic strategies.

Nicotine promotes renal interstitial fibrosis via upregulation of XIAP in an alpha7-nAChR-dependent manner

Renal fibrosis, characterized by excessive accumulation of the extracellular matrix in the renal tubulointerstitium, can lead to chronic kidney disease (CKD), resulting in a heavy burden on families and society. Clinical studies have shown that smoking is closely associated with CKD deterioration in patients with diabetes, hypertension, polycystic kidney disease, and kidney transplantation. However, the mechanism of action of nicotine in renal fibrosis pathogenesis remains largely unknown. X-linked inhibitor of apoptosis (XIAP), a member of the inhibitor of apoptosis protein (IAP) family, is involved in apoptosis, necroptosis, autophagy, and immune response. Here, the upregulated expression of XIAP and α7 nicotine acetylcholine receptor (α7-nAChR) was determined in the kidneys of the CKD smoking group in human and animal studies. A significant positive correlation between XIAP and cotinine was observed. In addition, the nuclear translocation and transcriptional activity of SP1 were promoted when nicotine bound to α7-nAChR, resulting in XIAP overexpression and renal interstitial fibrosis progression. This phenotype can be reversed by the nicotine receptor subtype α7-nAChR antagonists methyllycaconitine. Our results revealed the complex underlying mechanism of nicotine in promoting renal fibrosis by altering SP1 nucleocytoplasmic translocation and regulating XIAP expression. These results provide novel insights into the pathogenesis and treatment of CKD.

The toxic effects of electronic cigarette aerosol and cigarette smoke on cardiovascular, gastrointestinal and renal systems in mice

Electronic cigarette (EC) has been suggested to be less harmful than cigarette smoking, but the research on the full extent of their harm reduction potential is still lacking. This study aimed to evaluate the influence of EC aerosol and cigarette smoke (CS) on cardiovascular, gastrointestinal, and renal functions in mice after prolonged exposure. Forty-eight C57BL/6J male mice were randomly grouped and then exposed to fresh air (control), mung bean-flavored EC aerosol with low and high dose (EC1L, 6 mg/kg; EC1H, 12 mg/kg), watermelon-flavored EC aerosol with low and high dose (EC2L, 6 mg/kg; EC2H, 12 mg/kg), and finally a cigarette smoke (CS, 6 mg/kg), respectively. After 10 weeks of exposure, the heart rate increased for both the EC and CS groups, and the effect of CS on blood oxygen saturation was significantly higher than that of the EC group (P < 0.01). Proteomic analysis of the heart tissue showed that the overlapped differential expression protein from the EC and CS exposures was Crip2. For the gastrointestinal system, oral mucosa was significantly damaged in CS group. Compare with CS, EC had significantly fewer negative effects on most of the indictors which focused on in this study.

Nicotine exacerbates diabetic nephropathy through upregulation of Grem1 expression

BACKGROUND

Diabetic nephropathy (DN) is a major complication of diabetes mellitus. Clinical reports indicate that smoking is a significant risk factor for chronic kidney disease, and the tobacco epidemic exacerbates kidney damage in patients with DN. However, the underlying molecular mechanisms remain unclear.

METHOD

In the present study, we used a diabetic mouse model to investigate the molecular mechanisms for nicotine-exacerbated DN. Twelve-week-old female mice were injected with streptozotocin (STZ) to establish a hyperglycemic diabetic model. After four months, the control and hyperglycemic diabetic mice were further divided into four groups (control, nicotine, diabetic mellitus, nicotine + diabetic mellitus) by intraperitoneal injection of nicotine or PBS. After two months, urine and blood were collected for kidney injury assay, and renal tissues were harvested for further molecular assays using RNA-seq analysis, real-time PCR, Western blot, and immunohistochemistry. In vitro studies, we used siRNA to suppress Grem1 expression in human podocytes. Then we treated them with nicotine and high glucose to compare podocyte injury.

RESULT

Nicotine administration alone did not cause apparent kidney injury, but it significantly increased hyperglycemia-induced albuminuria, BUN, plasma creatinine, and the kidney tissue mRNA expression of KIM-1 and NGAL. Results from RNA-seq analysis, real-time PCR, Western blot, and immunohistochemistry analysis revealed that, compared to hyperglycemia or nicotine alone, the combination of nicotine treatment and hyperglycemia significantly increased the expression of Grem1 and worsened DN. In vitro experiments, suppression of Grem1 expression attenuated nicotine-exacerbated podocyte injury.

CONCLUSION

Grem1 plays a vital role in nicotine-exacerbated DN. Grem1 may be a potential therapeutic target for chronic smokers with DN.

Smoking is associated with a higher complication and failure rate in arteriovenous grafts for haemodialysis: A multi-centre experience

INTRODUCTION

Arteriovenous grafts (AVG) for haemodialysis (HD) access are recommended as a second line modality due to higher morbidity and mortality rates than arteriovenous fistulae (AVF). Smoking is already established as a risk factor in lower extremity bypass graft failure used for peripheral vascular disease, but its effect on AVGs remains unclear. We aimed to investigate the relationship of smoking on AVG outcomes.

METHODS

A 3 year (01/08/2015-01/08/2018) multi-centre retrospective study was carried out on patients receiving an AVG for HD. Data included patient demographics, medical history, operation, type of graft, postoperative course and primary and secondary patency rates. Statistical analyses performed were Kaplan-Meier curves and Cox's proportional hazard regression.

RESULTS

Fifty-five AVGs were performed (1052 AVF performed) in this period. The most common complication was thrombosis (38.9%). Primary patency at 6, 12 and 24 months were 55%, 45% and 44% respectively. Secondary patency at 6, 12 and 24 months were 63%, 56% and 54% respectively. Smoking was found to be a poor prognostic factor for primary (HR 3.734 (1.818-7.668 95% CI) p < 0.001) and secondary patency (HR 6.238 (2.729-14.257) p < 0.001). Smoking was also significantly associated with graft thrombosis (HR 5.741 (2.380-13.848 95% CI) p < 0.001).

DISCUSSION

Primary patency rates are lower than previous reports whilst secondary patency is equivalent. Smoking results in a greater risk of thrombosis and poorer primary and secondary patency. This is recognised in vascular surgical grafts, but has not been previously described in AVGs for HD access. Smoking is a modifiable risk factor and as AVGs are typically used for end-stage vascular access patients. Pre-operative strategies to promote smoking cessation, including patient education and prehabilitation should be employed to improve outcomes.

The impact of e-cigarette exposure on different organ systems: A review of recent evidence and future perspectives

The use of electronic cigarettes (e-cigs) is rapidly increasing worldwide and is promoted as a smoking cessation tool. The impact of traditional cigs on human health has been well-defined in both animal and human studies. In contrast, little is known about the adverse effects of e-cigs exposure on human health. This review summarizes the impact of e-cigs exposure on different organ systems based on the rapidly expanding recent evidence from experimental and human studies. A number of growing studies have shown the adverse effects of e-cigs exposure on various organ systems. The summarized data in this review indicate that while e-cigs use causes less adverse effects on different organs compared to traditional cigs, its long-term exposure may lead to serious health effects. Data on short-term organ effects are limited and there is no sufficient evidence on long-term organ effects. Moreover, the adverse effects of secondhand and third hand e-cigs vapour exposure have not been thoroughly investigated in previous studies. Although some studies demonstrated e-cigs used as a smoking cessation tool, there is a lack of strong evidence to support it. While some researchers suggested e-cigs as a safer alternative to tobacco smoking, their long-term exposure health effects remain largely unknown. Therefore, more epidemiological and prospective studies including mechanistic studies are needed to address the potential adverse health effects of e-cigs to draw a firm conclusion about their safe use. A wide variation in e-cigs products and the lack of standardized testing methods are the major barriers to evaluating the existing data. Specific regulatory guidelines for both e-cigs components and the manufacturing process may be effective to protect consumer health.

Prioritized polycystic kidney disease drug targets and repurposing candidates from pre-cystic and cystic mouse Pkd2 model gene expression reversion

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most prevalent monogenic human diseases. It is mostly caused by pathogenic variants in PKD1 or PKD2 genes that encode interacting transmembrane proteins polycystin-1 (PC1) and polycystin-2 (PC2). Among many pathogenic processes described in ADPKD, those associated with cAMP signaling, inflammation, and metabolic reprogramming appear to regulate the disease manifestations. Tolvaptan, a vasopressin receptor-2 antagonist that regulates cAMP pathway, is the only FDA-approved ADPKD therapeutic. Tolvaptan reduces renal cyst growth and kidney function loss, but it is not tolerated by many patients and is associated with idiosyncratic liver toxicity. Therefore, additional therapeutic options for ADPKD treatment are needed.

METHODS

As drug repurposing of FDA-approved drug candidates can significantly decrease the time and cost associated with traditional drug discovery, we used the computational approach signature reversion to detect inversely related drug response gene expression signatures from the Library of Integrated Network-Based Cellular Signatures (LINCS) database and identified compounds predicted to reverse disease-associated transcriptomic signatures in three publicly available Pkd2 kidney transcriptomic data sets of mouse ADPKD models. We focused on a pre-cystic model for signature reversion, as it was less impacted by confounding secondary disease mechanisms in ADPKD, and then compared the resulting candidates' target differential expression in the two cystic mouse models. We further prioritized these drug candidates based on their known mechanism of action, FDA status, targets, and by functional enrichment analysis.

RESULTS

With this in-silico approach, we prioritized 29 unique drug targets differentially expressed in Pkd2 ADPKD cystic models and 16 prioritized drug repurposing candidates that target them, including bromocriptine and mirtazapine, which can be further tested in-vitro and in-vivo.

CONCLUSION

Collectively, these results indicate drug targets and repurposing candidates that may effectively treat pre-cystic as well as cystic ADPKD.

The Influence of Smoking on Renal Functions Among Apparently Healthy Smokers

Background

Cigarette smoking is an important modifiable risk factor in kidney disease progression. Although long-term smoking has been associated with chronic kidney disease (CKD), its effect on kidney function in early stages has not been clarified.

Objective

To detect the early effects of smoking either active or passive on kidney functions.

Methodology

The current study was comparative cross sectional study conducted on 280 participants, 140 were non‑smokers and 140 were smokers (70 passive smokers and 70 active smokers). The two groups were comparable in terms of all parameters. We investigated the possible effects of smoking on kidney functions using both serum kidney function tests especially; serum urea, serum creatinine, serum cotinine levels and detection of albumin in urine. Smoking history, full Laboratory investigations, Ventilatory function test including (FEV1/FVC, FEV1, FEF 25-75%, VC and FVC) were done.

Results

Serum urea, serum creatinine, serum cotinine levels and urinary albumin were statistically significant higher in smokers group in comparison to nonsmokers, also the serum cotinine levels and urinary albumin were statistically significant in active smokers in comparison to passive smokers. There were positive correlations between the level of urinary albumin and pack/year (r = 0.9, p<0.05), smoking index (r = 0.9, p<0.05), smoking duration (r = 0.4, p<0.05), and serum cotinine (r = 0.6, p<0.050) with good statistical significance. The most significant predictive risk factors of microalbuminuria among smokers group in descending orders were active smoking, passive smoking, age and serum cotinine level.

Conclusion

Both active and passive smoking, especially among heavy smokers, is a significant risk factor for microalbuminuria. This finding increase the importance of early cessation of smoking in order to minimize early renal affection among healthy smokers that may not be discovered by routine renal function tests.

Scrutinizing pathways of Nicotine effect on renal Alpha-7 Nicotinic Acetylcholine receptor and Mitogen-activated protein kinase (MAPK) expression in Ehrlich ascites carcinoma-bearing Mice: role of Chlorella vulgaris

Nicotine is one of several physiologically stable and active chemicals found in tobacco. The mechanism through which nicotine causes kidney damage is still obscure. As a result, the goal of this research was to investigate how oral nicotine intake can lead to kidney damage. Naturaly occurring superfood green algae are immense supplements help us using extra chemicals during cancer prevalence if the patient is exposed to nicotine. Hence, the mitigating role of Chlorella vulgaris extract (CVE) against nicotine-nephrotoxic impact in Ehrlich ascites carcinoma (EAC)-bearing mice was studied. For this purpose, four groups of Swiss female mice were assigned, nicotine group (NIC) (100 µg/ml/kg), CVE group (100 mg/kg), CVE+Nicotine, and a control group. Renal dysfunction was evaluated by estimating serum biomarkers ofrenal damage. The expression pattern of Nf-_KB, MAPK, P53, and α7-nAchR, lipid peroxidation biomarker, and antioxidant enzyme activities were evaluated in kidney tissue. Also, micro-morphometric examination and apoptosis immunohistochemical reactivity of kidney tissue were applied. The obtained results indicated up-regulation of all estimated genes and oxidative stress. Moreover, a significant (P<0.05) increment in the apoptotic marker Caspase-3 and declined BCL-2 proteins were recorded. In serum, a significant (P<0.05) elevation of urea, creatinine, TNF-α, IL-1β, and Kim-1 were evident. Histological investigation reinforced the aforementioned data, revealing structural changes involving the tubules, glomeruli, and interstitium of mice kidneys. CVE may be a strong contender for protecting renal tissue damage since it reduces renal tissue injury and oxidative stress. Cancer patients who regularly use nicotine through direct smoking or second-hand exposure can benefit from CVE usage as a dietary supplement.

Morphofunctional study on the effects of passive smoking in kidneys of rats

Objective

To analyze whether passive inhalation of cigarette smoke causes morphological, structural, and functional changes in kidneys of rats.

Methods

Wistar rats, aged eight weeks, weighing on average 260g, were divided into Control Group and Smoking Group. Each group was subdivided into four groups of ten animals for morphofunctional analysis, in a period of seven and 28 days. The Smoking Group was exposed to smoke of 40 cigarettes per day, at certain times and in automated equipment for cigarette burning, called smoking machine (SM-MC-01). After the exposure period, urine and blood samples were collected for the functional analyses, and the kidneys were dissected and submitted to histological procedures for morphoquantitative analyses.

Results

After exposure of animals of the Smoking Group, the following were observed: lower weight gain; lower water and feed intake; decreased renal weight, diameter, and volume; reduction in cortical thickness and glomerular volume density; decrease in glomerular and capsular diameter; increase in mesangial density; decreased urine volume; increased levels of glucose, serum creatinine and microalbuminuria; decreased urinary creatinine levels and creatinine clearance rate.

Conclusion

Passive smoking negatively influences renal morphology and glomerular filtration rate, with effects similar to those described in the literature regarding active smoking.

Nicotine exacerbates tacrolimus-induced renal injury by programmed cell death

BACKGROUND/AIMS

Cigarette smoking is an important modifiable risk factor in kidney disease progression. However, the underlying mechanisms for this are lacking. This study aimed to assess whether nicotine (NIC), a major toxic component of cigarette smoking, would exacerbates tacrolimus (TAC)-induced renal injury.

METHODS

Sprague-Dawley rats were treated daily with NIC, TAC, or both drugs for 4 weeks. The influence of NIC on TAC-caused renal injury was examined via renal function, histopathology, oxidative stress, mitochondria, endoplasmic reticulum (ER) stress, and programmed cell death (apoptosis and autophagy).

RESULTS

Both NIC and TAC significantly impaired renal function and histopathology, while combined NIC and TAC treatment aggravated these parameters beyond the effects of either alone. Increased oxidative stress, ER stress, mitochondrial dysfunction, proinf lammatory and profibrotic cytokine expressions, and programmed cell death from either NIC or TAC were also aggravated by the two combined.

CONCLUSION

Our observations suggest that NIC exacerbates chronic TAC nephrotoxicity, implying that smoking cessation may be beneficial for transplant smokers taking TAC.

Sleeping, Smoking, and Kidney Diseases: Evidence From the NHANES 2017-2018

Study Objectives: Smoking and sleep are modifiable factors associated with the chronic kidney diseases. However, the interaction of smoking and sleep on the renal function are still unclear. Therefore, we aimed to evaluate the interactive impacts of smoking and sleep on the renal function. Methods: Data were obtained from the National Health and Nutrition Examination Survey. The study population were categorized into nine subgroups by smoking (smoking every day, sometimes, and non-smokers recently) and sleep duration (short duration ≤ 6 h, normal duration 6-9 h, and longer duration ≥ 9 h on the weekdays). Results: The study group with a short sleep duration had significantly higher serum cotinine and hydrocotinine levels compared with the other two sleep groups. After adjusting the demographic characteristics (age, race, body mass index, and marital status), sleep quality (snoring or breathing cessation), and comorbidities (diabetes mellitus, hypertension, high cholesterol, anemia, congestive heart failure, coronary heart disease, and stroke), non-smokers with short or long sleep duration had significant lower estimated glomerular filtration rate (eGFR) levels than the study group who smoked every day and slept ≤ 6 h. The effects of sleep duration on eGFR levels varied with smoking status. For the study group smoking every day, eGFR levels increased as sleep duration decreased, whereas for the study group smoking sometimes, eGFR levels increased as sleep duration increased. The U-shaped effects of eGFR levels were observed among non-smokers whose normal sleep duration was associated with better eGFR levels. Normal sleep duration was an important protective factor of the renal function for non-smokers than smokers. Conclusions: The effects of sleep duration on eGFR levels varied with smoking status. Normal sleep duration was a protective factor and more crucial for non-smokers than for smokers.

Measurement of harmful nanoparticle distribution among filters, smokers' respiratory systems, and surrounding air during cigarette smoking

This study was undertaken to investigate the filtration effect of filter on nanoparticle and the deposition behavior of nanoparticle in the human respiratory system from the aspect of nanoparticle number during cigarette smoking. For that, two kinds of experiments were designed. One is machine experiment, a well-controlled simulated respiratory system was designed to measure the raw emission and filter effect. Another is human experiment, volunteers were asked to inhale smoke into the oral cavity only and lungs, respectively, to distinguish smoke path. Results revealed that effective inhaled nanoparticle amount of a Taishan and a Hongtaishan cigarette were 5.8E + 9 (#) and 9.4E + 7 (#), respectively. The filter's integrated reduction rate was 41.65% for nanoparticle. For Taishan cigarette, 35.4% and 41.7% of raw emitted nanoparticles were deposited in the oral cavity and lungs, respectively, the rest of 22.9% was exhaled to surrounding air. The corresponding values were 25.6%, 41.5% and 32.9%, respectively, for Hongtaishan. The current findings are expected to provide basic assessments of filter effect and harm to human and to be a warning for smokers.

Urinary exosomal circular RNAs of sex chromosome origin are associated with gender-related risk differences of clinicopathological features in patients with IgA nephropathy

BACKGROUND

There are arguments for individualized treatments and the necessity of non-invasive biomarkers for patients with IgA nephropathy (IgAN) according to gender, but the rationale remains unclear. We aimed to investigate the relationship between urine exosomal circular RNA (circRNA) levels, related genes, clinical features, and renal pathological features in IgA nephropathy patients of different genders.

METHODS

Clinicopathological data from patients of different genders from a multicenter cohort were retrospectively analyzed. We used the Oxford classification to examine the severity of pathological damage in these patients. We compared clinical features and renal pathologies between IgAN patients of different genders. Using findings of urine exosomal circRNAs from male IgAN patients, we analyzed the relationship between this factor, the regulated genes located on the sex chromosomes, and renal pathologies.

RESULTS

A total of 502 IgAN patients were included. The proportion of male patients with crescent formation was higher than that of females (p = 0.019). Multivariate logistic regression analysis showed that proteinuria was an independent marker for crescent formation in male and female patients with IgAN, while smoking and higher low-density lipoprotein cholesterol (LDL-C) levels were independent risk factors for crescent formation in males alone. Urine exosomal circRNA chrY:15478147-15481229- located on the Y chromosome in male patients was negatively correlated with the expressions of UTY in specific regions of the Y chromosome.

CONCLUSION

Compared with female patients, males with IgAN had more severe renal dysfunction and a higher probability of glomerular crescent formation. Urine exosomal circRNA chrY:15478147-15481229- might participate in the pathogenesis of IgAN in male patients by altering UTY expressions.

Smoking, Smoking Cessation, and Progression of Chronic Kidney Disease: Results From KNOW-CKD Study

INTRODUCTION

In patients with chronic kidney disease (CKD), studies investigating the association between smoking and deterioration of kidney function are scarce.

AIMS AND METHODS

We analyzed data for 1,951 patients with an estimated glomerular filtration rate (eGFR) ≥15 mL/min/1.73 m2 enrolled in the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD) from 2011 to 2016. Patients were categorized by smoking load. Primary outcome was a composite of a ≥50% reduction in eGFR, initiation of dialysis, or kidney transplantation.

RESULTS

There were 967 never-smokers and 369, 276, and 339 smokers who smoked <15, 15 to 29, ≥30 pack-years, respectively. During a mean follow-up of 3.0 years, the incidence rates (95% confidence interval [CI]) of the primary outcome were 54.3 (46.4-63.5), 46.9 (35.9-61.4), 69.2 (52.9-90.6), and 76.3 (60.7-96.0) events per 1,000 person-yr in never-, <15, 15 to 29, and ≥30 pack-year smokers. In cause-specific hazard model after adjustment of confounding factors, smokers were associated with 1.09 (0.73-1.63), 1.48 (1.00-2.18), and 1.94 (1.35-2.77) fold increased risk (95% CI) of primary outcome in <15, 15-29, and ≥30 pack-year smokers compared with never-smokers. The association of longer smoking duration with higher risk of CKD progression was evident particularly in patients with eGFR < 45 mL/min/1.73 m2 and proteinuria ≥ 1.0 g/g. In contrast, the risk of adverse kidney outcome decreased with longer smoking-free periods among former-smokers.

CONCLUSIONS

These findings suggest potentially harmful effects of the degree of exposure to smoking on the progression of CKD.

IMPLICATIONS

Among patients with CKD, there has been lack of studies on the association between smoking and CKD progression and studies to date have yielded conflicting results. In this prospective cohort study involving Korean CKD patients, smoking was associated with significantly higher risk of worsening kidney function. Furthermore, the risk of adverse kidney outcome was incrementally higher as smoking pack-years were higher. As the duration of smoking cessation increased, the hazard ratios for adverse kidney outcome were attenuated, suggesting that quitting smoking may be a modifiable factor to delay CKD progression.

Nicotine, smoking, podocytes, and diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease. Besides glycemic and blood pressure control, environmental factors such as cigarette smoking (CS) adversely affect the progression of DN. The effects of CS on DN progression have been attributed to combustion-generated molecules without consideration to the role of nicotine (NIC), responsible for the addictive properties of both CS and electronic cigarettes (ECs). Podocytes are essential to preserve the structure and function of the glomerular filtration barrier, and strong evidence indicates that early podocyte loss promotes DN progression. We performed experiments in human podocytes and in a mouse model of diabetes that develops nephropathy resembling human DN. We determined that NIC binding to podocytes in concentrations achieved with CS and ECs activated NADPH oxidase, which sets in motion a dysfunctional molecular network integrated by cyclooxygenase 2, known to induce podocyte injury; downregulation of AMP-activated protein kinase, important for maintaining cellular energy stores and antioxidation; and upregulation of CD36, which increased lipid uptake and promoted apoptosis. In diabetic mice, NIC increased proteinuria, a recognized marker of chronic kidney disease progression, accompanied by reduced glomerular podocyte synaptopodin, a crucial stabilizer of the podocyte cytoskeleton, and increased fibronectin expression. This novel study critically implicates NIC itself as a contributor to DN progression in CS and EC users.NEW & NOTEWORTHY In this study, we demonstrate that nicotine increases the production of reactive oxygen species, increases cyclooxygenase-2 expression, and upregulates Cd36 while inducing downregulation of AMP-activated protein kinase. In vivo nicotine increases proteinuria and fibronectin expression in diabetic mice. This study demonstrates that effects of nicotine on podocytes are responsible, at least in part, for the deleterious effects of smoking in the progression of chronic kidney disease, including diabetic nephropathy.

Association of electronic cigarette exposure with serum uric acid level and hyperuricemia: 2016-2017 Korea National Health and Nutritional Examination Survey

OBJECTIVES

The present study evaluated the association of electronic cigarette (EC) exposure with serum uric acid (UA) level and hyperuricemia (HUA) using a nationally representative sample of South Korea.

METHODS

This study included 10,692 participants (9,905, 609, and 178, never, ever, and current EC users, respectively). Urinary cotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels were used to determine conventional smoking exposure among EC users. The association between EC use and UA level was evaluated by linear regression analysis. Multivariable logistic regression analysis was used to assess the association between EC and HUA. Subgroup analysis confined to cotinine-verified active smokers was performed to address the association between the dual use of EC and combustible cigarettes and serum UA levels.

RESULTS

The serum UA level was highest among current EC users, followed by ever and never EC users. The prevalence of HUA was 26.2%, 19.3%, and 10.8% in current, ever, and never EC users, respectively. Although EC exposure was positively associated with HUA in a dose-dependent manner only in men (Ptrend = 0.04), a similar tendency was also observed in women with marginal significance (Ptrend = 0.102). The positive association of HUA with EC exposure was more apparent among dual users (odds ratio [OR] = 1.96, 95% confidence interval [CI]: 1.29-2.99) than among those who only smoked combustible cigarettes.

CONCLUSIONS

EC exposure was associated with higher serum UA level and higher OR of HUA. The positive association between EC exposure and HUA was more prominent in dual users who concurrently consumed EC and combustible cigarettes.

Nicotine Causes Nephrotoxicity through the Induction of NLRP6 Inflammasome and Alpha7 Nicotinic Acetylcholine Receptor

Current cigarette smoking is associated with chronic kidney disease (CKD) or death from end-stage renal disease (ESRD). Mainstream cigarette smoke includes over 4000 compounds. Among the compounds present in tobacco smoke, nicotine is one of a large number of biologically stable and active compounds present in tobacco. However, the mechanisms by which nicotine exacerbates kidney disease progression have not been identified. It is known that the inflammasomes constitute an important innate immune pathway and contribute to the pathophysiology of diverse kidney diseases. The relationship between inflammasomes and nicotine-induced kidney damage still remains unclear. In the present study, we studied the mechanisms of nicotine-induced nephrotoxicity. We found that nicotine decreased cell viability and induced reactive oxygen species (ROS) generation in human kidney cells. Furthermore, nicotine significantly increased the expression of the alpha7 nicotinic acetylcholine receptor (α7nAChR). Nicotine activated the NLRP6 inflammasome and induced endoplasmic reticulum (ER) stress. Nicotine caused mild apoptosis and necrosis but triggered significant autophagy in human kidney cells. In addition, nicotine induced the NLRP6 inflammasome and autophagy via α7nAChR. In an animal model, the histological analysis in kidney showed evident changes and injury. The results indicated that α7nAChR, IRE1α, LC3 and NLRP6 expression in kidney sections was markedly increased in the nicotine groups. These findings suggest that nicotine causes kidney damage by modulating α7nAChR, NLRP6 inflammasome, ER stress and autophagy.

Sex-based differences in myocardial infarction-induced kidney damage following cigarette smoking exposure: more renal protection in premenopausal female mice

The impact of cigarette smoking (CS) on kidney homeostasis in the presence of myocardial infarction (MI) in both males and females remains poorly elucidated. C57BL6/J mice were exposed to 2 weeks of CS prior to MI induction followed by 1 week of CS exposure in order to investigate the impact of CS on kidney damage in the presence of MI. Cardiac hemodynamic analysis revealed a significant decrease in ejection fraction (EF) in CS-exposed MI male mice when compared with the relative female subjects, whereas cardiac output (CO) comparably decreased in CS-exposed MI mice of both sexes. Kidney structural alterations, including glomerular retraction, proximal convoluted tubule (PCT) cross-sectional area, and total renal fibrosis were more pronounced in CS-exposed MI male mice when compared with the relative female group. Although renal reactive oxygen species (ROS) generation and glomerular DNA fragmentation significantly increased to the same extent in CS-exposed MI mice of both sexes, alpha-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF) significantly increased in CS-exposed MI male mice, only. Metabolically, nicotinamide phosphoribosyltransferase (NAMPT) and nicotinamide riboside-1 (NMRK-1) substantially increased in CS-exposed MI female mice only, whereas sirtuin (SIRT)-1 and SIRT-3 substantially decreased in CS-exposed MI male mice compared with their relative female group. Additionally, renal NAD levels significantly decreased only in CS-exposed MI male mice. In conclusion, MI female mice exhibited pronounced renal protection following CS when compared with the relative male groups.

COX-2-derived prostaglandins as mediators of the deleterious effects of nicotine in chronic kidney disease

Tobacco smoking has been identified as a risk factor in the progression of chronic kidney disease (CKD). In previous studies, we showed that nicotine induces cyclooxygenase (COX)-2 expression in vivo and in vitro and that the administration of nicotine in vivo worsens the severity of renal injury in a model of subtotal renal ablation. In the present study, we tested the role of COX-2-derived prostaglandins on the deleterious effects of nicotine in CKD. Sham and 5/6 nephrectomy (5/6Nx) rats received tap water or nicotine (100 μg/mL) in the drinking water for 12 wk. Additional groups also systemically received the COX-2 inhibitor NS-398 (1.5 mg·kg^-1·day^-1 via osmotic minipump). The administration of nicotine worsened renal injury and proteinuria in 5/6Nx rats and increased proteinuria in sham rats. 5/6Nx rats had increased cortical production of the prostaglandins PGE₂, PGI₂, PGD₂, and PGF_2α and of thromboxane A₂. In these rats, nicotine reduced the production of all prostaglandins examined except thromboxane A₂. Treatment with the COX-2 inhibitor NS-398 resulted in complete inhibition of all prostaglandins studied and ameliorated renal injury and proteinuria in 5/6Nx rats on nicotine but not in 5/6 Nx rats on tap water. Nicotine also reduced the expression of megalin in all groups examined, and this was partially prevented by COX-2 inhibition. In the present study, we showed that in CKD, nicotine worsens renal injury at least in part by producing an imbalance in the production of prostaglandins. This imbalance in the production of prostaglandins likely plays a role in the deleterious effects of smoking on the progression of CKD.

Nicotine instigates podocyte injury via NLRP3 inflammasomes activation

Background/Aims: Recent studies have shown that nicotine induces podocyte damage. However, it remains unknown how nicotine induces podocyte injury. The present study tested whether nicotine induces NLRP3 inflammasomes activation and thereby contributes to podocyte injury.

Results: Nicotine treatment significantly increased the colocalization of NLRP3 with Asc, caspase-1 activity, IL-β production, cell permeability in podocytes compared to control cells. Pretreatment with caspase-1 inhibitor, WEHD significantly abolished the nicotine-induced colocalization of NLRP3 with Asc, caspase-1 activity, IL-1β production and cell permeability in podocytes. Immunofluorescence analysis showed that nicotine treatment significantly decreased the podocin and nephrin expression compared to control cells. However, prior treatment with WEHD attenuated the nicotine-induced podocin and nephrin reduction. In addition, we found that nicotine treatment significantly increased the O₂^.- production compared to control cells. However, prior treatment with WEHD did not alter the nicotine-induced O₂^.- production. Furthermore, prior treatment with ROS scavenger, NAC significantly attenuated the nicotine-induced caspase-1 activity, IL-1β production, podocin and nephrin reduction in podocytes.

Conclusions: Nicotine-induced the NLRP3 inflammasome activation in podocytes and thereby results in podocyte injury.

Methods: Inflammasome formation and immunofluorescence expressions were quantified by confocal microscopy. Caspase-1 activity, IL-1β production and O₂^.- production were measured by ELISA and ESR.

Bidirectional Associations among Nicotine and Tobacco Smoke, NeuroHIV, and Antiretroviral Therapy

People living with HIV (PLWH) in the antiretroviral therapy (ART) era may lose more life-years to tobacco use than to HIV. Yet, smoking rates are more than twice as high among PLWH than the general population, contributing not just to mortality but to other adverse health outcomes, including neurocognitive deficits (neuroHIV). There is growing evidence that synergy with chronic inflammation and immune dysregulation that persists despite ART may be one mechanism by which tobacco smoking contributes to neuroHIV. This review will summarize the differential effects of nicotine vs tobacco smoking on inflammation in addition to the effects of tobacco smoke components on HIV disease progression. We will also discuss biomarkers of inflammation via neuroimaging as well as biomarkers of nicotine dependence (e.g., nicotine metabolite ratio). Tobacco smoking and nicotine may impact ART drug metabolism and conversely, certain ARTs may impact nicotine metabolism. Thus, we will review these bidirectional relationships and how they may contribute to neuroHIV and other adverse outcomes. We will also discuss the effects of tobacco use on the interaction between peripheral organs (lungs, heart, kidney) and subsequent CNS function in the context of HIV. Lastly, given the dramatic rise in the use of electronic nicotine delivery systems, we will discuss the implications of vaping on these processes. Despite the growing recognition of the importance of addressing tobacco use among PLWH, more research is necessary at both the preclinical and clinical level to disentangle the potentially synergistic effects of tobacco use, nicotine, HIV, cognition and immune dysregulation, as well as identify optimal approaches to reduce tobacco use. Graphical Abstract Proposed model of the relationships among HIV, ART, smoking, inflammation, and neurocognition. Solid lines represent relationships supported by evidence. Dashed lines represent relationships for which there is not enough evidence to make a conclusion. (a) HIV infection produces elevated levels of inflammation even among virally suppressed individuals. (b) HIV is associated with deficits in cognition function. (c) Smoking rates are higher among PLWH, compared to the general population. (d) The nicotine metabolite ratio (NMR) is associated with smoking behavior. (e) HIV and tobacco use are both associated with higher rates of psychiatric comorbidities, such as depression, and elevated levels of chronic stress. These factors may represent other mechanisms linking HIV and tobacco use. (f) The relationship between nicotine, tobacco smoking, and inflammation is complex, but it is well-established that smoking induces inflammation; the evidence for nicotine as anti-inflammatory is supported in some studies, but not others. (g) The relationship between tobacco use and neurocognition may differ for the effects of nicotine (acute nicotine use may have beneficial effects) vs. tobacco smoking (chronic use may impair cognition). (h) Elevated levels of inflammation may be associated with deficits in cognition. (i) PLWH may metabolize nicotine faster than those without HIV; the mechanism is not yet known and the finding needs validation in larger samples. We also hypothesize that if HIV-infection increases nicotine metabolism, then we should observe an attenuation effect once ART is initiated. (j) It is possible that the increase in NMR is due to ART effects on CYP2A6. (k) We hypothesize that faster nicotine metabolism may result in higher levels of inflammation since nicotine has anti-inflammatory properties.

Effect of Harmine on Nicotine-Induced Kidney Dysfunction in Male Mice

Background:

The nicotine content of cigarettes plays a key role in the pathogenesis of kidney disease. Harmine is a harmal-derived alkaloid with antioxidant properties. This study was designed to evaluate the effects of harmine against nicotine-induced damage to the kidneys of mice.

Methods:

In this study, 64 male mice were randomly assigned to eight groups: saline and nicotine-treated groups (2.5 mg/kg), harmine groups (5, 10, and 15 mg/kg), and nicotine (2.5 mg/kg) + harmine-treated groups (5, 10, and 15 mg/kg). Treatments were administered intraperitoneally daily for 28 days. The weights of the mice and their kidneys, kidney index, glomeruli characteristics, thiobarbituric acid reactive species, antioxidant capacity, kidney function indicators, and serum nitrite oxide levels were investigated.

Results:

Nicotine administration significantly improved kidney malondialdehyde (MDA) level, blood urea nitrogen (BUN), creatinine, and nitrite oxide levels and decreased glomeruli number and tissue ferric reducing/antioxidant power (FRAP) level compared to the saline group (P < 0.05). The harmine and harmine + nicotine treatments at all doses significantly reduced BUN, kidney MDA level, creatinine, glomerular diameter, and nitrite oxide levels and increased the glomeruli number and tissue FRAP level compared to the nicotine group (P < 0.05).

Conclusions:

It seems that harmine administration improved kidney injury induced by nicotine in mice.

The effect of green tea consumption on the expression of antioxidant- and inflammation-related genes induced by nicotine

The aim of this study is to investigate the protective effect of green tea (GT) against the toxicity of nicotine. BALB/c mice were divided into four groups. Group I received food and water intake ad libidium, Group II received GT solution at a dose of 1 ml/kg body weight orally twice a day via gastric gavage, Group III was injected intraperitoneally with nicotine (2.5 mg/kg) once per day for 4 weeks, and Group IV received both nicotine and GT; GT was introduced using gastric gavage 1 hr before and 1 hr after the nicotine injection. The administration of nicotine altered the cellular antioxidant defense system by inducing inflammation and damage in the tissues of liver, lungs, and kidneys. In addition, nicotine treatment significantly enhanced the expression antioxidant- and inflammation-related genes. There were significant improvements when the nicotine-exposed mice treated with GT. PRACTICAL APPLICATIONS: In this study, it is revealed that the administration of nicotine altered the cellular antioxidant defense system by inducing inflammation manifested by the infiltration of inflammatory cells and damage seen in liver, lungs, and kidneys. GT contributed to the reduction of toxicity of nicotine, probably mediated by free radicals, through downregulation of nicotine-induced upregulated antioxidant- and inflammation-related genes. Never the less, further in depth investigation on characterization of the active constituents of GT responsible for their effect seen here and the mechanism that contributes to the effects seen in this reports is highly demanded. Furthermore, GT extract could be considered as a dietary supplement for the reduction of nicotine toxicity among cigarette smoker.

Nicotine-induced oxidative stress contributes to EMT and stemness during neoplastic transformation through epigenetic modifications in human kidney epithelial cells

Nicotine is a component of cigarette smoke and mounting evidence suggests toxicity and carcinogenicity of tobacco smoke in kidney. Carcinogenicity of nicotine itself in kidney and the underlying molecular mechanisms are not well-understood. Hence, the objective of this study was to determine the carcinogenic effects of chronic nicotine exposure in Hk-2 human kidney epithelial cells. The effects of nicotine exposure on the expression of genes for cellular reprogramming, redox status, and growth signaling pathways were also evaluated to understand the molecular mechanisms. Results revealed that chronic exposure to nicotine induced growth and neoplastic transformation in HK-2 cells. Increased levels of intracellular reactive oxygen species (ROS), acquired stem cell-like sphere formation, and epithelial-mesenchymal-transition (EMT) changes were observed in nicotine exposed cells. Treatment with antioxidant N-acetyl cysteine (NAC) resulted in abrogation of EMT and stemness in HK-2 cells, indicating the role of nicotine-induced ROS in these morphological changes. The result also suggests that ROS controls the stemness through regulation of AKT pathway during early stages of carcinogenesis. Additionally, the expression of epigenetic regulatory genes was altered in nicotine-exposed cells and the changes were reversed by NAC. The epigenetic therapeutics 5-aza-2'-deoxycytidine and Trichostatin A also abrogated the stemness. This suggests the nicotine-induced oxidative stress caused epigenetic alterations contributing to stemness during neoplastic transformation. To our knowledge, this is the first report showing the ROS-mediated epigenetic modifications as the underlying mechanism for carcinogenicity of nicotine in human kidney epithelial cells. This study further suggests the potential of epigenetic therapeutics for pharmacological intervention in nicotine-induced kidney cancer.

Associations between blood cadmium concentration and kidney function in the U.S. population: Impact of sex, diabetes and hypertension

BACKGROUND

Exposure to cadmium has been associated with nephropathy and implicated in the development of diabetes and hypertension. The role of environmental metal exposure may be an underexplored risk factor for decreased kidney function among people with diabetes and/or hypertension. The objective of this study was to examine the association of blood concentration of cadmium with kidney function parameters and evaluate sex, diabetes, and hypertension as effect modifiers of the association.

METHODS

This study used data from 12,577 adult participants in the National Health and Nutrition Examination Survey (NHANES) 2007-2012 cycles. We used multivariable linear and logistic regression models to conduct a cross-sectional analysis of the association between cadmium exposure quartiles and estimated glomerular filtration rate (eGFR), urine albumin to creatinine ratio (UACR), low eGFR (defined as eGFR <60 mL/minute/1.73 m²), and albuminuria (defined as UACR ≥ 30 mg/g). Models were adjusted for confounders and interaction terms were evaluated for cadmium concentration and sex, diabetes, and hypertension. Final models were stratified by sex and indices of existing diabetes and hypertension status.

RESULTS

The mean eGFR was 94.3 mL/minute/1.73 m² (SD 21.5) and the geometric mean of UACR was 7.9 mg/g (95% CI 7.6-8.2 mg/g). Blood cadmium concentration was inversely associated with eGFR and positively associated with UACR. We found significant effect modification of the association of eGFR with cadmium, predominantly for sex and hypertension. The strength of the association between cadmium quartiles and eGFR was more pronounced among females compared to males. Among females with hypertension and diabetes, eGFR was lower on average by 4.9 mL/minute/1.73 m² (95% CI -10.1 to 0.29) in the highest versus lowest cadmium quartile, and in females with hypertension alone, eGFR was lower on average by 5.8 mL/minute/1.73 m² (95% CI -8.2 to -3.3) in the highest versus lowest cadmium quartile. Among those in the highest exposure quartile, higher mean UACR was observed among participants with hypertension compared to those without.

CONCLUSIONS

Our results confirm that cadmium exposure is associated with decreased glomerular filtration and increased urine protein excretion, and provide evidence that the magnitude of these associations differ by sex and may vary based on preexisting diabetes and hypertension. Future prospective sex-specific investigations are necessary to address concerns of reverse causality and efforts should be made to reduce smoking and environmental contamination from cadmium to protect human health.

The association between cigarette smoking and diabetic nephropathy in Chinese male patients

AIMS

To investigate the association between cigarette smoking and the clinicopathological features and renal prognosis of type 2 diabetic mellitus (T2DM) patients with diabetic nephropathy (DN).

METHODS

A total of 223 T2DM male patients with biopsy-proven DN who received follow-up for at least 1 year were recruited. The patients were divided into two groups based on smoking status: smoking group and non-smoking group. Clinicopathologic differences were analyzed between the two groups. In addition, smokers were divided into two groups of binary analysis based on smoking amounts and two groups of former smokers and current smokers, and subgroups analysis based on age and DR, respectively. The influence of smoking on estimated glomerular filtration rate (eGFR) was estimated using logistic regression analysis and Cox regression on renal outcomes. Renal outcomes were defined by progression to end-stage renal disease (ESRD) or doubling of serum creatinine (D-SCr) level.

RESULTS

Compared with nonsmokers, smoking patients had more moderate decline eGFR (p = 0.032) and tubular atrophy and interstitial fibrosis (p = 0.033). The adjusted logistic regression analysis suggested cigarette smoking was negatively associated with more severe decline eGFR (p = 0.015), especially for patients with DR (p = 0.010) and patients of age ≤ 50 years (p = 0.012) in the subgroup analysis. In the prognosis analysis, no obvious significant risk factor was shown about smoking. Interestingly, it was observed that former smokers had lower levels of plasma glucose and triglycerides than current smokers (both p < 0.05), while smokers with small smoking amounts had lower levels of triglycerides than those with large smoking amounts (p < 0.05).

CONCLUSION

Cigarette smoking patients with T2DM and DN had more moderate decline eGFR, especially for DN patients with DR, and milder IFTA lesions, although an obviously significant risk factor was not shown about smoking for DN.

Chronic Nicotine Exposure Reduces Antioxidant Function of Simvastatin in Renal Proximal Tubule Cells

BACKGROUND/AIM

We have previously reported that simvastatin exhibits antioxidant properties via extracellular signal-regulated kinase (ERK)/cAMP-response element binding (CREB) protein-dependent induction of heme oxygenase-1 (HO1) and chronic nicotine exposure inhibits ERK/CREB signaling in renal proximal tubule cells (through p66shc). Herein, whether nicotine dampens simvastatin-dependent HO1 induction was determined.

MATERIALS AND METHODS

Renal proximal tubule (NRK52E) cells were pre-treated with 200 μM nicotine for 24 h followed by 10 μM simvastatin. Promoter activity of HO1 and manganese superoxide dismutase (MnSOD) and activation of CREB and ERK (via ELK1) were determined in luciferase reporter assays. CREB and p66shc were modulated via genetic means.

RESULTS

Nicotine suppressed simvastatin-dependent activation of HO1 and MnSOD promoters and activity of CREB and ELK1 via p66shc. Overexpression of CREB or knockdown of p66shc restored simvastatin-dependent induction of HO1 and MnSOD in the presence of nicotine.

CONCLUSION

Antioxidant efficiency of simvastatin might be significantly lessened in smokers/E-cigarette users.

Nicotine enhances mesangial cell proliferation and fibronectin production in high glucose milieu via activation of Wnt/β-catenin pathway

Diabetic nephropathy (DN) is a major complication of diabetes mellitus. Clinic reports indicate cigarette smoking is an independent risk factor for chronic kidney disease including DN; however, the underlying molecular mechanisms are not clear. Recent studies have demonstrated that nicotine, one of the active compounds in cigarette smoke, contributes to the pathogenesis of the cigarette smoking-accelerated chronic kidney disease. One of the characteristics of DN is the expansion of mesangium, a precursor of glomerular sclerosis. In the present study, we examined the involvement of Wnt/β-catenin pathway in nicotine-mediated mesangial cell growth in high glucose milieu. Primary human renal mesangial cells were treated with nicotine in the presence of normal (5 mM) or high glucose (30 mM) followed by evaluation for cell growth. In the presence of normal glucose, nicotine increased both the total cell numbers and Ki-67 positive cell ratio, indicating that nicotine stimulated mesangial cell proliferation. Although high glucose itself also stimulated mesangial cell proliferation, nicotine further enhanced the mitogenic effect of high glucose. Similarly, nicotine increased the expression of Wnts, β-catenin, and fibronectin in normal glucose medium, but further increased mesangial cell expression of these proteins in high glucose milieu. Pharmacological inhibition or genetic knockdown of β-catenin activity or expression with specific inhibitor FH535 or siRNA significantly impaired the nicotine/glucose-stimulated cell proliferation and fibronectin production. We conclude that nicotine may enhance renal mesangial cell proliferation and fibronectin production under high glucose milieus partly through activating Wnt/β-catenin pathway. Our study provides insight into molecular mechanisms involved in DN.

Sub-acute administration of lower doses of nicotine caused sex-dependent improvement of renal function in Wistar rats

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Exposure to nicotine is associated with sex-dependent variation in electrolyte disturbances.

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Lower doses of sub-acute nicotine administration enhanced renal function.

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Nicotine-enhanced renal function is more pronounced in female than in male Wistar rats.

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Nicotine-enhanced renal function may be mediated through α7-nAchR.

The adverse and beneficial health effects of nicotine (NIC), the major alkaloid found in cigarettes and tobacco, are controversial. Most studies on NIC have focused on its effects on cardiovascular and nervous functions. This study aimed at determining dose- and sex-specific effects of sub-acute (28 days) NIC administration on some indices of kidney function in Wistar rats. Forty rats (20 males and 20 females), 8–9 weeks old (each housed in separate metabolic cage), were used for this study such that graded doses of NIC (1, 2 and 4 mg/kg i.p. for 28 days) were administered to both sexes while each control received distilled water at 0.2 mL/100 g i.p. Blood was collected under ketamine anesthesia (10 mg/kg i.m) for analyses and results obtained were compared at p < 0.05. The result showed beneficial alterations in plasma and urine level of creatinine, urea and uric acid (p < 0.05) as well as plasma and urine electrolyte level (Na⁺ and K⁺) in both sexes (p < 0.05). Also, there was significant improvement in creatinine clearance (p < 0.05) with no appreciable difference in their histological examination. Although these beneficial effects were more pronounced in the female than in the male (p < 0.05), administration at the highest dose showed potentially deleterious alterations from normal beneficial trend (p < 0.05) in both sexes. It was concluded that sub-acute administration of lower doses of NIC improves kidney function of Wistar rats; an effect that was more pronounced in the females than their male counterparts.

Nonalcoholic fatty liver disease accelerates kidney function decline in patients with chronic kidney disease: a cohort study

This study aimed to investigate the association of nonalcoholic fatty liver disease (NAFLD) and its severity with the decline in kidney function in patients with chronic kidney disease (CKD). We conducted a cohort study of 1,525 CKD patients who underwent repeated health check-up examinations from January 2003 through December 2013. NAFLD was diagnosed by ultrasonography and its severity was assessed by the NAFLD fibrosis score. At baseline, the prevalence of NAFLD was 40.9%, and the mean estimated glomerular filtration rate (eGFR) was 59.1 ml/min/1.73 m2. The average follow-up was 6.5 years. The age- and sex-adjusted decline in eGFR was greater in patients with NAFLD (-0.79% per year, 95% CI -1.31%, -0.27%) compared to those without it (0.30%, 95% CI -0.14%, 0.76%; p = 0.002). In multivariable adjusted models, the average difference in annual percent change in decline in eGFR comparing patients with NAFLD to those without NAFLD was -1.06% (-1.73%, -0.38%; p = 0.002). The decline in eGFR associated with NAFLD was greater in patients with higher NAFLD fibrosis score, in those with proteinuria or with low eGFR at baseline ( <45 ml/min/1.73 m2), and in those who were smokers and hypertensive. Therefore, NAFLD is independently associated with CKD progression.

Alpha7 Nicotine Acetylcholine Receptor Agonist PNU-282987 Attenuates Acute Lung Injury in a Cardiopulmonary Bypass Model in Rats

OBJECTIVE

Cardiopulmonary bypass (CPB) carries a risk of lung ischemia-reperfusion, leading to acute lung injury (ALI). Alpha7 nicotinic acetylcholine receptor (alpha7nAChR) has been implicated in the release of high mobility group box1 (HMGB1), which promotes systemic inflammation in response to ischemia-reperfusion injury. However, the specific role of alpha7nAChR in CPB is poorly understood. This study employed the alpha7nAChR agonist PNU-282987 and a rat model of CPB to determine whether alpha7nAChR was associated with CPB-induced lung damage.

METHODS

Thirty Sprague-Dawley rats were randomly divided into five groups as follows: normal group, sham group, CPB group, PNU-282987 plus CPB group, and PNU-282987 plus sham group. Rats were subjected to CPB under anesthesia for 60 min. PNU-282987 (4.8 mg/kg) was administered via arterial inflow. Two hours post-CPB, samples of blood, bronchoalveolar lavage fluid (BALF), and lung tissues were processed for investigations.

RESULTS

In CPB rats, structural damage in the lung was marked. Density of alpha7nAChR of the lung in the CPB group was significantly less than all other groups, while lung edema, inflammatory markers in serum and lung, protein concentrations in BALF were significantly higher. In the PNU-282987 plus CPB group, by all the above measures the CPB-associated effects were significantly ameliorated but were not identical to the control groups.

CONCLUSION

Our results suggest that PNU-282987 affords protective effect against CPB-induced ALI, and inhibits HMGB1 release.