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

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.

The association between dental caries and steroid-sensitive nephrotic syndrome in children

BACKGROUND

Pathogenesis and relapse of steroid-sensitive nephrotic syndrome (SSNS) are primarily associated with infection. Dental caries is the most common chronic progressive oral infection in children. However, clinical studies of SSNS combined with dental caries in children are rare.

METHODS

In our retrospective cohort study from January 2021 to June 2022, 145 children with SSNS were included in the baseline analysis and 105 in the follow-up analysis. The follow-up period was 1 year. The primary study endpoints were the relapse-free period and frequently relapsing nephrotic syndrome (FRNS). Secondary endpoints included the number and triggers of relapses and concomitant medications.

RESULTS

The median age was 5.5 years, with a caries rate of 60.7%, the mean DMFT/dmft was 3.86, and the caries filling rate was 1.6%. Except for the lower proportion of high household income and high parental education observed in the caries group, no statistical differences were found when comparing the other baseline data with the non-caries group. The caries group had a shorter relapse-free period and a lower 1-year cumulative relapse-free survival rate (HR = 1.90, 95% CI 1.17-3.09, P = 0.009). Univariate regression analysis showed caries associated with FRNS (OR = 2.714, 95% CI 1.021-7.219, P = 0.045), but the correlation no longer remained in the multivariate analysis. Additionally, seven cases of caries-derived pulpal periapical inflammation triggered SSNS relapses. The caries group had more infection triggers and concomitant medication use.

CONCLUSION

Dental caries and relapse of SSNS are potentially associated, but careful evaluation is needed.

The complement system as a key modulator of the oral microbiome in health and disease

In this review, we address the interplay between the complement system and host microbiomes in health and disease, focussing on oral bacteria known to contribute to homeostasis or to promote dysbiosis associated with dental caries and periodontal diseases. Host proteins modulating complement activities in the oral environment and expression profiles of complement proteins in oral tissues were described. In addition, we highlight a sub-set of bacterial proteins involved in complement evasion and/or dysregulation previously characterized in pathogenic species (or strains), but further conserved among prototypical commensal species of the oral microbiome. Potential roles of these proteins in host-microbiome homeostasis and in the emergence of commensal strain lineages with increased virulence were also addressed. Finally, we provide examples of how commensal bacteria might exploit the complement system in competitive or cooperative interactions within the complex microbial communities of oral biofilms. These issues highlight the need for studies investigating the effects of the complement system on bacterial behaviour and competitiveness during their complex interactions within oral and extra-oral host sites.

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

BACKGROUND

The relationship between the major periodontal bacteria, Porphyromonas gingivalis, and the pathogenesis of IgA nephropathy (IgAN)-particularly with respect to galactose-deficient IgA1 (Gd-IgA1)-has not been fully elucidated.

METHODS

Saliva samples from 30 IgAN patients and 44 patients with chronic kidney disease (CKD) were subjected to analysis of P. gingivalis status via polymerase chain reaction using a set of P. gingivalis-specific primers. The associations between P. gingivalis presence and clinical parameters, including plasma Gd-IgA1, were analyzed in each group.

RESULTS

Compared with the CKD group, the IgAN group demonstrated significantly higher plasma Gd-IgA1 levels (p < 0.05). Compared with the P. gingivalis-negative subgroup, the P. gingivalis-positive subgroup exhibited significantly higher plasma Gd-IgA1 levels in both IgAN and CKD patients (p < 0.05). Additionally, among IgAN patients, the P. gingivalis-positive subgroup displayed significantly higher plasma Gd-IgA1 and urine protein levels, compared with the P. gingivalis-negative subgroup (p < 0.05). With respect to renal biopsy findings, the frequencies of segmental glomerulosclerosis and tubular atrophy/interstitial fibrosis were significantly greater in the P. gingivalis-positive subgroup than in the P. gingivalis-negative subgroup, according to the Oxford classification of IgAN (p < 0.05).

CONCLUSION

Our findings suggest an association between the presence of P. gingivalis in the oral cavity and the pathogenesis of IgAN, mediated by increased levels of Gd-IgA1.

An Overview of Chronic Kidney Disease Pathophysiology: The Impact of Gut Dysbiosis and Oral Disease

Chronic kidney disease (CKD) is a severe condition and a significant public health issue worldwide, carrying the burden of an increased risk of cardiovascular events and mortality. The traditional factors that promote the onset and progression of CKD are cardiometabolic risk factors like hypertension and diabetes, but non-traditional contributors are escalating. Moreover, gut dysbiosis, inflammation, and an impaired immune response are emerging as crucial mechanisms in the disease pathology. The gut microbiome and kidney disease exert a reciprocal influence commonly referred to as "the gut-kidney axis" through the induction of metabolic, immunological, and endocrine alterations. Periodontal diseases are strictly involved in the gut-kidney axis for their impact on the gut microbiota composition and for the metabolic and immunological alterations occurring in and reciprocally affecting both conditions. This review aims to provide an overview of the dynamic biological interconnections between oral health status, gut, and renal pathophysiology, spotlighting the dynamic oral-gut-kidney axis and raising whether periodontal diseases and gut microbiota can be disease modifiers in CKD. By doing so, we try to offer new insights into therapeutic strategies that may enhance the clinical trajectory of CKD patients, ultimately advancing our quest for improved patient outcomes and well-being.

A PRoliferation-Inducing Ligand (APRIL) in the Pathogenesis of Immunoglobulin A Nephropathy: A Review of the Evidence

A PRoliferation-Inducing Ligand (APRIL), the thirteenth member of the tumor necrosis factor superfamily, plays a key role in the regulation of activated B cells, the survival of long-lived plasma cells, and immunoglobulin (Ig) isotype class switching. Several lines of evidence have implicated APRIL in the pathogenesis of IgA nephropathy (IgAN). Globally, IgAN is the most common primary glomerulonephritis, and it can progress to end-stage kidney disease; yet, disease-modifying treatments for this condition have historically been lacking. The preliminary data in ongoing clinical trials indicate that APRIL inhibition can reduce proteinuria and slow the rate of kidney disease progression by acting at an upstream level in IgAN pathogenesis. In this review, we examine what is known about the physiologic roles of APRIL and evaluate the experimental and epidemiological evidence describing how these normal biologic processes are thought to be subverted in IgAN. The weight of the preclinical, clinical, and genetic data supporting a key role for APRIL in IgAN has galvanized pharmacologic research, and several anti-APRIL drug candidates have now entered clinical development for IgAN. Herein, we present an overview of the clinical results to date. Finally, we explore where more research and evidence are needed to transform potential therapies into clinical benefits for patients with IgAN.

Kynurenic acid inhibits macrophage pyroptosis by suppressing ROS production via activation of the NRF2 pathway

Macrophage pyroptosis and related inflammatory responses play an important role in periodontitis. Kynurenic acid (KA) is hypothesized to have anti‑inflammatory potential, but whether KA can inhibit macrophage pyroptosis and the underlying mechanisms remain unclear. Lipopolysaccharide (LPS) was used to induce pyroptosis in THP‑1‑derived macrophages. KA or ML385 was used to pretreat macrophages, after which, cell viability, NOD‑like receptor protein 3 (NLRP3) inflammasome‑related protein expression, oxidative stress levels and nuclear factor erythroid 2‑related factor 2 (NRF2) expression were measured. The results showed that KA improved the LPS‑induced decrease in macrophage viability and lactate dehydrogenase release. KA prevented THP‑1 macrophage pyroptosis induced by LPS by reducing the expression of NLRP3, Gasdermin‑D, and Caspase1, and decreased the expression of inflammatory factors. KA suppressed NLRP3 inflammasome activation by inhibiting ROS overproduction and increasing Heme Oxygenase 1 and glutathione levels. Moreover, KA promoted NRF2 translocation from the cytoplasm to the nucleus. In addition, the anti‑pyroptotic and antioxidant effects of KA were reversed by ML385 inhibition of NRF2. In the present study, it was found that KA significantly suppressed macrophage pyroptosis induced by LPS. It was further demonstrated that the anti‑pyroptotic effects of KA were mediated by activation of the NRF2 pathway.

Editorial for the IJMS Special Issue on "Infection and the Kidney"

The coronavirus disease (COVID-19) pandemic has highlighted the close relationship between infection and kidney injury [...].

The oral microbiome in autoimmune diseases: friend or foe?

The human body is colonized by abundant and diverse microorganisms, collectively known as the microbiome. The oral cavity has more than 700 species of bacteria and consists of unique microbiome niches on mucosal surfaces, on tooth hard tissue, and in saliva. The homeostatic balance between the oral microbiota and the immune system plays an indispensable role in maintaining the well-being and health status of the human host. Growing evidence has demonstrated that oral microbiota dysbiosis is actively involved in regulating the initiation and progression of an array of autoimmune diseases.Oral microbiota dysbiosis is driven by multiple factors, such as host genetic factors, dietary habits, stress, smoking, administration of antibiotics, tissue injury and infection. The dysregulation in the oral microbiome plays a crucial role in triggering and promoting autoimmune diseases via several mechanisms, including microbial translocation, molecular mimicry, autoantigen overproduction, and amplification of autoimmune responses by cytokines. Good oral hygiene behaviors, low carbohydrate diets, healthy lifestyles, usage of prebiotics, probiotics or synbiotics, oral microbiota transplantation and nanomedicine-based therapeutics are promising avenues for maintaining a balanced oral microbiome and treating oral microbiota-mediated autoimmune diseases. Thus, a comprehensive understanding of the relationship between oral microbiota dysbiosis and autoimmune diseases is critical for providing novel insights into the development of oral microbiota-based therapeutic approaches for combating these refractory diseases.

cnm-positive Streptococcus mutans is associated with galactose-deficient IgA in patients with IgA nephropathy

The presence of Streptococcus mutans expressing Cnm protein encoded by cnm (cnm-positive S. mutans) in the oral cavity is associated with immunoglobulin A (IgA) nephropathy (IgAN). However, the precise mechanism by which cnm-positive S. mutans is involved in the pathogenesis of IgAN remains unclear. The present study evaluated glomerular galactose-deficient IgA1 (Gd-IgA1) to clarify the association between the presence of cnm-positive S. mutans and glomerular Gd-IgA1 in patients with IgAN. The presence of S. mutans and cnm-positive S. mutans was evaluated by polymerase chain reaction in saliva specimens from 74 patients with IgAN or IgA vasculitis. Immunofluorescent staining of IgA and Gd-IgA1 using KM55 antibody in clinical glomerular tissues was then performed. There was no significant association between the glomerular staining intensity of IgA and the positive rate of S. mutans. However, there was a significant association between the glomerular staining intensity of IgA and the positive rate of cnm-positive S. mutans (P < 0.05). There was also a significant association between the glomerular staining intensity of Gd-IgA1 (KM55) and the positive rate of cnm-positive S. mutans (P < 0.05). The glomerular staining intensity of Gd-IgA1 (KM55) was not associated with the positive rate of S. mutans. These results suggest that cnm-positive S. mutans in the oral cavity is associated with the pathogenesis of Gd-IgA1 in patients with IgAN.

Transcriptomic analysis reveals the potential crosstalk genes and immune relationship between IgA nephropathy and periodontitis

Background

It is well known that periodontitis has an important impact on systemic diseases. The aim of this study was to investigate potential crosstalk genes, pathways and immune cells between periodontitis and IgA nephropathy (IgAN).

Methods

We downloaded periodontitis and IgAN data from the Gene Expression Omnibus (GEO) database. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were used to identify shared genes. Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on the shared genes. Hub genes were further screened using least absolute shrinkage and selection operator (LASSO) regression, and a receiver operating characteristic (ROC) curve was drawn according to the screening results. Finally, single-sample GSEA (ssGSEA) was used to analyze the infiltration level of 28 immune cells in the expression profile and its relationship with shared hub genes.

Results

By taking the intersection of WGCNA important module genes and DEGs, we found that the SPAG4, CCDC69, KRT10, CXCL12, HPGD, CLDN20 and CCL187 genes were the most important cross-talk genes between periodontitis and IgAN. GO analysis showed that the shard genes were most significantly enriched in kinase regulator activity. The LASSO analysis results showed that two overlapping genes (CCDC69 and CXCL12) were the optimal shared diagnostic biomarkers for periodontitis and IgAN. The immune infiltration results revealed that T cells and B cells play an important role in the pathogenesis of periodontitis and IgAN.

Conclusion

This study is the first to use bioinformatics tools to explore the close genetic relationship between periodontitis and IgAN. The SPAG4, CCDC69, KRT10, CXCL12, HPGD, CLDN20 and CCL187 genes were the most important cross-talk genes between periodontitis and IgAN. T-cell and B-cell-driven immune responses may play an important role in the association between periodontitis and IgAN.

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

BACKGROUND

The simultaneous presence of Streptococcus mutans expressing the Cnm protein encoded by cnm (i.e., cnm-positive S. mutans) and Campylobacter rectus in the oral cavity has been associated with proteinuria in patients with IgA nephropathy (IgAN).

OBJECTIVES

The present study evaluated the relationship between renal function and oral bacteria in patients with IgAN over 5 years of follow-up.

METHODS

The presence of C. rectus and cnm-positive S. mutans in saliva samples of 117 patients with IgAN was initially evaluated by polymerase chain reaction. Patients were then divided into four groups according to the results of C. rectus and cnm-positive S. mutans detection: group A: C. rectus (-), cnm-positive S. mutans (-); group B: C. rectus (+), cnm-positive S. mutans (-); group C: C. rectus (-), cnm-positive S. mutans (+); and group D: C. rectus (+), cnm-positive S. mutans (+). Clinical characteristics were prospectively followed for 5 years.

RESULTS

Serum creatinine levels were significantly higher in group D than in group A over 5 years of follow-up. Additionally, the proportion of patients with an estimated glomerular filtration rate <45 mL/min increased over time; it was significantly greater in group D than in group A over 5 years of follow-up.

CONCLUSION

These results suggest that the simultaneous presence of C. rectus and cnm-positive S. mutans in the oral cavity is associated with renal dysfunction in IgAN patients.