Periodontal disease bacteria specific to tonsil in IgA nephropathy patients predicts the remission by the treatment

Guidance of clinical management for patients with tonsillar focal disease

Tonsillar focal diseases (TFDs) are defined as "diseases caused by organic and/or functional damage in organs distant from tonsil, and the disease outcome is improved by tonsillectomy." Although several reports and reviews have shown the efficacy of tonsillectomy for TFDs, no guidelines for the clinical management of the diagnosis and treatment of TFDs have been reported. Therefore, the Society of Stomato-pharyngology established a committee to guide the clinical management of patients with TFDs, and the original guide was published in May 2023. This article summarizes the English version of the manuscript. We hope that the concept of TFDs will spread worldwide, and that one as many patients with TFDs will benefit from tonsillectomy.

Influence of IgA nephropathy on the progression of pulpitis and apical periodontitis in HIGA mice

OBJECTIVES

Immunoglobulin (Ig)A nephropathy has been associated with oral infections such as periodontitis, but its pathogenesis is not fully understood; no treatments exist. This study analyzes the influence of IgA nephropathy, an autoimmune disease, on the pathogenesis of pulpitis and apical periodontitis.

METHODS

Two groups of mice were used in pulp infection experiments: high serum IgA nephropathy model mice (HIGA) and control mice (BALB/c). Histologic analyses of the pulp and apical periodontal tissues were performed on days 3, 5, 7, 14, and 28 following oral bacterial infection. The dynamics of odontoblasts, apoptotic cells, and IgA expression were analyzed using anti-Nestin, TUNEL, and anti-IgA staining, respectively.

RESULTS

Inflammatory cells infiltrated the exposed pulp at day three in both groups and by 14 days, these cells had infiltrated from the pulp to the apical periodontal tissue. The area of necrotic pulp tissue increased significantly in the control group at seven days. Odontoblasts decreased from day three onwards and disappeared by 28 days in both groups. The number of apoptotic cells in the pulp and apical periodontal tissues was significantly higher in the experimental group at day 28. The experimental group exhibited a significant increase in IgA production in the pulp after 14 days. Bone resorption in the apical periodontal tissue was significantly decreased in the experimental group at day 28.

CONCLUSIONS

The results of this study suggest that IgA nephropathy may modulate the inflammatory response and sustain long-term biological defense responses in pulpitis and apical periodontitis in HIGA mice.

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.

Association between gingival bleeding and hematuria as biomarkers of periodontitis and renal disease: a review

Gingival bleeding is a common complaint and symptom in patients with periodontitis. In clinics, gingival bleeding is regarded as an important sign of gingival inflammation, which is also of great significance in predicting the activity of periodontitis. Existing research has indicated that periodontitis has an impact on distant sites, such as the kidney. Hematuria is the principal feature of glomerular disease, which can reflect the degree and condition of glomerular inflammation. Previous studies have revealed an association between periodontal diseases with renal diseases, so a study is necessary to discuss their representative signs of them. For the moment, there are no reports that are concerned about the correlation between gingival bleeding with hematuria. The main point of this text is to review the potential association between gingival bleeding with hematuria, reveal their underlying mechanisms, and provide instructions for the therapy of periodontitis and glomerular 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.

[Research Progress in the Correlation Between Oral Microbiota and Chronic Kidney Disease]

Chronic kidney disease (CKD), one of the common clinical urological diseases, is increasingly more prevalent in recent years and has emerged as a major concern of public health around the globe. The continuous recurrence of CKD caused by renal function impairment leads eventually to irreversible renal failure and severe systemic complications, which causes severe negative impact on the quality of life of the patient. As an essential component of human microbiome, oral microbiota plays a major role in maintaining health, and there has been research suggesting close association between oral dysbiosis and CKD. It is therefore of great clinical significance to understand the correlation between CKD and oral microbiota. Herein, we reviewed the characteristics of oral microbiota of CKD patients, the possible mechanisms of oral microbiota's involvement in the pathogenesis and development of CKD, and the latest research findings on oral dysbiosis and CKD, with a view to finding new approaches to early prevention and control of CKD through oral microbial targets.

Microbiota and glomerulonephritis: An immunological point of view

Glomerular injury is the major cause of chronic kidney diseases (CKD) worldwide and is characterized by proteinuria. Glomerulonephritis (GN) has a wide spectrum of etiologies, the intensity of glomerular damage, histopathology, and clinical outcomes that can be associated with the landscape of the nephritogenic immune response. Beyond impaired immune responses and genetic factors, recent evidence indicates that microbiota can be contributed to the pathogenesis of GN and patients' outcomes by impacting many aspects of the innate and adaptive immune systems. It is still unknown whether dysbiosis induces GN or it is a secondary effect of the disease. Several factors such as drugs and nutritional problems can lead to dysbiosis in GN patients. It has been postulated that gut dysbiosis activates immune responses, promotes a state of systemic inflammation, and produces uremic toxins contributing to kidney tissue inflammation, apoptosis, and subsequent proteinuric nephropathy. In this review, the impact of gastrointestinal tract (GI) microbiota on the pathogenesis of the primary GN will be highlighted. The application of therapeutic interventions based on the manipulation of gut microbiota with special diets and probiotic supplementation can be effective in GN.

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.

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

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

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

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

How will artificial intelligence and bioinformatics change our understanding of IgA Nephropathy in the next decade?

IgA nephropathy (IgAN) is the most common glomerulonephritis. It is characterized by the deposition of immune complexes containing immunoglobulin A (IgA) in the kidney’s glomeruli, triggering an inflammatory process. In many patients, the disease has a progressive course, eventually leading to end-stage kidney disease. The current understanding of IgAN’s pathophysiology is incomplete, with the involvement of several potential players, including the mucosal immune system, the complement system, and the microbiome. Dissecting this complex pathophysiology requires an integrated analysis across molecular, cellular, and organ scales. Such data can be obtained by employing emerging technologies, including single-cell sequencing, next-generation sequencing, proteomics, and complex imaging approaches. These techniques generate complex “big data,” requiring advanced computational methods for their analyses and interpretation. Here, we introduce such methods, focusing on the broad areas of bioinformatics and artificial intelligence and discuss how they can advance our understanding of IgAN and ultimately improve patient care. The close integration of advanced experimental and computational technologies with medical and clinical expertise is essential to improve our understanding of human diseases. We argue that IgAN is a paradigmatic disease to demonstrate the value of such a multidisciplinary approach.

Potential Roles of Oral Microbiota in the Pathogenesis of Immunoglobin A Nephropathy

Disturbance in microbiota affects the mucosal immune response, and it is gradually recognized to be associated with the Immunoglobin A nephropathy (IgAN). This study aims to explore the potential roles of oral microbiota in disease pathogenesis. Saliva samples were collected from 31 patients with IgAN and 30 controls for 16S rRNA gene sequencing. The evenness, diversity, and composition of oral microbiota were analyzed. Moreover, sub-phenotype association analysis was conducted. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database was used to investigate microbiota functions. Compared to healthy controls, microbial diversity tended to decrease in IgAN, and the microbial profiles were remarkably distinguished. The relative abundance of Capnocytophaga and SR1_genera_incertae_sedis were enriched, whereas 17 genera, such as Rothia, were significantly reduced in IgAN. Variable importance in projection scores showed that 12 genera, including Capnocytophaga, Rothia, and Haemophilus, could discriminate between the two groups. In the sub-phenotype correlation analysis, the relative abundance of Capnocytophaga and Haemophilus was positively associated with levels of proteinuria and serum IgA, respectively. Further metabolic pathway analysis showed 7 predictive functional profiles, including glycosphingolipid biosynthesis, oxidative phosphorylation, and N-glycan biosynthesis were enriched in IgAN. In conclusion, disturbance in oral microbiota was observed to be associated with IgAN and its sub-phenotypes, which may shed novel insights into disease pathogenesis from a microbiome perspective.

Streptococcus mutans induces IgA nephropathy-like glomerulonephritis in rats with severe dental caries

The mechanisms underlying immunoglobulin A nephropathy (IgAN), the most common chronic form of primary glomerulonephritis, remain poorly understood. Streptococcus mutans, a Gram-positive facultatively anaerobic oral bacterium, is a common cause of dental caries. In previous studies, S. mutans isolates that express Cnm protein on their cell surface were frequently detected in IgAN patients. In the present study, inoculation of Cnm-positive S. mutans in the oral cavities of 2-week-old specific-pathogen free Sprague-Dawley rats fed a high-sucrose diet for 32 weeks produced severe dental caries in all rats. Immunohistochemical analyses of the kidneys using IgA- and complement C3-specific antibodies revealed positive staining in the mesangial region. Scanning electron microscopy revealed a wide distribution of electron dense deposits in the mesangial region and periodic acid-Schiff staining demonstrated prominent proliferation of mesangial cells and mesangial matrix. These results suggest that IgAN-like glomerulonephritis was induced in rats with severe dental caries by Cnm-positive S. mutans.

Dysbiosis in the Salivary Microbiome Associated with IgA Nephropathy-‍A‍ ‍Japanese Cohort Study

IgA nephropathy is one of the leading causes of chronic kidney disease in Japan. Since the origin and mechanisms by which IgA nephropathy develops currently remain unclear, a confirmed disease diagnosis is currently only possible by highly invasive renal biopsy. With the background of the salivary microbiome as a rich source of biomarkers for systemic diseases, we herein primarily aimed to investigate the salivary microbiome as a tool for the non-invasive diagnosis of IgA nephropathy. In a comparison of salivary microbiome profiles using 16S rRNA amplicon sequencing, significant differences were observed in microbial diversity and richness between IgA nephropathy patients and healthy controls. Furthermore, recent studies reported that patients with IgA nephropathy are more likely to develop inflammatory bowel diseases and that chronic inflammation of the tonsils triggered the recurrence of IgA nephropathy. Therefore, we compared the salivary microbiome of IgA nephropathy patients with chronic tonsillitis and ulcerative colitis patients. By combining the genera selected by the random forest algorithm, we were able to distinguish IgA nephropathy from healthy controls with an area under the curve (AUC) of 0.90, from the ulcerative colitis group with AUC of 0.88, and from the chronic tonsillitis group with AUC of 0.70. Additionally, the genus Neisseria was common among the selected genera that facilitated the separation of the IgA nephropathy group from healthy controls and the chronic tonsillitis group. The present results indicate the potential of the salivary microbiome as a biomarker for the non-invasive diagnosis of IgA nephropathy.

Upregulated Expression of Intestinal Antimicrobial Peptide HD5 Associated with Renal Function in IgA Nephropathy

PURPOSE

It was reported that gut-kidney axis may play an important role in IgA nephropathy (IgAN). Previous five GWASs of different populations for IgAN have discovered several genes related to intestinal immunity, including DEFA gene. However, the roles of the encoded proteins of DEFA5/6 which were called intestinal antimicrobial peptides HD5 and HD6 were not clear in kidney disease, such as IgAN. The purpose of this study was to clarify the association of HD5 and HD6 with IgAN.

METHODS

We measured HD5 and HD6 in serum, urine, and kidney of IgAN patients and normal controls by ELISA, Western blot, and immunofluorescence. The association of HD5 or HD6 levels with clinical and pathologic phenotypes was analyzed.

RESULTS

Serum levels of HD5 and HD6 were significantly higher in IgAN patients than those in normal controls. Baseline serum HD5 levels were significantly associated with eGFR (P = 0.002) and tubular atrophy/interstitial fibrosis (P = 0.002) and tubular atrophy/interstitial fibrosis (P = 0.002) and tubular atrophy/interstitial fibrosis (P = 0.002) and tubular atrophy/interstitial fibrosis (.

CONCLUSIONS

In IgAN patients, an elevated serum HD5 level at the time of renal biopsy was associated with poor renal outcomes. HD5 rather than HD6 was probably associated with renal function of IgAN patients.

Comparative analysis of the tonsillar microbiota in IgA nephropathy and other glomerular diseases

Immunoglobulin A nephropathy (IgAN) involves repeated events of gross haematuria with concurrent upper airway infections. The mucosal immune system, especially the tonsil, is considered the initial site of inflammation, although the role of the tonsillar microbiota has not been established in IgAN. In this study, we compared the tonsillar microbiota of patients with IgAN (n = 21) and other glomerular diseases (n = 36) as well as, healthy controls (n = 23) from three medical centres in Korea. The microbiota was analysed from tonsil swabs using the Illumina MiSeq system based on 16S rRNA gene. Tonsillar bacterial diversity was higher in IgAN than in other glomerular diseases, although it did not differ from that of healthy controls. Principal coordinates analysis revealed differences between the tonsillar microbiota of IgAN and both healthy and disease controls. The proportions of Rahnella, Ruminococcus_g2, and Clostridium_g21 were significantly higher in patients with IgAN than in healthy controls (corrected p < 0.05). The relative abundances of several taxa were correlated with the estimated glomerular filtration rate, blood urea nitrogen, haemoglobin, and serum albumin levels. Based on our findings, tonsillar microbiota may be associated with clinical features and possible immunologic pathogenesis of IgAN.

Intravenous administration of Streptococcus mutans induces IgA nephropathy-like lesions

Background

IgA nephropathy (IgAN) is one of the most frequently occurring types of chronic glomerulonephritis. Previous analyses have revealed that a major pathogen of dental caries, Streptococcus mutans [which expresses collagen-binding protein (Cnm) on its surface], is involved in the pathogenesis of IgAN.

Methods

Cnm-positive S. mutans isolated from a patient with IgAN was intravenously administered to specific pathogen-free Sprague–Dawley rats to evaluate their kidney conditions.

Results

The urinary protein level of the S. mutans group reached a plateau at 30 days, with increased numbers of mesangial cells and an increased mesangial matrix. The numbers of rats with IgA-positive and/or C3-positive glomeruli were significantly greater in the S. mutans group than in the control group at 45 days (P < 0.05). Electron microscopy analyses revealed electron-dense depositions in the mesangial area among rats in the S. mutans group. There were significantly more CD68-positive cells (macrophages) in the glomeruli of the S. mutans group than in the glomeruli of the control group during the late phase (P < 0.05), similar to the findings in patients with IgAN.

Conclusion

Our results suggested that intravenous administration of Cnm-positive S. mutans caused transient induction of IgAN-like lesions in rats.

Analysis of microbial changes in the tonsillar formalin-fixed paraffin-embedded tissue of Chinese patients with IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is a prevalent chronic glomerular disease contribution to end-stage renal failure (ESRD). The tonsillar microbiota is closely associated with IgAN diseases based on the mucosal immune response. However, the composition and function of in tonsillar microbiota in participant patients with IgAN remains unknown. In this study, we detected the tonsillar microbiota changes of IgAN patients in Heilongjiang province located in northeast China.

MATERIAL AND METHODS

We collected from 21 patients with IgAN and 16 patients with chronic tonsillitis (CT) who had undergone tonsillectomy previously. Histological review of all samples from formalin-fixed paraffin-embedded (FFPE) tissue were performed. Extracted DNA from FFPE tissue blocks, after that V4 regions of 16S ribosomal RNA (rRNA) sequencing and comparative analyses of tonsillar flora between two groups were performed. The statistical analysis used the SPSS version of 21.

RESULTS

Visualization of microorganisms by Gram and Warthin-Starry (WS) silver stains, preliminarily observed the morphological characteristics of microbiome in FFPE tissue cases, such as bacteria or fungi. Tonsillar FFPE samples from the IgAN patients and CT controls showed significant differences in tonsillar microbial certain compositions and functions. We found that there were eight dominant genera that can be available to distinguish IgAN patients from CT controls. Compared with CT controls, at genus level, the relative abundances of Methylocaldum and unclassified_f_Prevotellaceae were significantly higher, while the abundances of Anaerosphaera, Halomonas, Trichococcus, Peptostreptococcus, norank_f_Synergistaceae and unclassified_k_norank_d_Bacteria were significantly lower in IgAN patients. Principal co-ordinates analysis (PCOA) distinguished IgAN patients from CT controls, and receiver operating characteristic (ROC) curves analysis confirmed that the diagnosis of disease has certain diagnostic significance. In addition, Functional analysis revealed that partly Enzymes and KOs were increased in the IgAN patients.

CONCLUSIONS

Histological screening results were very helpful for further gene sequencing, not only to supplement the observation of bacterial morphology and structure, but also to prepare for subsequent gene sequencing and bioinformatics analysis. We elucidated subtle relevance between changes in tonsillar microbiota and IgAN patients, which can be utilized to predict the incidence of IgAN disease. In addition, we predicted that some enzymes, and KOs were closely related to IgAN.

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

BACKGROUND

Steroid therapy is one of the important therapies for IgA nephropathy (IgAN), but the features of the IgAN patients who have the benefit from this therapy remained unclear.

METHODS

This retrospective observational study, using data of 874 patients with IgAN analyzed the proteinuria and kidney function of IgAN patients who had beneficial effect by steroid therapy. Two advantages of the present study were a large cohort and a long observational period.

RESULTS

Corticosteroid therapy had ameliorated the kidney prognosis [incident rate ratio (IRR) 0.57 (95%CI 0.34-0.92), P = 0.029]. Because of interaction between kidney function and use of corticosteroid (P = 0.047), stratification analysis by kidney function revealed that prognosis of kidney function in IgAN patients whose eGFR was less than 60 ml/min/1.73m² was ameliorated by corticosteroid therapy [IRR 0.50 (95%CI 0.26-0.97), P = 0.015); while, there was no change of kidney prognosis in IgAN patients whose eGFR was above 60 ml/min/1.73 m². To make the target of corticosteroid therapy for IgAN patients more clear, IgAN patients, whose eGFR were less than 60 ml/min/1.73 m², were stratified by proteinuria (1 g/day). In IgAN patients whose eGFR were under 60 ml/min/1.73 m² and whose proteinuria were over 1.0 g/day, corticosteroid therapy seemed to ameliorate kidney function [IRR 0.39 (95%CI 0.19-0.86), P < 0.05]; while, there was obviously no change by corticosteroid therapy in IgAN patients whose eGFR were less than 60 ml/min/1.73 m² and whose proteinuria were less than 1.0 g/day.

CONCLUSION

Our results suggested that steroid therapy was especially effective for IgAN patients whose eGFR was less than 60 ml/min/1.73 m² and whose proteinuria was more than 1.0 g/day.

Tonsillar immunology in IgA nephropathy

As one of the most common types of primary glomerulonephritis, IgA nephropathy (IgAN) is often characterized by the immunoprecipitation of IgA1 in mesangial area. In clinical terms, IgA nephropathy can be treated with tonsillectomy or conservative treatment, basing on modern immunology knowledge in which the mucosa immune system (MIS), especially the widely distributed mucosa-associated lymphoid tissue (MALT) is focused accordingly In terms of basic research, IgAN has been shown correlated with multiple factors, including serum Gd-IgA1 level, IgA-IgG immunity, tonsil-associated bacteria,GADD34, CX3CR1, FOXP3 and the expression of other related intrinsic immune antibody. Therefore, it is reasonable there could be mutual correlation among IgAN-associated factors. The purpose of this study is to review the new progress on the treatment and prevention of IgAN diseases and related mechanisms of IgAN tonsils, which will be of great significance for the therapy of IgAN patients.

Specific strains of Streptococcus mutans, a pathogen of dental caries, in the tonsils, are associated with IgA nephropathy

Streptococcus mutans is known to be a major causative agent of dental caries, and strains expressing the cell surface collagen-binding Cnm protein contribute to the development of several systemic diseases. A relationship between tonsillar immunity and glomerulonephritis has been recognized in IgA nephropathy (IgAN), and specific pathogens may have effects on tonsillar immunity (mucosal immunity). Here, we present findings showing a relationship between the presence of Cnm-positive S. mutans strains in the tonsils of IgAN patients and IgAN condition/pathogenesis. Analyses of tonsillar specimens obtained from patients with IgAN (n = 61) and chronic tonsillitis (controls; n = 40) showed that the Cnm protein-positive rate was significantly higher in IgAN patients. Among IgAN patients, the tonsillar Cnm-positive group (n = 15) had a significantly higher proportion of patients with high urinary protein (>1.5 g/gCr) and lower serum albumin level than the Cnm-negative group (n = 46). Additionally, Cnm protein and CD68, a common human macrophage marker, were shown to be merged in the tonsils of IgAN patients. These findings suggest that Cnm-positive S. mutans strains in the tonsils may be associated with severe IgAN.

Salivary microbial analysis of Chinese patients with immunoglobulin A nephropathy

Microbiota plays an important role in immunoglobulin A (IgA) nephropathy (IgAN); however, the pathogenesis, early diagnosis, and treatment of IgAN remain unclear. The aim of the present study was to develop a preliminary model based on saliva‑specific microbes and clinical indicators to facilitate the early diagnosis of IgAN and obtain insights into its treatment. The microbial profile of the saliva of 28 IgAN patients and 25 healthy control subjects was investigated using high‑throughput sequencing and bioinformatics analyses of the V4 region in microbial 16S rRNA genes. IgAN patients and healthy subjects did not differ significantly in α‑diversity indices (Chao1 and Shannon index) or phylum composition. At the genus level, however, Granulicatella was significantly less abundant in healthy individuals than in IgAN patients, while Prevotella and Veillonella were significantly more abundant in the healthy subjects than in IgAN patients (P<0.05 and P<0.01, respectively). Correlation analysis between biochemical indicators and operational taxonomic units (OTUs) revealed that the glomerular filtration rate was positively correlated with OTU86 and OTU287 at P<0.05, positively correlated with OTU165 at P<0.001, and negatively correlated with OTU455 at P<0.05. The serum creatinine index was negatively correlated with OTU287 at P<0.05 and negatively correlated with OTU165 at P<0.001. The pathological changes were positively correlated with OTU255 at P<0.05, OTU200 at P<0.01, and OTU455 and OTU75 at P<0.001, and negatively correlated with OTU86, OTU287, and OTU788 at P<0.05 and with OTU165 at P<0.01. The differences between Chinese IgAN patients and healthy subjects in terms of OTUs and biochemical indicators were analyzed and a mathematical model to facilitate the clinical diagnosis of IgAN was established.

Comprehensive microbiome analysis of tonsillar crypts in IgA nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is the most prevalent primary chronic glomerular disease, in which the mucosal immune response elicited particularly in the tonsils or intestine has been estimated to be involved in the development of the disease. To explore the relationship between IgAN and bacterial flora in the tonsils, we conducted a comprehensive microbiome analysis.

Methods

We enrolled 48 IgAN patients, 21 recurrent tonsillitis (RT) patients without urine abnormalities and 30 children with tonsillar hyperplasia (TH) who had undergone tonsillectomy previously. Genomic DNA from tonsillar crypts of each patient was extracted, and V4 regions of the 16S ribosomal RNA gene were amplified and analysed using a high-throughput multiplexed sequencing approach. Differences in genus composition among the three study groups were statistically analysed by permutational multivariate analysis of variance and visualized by principal component analysis (PCA).

Results

Substantial diversity in bacterial composition was detected in each sample. Prevotella spp., Fusobacterium spp., Sphingomonas spp. and Treponema spp. were predominant in IgAN patients. The percentage of abundance of Prevotella spp., Haemophilus spp., Porphyromonas spp. and Treponema spp. in IgAN patients was significantly different from that in TH patients. However, there was no significant difference in the percentage of abundance of any bacterial genus between IgAN and RT patients. PCA did not distinguish IgAN from RT, although it discriminated TH. No significant differences in microbiome composition among the groups of IgAN patients according to clinicopathological parameters were observed.

Conclusions

Similar patterns of bacteria are present in tonsillar crypts of both IgAN and RT patients, suggesting that the host response to these bacteria might be important in the development of IgAN.

Campylobacter rectus in the Oral Cavity Correlates with Proteinuria in Immunoglobulin A Nephropathy Patients

BACKGROUND

Periodontitis-related pathogens, such as Campylobacter or Treponema species, have recently been shown to be associated with immunoglobulin A nephropathy (IgAN). Some strains of Streptococcus mutans, a major pathogen of dental caries, harbour the cnm gene that encodes a collagen-binding protein (Cnm). This has also been demonstrated to be associated with urinary protein levels in IgAN patients.

OBJECTIVES

The purpose of the present study was to analyse the association of IgAN with C. rectus, Treponema denticola and cnm-positive S. mutans in the oral cavity of humans.

METHODS

The presence of C. rectus, T. denticola and cnm-positive S. mutans strains in saliva samples of 117 IgAN patients and 56 healthy controls was evaluated by PCR, and the subjects' clinical parameters were analysed.

RESULTS

C. rectus was significantly more prevalent in the IgAN group than in the control group (p < 0.05). The C. rectus-positive group was significantly associated with proteinuria in the IgAN group (p < 0.05). In addition, the C. rectus-positive and cnm-positive S. mutans group was shown to be more closely associated with urinary protein levels than the other groups (p < 0.0083).

CONCLUSION

Our results suggest that harbouring C. rectus in the oral cavity could be associated with proteinuria in IgAN patients.

Toll-Like Receptor 9 Stimulation Induces Aberrant Expression of a Proliferation-Inducing Ligand by Tonsillar Germinal Center B Cells in IgA Nephropathy

The TNF family member a proliferation-inducing ligand (APRIL; also known as TNFSF13), produced by myeloid cells, participates in the generation and survival of antibody-producing plasma cells. We studied the potential role of APRIL in the pathogenesis of IgA nephropathy (IgAN). We found that a significant proportion of germinal centers (GCs) in tonsils of patients with IgAN contained cells aberrantly producing APRIL, contributing to an overall upregulation of tonsillar APRIL expression compared with that in tonsils of control patients with tonsillitis. In IgAN GC, antigen-experienced IgD^-CD38^+/-CD19⁺ B cells expressing a switched IgG/IgA B cell receptor produced APRIL. Notably, these GC B cells expressed mRNA encoding the common cleavable APRIL-α but also, the less frequent APRIL-δ/ζ mRNA, which encodes a protein that lacks a furin cleavage site and is, thus, the uncleavable membrane-bound form. Significant correlation between TLR9 and APRIL expression levels existed in tonsils from patients with IgAN. In vitro, repeated TLR9 stimulation induced APRIL expression in tonsillar B cells from control patients with tonsillitis. Clinically, aberrant APRIL expression in tonsillar GC correlated with greater proteinuria, and patients with IgAN and aberrant APRIL overexpression in tonsillar GC responded well to tonsillectomy, with parallel decreases in serum levels of galactose-deficient IgA1. Taken together, our data indicate that antibody disorders in IgAN associate with TLR9-induced aberrant expression of APRIL in tonsillar GC B cells.

Presence of Streptococcus mutans strains harbouring the cnm gene correlates with dental caries status and IgA nephropathy conditions

Streptococcus mutans is a major pathogen of human dental caries. Strains harbouring the cnm gene, which encodes Cnm, a collagen-binding protein, contribute to the development of several systemic diseases. In this study, we analysed S. mutans strains isolated from the oral cavity of immunoglobulin (Ig)A nephropathy (IgAN) patients to determine potential relationships between cnm and caries status as well as IgAN conditions. Saliva specimens were collected from 109 IgAN patients and the cnm status of isolated S. mutans strains was determined using PCR. In addition, the dental caries status (decayed, missing or filled teeth [DMFT] index) in patients who agreed to dental consultation (n = 49) was evaluated. The DMFT index and urinary protein levels in the cnm-positive group were significantly higher than those in the cnm-negative group (p < 0.05). Moreover, the urinary protein levels in the high DMFT (≥15) group were significantly higher than those in the low DMFT (<15) group (p < 0.05). Our results show that isolation of cnm-positive S. mutans strains from the oral cavity may be associated with urinary protein levels in IgAN patients, especially those with a high dental caries status.

Serum Uric Acid Level Predicts Progression of IgA Nephropathy in Females but Not in Males

Background

Immunoglobulin A nephropathy (IgAN) is one of most common forms of glomerulonephritis. At this point, the clinical impact of hyperuricemia on IgAN is not clear. The aim of the present study was to explore the clinical impact of hyperuricemia on the progression of IgAN.

Study Design

Multicenter retrospective cohort study.

Setting & Participants

935 IgAN patients who were diagnosed by kidney biopsy at Osaka University Hospital, Osaka General Hospital, and Osaka Rosai Hospital. were included in this study.

Predictor

Uric acid levels at renal biopsy.

Outcomes

The outcome of interest was the time from the kidney biopsy to the time when a 50% increase in the baseline serum creatinine level was observed, which was defined as "progression".

Measurements

The baseline characteristics according to the kidney biopsy at the time of diagnosis were collected from the medical records, and included age, gender, body mass index, hypertension, diabetes (use of antidiabetic drugs), serum levels of creatinine, urinary protein, smoking status, RAAS blockers and steroid therapy.

Results

An elevated serum uric acid level was an independent risk factor for progression in female patients (per 1.0 mg/dL, multivariate-adjusted incident rate ratio 1.33 [95% confidence interval 1.07, 1.64], P = 0.008) but not in male patients (1.02 [0.81, 1.29], P = 0.855). To control a confounding effect of renal function on an association between serum uric acid level and progression in female patients, age- and serum creatinine-matched and propensity score-matched analyses were performed, and these results also supported the effect by uric acid on kidney disease progression independent of basal kidney function.

Limitations

A cohort analyzed retorospectively.

Conclusions

This study revealed that an elevated uric acid level was an independent risk factor for ESKD in female IgAN patients. Therefore, uric acid might be a treatable target in female IgAN patients.

IFI27 Is a Useful Genetic Marker for Diagnosis of Immunoglobulin A Nephropathy and Membranous Nephropathy Using Peripheral Blood

Diagnosis of chronic glomerulonephritis (CGN) depends primarily on renal biopsy, which is expensive and requires hospitalization, creating a demand for noninvasive diagnostic method for this disease. We used DNA microarray analysis to search for genes whose expression levels in peripheral blood mononuclear cells (PBMCs) could distinguish between patients with CGN and healthy volunteers (HVs). We selected immunoglobulin A nephropathy (IgAN) and membranous nephropathy (MN) as typical forms of CGN. The mRNA level of the gene encoding interferon (IFN)-alpha-inducible protein 27, IFI27, which is preferentially expressed in podocytes of glomeruli, was lower in PBMCs of IgAN and MN patients than in those of HVs. This result was confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Moreover, qRT-PCR analysis revealed that the IFI27 mRNA level was reduced in PBMCs of patients with other types of chronic glomerulonephritis. IFI27 immunohistochemical staining of biopsied specimens also confirmed reduced expression of IFI27 protein in IgAN and MN patients. Based on these results, we propose that IFI27 could serve as a noninvasive diagnostic marker for CGNs using peripheral blood.

Decreased expression of follicular dendritic cell-secreted protein correlates with increased immunoglobulin A production in the tonsils of individuals with immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is characterized by a qualitative abnormality of IgA in the circulation and IgA deposition in the renal mesangium. Recent research has indicated that pathogenic IgA may originate from affected tonsils. Follicular dendritic cell-secreted protein (FDC-SP), a small novel secretory protein that may regulate the induction of B-cell responses, has been suggested to control IgA production. Given this background, this study investigated the expression of FDC-SP and its correlation with IgA production in the tonsils of IgAN patients. Immunohistochemistry and reverse transcription-polymerase chain reaction were used to compare the expression of FDC-SP in the tonsils of IgAN patients with tonsillitis and of non-IgAN patients with chronic tonsillitis. The location of FDC-SP in tonsillar tissue was confirmed by double immunofluorescence. We found that FDC-SP expression significantly decreased and was correlated negatively with enhanced IgA production in the tonsils of IgAN patients. FDC-SP secreted by follicular dendritic cells may act on germinal center B cells and participate in the modulation of IgA generation in the tonsils. Our study demonstrated that FDC-SP may be involved in IgA production in the tonsils of IgAN patients, making this protein an attractive candidate immunomodulator, and highlighting a promising strategy for therapeutic intervention in IgAN.

Salivary Microbiota Associated with Immunoglobulin A Nephropathy

This study aimed at investigating the salivary microbiota of 28 patients affected by immunoglobulin A nephropathy (IgAN). Fourteen healthy volunteers (HC) were used as control. Compared to HC, the number of some cultivable bacteria groups (e.g., total anaerobes) significantly (P < 0.05) decreased in the salivary samples of IgAN patients. Total bacteria from salivary samples of IgAN patients and HC subjects were analyzed by pyrosequencing of 16S rRNA gene. Paired t test showed no significant (P > 0.05) differences of alpha-diversity parameters (OTU, ACE, Chao1, and Shannon index) between the salivary samples of HC and IgAN patients. The difference for the community structure was further analyzed using three phylogeny-based beta-diversity measures. Compared to HC, the ratio between Firmicutes/Proteobacteria markedly decreased in IgAN patients. Gemella haemolysins, Granulicatella adiacens, and Veillonella parvula were positively associated (P < 0.05) with HC. Within the phylum Bacteroidetes, Prevotella species (Prevotella nigrescens, Prevotella intermedia, Prevotella pallens, and Prevotella salivae) were the highest in HC. The only exception was for Prevotella aurantiaca. Compared to HC, the percentage of abundance of some species, belonging to Pasteurellaceae family (e.g., Haemophylus parainfluenzae), increased in IgAN patients. Fusobacteriaceae (Fusobacterium) and Corynebacterium sp. also differed between the salivary samples of HC and IgAN patients.

The Influence and Role of Microbial Factors in Autoimmune Kidney Diseases: A Systematic Review

A better understanding of the pathophysiology of autoimmune disorders is desired to allow tailored interventions. Despite increased scientific interest a direct pathogenic factor in autoimmune renal disease has been described only in a minority like membranous nephropathy or ANCA-associated vasculitis. Nonetheless the initial step leading to the formation of these antibodies is still obscure. In this review we will focus on the possible role of microbial factors in this context. Staphylococcus aureus may be a direct pathogenetic factor in granulomatosis with polyangiitis (GPA). Chronic bacterial colonization or chronic infections of the upper respiratory tract have been proposed as trigger of IgA vasculitis and IgA nephropathy. Interventions to remove major lymphoid organs, such as tonsillectomy, have shown conflicting results but may be an option in IgA vasculitis. Interestingly no clear clinical benefit despite similar local colonization with bacterial strains has been detected in patients with IgA nephropathy. In systemic lupus erythematosus injection of bacterial lipopolysaccharide induced progressive lupus nephritis in mouse models. The aim of this review is to discuss and summarize the knowledge of microbial antigens in autoimmune renal disease. Novel methods may provide insight into the involvement of microbial antigens in the onset, progression, and prognosis of autoimmune kidney disorders.

Distribution of Streptococcus mutans strains with collagen-binding proteins in the oral cavity of IgA nephropathy patients

BACKGROUND

IgA nephropathy (IgAN) is the most common primary chronic glomerulonephritis; however, its precise initiating pathogenesis remains unclear. Streptococcus mutans is a major pathogen of human dental caries. S. mutans strains with the cnm gene encoding Cnm, a collagen-binding protein, have been reported to contribute to the development of systemic diseases. However, the contribution of S. mutans with Cnm in the development of IgAN has not been reported. The aim of this study was to investigate the prevalence of cnm-positive S. mutans in IgAN patients and clarify the effects of cnm-positive S. mutans on the histological pathology of IgAN.

METHODS

We identified the cnm gene in S. mutans isolated in saliva specimens, which were collected from IgAN patients (n = 53) and control subjects (n = 50). We evaluated the collagen-binding properties of S. mutans in IgAN patients and controls. The clinical parameters and histological scores were also assessed in IgAN patients.

RESULTS

The rates of S. mutans isolation in IgAN and control groups were 84.0 and 84.9 %, respectively, not significantly dfferent. cnm-positive strains were significantly more prevalent in the IgAN group than in controls (32.1 vs. 14.0 %, p < 0.05). With regard to collagen-binding assays, the binding rates of cnm-positive strains were significantly higher in the IgAN group than in controls (96.6 vs. 30.0, p < 0.05). In addition, the segmental glomerulosclerosis scores were significantly higher in cnm-positive patients with IgAN than in cnm-negative patients with IgAN (0.94 vs. 0.57, p < 0.05).

CONCLUSION

cnm-positive S. mutans strains are potentially associated with the pathogenesis of IgAN.

Periodontitis: Tip of the iceberg in chronic kidney disease

The prevalence of chronic kidney disease (CKD) is constantly escalating not only in industrialized countries but throughout the world. It is of major significance because of to its high morbidity and mortality. Strategies to tackle this worldwide health problem include identification of its associated risk factors, comorbidities, and complications as well as proper management to handle all the pertinent issues. Periodontal disease, a treatable infectious state of the dental supporting tissues, is common in CKD patients. Its association with CKD is believed to be in a reciprocal or bidirectional fashion and has been massively studied. This paper, therefore, aims to review the recent evidence pertaining to the association between periodontal disease and a variety of renal illnesses. Most of the current evidence was collected from cross-sectional studies and clinical trials. There is substantial evidence indicating that periodontal disease contributes markedly to the chronic systemic inflammatory burden, leading to cardiovascular and cerebrovascular complications, the principal causes of death among chronic renal disease patients. Furthermore, several studies demonstrated that proper periodontal intervention could help improve systemic inflammation and even nutritional status among CKD patients, resulting in a better quality of life. Suggestions have been made that periodontal disease should be diagnosed early, and managed and controlled to, at least, eradicate a source of inflammation in this population. Awareness of such an important issue should be increased in the relevant medical personnel.

Association between plasminogen activator inhibitor-1 4G/5G gene polymorphism and immunoglobulin A nephropathy susceptibility

The association between plasminogen activator inhibitor-1 (PAI-1) 4 G/5 G gene polymorphism and immunoglobulin A nephropathy (IgAN) risk is still controversial. A meta-analysis was performed to evaluate the association between PAI-1 4 G/5 G gene polymorphism and IgAN susceptibility. A predefined literature search and selection of eligible relevant studies were performed to collect data from electronic database. Four articles were identified for the analysis of association between PAI-1 4 G/5 G gene polymorphism and IgAN risk. 4 G allele was not associated with IgAN susceptibility in overall populations and in Asians. Furthermore, 4 G/4 G and 5 G/5 G genotype were not associated with IgAN for overall populations, Asians. In conclusion, PAI-1 4 G/5 G gene polymorphism was not associated with IgAN risk in overall populations and in Asians. However, more studies should be performed in the future.