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Objective This study systematically aims to evaluate the salivary microbiome in patients with primary Sjögren's syndrome (pSS) using 16S rRNA sequencing approach. Methods DNA isolation and 16S rRNA sequencing was performed on saliva of 37 pSS and 35 control (CC) samples on HiSeq 2500 platform. 16S rRNA sequence analysis was performed independently using two popular computational pipelines, QIIME and less operational taxonomic units scripts (LoTuS). Results There were no significant changes in the alpha diversity between saliva of patients and controls. However, four genera including Bifidobacterium, Lactobacillus, Dialister and Leptotrichia were found to be differential between the two sets, and common between both QIIME and LoTuS analysis pipelines (Fold change of 2 and p < .05). Bifidobacterium, Dialister and Lactobacillus were found to be enriched, while Leptotrichia was significantly depleted in pSS compared to the controls. Exploration of microbial diversity measures (Chao1, observed species and Shannon index) revealed a significant increase in the diversity in patients with renal tubular acidosis. An opposite trend was noted, with depletion of diversity in patients with steroids. Conclusion Our analysis suggests that while no significant changes in the diversity of the salivary microbiome could be observed in Sjögren's syndrome compared to the controls, a set of four genera were significantly and consistently differential in the saliva of patients with pSS. Additionally, a difference in alpha diversity in patients with renal tubular acidosis and those on steroids was observed.

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Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease.1 The spectrum of presentation varies from minor skin manifestation to life-threatening disease.2 Among the manifestations, renal and central nervous system involvement are major causes of morbidity and mortality. Renal involvement is a major complication, occurring in approximately 50% of patients.2 Patients with nephritis are at higher risk for progressive renal insufficiency.3 There is over 3 decades of clinical experience with cyclophosphamide (CYC)

BackgroundDysbiosis has been hypothesized to play a role in the pathogenesis of autoimmune disease. Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by sicca symptoms resulting from salivary and lacrimal gland dysfunction. This could result in dysbiosis of oral cavity. At the same time, dysbiosis could also be hypothesized to have a causative role. Previous studies using culture dependent approaches have provided evidence for altered oral microflora in pSS. However culture dependent approaches have caveats which have been abrogated with the advent of culture independent methodologies.ObjectivesTo systematically evaluate the microbiome in the oral cavity in patients with pSS using a culture independent shotgun metagenome sequencingMethodsCases included adult patients fulfilling criteria for pSS by American-European Consensus Group (AECG) 2002 or American College of Rheumatology (ACR) 2012 classification criteria, while controls included healthy volunteers. Neither cases nor controls had oral disease or other obvious co morbidities, recent antibiotic intake. Individuals who had chronic intake of alcohol and tobacco were excluded. Saliva was collected in sterile tubes with buffer. DNA was extracted using Qiagen DNA isolation kit. Libraries were prepared and sequenced on Illumina Hiseq 2500 (Illumina Inc, USA). Reads mapping to the Human reference genome (hg19) were tagged. Reads were further reference mapped to the core oral microbiome sequences available from the Human Oral Microbiome Database. The read counts were normalized for the input reads as well as the genome size of the organism. A fold change (FC) of >2 and p value <0.05 by Student's t-test was considered significant.ResultsOral microbiome of 13 pSS patients and 12 healthy controls were analysed. Organisms significantly enriched in pSS included the following (FC; p-value) Capnocytophaga (2.09; 0.01), Dialister (2.13; 0.02), Fusobacterium (2.84; 0.04), Helicobacter (4.83; 0.03), Streptococcus (3.33; 0.01) and Veilonella (3.82; 0.006) spp. A paucity of Pseudomonas (8.9;0.03) spp. was noted compared to controls.ConclusionsA distinct subset of organisms was enriched in the oral cavity of patients with pSS. This subset includes Capnocytophaga previously shown to be associated with the pathogenesis and T cell activation in pSS.ReferencesAlmståhl A, Kroneld U, Tarkowski A, Wikström M. Oral microbial flora in Sjögren's syndrome. J Rheumatol. 1999;26:110-4.Almståhl A, Wikström M, Kroneld U. Microflora in oral ecosystems in primary Sjögren's syndrome. J Rheumatol. 2001;28:1007-13.Szymula A, Rosenthal J, Szczerba BM, Bagavant H, Fu SM, Deshmukh US.T cell epitope mimicry between Sjögren's syndrome Antigen A (SSA)/Ro60 and oral, gut, skin and vaginal bacteria. Clin Immunol. 2014;152:1-9.AcknowledgementsAuthors acknowledge colleagues at Department of Clinical Immunology and Rheumatology, CMC Vellore for help in recruiting volunteers for the study. Authors VS and SS acknowledge funding from CSIR, India through Grant OLP1105 (EMPOWER).Disclosure of ...