Poster Topical Area: Nutritional Immunology
Location: Hall D
Poster Board Number: 853
Globally, active tuberculosis is the ninth leading cause of death. Prior studies indicate that inflammation has a dual role in mediating both the pathogenesis of and human host immune response against Mycobacterium tuberculosis. Therefore, understanding key immunomodulatory human host factors (including vitamin D, the gut microbiome) is important in mitigating tuberculosis (TB) transmission and the burden from active TB disease. As an initial step towards understanding these complex associations, we investigated the gut microbiome composition among patients with ATBD at ATT initiation and assessed its association with vitamin D status in a rural setting in India.
In this cross-sectional study, outpatients (n=32) with ATBD (Xpert MTB/RIF-confirmed) were enrolled at initiation of ATT at a hospital. Rectal swab samples were assayed by 16S rRNA sequencing (Illumina MiSeq; V3-V4 hypervariable regions). Serum 25-hydroxyvitamin D (25[OH]D) concentrations were assessed by liquid chromatography mass spectrometry and categorized by cut-off values (<25, <40, <50, <75 nmol/L) and quintiles.
Median serum 25(OH)D concentration was 46.0 nmol/L (IQR 36.1, 60.7). Overall, the majority of identified sequences were from four phyla: Firmicutes (median 46.1% [IQR 36.5, 51.6]), Bacteroidetes (32.4% [24.5, 40.4]), Proteobacteria (9.3% [6.1, 55.3]), and Actinobacteria (2.1% [1.3, 4.2]). The median Firmicutes:Bacteroidetes ratio was 1.3 (IQR 1.0, 1.8). Mean alpha diversity indices were: Shannon (5.1 [SD 1.1]), and Chao1 (1023.6 [350.5]); the median Simpson index was 0.9 (IQR 0.9, 1.0). Alpha diversity indices did not differ by vitamin D status (cut-off values and quintiles; all p>0.05). CRP was inversely correlated (β -2.57 [SE 1.10]; p<0.05) with 25(OH)D, adjusting for age and sex.
Among this population of adult outpatients with ATBD, the relative abundance of identified operational taxonomic units were predominantly in the Bacteroidetes and Firmicutes phyla, which is consistent with previous literature among healthy populations. Further longitudinal and mechanistic studies are needed to assess the roles of vitamin D and the human microbiome in the context of inflammation and ATBD, particularly in resource-limited environments.
Research reported in this publication was supported by Cornell University (Division of Nutritional Sciences), Arogyavaram Medical Centre, and the National Institutes of Health (National Institute of Diabetes and Digestive and Kidney Diseases; T32-DK007158 award; for E.A.Y.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) or the National Institutes of Health.
Ithaca, New York