LAUSR

Both human and animal studies suggest that the gut microbe-derived metabolite Trimethylamine N-oxide (TMAO) is strongly associated with several autoimmune disease including Rheumatoid arthritis and psoriatic arthropathy. TMAO has been previously studied as a discriminator between SLE patients and healthy volunteers with higher reported TMAO levels in the SLE group; this suggests that gut microbiota may enhance TMAO generation in response to disease severity. The aim of this study was to investigate the diagnostic and prognostic validity of TMAO as a potential biomarker in lupus nephritis patients. To the best of our knowledge this is the first study to investigate the gut microbe-derived metabolite Trimethylamine N-oxide (TMAO) in patients with lupus nephritis correlating to the criteria of disease severity. A total of 90 subjects were included in this cross-sectional study and divided into 3 equivalent groups; group I (lupus nephritis patients (LN)), group II (SLE patients without nephritis (NN)), and group III (healthy controls). Serum Trimethylamine Levels were assessed, compared between the study groups and correlated to the clinical, laboratory and Histo-pathological criteria obtained from kidney biopsies of the included patients. Unpredictably, TMAO levels were found to be significantly higher in healthy controls compared to the total SLE population (p=0.003), and to LN, and NN groups individually (p=0.01). There was no significant statistical difference of TMAO levels between (NN) and (LN) patients (p=0.62). TMAO levels correlated to Anti-dsDNA titres (p=0.02) and Red Blood Cells count (p=0.02) among LN patients while they haven’t shown any correlations to the other studied clinical-laboratory and histopathological factors. Contrary to the results of the previous studies, TMAO levels were found to be higher in healthy controls rather than SLE patients and did not discriminate between LN and NN patients as well as did not show significant correlation to most studied criteria of disease severity. The possible confounding effect of the dietary pattern and ingested drugs on the gut microbiome underestimate the diagnostic and prognostic utility of TMAO as a potential marker in different diseases. Further studies considering the dietary pattern of the included patients are still warranted.