Integrative analysis of systemic lupus erythematosus biomarkers: Role of fecal hsa-mir-223-3p and gut microbiota in transkingdom dynamics.

Systemic lupus erythematosus (SLE) involves a florid set of clinical manifestations whose autoreactive origin is characterized by an overactivation of the immune system and the production of a large number of autoantibodies. Because it is a complex pathology with an inflammatory component, its pathogenesis is not yet fully understood, assuming both genetic and environmental predisposing factors. Currently, it is known that the role of the human microbiome is crucial in maintaining the transkingdom balance between commensal microorganisms and the immune system. In the present work we study the intestinal microbiota of Argentine patients with different stages of SLE receiving or not different treatments. Microbiota composition and fecal miRNAs were assessed by 16 S sequencing and qPCR. hsa-miR-223-3p, a miRNA involved in several inflammation regulation pathways, was found underexpressed in SLE patients without immunosuppressive treatment. In terms of microbiota there were clear differences in population structure (Weighted and Unweighted Unifrac distances, p-value <0.05) and core microbiome between cases and controls. In addition, Collinsella, Bifidobacterium, Streptococcus genera and aromatics degradation metabolisms were overrepresented in the SLE group. Medical treatment was also determinant as several microbial metabolic pathways were influenced by immunosuppressive therapy. Particularly, allantoin degradation metabolism was differentially expressed in the group of patients receiving immunosuppressants. Finally, we performed a logistic regression model (LASSO: least absolute shrinkage and selection operator) considering the expression levels of the fecal hsa-miR223-3p; the core microbiota; the differentially abundant bacterial taxa and the differentially abundant metabolic pathways (p<0.05). The model predicted that SLE patients could be associated with greater relative abundance of the formaldehyde oxidation pathway (RUMP_PWY). On the contrary, the preponderance of the ketodeoxyoctonate (Kdo) biosynthesis and activation route (PWY_1269) and the genera Lachnospiraceae_UCG_004, Lachnospira, Victivallis and UCG_003 (genus belonging to the family Oscillospiraceae of the class Clostridia) were associated with a control phenotype. Overall, the present work could contribute to the development of integral diagnostic tools for the comprehensive phenotyping of patients with SLE. In this sense, studying the commensal microbial profile and possible pathobionts associated with SLE in our population proposes more effective and precise strategies to explore possible treatments based on the microbiota of SLE patients.

A Two-Time Point Analysis of Gut Microbiota in the General Population of Buenos Aires and Its Variation Due to Preventive and Compulsory Social Isolation During the COVID-19 Pandemic.

The COVID-19 pandemic poses a great challenge to global public health. The extraordinary daily use of household disinfectants and cleaning products, social distancing and the loss of everyday situations that allow contact between individuals, have a direct impact on the transfer of microorganisms within the population. Together, these changes, in addition to those that occur in eating habits, can affect the composition and diversity of the gut microbiota. A two-time point analysis of the fecal microbiota of 23 Metropolitan Buenos Aires (BA) inhabitants was carried out, to compare pre-pandemic data and its variation during preventive and compulsory social isolation (PCSI) in 2020. To this end, 23 healthy subjects, who were previously studied by our group in 2016, were recruited for a second time during the COVID-19 pandemic, and stool samples were collected from each subject at each time point (n = 46). The hypervariable region V3-V4 of the 16S rRNA gene was high-throughput sequenced. We found significant differences in the estimated number of observed features (p < 0.001), Shannon entropy index (p = 0.026) and in Faith phylogenetic diversity (p < 0.001) between pre-pandemic group (PPG) vs. pandemic group (PG), being significantly lower in the PG. Although no strong change was observed in the core microbiota between the groups in this study, a significant decrease was observed during PCSI in the phylum Verrucomicrobia, which contributes to intestinal health and glucose homeostasis. Microbial community structure (beta diversity) was also compared between PPG and PG. The differences observed in the microbiota structure by unweighted UniFrac PCoA could be explained by six differential abundant genera that were absent during PCSI. Furthermore, putative functional genes prediction using PICRUSt infers a smaller predicted prevalence of genes in the intestinal tryptophan, glycine-betaine, taurine, benzoate degradation, as well as in the synthesis of vitamin B12 during PCSI. This data supports the hypothesis that the microbiome of the inhabitants of BA changed in the context of isolation during PCSI. Therefore, these results could increase the knowledge necessary to propose strategic nutraceutical, functional food, probiotics or similar interventions that contribute to improving public health in the post-pandemic era.

Getting to Know the Gut Microbial Diversity of Metropolitan Buenos Aires Inhabitants.

In recent years, the field of immunology has been revolutionized by the growing understanding of the fundamental role of microbiota in the immune system function. The immune system has evolved to maintain a symbiotic relationship with these microbes. The aim of our study was to know in depth the uncharacterized metagenome of the Buenos Aires (BA) city population and its metropolitan area, being the second most populated agglomeration in the southern hemisphere. For this purpose, we evaluated 30 individuals (age: 35.23 ± 8.26 years and BMI: 23.91 ± 3.4 kg/m2), from the general population of BA. The hypervariable regions V3-V4 of the bacterial 16S gene was sequenced by MiSeq-Illumina system, obtaining 47526 ± 4718 sequences/sample. The dominant phyla were Bacteroidetes, Firmicutes, Proteobacteria, Verrucomicrobia, and Actinobacteria. Additionally, we compared the microbiota of BA with other westernized populations (Santiago de Chile, Rosario-Argentina, United States-Human-microbiome-project, Bologna-Italy) and the Hadza population of hunter-gatherers. The unweighted UniFrac clustered together all westernized populations, leaving the hunter-gatherer population from Hadza out. In particular, Santiago de Chile's population turns out to be the closest to BA's, principally due to the presence of Verrucomicrobiales of the genus Akkermansia. These microorganisms have been proposed as a hallmark of a healthy gut. Finally, westernized populations showed more abundant metabolism related KEEG pathways than hunter-gatherers, including carbohydrate metabolism (amino sugar and nucleotide sugar metabolism), amino acid metabolism (alanine, aspartate and glutamate metabolism), lipid metabolism, biosynthesis of secondary metabolites, and sulfur metabolism. These findings contribute to promote research and comparison of the microbiome in different human populations, in order to develop more efficient therapeutic strategies for the restoration of a healthy dialogue between host and environment.

Functional characterization of TLR4 +3725 G/C polymorphism and association with protection against overweight.

Subclinical low-grade systemic inflammation has been associated with obesity, insulin resistance and metabolic syndrome (MS). Recent studies have highlighted the role of gut microbiota in these disorders. The toll-like receptor 4 (TLR4) plays a key role in the innate immune response activation. We studied two polymorphisms (+3725G/C and 11350G/C) in the 3' untranslated region (3'UTR) of the TLR4 gene that may alter its expression and their association with metabolic disorders related to systemic inflammation. We cloned the 3'UTR into a luciferase reporter system and compared wild-type 3'UTR (WT) and +3725C variant (MUT) constructs luciferase activities. MUT construct reduced the reporter gene activity by 30% compared to WT (P = 0.0001). To evaluate the association between these polymorphisms with biochemical and clinical overweight related variables, we conducted a population cross-sectional study in 966 men of Argentine general population. Considering smoking as a confounding variable that causes systemic inflammation, we studied these possible effects in both, smokers and nonsmokers. The 11350G/C polymorphism was not detected in our sample whereas the CC genotype of +3725 polymorphism was associated with lean subjects (p = 0.011) and higher Adiponectin levels (p = 0.021). Subjects without any NCEP/ATP III MS component were associated with this genotype as well (p = 0.001). These results were strengthened in nonsmokers, in which CC genotype was associated with lean subjects (p = 0.003) and compared with G carriers showed significantly lower BMI (25.53 vs. 28.60 kg/m2; p = 0.023) and waist circumference (89.27 vs. 97.51 cm; p = 0.025). None of these associations were found in smokers. These results showed that +3725C variant has a functional effect down-regulating gene expression and it could be considered as a predictive factor against overweight, particularly in nonsmokers. Considering the role of TLR4 in inflammation, these findings would suggest that the presence of +3725C variant could predict a lower prevalence of chronic metabolic disorders.