Pulmonary Arterial Hypertension Affects the Rat Gut Microbiome

We have analysed whether pulmonary arterial hypertension (PAH) alters the rat faecal microbiota. Wistar rats were injected with the VEGF receptor antagonist SU5416 (20 mg/kg s.c.) and followed for 2 weeks kept in hypoxia (10% O2, PAH) or injected with vehicle and kept in normoxia (controls). Faecal samples were obtained and microbiome composition was determined by 16S rRNA gene sequencing and bioinformatic analysis. No effect of PAH on the global microbiome was found (α- or β-diversity). However, PAH-exposed rats showed gut dysbiosis as indicated by a taxonomy-based analysis. Specifically, PAH rats had a three-fold increase in Firmicutes-to-Bacteroidetes ratio. Within the Firmicutes phylum, there were no large changes in the relative abundance of the bacterial families in PAH. Among Bacteroidetes, all families were less abundant in PAH. A clear separation was observed between the control and PAH clusters based on short chain fatty acid producing bacterial genera. Moreover, acetate was reduced in the serum of PAH rats. In conclusion, faecal microbiota composition is altered as a result of PAH. This misbalanced bacterial ecosystem might in turn play a pathophysiological role in PAH by altering the immunologic, hormonal and metabolic homeostasis.This study is supported by grants from Mineco (SAF2014-55399-R, SAF2014-55523-R, SAF2016-77222 and SAF2017-84494-C2-1R), Instituto de Salud Carlos III (PI15/01100), with funds from the European Union (Fondo Europeo de Desarrollo Regional FEDER). M.C., G.M-P. and S.E-R. are funded by Universidad Complutense, Fondo de Garantía Juvenil (Comunidad de Madrid) and Ciberes grant with funds from Fundación Contra la Hipertensión Pulmonar, a FPU grant from Ministerio de Educación, respectively. J.L.I.G is a CNIC IPP COFUND Fellow and has received funding from the People Programme (Marie Curie Actions) of the FP7/2007-2013 under REA grant agreement n° 600396. The CNIC is supported by MEIC-AEI and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (MEIC award SEV-2015-0505)

Early-life gut dysbiosis linked to juvenile mortality in ostriches

Imbalances in the gut microbial community (dysbiosis) of vertebrates have been associated with several gastrointestinal and autoimmune diseases. However, it is unclear which taxa are associated with gut dysbiosis, and if particular gut regions or specific time periods during ontogeny are more susceptible. We also know very little of this process in non-model organisms, despite an increasing realization of the general importance of gut microbiota for health

Role of the N-Terminal Seven Residues of Surfactant Protein B (SP-B)

Breathing is enabled by lung surfactant, a mixture of proteins and lipids that forms a surface-active layer and reduces surface tension at the air-water interface in lungs. Surfactant protein B (SP-B) is an essential component of lung surfactant. In this study we probe the mechanism underlying the important functional contributions made by the N-terminal 7 residues of SP-B, a region sometimes called the “insertion sequence”. These studies employed a construct of SP-B, SP-B (1–25,63–78), also called Super Mini-B, which is a 41-residue peptide with internal disulfide bonds comprising the N-terminal 7-residue insertion sequence and the N- and C-terminal helices of SP-B. Circular dichroism, solution NMR, and solid state 2H NMR were used to study the structure of SP-B (1–25,63–78) and its interactions with phospholipid bilayers. Comparison of results for SP-B (8–25,63–78) and SP-B (1–25,63–78) demonstrates that the presence of the 7-residue insertion sequence induces substantial disorder near the centre of the lipid bilayer, but without a major disruption of the overall mechanical orientation of the bilayers. This observation suggests the insertion sequence is unlikely to penetrate deeply into the bilayer. The 7-residue insertion sequence substantially increases the solution NMR linewidths, most likely due to an increase in global dynamics

Gastrointestinal tract: microbial metabolism of steroids

The human gastro-intestinal tract hosts a complex and diverse microbial community, whose microbiome encodes biochemical pathways that humans have not evolved. As a consequence, the gut microbiota produces metabolites from a large range of molecules that host’s enzymes are not able to convert. This is of first importance as these bacterial metabolites may have beneficial or deleterious effects on human health. In particular, cholesterol and bile acids are exposed to the gut microbiota and undergo bacterial metabolism: cholesterol is mainly converted into coprostanol, a non absorbable sterol which is excreted in the feces. Conversely, over twenty different secondary bile acid metabolites are produced by the gut microbiota from the primary bile acids: cholic and chenodeoxycholic acids. The main bile salt conversions in the human gut include deconjugation, oxidation and epimerization of hydroxyl groups at C3, C7 and C12, 7-dehydroxylation, esterification and desulfatation