The global increase in obesity has significant health implications, with an increased BMI as a known risk factor for diseases such as type 2 diabetes, cardiovascular diseases, or different cancer types. Long-term effectiveness of diet therapy in addressing morbid obesity is extremely limited with no adequate pharmaceutical agents available as treatment option resulting in bariatric surgery as being the only viable option to achieve and maintain significant long-term weight loss. One important role in the overall human health plays the gut microbiome and its complex composition, which is usually altered and reduced in complexity/diversity in severely obese patients. In this study, the influence of bariatric surgery and the resulting weight-loss on the gut microbiome composition of twelve morbid obese (BMI ≥ 40) female adult central European patients was investigated by comparing the relative abundances of the major microbial phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria prior- and post-surgery. We also aimed to give insight into the major changes of individual prominent and promising future probiotic bacteria characterized by an overall increase in abundance accompanied by a switch of enterotypes. Identifying specific microbial alterations associated with successful weight-loss outcomes may contribute to the development of future therapeutic interventions by supplementation with next-generation probiotics.

Advanced derivatives of the CXCR4 antagonist EPI-X4 have shown therapeutic efficacy upon topical administration in animal models of asthma and dermatitis. Here, we studied plasma stability of the EPI-X4 lead compounds WSC02 and JM#21, using mass spectrometry to monitor the chemical integrity of the peptides and a functional fluorescence-based assay that determines peptide function in a CXCR4-antibody competition assay. Although mass spectrometry revealed a very rapid disappearance of both peptides in human plasma within seconds, the functional assay revealed a significantly higher half-life of 9 minutes for WSC02 and 6 minutes for JM#21, respectively. Further analyses demonstrated that WSC02 and JM#21 interact with low molecular weight plasma components and serum albumin. Albumin binding is mediated by the formation of a disulfide bridge between Cys10 in the EPI-X4 peptides and Cys34 in albumin. These covalently linked albumin-peptide complexes have a higher stability in plasma as compared to the non-bound peptides and retain the ability to bind and antagonize CXCR4. Remarkably, chemically synthesized albumin-EPI-X4 conjugates coupled by non-breakable bonds have a drastically increased plasma stability of over 2 hours. Thus, covalent coupling of EPI-X4 to albumin in vitro before administration or in vivo post administration may significantly increase the pharmacokinetic properties of the new class of CXCR4 antagonists.