Effects of Leishmania major infection on the gut microbiome of resistant and susceptible mice.

Cutaneous leishmaniasis, a parasitic disease caused by Leishmania major, is a widely frequent form in humans. To explore the importance of the host gut microbiota and to investigate its changes during L. major infection, two different groups of mouse models were assessed. The microbiome of two parts of the host gut-ileum and colon-from infected and non-infected mice were characterised by sequencing of 16S rDNA using an Ion Torrent PGM platform. Microbiome analysis was performed to reveal changes related to the susceptibility and the genetics of mice strains in two different gut compartments and to compare the results between infected and non-infected mice. The results showed that Leishmania infection affects mainly the ileum microbiota, whereas the colon bacterial community was more stable. Different biomarkers were determined in the gut microbiota of infected resistant mice and infected susceptible mice using LEfSe analysis. Lactobacillaceae was associated with resistance in the colon microbiota of all resistant mice strains infected with L. major. Genes related to xenobiotic biodegradation and metabolism and amino acid metabolism were primarily enriched in the small intestine microbiome of resistant strains, while genes associated with carbohydrate metabolism and glycan biosynthesis and metabolism were most abundant in the gut microbiome of the infected susceptible mice. These results should improve our understanding of host-parasite interaction and provide important insights into the effect of leishmaniasis on the gut microbiota. Also, this study highlights the role of host genetic variation in shaping the diversity and composition of the gut microbiome. KEY POINTS: • Leishmaniasis may affect mainly the ileum microbiota while colon microbiota was more stable. • Biomarkers related with resistance or susceptibility were determined in the gut microbiota of mice. • Several pathways were predicted to be upregulated in the gut microbiota of resistant or susceptible mice.

Functional stapled fragments of human preptin of minimised length.

Preptin is a 34-amino-acid-long peptide derived from the E-domain of a precursor of insulin-like growth factor 2 (pro-IGF2) with bone-anabolic and insulin secretion amplifying properties. Here, we describe the synthesis, structures, and biological activities of six shortened analogues of human preptin. Eight- and nine-amino-acid-long peptide amides corresponding to the C-terminal part of human preptin were stabilised by two types of staples to induce a higher proportion of helicity in their secondary structure. We monitored the secondary structure of the stapled peptides using circular dichroism. The biological effect of the structural changes was determined afterwards by the ability of peptides to stimulate the release of intracellular calcium ions. We confirmed the previous observation that the stabilisation of the disordered conformation of human preptin has a deleterious effect on biological potency. However, surprisingly, one of our preptin analogues, a nonapeptide stabilised by olefin metathesis between positions 3 and 7 of the amino acid chain, had a similar ability to stimulate calcium ions' release to the full-length human preptin. Our findings could open up new ways to design new preptin analogues, which may have potential as drugs for the treatment of diabetes and osteoporosis.

A novel locus on mouse chromosome 7 that influences survival after infection with tick-borne encephalitis virus.

BACKGROUND: Tick-borne encephalitis (TBE) is the main tick-borne viral infection in Eurasia. Its manifestations range from inapparent infections and fevers with complete recovery to debilitating or fatal encephalitis. The basis of this heterogeneity is largely unknown, but part of this variation is likely due to host genetic. We have previously found that BALB/c mice exhibit intermediate susceptibility to the infection of TBE virus (TBEV), STS mice are highly resistant, whereas the recombinant congenic strain CcS-11, carrying 12.5% of the STS genome on the background of the BALB/c genome is even more susceptible than BALB/c. Importantly, mouse orthologs of human TBE controlling genes Oas1b, Cd209, Tlr3, Ccr5, Ifnl3 and Il10, are in CcS-11 localized on segments derived from the strain BALB/c, so they are identical in BALB/c and CcS-11. As they cannot be responsible for the phenotypic difference of the two strains, we searched for the responsible STS-derived gene-locus. Of course the STS-derived genes in CcS-11 may operate through regulating or epigenetically modifying these non-polymorphic genes of BALB/c origin. METHODS: To determine the location of the STS genes responsible for susceptibility of CcS-11, we analyzed survival of TBEV-infected F2 hybrids between BALB/c and CcS-11. CcS-11 carries STS-derived segments on eight chromosomes. These were genotyped in the F2 hybrid mice and their linkage with survival was tested by binary trait interval mapping. We have sequenced genomes of BALB/c and STS using next generation sequencing and performed bioinformatics analysis of the chromosomal segment exhibiting linkage with TBEV survival. RESULTS: Linkage analysis revealed a novel suggestive survival-controlling locus on chromosome 7 linked to marker D7Nds5 (44.2 Mb). Analysis of this locus for polymorphisms between BALB/c and STS that change RNA stability and genes' functions led to detection of 9 potential candidate genes: Cd33, Klk1b22, Siglece, Klk1b16, Fut2, Grwd1, Abcc6, Otog, and Mkrn3. One of them, Cd33, carried a nonsense mutation in the STS strain. CONCLUSIONS: The robust genetic system of recombinant congenic strains of mice enabled detection of a novel suggestive locus on chromosome 7. This locus contains 9 candidate genes, which will be focus of future studies not only in mice but also in humans.

Characterization of hFOB 1.19 Cell Line for Studying Zn-Based Degradable Metallic Biomaterials.

In vitro testing is the first important step in the development of new biomaterials. The human fetal osteoblast cell line hFOB 1.19 is a very promising cell model; however, there are vast discrepancies in cultivation protocols, especially in the cultivation temperature and the presence of the selection reagent, geneticin (G418). We intended to use hFOB 1.19 for the testing of Zn-based degradable metallic materials. However, the sensitivity of hFOB 1.19 to zinc ions has not yet been studied. Therefore, we compared the toxicity of zinc towards hFOB 1.19 under different conditions and compared it with that of the L929 mouse fibroblast cell line. We also tested the cytotoxicity of three types of Zn-based biomaterials in two types of media. The presence of G418 used as a selection reagent decreased the sensitivity of hFOB 1.19 to Zn2+. hFOB 1.19 cell line was more sensitive to Zn2+ at elevated (restrictive) temperatures. hFOB 1.19 cell line was less sensitive to Zn2+ than L929 cell line (both as ZnCl2 and extracts of alloys). Therefore, the appropriate cultivation conditions of hFOB 1.19 during biomaterial testing should be chosen with caution.

The final walk with preptin.

Preptin, a 34-amino acid peptide derived from pro-IGF2, is believed to influence various physiological processes, including insulin secretion and the regulation of bone metabolism. Despite its recognized involvement, the precise physiological role of preptin remains enigmatic. To address this knowledge gap, we synthesized 16 analogs of preptin, spanning a spectrum from full-length forms to fragments, and conducted comprehensive comparative activity evaluations alongside native human, mouse and rat preptin. Our study aimed to elucidate the physiological role of preptin. Contrary to previous indications of broad biological activity, our thorough analyses across diverse cell types revealed no significant biological activity associated with preptin or its analogs. This suggests that the associations of preptin with various diseases or tissue-specific abundance fluctuations may be influenced by factors beyond preptin itself, such as higher levels of IGF2 or IGF2 proforms present in tissues. In conclusion, our findings challenge the conventional notion of preptin as an isolated biologically active molecule and underscore the complexity of its interactions within biological systems. Rather than acting independently, the observed effects of preptin may arise from experimental conditions, elevated preptin concentrations, or interactions with related molecules such as IGF2.

Non-glycosylated IGF2 prohormones are more mitogenic than native IGF2.

Insulin-like Growth Factor-2 (IGF2) is important for the regulation of human embryonic growth and development, and for adults' physiology. Incorrect processing of the IGF2 precursor, pro-IGF2(156), leads to the formation of two IGF2 proforms, big-IGF2(87) and big-IGF2(104). Unprocessed and mainly non-glycosylated IGF2 proforms are found at abnormally high levels in certain diseases, but their mode of action is still unclear. Here, we found that pro-IGF2(156) has the lowest ability to form its inactivating complexes with IGF-Binding Proteins and has higher proliferative properties in cells than IGF2 and other IGF prohormones. We also showed that big-IGF2(104) has a seven-fold higher binding affinity for the IGF2 receptor than IGF2, and that pro-IGF2(87) binds and activates specific receptors and stimulates cell growth similarly to the mature IGF2. The properties of these pro-IGF2 forms, especially of pro-IGF2(156) and big-IGF2(104), indicate them as hormones that may be associated with human diseases related to the accumulation of IGF-2 proforms in the circulation.