A novel peptide identified from skin secretions of Bombina maxima possesses LPS-neutralizing activity.

Lipopolysaccharide (LPS) is a major pathogenic factor in endotoxin shock or sepsis. Most antibiotics have little clinical anti-endotoxin activity, but some antimicrobial peptides (AMPs) have been shown to be effective in blocking LPS. We identified a novel peptide from the skin secretions of Bombina maxima (B. _maxima) by challenging the skin of frogs with an LPS solution. Peptide 2 has an amino acid sequence of LVGKLLKGAVGDVCGLLPIC. Peptide 2 possesses low hemolytic activity, low cytotoxicity against RAW 264.7 cells, and strong anti-inflammatory activity. Moreover, peptide 2 plays an anti-inflammatory role by inhibiting inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). A biolayer interferometry (BLI) assay indicated that peptide 2 binds to LPS with strong affinity and that this interaction has an affinity constant (KD) value of 1.05 × 10-9 M. A survival study showed that peptide 2 possesses potent LPS-neutralizing activity to protect LPS-treated mice from death. In conclusion, we have identified a potent peptide with LPS neutralizing activity, which lays a foundation for future research and development.

Fragments of bombinakinin M exist in lipopolysaccharide-stimulated skin secretions of Bombina maxima and show lipopolysaccharide-neutralizing activity.

Lipopolysaccharide (LPS) is a major pathogen-associated pattern molecule that can initiate lethal sepsis. Bioactive peptides in amphibian skin secretions, especially antimicrobial peptides, are essential components of the host immune system and help fight the microbial invasion. In this study, two peptides: peptide 1 (KINRKGPRPPG) and peptide 2 (INRKGPRPPG) were isolated, from skin secretions of the Chinese red belly frog (Bombina maxima). After stimulation with LPS, peptide 1 showed direct LPS-binding activity, low cytotoxicity, immunoregulatory functions in vitro, and neutralizing LPS effects in animal models. Thus, natural peptide 1 exhibits potential as an ideal candidate against LPS.

Exosomal long noncoding RNA HOXD-AS1 promotes prostate cancer metastasis via miR-361-5p/FOXM1 axis.

Development of distant metastasis is the main cause of deaths in prostate cancer (PCa) patients. Understanding the mechanism of PCa metastasis is of utmost importance to improve its prognosis. The role of exosomal long noncoding RNA (lncRNA) has been reported not yet fully understood in the metastasis of PCa. Here, we discovered an exosomal lncRNA HOXD-AS1 is upregulated in castration resistant prostate cancer (CRPC) cell line derived exosomes and serum exosomes from metastatic PCa patients, which correlated with its tissue expression. Further investigation confirmed exosomal HOXD-AS1 promotes prostate cancer cell metastasis in vitro and in vivo by inducing metastasis associated phenotype. Mechanistically exosomal HOXD-AS1 was internalized directly by PCa cells, acting as competing endogenous RNA (ceRNA) to modulate the miR-361-5p/FOXM1 axis, therefore promoting PCa metastasis. In addition, we found that serum exosomal HOXD-AS1 was upregulated in metastatic PCa patients, especially those with high volume disease. And it is correlated closely with Gleason Score, distant and nodal metastasis, Prostatic specific antigen (PSA) recurrence free survival, and progression free survival (PFS). This sheds a new insight into the regulation of PCa distant metastasis by exosomal HOXD-AS1 mediated miR-361-5p/FOXM1 axis, and provided a promising liquid biopsy biomarker to guide the detection and treatment of metastatic PCa.