Beta-defensin 41

To evaluate the administration of Bifidobacterium animalis subsp. lactis, BB-12® (BB-12) on infant colic in breastfed infants, a double-blind, placebo-controlled randomised study was conducted in Chengdu, China from April 2016 to October 2017 with 192 full-term infants less than 3 months of age and meeting the ROME III criteria for infant colic. After a 1-week run-in the infants were randomly assigned to receive daily BB-12 (1×109 cfu/day) or placebo for 3 weeks. Crying/fussing time were recorded using a 24 h structured diary. The primary endpoint was the proportion of infants achieving a reduction in crying and fussing time of ≥50% from baseline. Parent's/caregiver's health related quality of life was measured using a modified PedsQL™ 2.0 Family Impact Module and immunological biomarkers were evaluated from faecal samples at baseline and after the 21-day intervention. The percentage of infants achieving a reduction in the daily crying/fussing time ≥50% after the 21-day intervention was significantly higher in the infants supplemented with BB-12 (P<0.001). The mean number of crying episodes was significantly reduced in the BB-12 group compared to the placebo group (10.0±3.0 to 5.0±1.87 vs 10.5±2.6 to 7.5±2.8, respectively) (P<0.001) and the mean daily sleep duration was markedly increased from baseline to end of intervention in the BB-12 group compared to the infants in the placebo group (60.7±104.0 vs 31.9±102.7 min/day, respectively) (P<0.001). The faecal levels of human beta defensin 2, cathelicidin, slgA, calprotectin and butyrate were statistically higher in the BB-12 group compared to the placebo group after the 21-day intervention. At the end of the intervention the parent's/caregiver's physical, emotional and social functioning scores were significantly higher for the BB-12 group compared to the placebo group (all P<0.05). Supplementation of BB-12 is effective in reducing crying and fussing in infants diagnosed with infant colic.

During epididymal maturation, sperm acquire the ability to swim progressively by interacting with proteins secreted by the epididymal epithelium. Beta-defensin proteins, expressed in the epididymis, continue to regulate sperm motility during capacitation and hyperactivation in the female reproductive tract. We characterized the mouse beta-defensin 41 (DEFB41), by generating a mouse model with iCre recombinase inserted into the first exon of the gene. The homozygous Defb41(iCre/iCre) knock-in mice lacked Defb41 expression and displayed iCre recombinase activity in the principal cells of the proximal epididymis. Heterozygous Defb41(iCre/+) mice can be used to generate epididymis specific conditional knock-out mouse models. Homozygous Defb41(iCre/iCre) sperm displayed a defect in sperm motility with the flagella primarily bending in the pro-hook conformation while capacitated wild-type sperm more often displayed the anti-hook conformation. This led to a reduced straight line motility of Defb41(iCre/iCre) sperm and weaker binding to the oocyte. Thus, DEFB41 is required for proper sperm maturation.

Defensins are a group of small cationic and cysteine-rich peptides that are important components of the innate immune system. However, studies on defensins in teleosts are very limited, particularly studies on defensin functions through in vivo assays. In this study, we cloned and identified one β-defensin (TroBD) the golden pompano, Trachinotus ovatus, and analyzed the functions of TroBD in both in vivo and in vitro assays. TroBD is composed of 63 amino acids and shares high sequence identities (27.27-98.41%) with known β-defensins of other teleosts. The protein has a signature motif of six conserved cysteine residues within the mature peptide. The expression of TroBD was most abundant in the head kidney and spleen and was significantly upregulated following infection by Vibrio harveyi and viral nervous necrosis virus (VNNV). Purified recombinant TroBD (rTroBD) inhibited the growth of V. harveyi, and its antimicrobial activity was influenced by salt concentration. TroBD was found to have a chemotactic effect on macrophages in vitro. The results of an in vivo study demonstrated that TroBD overexpression/knockdown in T. ovatus significantly reduced/increased bacterial colonization or viral copy numbers in tissues. Taken together, these results indicate that TroBD plays a significant role in both antibacterial and antiviral immunity and provide new avenues for protection against pathogen infection in the aquaculture industry.