Search Results (263)

Antimicrobial peptides (AMPs) are the promising candidates for the development of next-generation antimicrobials for agriculture and medicine; however, their large-scale production is costly. The γ-core motif peptides, functionally significant fragments of AMPs responsible for the antimicrobial activity, provide a more economical and feasible approach for the commercial development of novel antimicrobials. In the present work, we undertook a comprehensive study of antimicrobial properties of several γ-core peptides derived from defensins and snakins of Filipendula ulmaria, a medicinal plant known for its valuable pharmacological properties. The γ-core peptides were produced by solid-phase synthesis and purified by RP-HPLC. Their physicochemical properties underlying biological activity were predicted. All the peptides ranging in size from 14 to 18 amino acid residues were positively charged. All peptides except one were predicted to be α-helical and antimicrobial. The synthetic peptides were in vitro tested against a wide panel of plant and human fungal and bacterial pathogens. A short overview of the pathogens used in antimicrobial assays with a special emphasis on their economic, social, and medicinal impacts is provided. As a result of our work, we identified the peptides with pronounced activity in low-micromolar range against particular pathogens that can serve as prototypes for the development of novel biopesticides and antimicrobials for medicine. We also revealed synergism of action between particular γ-core peptide pairs and demonstrated that interference with membrane permeabilization contributes to the peptides’ mode of action. The results obtained broaden our understanding of plant AMPs, the key players in plant immunity, and provide novel highly efficient peptides with high potential in practical applications. Full article

Background/Objectives: The role of intestinal dysbiosis as an important driver of inflammation in metabolic disorders is becoming increasingly evident. Beta-defensin 2 is an antimicrobial peptide that contributes to innate immunity, while recently it has been suggested as a novel biomarker of gut dysbiosis. However, its role in obesity remains unexplored. This study aimed to compare circulating beta-defensin 2 levels between individuals with overweight and obesity and lean controls. An additional objective was to explore potential correlations between beta-defensin 2 and other inflammatory markers in this population. Methods: The study population consisted of 81 participants (61.7% females) divided into obesity (n = 27), overweight (n = 34), and normal body mass index (n = 20) groups. All participants were free of infection and diabetes mellitus. Beta-defensin 2, interleukin-6, presepsin, high-sensitivity C-reactive protein (hs-CRP), and ferritin were evaluated in the study groups. Results: We did not find significant differences in beta-defensin 2 levels between the groups (p = 0.936). In contrast, hs-CRP levels were higher in people with obesity compared to the sum of participants in the overweight and control groups (p = 0.044), after adjusting for the effects of age, sex, smoking, and vitamin D status. Furthermore, a positive correlation was established between beta-defensin 2 and presepsin values (p = 0.012). Conclusions: The results of the present study demonstrate that obesity is characterized by an aggravation of inflammation, as expressed by elevated hs-CRP levels. Although the study design cannot prove causal relationships, our findings also suggest that beta-defensin 2 levels correlate with the magnitude of systemic inflammation in infection-free individuals living with obesity. The value of the combined evaluation of different biomarkers in obesity-related outcomes warrants further investigation by larger studies. Full article

Marathon running exerts physical stress and may lead to transient immune dysregulation, increasing susceptibility to airway inflammation and exercise-induced bronchoconstriction (EIB). This study investigated systemic levels of antimicrobial peptides in athletes and their association with EIB. Serum concentrations of angiogenin, human beta-defensin 2 (hBD-2), major basic protein (MBP), S100A8, and S100A8/A9 were measured in 34 marathoners and 36 half-marathoners at baseline, immediately after a race, and seven days postrace using enzyme-linked immunosorbent assays and compared with 30 sedentary controls. Lung function was assessed by spirometry to identify bronchoconstriction. Levels of hBD-2 and S100A8/A9 were significantly elevated postrace in runners compared to baseline and controls, returning to baseline during recovery. During recovery, S100A8 levels remained slightly elevated in marathoners with EIB. Similarly, human beta-defensin 2 was modestly increased in runners who developed bronchoconstriction. Notably, S100A8 levels correlated negatively with lung function parameters, including forced expiratory volume and mid-expiratory flows. These findings suggest that endurance running induces systemic inflammatory responses and modulates innate immune peptides, particularly in individuals prone to bronchoconstriction. These peptides may serve as biomarkers of respiratory stress and help guide personalized strategies in endurance sports. Full article

Hermetia illucens, the black soldier fly, is a common and widespread fly of the family Stratiomyidae. Its ability to grow on contaminated substrates suggests the production of antimicrobial peptides that enable its survival. This study aimed to verify the impact of direct and indirect infection with Salmonella enteritidis on the expression of defensins and cecropins in Hermetia illucens larvae. In addition to an infection with a microorganism, it was interesting to verify if the expression of peptides and the relative action of hemolymph changed in larvae subjected to mechanical stress by abdominal puncture. The peptide fraction of the hemolymph of infected larvae was tested using antibiogram and minimum inhibitory concentration tests against Salmonella enteritidis and Salmonella typhimurium. Both molecular and microbiological tests were carried out at three different time points, on larvae not subjected to any treatment (T-0), four hours after treatment (T-1), and 24 h after treatment (T-2). The results of the microbiological tests showed the antimicrobial action of the peptide fraction of the hemolymph against both S. typhimurium and S. enteritidis; for the latter one, the action was more marked. Interesting results were also found for larvae subjected only to mechanical stress by puncture. Molecular tests on the expression of defensins and cecropins were in full agreement with those obtained in the microbiological tests, with expression more pronounced in larvae infected directly with Salmonella enteritidis. Temporal and condition-specific regulation of defensins and cecropins highlights the complexity of the immune response and suggests sophisticated mechanisms by which the host fine-tunes antimicrobial peptide expression to enhance pathogen defense while preventing excessive immune activation. Full article

Defensins, one of the members of the antimicrobial peptide family, play a vital role in resisting microbial invasion and immune regulation. Porcine β-defensin 2 possesses excellent stability, making it an ideal antibiotic alternative for feed additives. In this study, a total of 15 piglets were used to investigate the effects of supplementing diets with 2.5 mg/kg (LP group) and 5 mg/kg (HP group) of pBD2 to weaned piglets. The results revealed that pBD2 significantly increased the total weight gain and average daily weight gain (p < 0.05), the contents of T-AOC, SOD, IgM, and IL-10 in serum (p < 0.05), the villus-to-crypt ratios, and the expression of tight-junction proteins ZO-1 and claudin-1 (p < 0.05) in the small intestine. Furthermore, pBD2 increased the abundance of beneficial bacteria related to nutrient and energy metabolism while decreasing the abundance of harmful bacteria associated with intestinal inflammation and diarrhea. Alterations in the gut microbiota were closely associated with the levels of T-AOC, SOD, IgM, and IL-10 in serum. pBD2 primarily enhanced the health of weaned piglets by influencing antioxidant capacity, intestinal barrier function, and the intestinal microbiota. Our research provides a novel perspective for addressing the issue of antibiotic residues in feed. Full article

This study evaluated immune gene expression and locomotor behavior across five Apis mellifera subspecies (Carniolan, Caucasian, Syrian, Muğla ecotype, and Yığılca ecotype) following controlled Vairimorpha ceranae infection. Six days post-infection, Caucasian, Carniolan, and Yığılca bees exhibited a significant upregulation of antimicrobial peptide (AMP) transcripts—hymenoptaecin, abaecin, defensin, and apidaecin—indicating a robust humoral response. Conversely, Syrian and Muğla bees showed weaker AMP expression and higher V. ceranae mRNA levels, indicating lower immunity and higher susceptibility. Positive correlations among AMP transcripts, especially in Caucasian, Carniolan, and Yığılca bees, suggested a coordinated response. Eater gene expression, critical for cellular immunity, decreased in infected Caucasian and Yığılca bees, coinciding with AMP upregulation. Vitellogenin expression, linked to immunity and longevity, increased in Carniolan and Syrian bees, correlating with higher early locomotor activity. Locomotor analysis revealed subspecies-specific behavioral responses. Syrian bees maintained the highest activity despite elevated V. ceranae mRNA and minimal AMP expression, suggesting unique resilience possibly mediated by vitellogenin. Muğla bees, despite high pathogen loads, exhibited decreased activity. Caucasian bees showed strong immune responses but reduced activity post-infection, reflecting potential physiological trade-offs. Overall, these findings underscore the role of genetic variability in shaping honey bee immune and behavioral responses to Vairimorpha and support subspecies-targeted breeding and disease management strategies to enhance resilience. Full article

Until recently, it was believed that bacterial translocation occurs as a result of leaky gut syndrome or sepsis. To confirm or exclude the process of bacterial translocation, biomarkers can be used. One such biomarker is defensins, which indicate immune activity, as defensins are cationic peptides with antibacterial properties produced by intestinal epithelial cells. Also, fatty acid-binding proteins (I-FABP and L-FABP) can serve as useful serological markers for intestinal epithelial damage, indicating impaired intestinal permeability or organ damage, as high concentrations of them are found in tissues and low concentrations in blood serum. In the context of obesity, the integrity of the intestinal barrier, which can be disrupted by dietary fat, leads to increased intestinal permeability. Since bacterial translocation and microbiota contribute to obesity and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) associated with metabolic dysfunction, intestinal barrier markers can be used to study the role of the gut–liver axis. The aim of this study was to gain insight into the pathogenesis of MASLD and examine the impact of bacterial translocation markers and intestinal and hepatic fatty acid-binding proteins (I-FABP and L-FABP) in children with MASLD. Method: We examined 60 children with MASLD and overweight/obesity (MASLD was diagnosed based on increased liver echogenicity in ultrasound and elevated ALT activity), aged 14.5 years (range 8.5 to 15.8); 33 children with overweight/obesity without MASLD, aged 13.0 years (range 11.4 to 15.8); and 16 healthy controls aged 11.0 years (range 7.0 to 16.2). Defensin, I-FABP, and L-FABP levels were measured using commercial kits: ELISA kits (Drg Medtek) were used to assess α-5 and α-6 defensin concentrations (HBD5, HBD6). I-FABP and L-FABP concentrations were measured using commercial ELISA kits (Hycult Biotech Inc., Wayne, PA, USA). ANOVA analysis was used to compare results across the three study groups. Results: A significant difference was found for the following tests among children with MASLD, obesity, and healthy controls: defensin 6 (14.4 ng/mL vs. 6.13 ng/mL vs. 17.2 ng/mL, respectively), L-FABP (9168 pg/mL vs. 7954 pg/mL vs. 7620 pg/mL, respectively), and I-FABP (272 pg/mL vs. 321 pg/mL vs. 330 pg/mL, respectively). No differences were found in defensin 5 levels (median 567.2 pg/mL vs. 485.7 pg/mL vs. 601.8 pg/mL). No differences were observed in cholesterol levels (HDL, LDL) or triglyceride concentrations, as well as apolipoprotein levels. Conclusions: Based on our study, it was concluded that inflammation and intestinal barrier damage lead to increased L-FABP levels, as it is released from enterocytes in response to oxidative stress or tissue damage. Defensin 6 may indirectly affect L-FABP through microbiota regulation and protection of the intestinal barrier. Defensin 6 also exerts antimicrobial activity and may accompany liver inflammation, with its increased concentration in comparison to obesity explained by the activation of defense mechanisms. Full article

Objectives: The oral cavity hosts one of the most complex microbial communities in the body. A disruption of the balance favors the growth of pathogenic species, contributing to oral diseases. The rise in microbial resistance has limited the effectiveness of conventional treatments, shifting the interest to natural product-based alternatives. Given its superior bioavailability and bioactivity in other models, this study investigates the antifungal potential of a novel curcumin derivative, PAC (3,5-bis(4-hydroxy-3-methoxybenzylidene)-N-methyl-4-piperidone), and studies its impact on host–pathogen dynamics and host defense mechanisms. Methods: Candida albicans was used as the model organism. Viability, growth kinetics, and colony formation were evaluated using optical density, agar culture, and MTT assay. Biofilm formation was assessed through electron microscopy and total sugar quantification. The morphological transition from hyphae to the less virulent blastospore was monitored using an optical microscope. The gene expression of adhesion factors and host defense markers was analyzed using RT-PCR. Results: PAC impairs C. albicans viability and reduces virulence by compromising biofilm formation and ensuring phenotypic transition to a blastospore form. Also, PAC controls C. albicans growth via necrosis/ROS pathways. As a result, PAC appears to repress host–pathogen interaction by downregulating SAPs, EAP1, and HWP1 adhesion genes, thus relieving the need to activate gingival epithelial cell defense mechanisms. This is highlighted by recording baseline levels of IL-6, IL-8, and IL-1β cytokines and antimicrobial β-defensin peptides in the presence of less virulent candida forms. Conclusions: PAC effectively reduces C. albicans virulence by limiting biofilm formation and adhesion while minimizing inflammatory responses. These findings support its potential as a promising therapeutic agent for infectious disease control. Full article

Enterotoxigenic Escherichia coli (ETEC), a common intestinal pathogen, can colonize the intestines and induce diarrhea in piglets, which brings great economic losses to the swine industry. Antibiotics are recommended to the treatment for diarrhea caused by ETEC in weaned piglets. However, with the emergence and spread of multidrug-resistant ETEC, there is an urgent need to develop alternatives to antibiotics. Due to the unique antibacterial mechanism of targeting bacterial membranes, antimicrobial peptides (AMPs) are promising candidates. In this study, the activity of crude recombinant porcine β-defensin 2 (rPBD2) expressed in Pichia pastoris (P. pastoris) was measured in vitro. Mice infected with ETEC were orally administered 16, 8, and 4 AU crude rPBD2 for 7 consecutive days to evaluate its anti-infective activity in vivo. The results showed that in addition to broad antibacterial activity against Gram-positive and -negative bacteria, crude rPBD2 displayed high tolerance to temperatures ranging from 20 to 60 °C, a broad range of pH, trypsin, pepsin, and physiological concentrations of salts. In an ETEC-induced mouse model, the oral administration of crude rPBD2 decreased diarrhea scores and the intestinal/carcass ratio and alleviated body weight loss. Additionally, crude rPBD2 decreased bacterial loads in stools and the colon (HP group), and the levels of serum pro-inflammatory cytokines IL-6 (HP group) and TNF-α (HP and MP groups), and increased the villus height and the ratio of villus height to crypt depth (VH/CD) in the ileum (HP and MP groups). Our study provides a cost-effective way for PBD2 production and identifies it as a promising candidate to combat ETEC-induced infection. Full article

Breast milk is vital for infant survival, protecting against infections and strengthening the immune system. In addition to nutrients, breast milk contains beneficial microorganisms, antimicrobial peptides and proteins (APPs), including lactoferrin and lysozyme, and peptides such as defensins and cathelicidins that destroy harmful bacteria and regulate the neonatal immune response. Breast milk also promotes the growth of beneficial gut bacteria (Bacteroidaceae and Bifidobacteriaceae) while reducing harmful pathogens, fostering a healthy gut microbiome, and supporting long-term infant health. Traditionally, research on antimicrobial proteins and milk microbiota has been conducted in isolation. However, at the molecular level, these components do not function independently; they interact synergistically, influencing immunomodulation, inflammation, and the composition of the gut microbiome. Therefore, this review aims to provide an overview of the discovery and identification of APPs in breast milk, the dynamic relationship between the breast milk microbiota, and the potentiation of artificial feeding with supplemented formulas when breastfeeding is impossible, benefits on newborn immune systems, and even the benefits to breast tissue. Full article

Background: The use of antimicrobial peptides (AMPs) as biotechnological tools is an area of growing interest in the research that seeks to improve crop defense. SmAP_α1–21 and SmAP_γ27–44 were previously reported to inhibit Fusarium graminearum, permeabilize the plasma membrane and induce cytoplasmic disorganization. To exert its activity, SmAP_α1–21 initially enters through the basal and apical cells of F. graminearum conidia and then displays a general but non-homogeneous distribution in the cytoplasm of all conidial cells, in contrast. Methods: We analyzed, focusing on membrane interaction, the mode of action of SmAP_γ27–44, a peptide based on the γ-core of defensins DefSm2-D and DefSm3, and SmAP_α1–21, based on the α-core of DefSm2-D. Additionally, we compared the behavior of SmAP_α1–21 with that of SmAP3_α1–21 based on DefSm3 but with no activity against F. graminearum. Results: In this study, we showed that SmAP_γ27–44 enters the cells with discrete intracellular localization. Furthermore, both peptides disrupted the plasma membrane, but with different modes of action. When large unilamellar liposomes (LUVs) containing phosphatidic acid and ergosterol were used as a filamentous fungal plasma membrane model, SmAP_γ27–44 strongly induced aggregation concomitantly with the solubilization of the liposomes and showed the maximal insertion of its tryptophan moiety into the membrane’s hydrophobic interior. In comparison, SmAP_α1–21 showed a high effect on the ζ potential of anionic vesicles, vesicle aggregation capacity after reaching a concentration threshold, and moderate transfer of tryptophan to the membrane. SmAP3_α1–21, on the other hand, showed poor superficial adsorption to liposomes. Conclusions: In view of our results, a cell penetration peptide-like effect was pictured for the γ-core defensin-derived peptide and a classical AMP action was observed for the α-core defensin-derived one. Full article

Excessive glucose absorption is a major contributing factor of metabolic disorders that necessitates effective therapeutic strategies. This study investigates the potential of fermented Aralia cordata extract (FACE) in regulating glucose transport and immune responses under high-glucose stress conditions. Caco-2 intestinal cells and L cells were treated with FACE to determine effects on key glucose-regulating proteins and cytokines. FACE treatment inhibited the expression of glucose transporters SGLT1 and GLUT2 while promoting GLP-1 secretion. This effect was associated with HDAC and somatostatin suppression, along with AMPK-γ upregulation. Notably, FACE inhibited DPP-4 expression, further enhancing GLP-1 stability and function. Immunomodulatory effects also occurred, specifically FACE promotion of T lymphocyte differentiation, with a stronger influence on Th2 cell development. Additionally, FACE increased the secretion of essential molecules for immune balance and inflammation control, including antimicrobial peptides LL-37 and defensin, along with cytokines IL-4 and IL-13. These findings suggest that FACE exerts dual effects of improving glucose regulation and modulating immune responses, highlighting its potential as a novel bioactive material for managing metabolic disorders and enhancing intestinal immunity. Further research is warranted to explore its clinical applicability in therapeutic formulations. Full article

Plant defensins (PDFs) are a group of cationic antimicrobial peptides that are distinguished by their unique tertiary structure and play significant roles in physiological metabolism, growth, and stress tolerance. Defensins are key components of plant innate immunity; they can target a wide variety of microorganisms. This study aimed to identify and investigate the role of Triticum durum PDFs (TdPDFs) in response to environmental stresses. Prior to this, in silico analyses of TdPDF genes were conducted to assess their chromosomal locations, conserved motifs, exon–intron distribution, and cis-regulatory elements in the promoter regions. Additionally, bioinformatic analyses were performed to characterize the structure of TdPDF proteins, evaluate their phylogenetic relationships, predict their subcellular localization, and estimate their physicochemical properties. Docking studies were conducted to assess the interactions between TdPDF proteins and the fungal plasma membrane. A total of 28 TdPDF genes were identified in durum wheat based on their conserved domain PF00304 (gamma-thionin). These genes are distributed across all chromosomes of the durum wheat genome, except for chromosomes 4A and 7A. Analysis of the promoters of these genes revealed numerous elements associated with development, hormone responsiveness, and environmental stress. The majority of TdPDF proteins were predicted to be located extracellular. In addition, TdPDF proteins were classified into three clusters based on sequence similarity. Phylogenetic analysis suggested that TdPDF proteins share ancestral similarities with the PDF sequences of other monocotyledonous species. Molecular docking studies revealed that TdPDF proteins interact with fungal plasma membranes, suggesting that they play a critical role in the resistance of plants to pathogen infections. Expression analysis underlined the crucial role of nine TdPDF genes in the defense responses of durum wheat against both pathogenic and environmental stressors. Overall, our findings underscore the potential of TdPDF genes in host-plant resistance and highlight opportunities for their application in crop improvement toward stress tolerance. Full article

Background/Objectives: β-defensins are a family of classical endogenous antimicrobial peptides involved in innate immune response. β-defensins are encoded by a large number of loci and known to show extensive copy number variations (CNVs) that may be useful as DNA markers for host resilience against pathogenic infections. Methods: We developed a quantitative PCR-based method to estimate the genomic copy numbers of 13 pig β-defensin (pBD) genes and analyzed the range and extent of CNVs across several commercial pig breeds. Results: We assessed 38 animals from four pure breeds and a crossbreed and observed CNVs ranging from two to five genomic copies from pBD114, pBD115, pBD119, pBD124, pBD128, and pBD129, indicating extensive individual variations of gene copy numbers of these genes within each breed. The mean copy numbers of these pBDs were lower in Landrace and higher in Berkshire than in other breeds. We also observed a strong correlation between the genomic copy number and their expression levels with the correlation coefficient (r) > 0.9 for pBD114, pBD119, and pBD129 in the kidney, with these genes being highly expressed. Conclusions: Although we only analyzed 13 pBDs among 29 reported genes, our results showed the presence of extensive CNVs in β-defensins from pigs. The genomic copy number of β-defensins may contribute to improving animal resilience against pathogenic infections and other associated phenotypes. Full article

(1) The aim of this study was to elucidate the role of the Gallus gallus avian β-defensin 11 (AvBD11) in the immune response induced by the avian influenza virus H9N2. (2) AvBD11 was expressed using E. coli, and the effects of different concentrations of AvBD11 on cytokine expression in the ex vivo and in vivo erythrocytes of chickens infected with the avian influenza subtype H9N2 were detected by using fluorescence quantification. (3) The results showed that cytokine expression varied among the test groups compared to the control group in the in vitro assay at 2, 6, and 10 h. Lipopolysaccharide induced TNF factor (LITAF) and Interferon-γ (IFN-γ) were significantly increased in the AvBD11 group with the addition of the final concentration of 15 μg/mL at 6 h. At 10 h, Interleukin-1β (IL-1β) and IFN-γ were both more significantly increased in the 15 and 10 μg/mL groups than in the H9N2 group alone. In the in vivo test, IFN-γ and Interleukin-10 (IL-10) were significantly increased in the high-dose group than in the H9N2 group at 3 d and 7 d. (4) In conclusion, the ability of AvBD11 to induce the expression of more cytokines by chicken erythrocytes in a short period of time suggests that it is not only an antimicrobial peptide but also a possible immunomodulator. Full article