β-Defensin 129 Attenuates Bacterial Endotoxin-Induced Inflammation and Intestinal Epithelial Cell Apoptosis

Protective effect of dihydromyricetin on intestinal epithelium in weaned pigs upon enterotoxigenic Escherichia coli challenge

Dihydromyricetin (DMY), a natural flavonoid compound, are believed to prevent inflammatory response, dealing with pathogens and repairing the intestinal barrier. The objective of this study was to investigate whether DMY supplementation could attenuate intestinal damage in the context of enterotoxigenic Escherichia coli K88 (ETEC F4+) infection. After weaning, different litters of pigs were randomly assigned to one of the following treatments: (1) non-challenged control (CON, fed with basal diet); (2) ETEC-challenged control (ECON, fed with basal diet); and (3) ETEC challenge + DMY treatment (EDMY, fed with basal diet plus 300 mg kg-1 DMY). We observed a significant reduction in fecal Escherichia coli shedding and diarrhea incidence, but an increase in ADG in pigs of EDMY group compared to the pigs of ECON group. Relative to the pigs of ECON group, dietary DMY treatment decreased (P < 0.05) concentrations of the serum D-xylose, D-lactate and diamine oxidase (DAO), but increased the abundance of zonula occludens-1 (ZO-1) in the jejunum of pigs. In addition, DMY also decreased (P < 0.05) the number of S-phase cells and the percentage of total apoptotic epithelial cells of jejunal epithelium in pigs of the EDMY group compared to the pigs of the ECON group. Furthermore, DMY decreased the mRNA expression levels of critical immune-associated genes TLR4, NFκB, Caspase3, Caspase9, IL-1β, IL-6, TNF-α and the protein p-NFκB and p-IκBα expressions of intestinal epithelium in pigs of the EDMY group compared to the pigs of the ECON group. Compared to the ECON group, DMY elevated (P < 0.05) the expression levels of β-defensins PBD1, PBD2, PBD3, PBD129, as well as the abundance of secreted IgA in intestinal mucosae of the EDMY group. Thus, our results indicate that DMY may relieve intestinal integrity damage due to Escherichia coli F4.

Protective Effect of Coated Benzoic Acid on Intestinal Epithelium in Weaned Pigs upon Enterotoxigenic Escherichia coli Challenge

The study was designed to investigate the protective effect of dietary supplementation with coated benzoic acid (CBA) on intestinal barrier function in weaned pigs challenged with enterotoxigenic Escherichia coli (ETEC). Thirty-two pigs were randomized to four treatments and given either a basal diet or a basal diet supplemented with 3.0 g/kg CBA, followed by oral administration of ETEC or culture medium. The results showed that CBA supplementation increased the average daily weight gain (ADWG) in the ETEC-challenged pigs (p < 0.05). CBA also increased the serum activity of total superoxide dismutase (T-SOD) and the total antioxidant capacity (T-AOC), as it decreased the serum concentrations of endotoxin, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the ETEC-challenged pigs (p < 0.05). Interestingly, the CBA alleviated the ETEC-induced intestinal epithelial injury, as indicated by a reversal of the decrease in D-xylose absorption and a decrease in the serum levels of D-lactate and diamine oxidase (DAO) activity, as well as a decrease in the quantity of apoptotic cells in the jejunal epithelium following ETEC challenge (p < 0.05). Moreover, CBA supplementation significantly elevated the mucosal antioxidant capacity and increased the abundance of tight junction protein ZO-1 and the quantity of sIgA-positive cells in the jejunal epithelium (p < 0.05). Notably, CBA increased the expression levels of porcine beta defensin 2 (PBD2), PBD3, and nuclear factor erythroid-2 related factor 2 (Nrf-2), while downregulating the expression of toll-like receptor 4 (TLR4) in the jejunal mucosa (p < 0.05). Moreover, CBA decreased the expression levels of interleukin-1β (IL-1β), myeloid differentiation factor 88 (MyD88), and nuclear factor-kappa B (NF-κB) in the ileal mucosa upon ETEC challenge (p < 0.05). These results suggest that CBA may attenuate ETEC-induced damage to the intestinal epithelium, resulting in reduced inflammation, enhanced intestinal immunity and antioxidant capacity, and improved intestinal epithelial function.

Porcine beta defensin 2 attenuates inflammatory responses in IPEC-J2 cells against Escherichia coli via TLRs-NF-κB/MAPK signaling pathway

BACKGROUND

Porcine beta defensin 2 (pBD2) is one of the porcine beta defensins that has antibacterial activity, and plays an important role in the immunomodulatory activity that protects cells from pathogens. It has been reported that pBD2 plays their immunomodulatory functions related to the TLR4-NF-κB signal pathways. However, it is not completely clear how pBD2 reduces the inflammatory response caused by pathogens.

RESULTS

In this study, the effect of pBD2 on the expression of genes in the TLRs signaling pathway was investigated after IPEC-J2 cells were challenged with E. coli. The results showed that pBD2 decreased the expression of IL-8 induced by E. coli (P < 0.05), and pBD2 significantly decreased the expression of TLR4, TLR5 and TLR7 (P < 0.05), as well as the key downstream genes p38 and JNK which activated by E. coli (P < 0.05). In addition, pBD2 inhibited the p-p65, p-p38 and p-JNK which were up-regulated by E. coli.

CONCLUSIONS

pBD2 could reduce the inflammatory response induced by E. coli perhaps by inhibiting the TLRs-TAK1-NF-κB/MAPK signaling pathway which was activated by E. coli in IPEC-J2 cells. Our study further reveals the immunomodulatory activity of recombinant pBD2 against E. coli, and provides insights into the molecular mechanisms that protect cells from E. coli infection.

Porcine β-Defensin 114: Creating a Dichotomous Response to Inflammation

The immunity-related functions of defensins seem to be dependent on environmental stimuli, the cell type, and the concentration of peptides. However, the function and mechanism of porcine β-defensin 114 (pBD114) in regulating the inflammatory response to macrophages are unclear. Therefore, the modulatory effects of porcine pBD114 on the inflammatory response were investigated by treating the mouse monocyte macrophage cell line RAW264.7 with different concentrations of pBD114 with or without lipopolysaccharide (LPS). RNA-seq analysis was performed to investigate the mechanisms underlying pBD114's regulation of inflammatory responses in macrophages. In addition, the inflammatory response-modulating effects of pBD114 were also further verified with a mouse assay. The results showed that 100 μg/mL of pBD114 significantly promoted the secretion of TNF-α and IL-10 in RAW264.7. However, the LPS-induced increase in TNFα in the RAW264.7 cell cultures was significantly decreased with 10 μg/mL of pBD114. These results suggest that pBD114 can exhibit pro-inflammatory activities under normal physiological conditions with 100 μg/mL of pBD114, and anti-inflammatory activities during an excessive inflammatory response with 10 μg/mL of pBD114. RNA-seq analysis was performed to gain further insights into the effects of pBD114 on the inflammatory response. Among the pBD114-promoting RAW264.7 pro-inflammatory responses, pBD114 significantly up-regulated 1170 genes and down-regulated 724 genes. KEGG enrichment showed that the differentially expressed genes (DEGs) were significantly enriched in the immune- and signal-transduction-related signaling pathways. Protein-Protein Interaction (PPI) and key driver analysis (KDA) analyses revealed that Bcl10 and Bcl3 were the key genes. In addition, pBD114 significantly up-regulated 12 genes and down-regulated 38 genes in the anti-inflammatory response. KEGG enrichment analysis revealed that the DEGs were mainly enriched in the "Cytokine-cytokine receptor interaction" signaling pathway, and PPI and KDA analyses showed that Stat1 and Csf2 were the key genes. The results of qRT-PCR verified those of RNA-seq. In vivo mouse tests also confirmed the pro- or anti-inflammatory activities of pBD114. Although the inflammatory response is a rapid and complex physiological reaction to noxious stimuli, this study found that pBD114 plays an essential role mainly by acting on the genes related to immunity, signal transduction, signaling molecules, and interactions. In conclusion, this study provides a certain theoretical basis for the research and application of defensins.

Porcine β-defensin-2 alleviates aflatoxin B1 induced intestinal mucosal damage via ROS-Erk1/2 signaling pathway

Aflatoxin B1 (AFB1) is a highly toxic fungal toxin that causes severe damage to animal intestines. Porcine beta-defensin-2 (pBD-2) is a well-studied antimicrobial peptide in pigs that can protect animal intestines and improve productivity. This study aimed to investigate the molecular mechanisms of pBD-2 in alleviating AFB1-induced oxidative stress and intestinal mucosal damage using porcine intestinal epithelial cells (IPEC-J2 cells) and Kunming (KM) mice. The maximum destructive concentration of AFB1 for IPEC-J2 cells and the optimal therapeutic concentration of pBD-2 were determined by CCK-8 and RT-qPCR. We then investigated the oxidative stress and intestinal damage induced by AFB1 and the alleviating effect of pBD-2 by detecting changes of reactive oxygen species (ROS), inflammatory cytokines, tight junction proteins (TJPs) and mucin. Finally, the molecular mechanism of pBD-2 mitigates AFB1-induced oxidative stress and intestinal mucosal damage were explored by adding ROS and Erk1/2 pathway inhibitors to comparative analysis. In vivo, the therapeutic effect of pBD-2 on AFB1-induced intestinal damage was analyzed from aspects such as average daily gain (ADG), pathological damage, inflammation, and mucosal barrier in KM mice. The study found that low doses of pBD-2 promoted cell proliferation and prevented AFB1-induced cell death, and pBD-2 significantly restored the feed conversion rate and ADG of KM mice reduced by long-term exposed AFB1. Increasing the intracellular ROS and the expression and phosphorylation of Erk1/2, AFB1 promoted inflammation by altering inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8, and disrupted the mucosal barrier by interfering with Claudin-3, Occludin, and MUC2, while pBD-2 significantly reduced ROS and decreased the expression and phosphorylation of Erk1/2 to restored their expression to alleviate AFB1-induced oxidative stress and intestinal mucosal damage in IPEC-J2 cells and the small intestine of mice.

Melatonin Ameliorates Apoptosis of A549 Cells Exposed to Chicken House PM2.5: A Novel Insight in Poultry Production

The particulate matter 2.5 (PM_2.5) from the chicken production system can cause lung injury and reduce productivity through prolonged breath as it attaches large amounts of harmful substances and microbes. Melatonin has acted to regulate physiological and metabolic disorders and improve growth performance during poultry production. This research would investigate the apoptosis caused by chicken house PM_2.5 on lung pulmonary epithelial cells and the protective action of melatonin. Here, the basal epithelial cells of human lung adenocarcinoma (A549 cells) were subjected to PM_2.5 from the broiler breeding house to investigate the apoptosis induced by PM_2.5 as well as the alleviation of melatonin. The apoptosis was aggravated by PM_2.5 (12.5 and 25 μg/mL) substantially, and the expression of Bcl-2, Bad, Bax, PERK, and CHOP increased dramatically after PM_2.5 treatment. Additionally, the up-regulation of cleaved caspase-9 and cleaved caspase-3 as well as endoplasmic reticulum stress (ERS)-related proteins, including ATF6 and CHOP, was observed due to PM_2.5 exposure. It is worth noting that melatonin could support A549 cells' survival, in which reduced expression of Bax, Bad, cleaved caspase-3, and cleaved caspase-9 appeared. Concurrently, the level of malondialdehyde (MDA) was down-regulated and enhanced the intracellular content of total superoxide dismutase (T-SOD) and catalase (CAT) after treatment by PM_2.5 together with melatonin. Collectively, our study underlined that melatonin exerted an anti-apoptotic action on A549 cells by strengthening their antioxidant capacity.

Porcine β-defensin-2 alleviates AFB1-induced intestinal mucosal injury by inhibiting oxidative stress and apoptosis

Aflatoxin B1 (AFB1) is the most toxic mycotoxin contaminant, which is widely present in crops and poses a major safety hazard to animal and human health. To alleviate the cytotoxic effects of AFB1 on the intestine, we tested the protective effects of porcine β-defensin-2 (pBD-2). Results demonstrated that pBD-2 inhibited oxidative stress induced by AFB1 via decreasing the levels of ROS and enhancing the expression of antioxidant factors SOD-2 and NQO-1. In addition, pBD-2 attenuated AFB1-induced intestinal porcine epithelial cell line-J2 (IPEC-J2) injury through blocking mitochondria-mediated apoptosis. In vivo, pBD-2 treatment restored the intestinal mucosal structure and reduced the expression levels of apoptosis factors caspase-3 and Bax/Bcl-2. In conclusion, these results indicated that pBD-2 can alleviate AFB1-induced intestinal mucosal injury by inhibiting oxidative stress and mitochondria-mediated apoptosis. This study provides an effective strategy in developing pBD-2 as green feed additive to prevent AFB1 damage to animals.

Gut microbiota and intestinal barrier function in subjects with cognitive impairments: a cross-sectional study

Background

Gut-brain axis might play an important role in cognitive impairments by various diseases including Alzheimer's disease (AD).

Objective

To investigate the differences in gut microbial composition, intestinal barrier function, and systemic inflammation in patients with AD or mild cognitive impairment (MCI), and normal control (NC) cases.

Methods

A total of 118 subjects (45 AD, 38 MCI, and 35 NC) were recruited. Cognitive function was assessed using Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment Scale (MoCA). Functional ability was assessed using Activity of Daily Living Scale (ADL). The composition of gut microbiome was examined by 16S rRNA high-throughput sequencing. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was used to predict functional transfer of gut microbiota. Gut barrier dysfunction was evaluated by measuring the levels of diamine oxidase (DAO), D-lactic acid (DA), and endotoxin (ET). The serum high-sensitivity C-reactive protein (hs-CRP) level was used to indicate systemic inflammation.

Results

Compared with normal controls, patients with cognitive impairments (AD and MCI) had lower abundance of Dorea and higher levels of DAO, DA, and ET. Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that the pathways related to glycan biosynthesis and metabolism increased in MCI patients, while the ones related to membrane transport decreased. The abundance of Bacteroides and Faecalibacterium was negatively correlated with the content of ET, and positively correlated with the scores of MMSE and MoCA. The hs-CRP levels were similar among the three groups. A significant negative correlation was observed between the severity of gut barrier dysfunction and cognitive function.

Conclusion

Cognitive impairments might be associated with gut microbial dysbiosis and intestinal barrier dysfunction.

Bifidobacterium longum supplementation improves age-related delays in fracture repair

Age-related delays in bone repair remains an important clinical issue that can prolong pain and suffering. It is now well established that inflammation increases with aging and that this exacerbated inflammatory response can influence skeletal regeneration. Recently, simple dietary supplementation with beneficial probiotic bacteria has been shown to influence fracture repair in young mice. However, the contribution of the gut microbiota to age-related impairments in fracture healing remains unknown. Here, we sought to determine whether supplementation with a single beneficial probiotic species, Bifidobacterium longum (B. longum), would promote fracture repair in aged (18-month-old) female mice. We found that B. longum supplementation accelerated bony callus formation which improved mechanical properties of the fractured limb. We attribute these pro-regenerative effects of B. longum to preservation of intestinal barrier, dampened systemic inflammation, and maintenance of the microbiota community structure. Moreover, B. longum attenuated many of the fracture-induced systemic pathologies. Our study provides evidence that targeting the gut microbiota using simple dietary approaches can improve fracture healing outcomes and minimize systemic pathologies in the context of aging.

Anti-Inflammatory Protein Isolated from Tamarind Promotes Better Histological Aspects in the Intestine Regardless of the Improvement of Intestinal Permeability in a Preclinical Study of Diet-Induced Obesity

Obesity is associated with metabolic and physiological effects in the gut. In this study, we evaluated the anti-inflammatory effect of trypsin inhibitor isolated from tamarind seeds (TTI) in vitro (interaction with lipopolysaccharide (LPS) and inhibitory activity against human neutrophil elastase (HNE)), and using intestinal co-cultures of Caco-2:HT29-MTX cell lines inflamed with TNF-α (50 ng/mL) and a Wistar rat model of diet-induced obesity (n = 15). TTI was administered to animals by gavage (10 days), and the treated group (25 mg/kg/day) was compared to animals without treatment or treated with a nutritionally adequate diet. In the in vitro study, it showed inhibitory activity against HNE (93%). In co-cultures, there was no protection or recovery of the integrity of inflamed cell monolayers treated with TTI (1.0 mg/mL). In animals, TTI led to lower plasma concentrations of TNF-α and IL-6, total leukocytes, fasting glucose, and LDL-c (p < 0.05). The intestines demonstrated a lower degree of chronic enteritis, greater preservation of the submucosa, and greater intestinal wall thickness than the other groups (p = 0.042). Therefore, the better appearance of the intestine not reflected in the intestinal permeability added to the in vitro activity against HNE point to possibilities for new studies and applications related to this activity.

Involvement of Porcine β-Defensin 129 in Sperm Capacitation and Rescue of Poor Sperm in Genital Tract Infection

In mammals, β-defensins have been reported to play pivotal roles in sperm protection and fertilization. However, the function and mechanism of porcine β-defensin 129 (pBD129) in the sperm remain unclear. Here, we demonstrate that pBD129 is a glycosylated protein and broadly exists in accessory sex glands and coats the sperm surface. We inhibited the pBD129 protein on the sperm surface with an anti-pBD129 antibody and found that sperm motility was not significantly affected; however, sperm acrosome integrity and tyrosine phosphorylation levels increased significantly with time (p < 0.05) during capacitation. These changes were accompanied by an increase in sperm Ca2+ influx, resulting in a significantly reduced in vitro fertilization cleavage rate (p < 0.05). Further investigation revealed that treatment with recombinant pBD129 markedly restored the sperm motility in semen contaminated with Escherichia coli. The results suggest that pBD129 is not only associated with poor sperm motility after genital tract infection but can also protect the spermatozoa from premature capacitation, which may be beneficial for semen preservation.

Recombinant porcine beta defensin 2 alleviates inflammatory responses induced by Escherichia coli in IPEC-J2 cells

pBD2 is one of the porcine beta defensins with broad antimicrobial activity, and plays an important role in immune regulation. However, the activities and mechanisms of pBD2 regulating host resistance to Escherichia coli infection are unclear. In this study, the immunomodulatory activity and mechanisms of recombinant pBD2 against Escherichia coli infection were explored in IPEC-J2 cells. Recombinant pBD2 had no obvious effect on the growth of cells below 80 μg/mL, however, it reduced the number of E. coli adhering to cells. Furthermore, pBD2 restored the abnormal expression of ZO-1 and occludin in cells challenged with E. coli. pBD2 treatment also reduced cell apoptosis and decreased the expression of the apoptosis-related genes Cox-2 and Caspase-3, and decreased the expression of the pro-inflammatory IL-6, IL-8, IL-1α and TNF-α, and Cxcl2 and Ccl20. pBD2 also reduced the expression of TAK1, and inhibited the phosphorylation of NF-κB p65 following E. coli infection. In addition, pBD2 was localized in the cytoplasm. Collectively, pBD2 appeared to penetrate cells and alleviate inflammatory responses via the TAK1-NF-κB signaling pathway. Our results revealed the immunomodulatory activity of recombinant pBD2 against E. coli and provided insights into the molecular mechanisms that protected cells from E. coli infection.

Recombinant human β-defensin130 inhibited the growth of foodborne bacteria through membrane disruption and exerted anti-inflammatory activity

Foodborne pathogens causing food poisoning and infections are detrimental to human health, and the abuse of antibiotics induced severe antibiotic resistance in past decades. Thus, it is urgent to develop new antimicrobial agents. In the current study, human β-defensin 130 (hBD130), which is an antimicrobial peptide identified in human macrophages in 2017, was initially produced in Pichia pastoris. The purified hBD130 demonstrated broad bactericidal spectrum against foodborne pathogens through a membrane disruption, with concentrations ranging from 10 to 45 μg/mL. Moreover, hBD130 showed a low hemolytic effect and nearly no cytotoxicity to mammalian cells with a dosage of 400 μg/mL. In addition, the secretion amounts and mRNA levels of NO, IL-6, IL-1β, and TNF-α in LPS-induced mouse macrophage were significantly decreased with 1 mg/mL of hBD130. Taken together, these results showed that hBD130 is a promising antimicrobial agent to treat foodborne bacterial infections and inflammation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01087-y.

β-defensin 118 attenuates inflammation and injury of intestinal epithelial cells upon enterotoxigenic Escherichia coli challenge

Background

Antimicrobial peptides including various defensins have been attracting considerable research interest worldwide, as they have potential to substitute for antibiotics. Moreover, AMPs also have immunomodulatory activity. In this study, we explored the role and its potential mechanisms of β-defensin 118 (DEFB118) in alleviating inflammation and injury of IPEC-J2 cells (porcine jejunum epithelial cell line) upon the enterotoxigenic Escherichia coli (ETEC) challenge.

Results

The porcine jejunum epithelial cell line (IPEC-J2) pretreated with or without DEFB118 (25 μg/mL) were challenged by ETEC (1×10⁶ CFU) or culture medium. We showed that DEFB118 pretreatment significantly increased the cell viability (P<0.05) and decreased the expressions of inflammatory cytokines such as the interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in IPEC-J2 cells exposure to ETEC (P<0.05). Interestingly, DEFB118 pretreatment significantly elevated the abundance of the major tight-junction protein zonula occludens-1 (ZO-1), but decreased the number of apoptotic cells upon ETEC challenge (P<0.05). The expression of caspase 3, caspase 8, and caspase 9 were downregulated by DEFB118 in the IPEC-J2 cells exposure to ETEC (P<0.05). Importantly, DEFB118 suppressed two critical inflammation-associated signaling proteins, nuclear factor-kappa-B inhibitor alpha (IκB-α) and nuclear factor-kappaB (NF-κB) in the ETEC-challenged IPEC-J2 cells.

Conclusions

DEFB118 can alleviate ETEC-induced inflammation in IPEC-J2 cells through inhibition of the NF-κB signaling pathway, resulting in reduced secretion of inflammatory cytokines and decreased cell apoptosis. Therefore, DEFB118 can act as a novel anti-inflammatory agent.

Tetrastigma hemsleyanum Diels et Gilg ameliorates lipopolysaccharide induced sepsis via repairing the intestinal mucosal barrier

OBJECTIVE

Sepsis causes excessive systemic inflammation and leads to multiple organ dysfunction syndrome (MODS). The intestine plays a key role in the occurrence and development of sepsis. Tetrastigma hemsleyanum Diels et Gilg (San ye qing, SYQ), a precious Chinese medicine, has been widely used for centuries due to its high traditional value, such as a remarkable anti-inflammatory effect. However, the role of SYQ in intestinal permeability during the development of sepsis needs to be discovered.

METHODS

Mice were intraperitoneally injected with lipopolysaccharide (LPS) to simulate intestinal mucosal barrier function damage in sepsis. Pathological section, inflammatory cytokines, tight junctions, cell apoptosis, and intestinal flora were detected to evaluate the protective effect of SYQ on intestinal mucosal barrier injury in LPS-induced septic mice.

RESULTS

The results showed that SYQ treatment obviously attenuated LPS-induced intestinal injury and reduced the production of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and interleukin 6 (IL-6). Besides, SYQ also up-regulated the expressions of tight junctions, including Zonula occludens 1 (ZO-1), Claudin-5, and Occludin along with a decreased in the levels of myosin light chain kinase (MLCK) and myosin light chain (MLC). In addition, SYQ down-regulated the expression of Bax/Bcl2 as well as that of cleaved caspase-3 to prevent the cells from undergoing apoptosis. Further, SYQ restored the diversity of the intestinal flora, increased the abundance of Firmicutes, and decreased the abundance of Bacteroidota.

CONCLUSIONS

The study indicated that SYQ exerted its protective effect on intestinal mucosal barrier injury in LPS-induced septic mice by reducing inflammatory response, improving the tight junction protein expression, inhibiting cell apoptosis, and adjusting the intestinal flora structure.

Expression of anti-fungal peptide, β-defensin 118 in oral fibroblasts induced by C. albicans β-glucan-containing particles

Objective:

Methodology:

Results:

Conclusion:

Reserpine improves Enterobacteriaceae resistance in chicken intestine via neuro-immunometabolic signaling and MEK1/2 activation

Salmonella enterica persist in the chicken gut by suppressing inflammatory responses via expansion of intestinal regulatory T cells (Tregs). In humans, T cell activation is controlled by neurochemical signaling in Tregs; however, whether similar neuroimmunological signaling occurs in chickens is currently unknown. In this study, we explore the role of the neuroimmunological axis in intestinal Salmonella resistance using the drug reserpine, which disrupts intracellular storage of catecholamines like norepinephrine. Following reserpine treatment, norepinephrine release was increased in both ceca explant media and Tregs. Similarly, Salmonella killing was greater in reserpine-treated explants, and oral reserpine treatment reduced the level of intestinal Salmonella Typhimurium and other Enterobacteriaceae in vivo. These antimicrobial responses were linked to an increase in antimicrobial peptide and IL-2 gene expression as well as a decrease in CTLA-4 gene expression. Globally, reserpine treatment led to phosphorylative changes in epidermal growth factor receptor (EGFR), mammalian target of rapamycin (mTOR), and the mitogen-associated protein kinase 2(MEK2). Exogenous norepinephrine treatment alone increased Salmonella resistance, and reserpine-induced antimicrobial responses were blocked using beta-adrenergic receptor inhibitors, suggesting norepinephrine signaling is crucial in this mechanism. Furthermore, EGF treatment reversed reserpine-induced antimicrobial responses, whereas mTOR inhibition increased antimicrobial activities, confirming the roles of metabolic signaling in these responses. Finally, MEK1/2 inhibition suppressed reserpine, norepinephrine, and mTOR-induced antimicrobial responses. Overall, this study demonstrates a central role for MEK1/2 activity in reserpine induced neuro-immunometabolic signaling and subsequent antimicrobial responses in the chicken intestine, providing a means of reducing bacterial colonization in chickens to improve food safety.

Extracellular Signal-Regulated Kinase1 (ERK1)-Mediated Phosphorylation of Voltage-Dependent Anion Channel (VDAC) Suppresses its Conductance

ERK1 is one of the members of the mitogen-activated protein kinases that regulate important cellular functions. VDAC is located at the outer membrane of mitochondria. Here, an interaction between VDAC and ERK1 has been studied on an artificial planar lipid bilayer using in vitro electrophysiology experiments. We report that VDAC is phosphorylated by ERK1 in the presence of Mg²⁺-ATP and its single-channel currents are inhibited on the artificial bilayer membrane. Treatment of Alkaline phosphatase on ERK1 phosphorylated VDAC leads to partial recovery of the single-channel VDAC currents. Later, phosphorylation of VDAC was demonstrated by Pro-Q diamond dye. Mass Spectrometric studies indicate phosphorylation of VDAC at Threonine 33, Threonine 55, and Serine 35. In a nutshell, phosphorylation of VDAC leads to the closure of the channel.

The immunomodulatory function of the porcine β-defensin 129: Alleviate inflammatory response induced by LPS in IPEC-J2 cells

β-defensin family plays a critical role in host defense against infections. In this study, we found that pBD129 are widely expressed in porcine tissues such as the intestine, liver, and spleen. Interestingly, the expression level of pBD129 in most tissues was higher in Tibetan pigs than in DLY (Duroc × Landrace × Yorkshire) pigs (P < 0.05), and was significantly upregulated upon E. coli K88 infection (P < 0.05). The pBD129 protein was successfully expressed in E. coli and the molecule weight was estimated by SDS-PAGE to be 37.2 kDa. Mass spectrometry verified the protein as a pBD129. The protein showed antibacterial activities against Streptococcus and E. coli DH5α with a minimal inhibitory concentration (MIC) of 32 μg/mL. Hemolytic and cytotoxicity assays indicated that pBD129 had no detrimental effect on cell viability. Importantly, pBD129 significantly reduced the apoptosis of porcine intestinal epithelial cells exposure to bacterial endotoxins, which was associated with down-regulation of inflammatory cytokines such as the IL-1β, IL-6 and TNFα (P < 0.05), and down-regulation of apoptosis-related genes such as the caspase-3, caspase-8, and caspase-9 (P < 0.05). These results suggested that pBD129 is a novel modulator of innate immunity involved in mammalian inflammatory responses.

Pigs Overexpressing Porcine β-Defensin 2 Display Increased Resilience to Glaesserella parasuis Infection

As the causative agent of Glässer’s disease, Glaesserella (Haemophilus) parasuis has led to serious economic losses to the swine industry worldwide. Due to the low cross-protection of vaccines and increasing antimicrobial resistance of G. parasuis, it is important to develop alternative approaches to prevent G. parasuis infection. Defensins are host defense peptides that have been suggested to be promising substitutes for antibiotics in animal production, while porcine β-defensin 2 (PBD-2) is a potent antimicrobial peptide discovered in pigs. Our previous study generated transgenic (TG) pigs overexpressing PBD-2, which displayed enhanced resistance to Actinobacillus pleuropneumoniae. In this study, the antibacterial activities of PBD-2 against G. parasuis are determined in vitro and in the TG pig model. The concentration-dependent bactericidal activity of synthetic PBD-2 against G. parasuis was measured by bacterial counting. Moreover, after being infected with G. parasuis via a cohabitation challenge model, TG pigs overexpressing PBD-2 displayed significantly milder clinical signs and less severe gross pathological changes than their wild-type (WT) littermates. The TG pigs also exhibited alleviated lung and brain lesions, while bacterial loads in the lung and brain tissues of the TG pigs were significantly lower than those of the WT pigs. Additionally, lung and brain homogenates from TG pigs possessed enhanced antibacterial activity against G. parasuis when compared with those from the WT pigs. Altogether, these proved that overexpression of PBD-2 could also endow pigs with increased resilience to G. parasuis infection, which further confirmed the potential of using the PBD-2 coding gene to develop disease-resistant pigs and provided a novel strategy to combat G. parasuis as well.

Expression and Functional Characterization of a Novel Antimicrobial Peptide: Human Beta-Defensin 118

Purpose

β-Defensin 118 (DEFB118) is a novel host defense peptide (HDP) identified in humans. To evaluate its potentials for future utilization, the DEFB118 gene was expressed in Escherichia coli (E. coli) and the recombinant protein was fully characterized.

Methods

The DEFB118 protein was obtained by heterologous expression using E. coli Rosetta (DE3). Antibacterial activity of DEFB118 was determined by using various bacterial strains. IPEC-J cells challenged by E. coli K88 were used to determine its influences on inflammatory responses.

Results

The E. coli transformants yielded more than 250 μg/mL DEFB118 protein after 4 h induction by 1.0 mM IPTG. The DEFB118 was estimated by SDS-PAGE to be 30 kDa, and MALDI-TOF analysis verified that it is a human β-defensin 118. Importantly, the DEFB118 showed antimicrobial activities against both Gram-negative bacteria (E. coli K88 and E. coli DH5α) and Gram-positive bacteria (S. aureus and B. subtilis), with a minimum inhibitory concentration (MIC) of 4 μg/mL. Hemolytic assays showed that DEFB118 had no detrimental impact on cell viability. Additionally, DEFB118 was found to elevate the viability of IPEC-J2 cells upon E. coli K88 challenge. Moreover, DEFB118 significantly decreased cell apoptosis in the late apoptosis phase and downregulated the expression of inflammatory cytokines such as IL-1β and TNF-α in IPEC-J2 cell exposure to E. coli K88.

Conclusions

These results suggested a novel function of the mammalian defensins, and the antibacterial and anti-inflammatory properties of DEFB118 may allow it as a potential substitute for conventionally used antibiotics or drugs.

Human β-Defensin 118 Attenuates Escherichia coli K88-Induced Inflammation and Intestinal Injury in Mice

Antibiotics are widely used to treat various inflammatory bowel diseases caused by enterotoxigenic Escherichia coli (ETEC). However, continuous use of antibiotics may lead to drug resistance. In this study, we investigated the role of human β-defensin 118 (DEFB118) in regulating the ETEC-induced inflammation and intestinal injury. ETEC-challenged or non-challenged mice were treated by different concentrations of DEFB118. We show that ETEC infection significantly increased fecal score (P < 0.05) and serum concentrations of interlukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Moreover, the concentrations of D-lactic acid, C-reactive protein (CRP), creatinine (CREA), and urea (P < 0.05) were both increased in the ETEC-challenged mice. However, DEFB118 significantly decreased their concentrations in the serum (P < 0.05). DEFB118 not only alleviated tissue damage in spleen upon ETEC challenge, but also increased the villus height in duodenum and ileum (P < 0.05). Moreover, DEFB118 improved the localization and abundance of tight junction protein ZO-1 in jejunal epithelium. Interestingly, DEFB118 decreased the expression levels of critical genes involving in mucosal inflammatory responses (NF-κB, TLR4, IL-1β, and TNF-α) and the apoptosis (caspase3) upon ETEC challenge (P < 0.05), whereas DEFB118 significantly upregulated the expression of mucosa functional genes such as the mucin1 (MUC1) and sodium-glucose transporter-1 (SGLT-1) in the ETEC-challenged mice (P < 0.05). These results indicated a novel function of the DEFB118. The anti-inflammatory effect of DEFB118 should make it an attractive candidate to prevent various bacteria-induced inflammatory bowel diseases.

Antimicrobial Mechanism of pBD2 against Staphylococcus aureus

Antimicrobial peptides (AMPs) show high antibacterial activity against pathogens, which makes them potential new therapeutics to prevent and cure diseases. Porcine beta defensin 2 (pBD2) is a newly discovered AMP and has shown antibacterial activity against different bacterial species including multi-resistant bacteria. In this study, the functional mechanism of pBD2 antibacterial activity against Staphylococcus aureus was investigated. After S. aureus cells were incubated with different concentrations of pBD2, the morphological changes in S. aureus and locations of pBD2 were detected by electron microscopy. The differentially expressed genes (DEGs) were also analyzed. The results showed that the bacterial membranes were broken, bulging, and perforated after treatment with pBD2; pBD2 was mainly located on the membranes, and some entered the cytoplasm. Furthermore, 31 DEGs were detected and confirmed by quantitative real-time PCR (qRT-PCR). The known functional DEGs were associated with transmembrane transport, transport of inheritable information, and other metabolic processes. Our data suggest that pBD2 might have multiple modes of action, and the main mechanism by which pBD2 kills S. aureus is the destruction of the membrane and interaction with DNA. The results imply that pBD2 is an effective bactericide for S. aureus, and deserves further study as a new therapeutic substance against S. aureus.

C-reactive protein as an early marker of immune-related adverse events

PURPOSE

Immune checkpoint inhibitors (ICIs) are effective against a wide variety of cancers. However, they also induce a plethora of unique immune-related adverse events (irAEs). Since for many organ systems symptoms can be unspecific, differential diagnosis with progression of disease or infection may be difficult. C-reactive protein (CRP) has been suggested as a marker for infection. The purpose of this study was to evaluate the diagnostic value of CRP in differentiating infectious causes from autoimmune side effects induced by ICIs.

METHODS

In order to investigate the role of CRP in irAEs, we screened our patient data base. Only events with full infectious workup were included. In total 88 events of irAEs in 37 melanoma patients were analyzed. CRP levels before and during irAEs were evaluated. Statistical analyses were conducted using the Chi-square test for categorical variables.

RESULTS

At the onset of irAE, CRP rose in 93% of cases to a mean of 52.7 mg/L (CI 35.1-70.3) from 8.4 mg/L at baseline (normal < 5 mg/L) (P < 0.0001). Other causes of CRP elevation including infectious diseases were excluded, and procalcitonin (PCT) levels were normal in 92% of events. Importantly, in 42% of cases CRP elevations preceded clinical symptoms.

CONCLUSION

CRP elevation can predict the onset of irAEs in patients treated with ICIs in the absence of infectious disease.