Defensins and other antimicrobial peptides in inflammatory bowel disease

Phytochemical Properties of Crataegus azarolus Berries Decoction Extract and Evaluation of its Protective Activity Against Acetic Acid-Induced Ulcerative Colitis in Rats

The present study aims to evaluate the protective effect of Crataegus azarolus berries decoction extract (CAB-DE) against acetic acid-induced ulcerative colitis as well as the mechanisms implicated in such protection. Adult male Wistar rats were separated into seven groups: Control (H2O), acetic acid (AA), AA + various doses of CAB-DE (100, 200, and 400 mg/kg, b.w.,p.o.), and AA + sulfasalazine (100 mg/kg, b.w.,p.o.) or gallic acid (50 mg/kg, b.w.,p.o.) during 10 days. All rats were kept fasting overnight and ulcerative colitis was induced by rectal infusion of AA (300 mg kg-1, b.w.) (3%, v/v, 5 mL kg-1 b.w), for 30 s. The colon was rapidly excised and macroscopically examined to measure ulcerated surfaces and the ulcer index. In vitro, we found that CAB-DE exhibited a high antioxidant activity against DPPH radical (IC50 = 164.17 ± 4.78 μg/mL). In vivo, pretreatment with CAB-DE significantly protected the colonic mucosa against AA-induced damage by stimulating mucus secretion, reducing ulcer index as well as histopathological changes. Also, CAB-DE limited the oxidative status induced by AA in the colonic mucosa, as assessed by MDA and H2O2 increased levels and the depletion of both enzymatic activities and non-enzymatic levels. In addition, AA intoxication increased iron and calcium levels in colonic mucosa and plasma, while CAB-DE pretreatment regulated all intracellular mediators deregulation and significantly reduced inflammatory markers such as CRP (1.175 ± .04 ─ .734 ± .06 μg/dl) and ALP (161.53 ± 5.02 ─ 98.60 ± 4.21 UI/L) levels. We suggest that CAB-DE protected against AA-induced ulcerative colitis due in part to its antioxidant and anti-inflammatory properties.

The Role of Genetically Engineered Probiotics for Treatment of Inflammatory Bowel Disease: A Systematic Review

BACKGROUND

Many preclinical studies have demonstrated the effectiveness of genetically modified probiotics (gm probiotics) in animal models of inflammatory bowel disease (IBD).

OBJECTIVE

This systematic review was performed to investigate the role of gm probiotics in treating IBD and to clarify the involved mechanisms.

METHODS

PubMed, Web of Science, Cochrane Library, and Medline were searched from their inception to 18 September 2022 to identify preclinical and clinical studies exploring the efficacy of gm probiotics in IBD animal models or IBD patients. Two independent researchers extracted data from the included studies, and the data were pooled by the type of study; that is, preclinical or clinical.

RESULTS

Forty-five preclinical studies were included. In these studies, sodium dextran sulfate and trinitrobenzene sulfonic acid were used to induce colitis. Eleven probiotic species have been genetically modified to produce therapeutic substances, including IL-10, antimicrobial peptides, antioxidant enzymes, and short-chain fatty acids, with potential therapeutic properties against colitis. The results showed generally positive effects of gm probiotics in reducing disease activity and ameliorating intestinal damage in IBD models; however, the efficacy of gm probiotics compared to that of wild-type probiotics in many studies was unclear. The main mechanisms identified include modulation of the diversity and composition of the gut microbiota, production of regulatory metabolites by beneficial bacteria, reduction of the pro- to anti-inflammatory cytokine ratio in colonic tissue and plasma, modulation of oxidative stress activity in the colon, and improvement of intestinal barrier integrity. Moreover, only one clinical trial with 10 patients with Crohn's disease was included, which showed that L. lactis producing IL-10 was safe, and a decrease in disease activity was observed in these patients.

CONCLUSIONS

Gm probiotics have a certain efficacy in colitis models through several mechanisms. However, given the scarcity of clinical trials, it is important for researchers to pay more attention to gm probiotics that are more effective and safer than wild-type probiotics to facilitate further clinical translation.

Clinical Significance of Serum Elafin in Children with Inflammatory Bowel Disease

BACKGROUND

The role of elafin in the pathophysiology of inflammatory bowel disease (IBD) has not been not elucidated. We aimed to evaluate serum elafin in children with IBD and assess its relationship with disease activity.

METHODS

We enrolled children with IBD in the study group and children with functional abdominal pain in the control group. We evaluated serum elafin using enzyme-linked immunosorbent assay kits.

RESULTS

In children with IBD, serum elafin (mean ± SD: 4.192 ± 1.424 ng/mL) was significantly elevated compared with controls (mean ± SD: 3.029 ± 1.366 ng/mL) (p = 0.0005). Elafin was significantly increased in children in the active phase of IBD (mean ± SD: 4.424 ± 1.449 ng/mL) compared with the control group (p = 0.0003). In IBD remission, only children with ulcerative colitis (mean ± SD: 4.054 ± 1.536 ng/mL) had elevated elafin compared with controls (p = 0.004). ROC analysis revealed that the area under the curve (AUC) of serum elafin was 0.809 while discriminating patients with ulcerative colitis from the control group, and the AUC was 0.664 while differentiating patients with Crohn's disease from the control group.

CONCLUSIONS

Serum elafin was found to be elevated in our cohort of children with IBD, depending on disease activity. Serum elafin was increased in the active phases of both ulcerative colitis and Crohn's disease, but only in the remission of ulcerative colitis. Elafin appears to be a potential candidate for a biomarker of ulcerative colitis.

Role of Paneth cells-associated Crohn's disease susceptibility genes in development of Crohn's disease

Crohn's disease (CD) is a chronic inflammatory digestive tract disease, and its pathogenesis involves many factors such as genetics, environment, and flora. In terms of genetic factors, many susceptibility genes and pathogenic pathways of CD are associated with Paneth cells (PCs). Numerous studies have demonstrated that PCs are involved in the pathogenesis of CD by affecting the gut microbiota and inducing intestinal epithelial barrier dysfunction and immune abnormalities. These advances provide new ideas for the prevention of CD and potential therapeutic targets for this disease. This article reviews the role of PCs-associated CD susceptibility genes in the pathogenesis of CD.

Patient-derived organoids for therapy personalization in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders of the intestinal tract that have emerged as a growing problem in industrialized countries. Knowledge of IBD pathogenesis is still incomplete, and the most widely-accepted interpretation considers genetic factors, environmental stimuli, uncontrolled immune responses and altered intestinal microbiota composition as determinants of IBD, leading to dysfunction of the intestinal epithelial functions. In vitro models commonly used to study the intestinal barrier do not fully reflect the proper intestinal architecture. An important innovation is represented by organoids, 3D in vitro cell structures derived from stem cells that can self-organize into functional organ-specific structures. Organoids may be generated from induced pluripotent stem cells or adult intestinal stem cells of IBD patients and therefore retain their genetic and transcriptomic profile. These models are powerful pharmacological tools to better understand IBD pathogenesis, to study the mechanisms of action on the epithelial barrier of drugs already used in the treatment of IBD, and to evaluate novel target-directed molecules which could improve therapeutic strategies. The aim of this review is to illustrate the potential use of organoids for therapy personalization by focusing on the most significant advances in IBD research achieved through the use of adult stem cells-derived intestinal organoids.

A combination of fecal calprotectin and human beta-defensin 2 facilitates diagnosis and monitoring of inflammatory bowel disease

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) show a large overlap in clinical presentation, which presents diagnostic challenges. As a consequence, invasive and burdensome endoscopies are often used to distinguish between IBD and IBS. Here, we aimed to develop a noninvasive fecal test that can distinguish between IBD and IBS and reduce the number of endoscopies.We used shotgun metagenomic sequencing to analyze the composition and function of gut microbiota of 169 IBS patients, 447 IBD patients and 1044 population controls and measured fecal Calprotectin (FCal), human beta defensin 2 (HBD2), and chromogranin A (CgA) in these samples. These measurements were used to construct training sets (75% of data) for logistic regression and machine learning models to differentiate IBS from IBD and inactive from active IBD. The results were replicated on test sets (remaining 25% of the data) and microbiome data obtained using 16S sequencing.Fecal HBD2 showed high sensitivity and specificity for differentiating between IBD and IBS (sensitivity = 0.89, specificity = 0.76), while the inclusion of microbiome data with biomarkers (HBD2 and FCal) showed a potential for improvement in predictive power (optimal sensitivity = 0.87, specificity = 0.93). Shotgun sequencing-based models produced comparable results using 16S-sequencing data. HBD2 and FCal were found to have predictive power for IBD disease activity (AUC ≈ 0.7).HBD2 is a novel biomarker for IBD in patients with gastro-intestinal complaints, especially when used in combination with FCal and potentially in combination with gut microbiome data.

The Role of Antimicrobial Peptides in Preterm Birth

Antimicrobial peptides (AMPs) are short cationic amphipathic peptides with a wide range of antimicrobial properties and play an important role in the maintenance of immune homeostasis by modulating immune responses in the reproductive tract. As intra-amniotic infection and microbial dysbiosis emerge as common causes of preterm births (PTBs), a better understanding of the AMPs involved in the development of PTB is essential. The altered expression of AMPs has been reported in PTB-related clinical presentations, such as preterm labor, intra-amniotic infection/inflammation, premature rupture of membranes, and cervical insufficiency. Moreover, it was previously reported that dysregulation of AMPs may affect the pregnancy prognosis. This review aims to describe the expression of AMPs associated with PTBs and to provide new perspectives on the role of AMPs in PTB.

Cathelicidin - A Novel Potential Marker of Pediatric Inflammatory Bowel Disease

Introduction

Cathelicidin is a multifunctional host defense peptide which may also exert pro-inflammatory signals and contribute to the development of autoimmune disorders. We aimed to assess serum concentration of cathelicidin in children with inflammatory bowel disease (IBD) compared to healthy controls and to evaluate its relationship with disease activity and phenotype.

Patients and Methods

The study group included 68 children with IBD. The control group comprised 20 children with functional abdominal pain. All patients and controls were tested for complete blood count, C-reactive protein, erythrocyte sedimentation rate and cathelicidin. Stool samples were collected to assess calprotectin.

Results

Cathelicidin was significantly increased in patients with ulcerative colitis (1073.39±214.52 ng/mL) and Crohn’s disease (1057.63±176.03 ng/mL) patients compared to controls (890.56±129.37 ng/mL) (H=16.28; p=0.0003). Cathelicidin was significantly elevated in children with active IBD (1044.90±176.17 ng/mL) and IBD remission (1098.10±227.87 ng/mL) compared to controls (Z=3.21; p=0.001; Z=−4.12; p<0.0001, respectively). Negative correlation between cathelicidin and calprotectin in children with ulcerative colitis was found (R=−0.39; p=0.02). Cathelicidin exhibited AUC of 0.815 for differentiation children with ulcerative colitis from the control group.

Conclusion

Serum cathelicidin is increased in children with Crohn’s disease and ulcerative colitis regardless of clinical activity of the disease suggesting that it may be a potential biomarker of IBD. Inverse correlation between cathelicidin and fecal calprotectin may imply a disparate role of these molecules in the pathophysiology of pediatric ulcerative colitis.

Pulling the Brakes on Fast and Furious Multiple Drug-Resistant (MDR) Bacteria

Life-threatening bacterial infections have been managed by antibiotics for years and have significantly improved the wellbeing and lifetime of humans. However, bacteria have always been one step ahead by inactivating the antimicrobial agent chemically or by producing certain enzymes. The alarming universal occurrence of multidrug-resistant (MDR) bacteria has compelled researchers to find alternative treatments for MDR infections. This is a menace where conventional chemotherapies are no longer promising, but several novel approaches could help. Our current review article discusses the novel approaches that can combat MDR bacteria: starting off with potential nanoparticles (NPs) that efficiently interact with microorganisms causing fatal changes in the morphology and structure of these cells; nanophotothermal therapy using inorganic NPs like AuNPs to destroy pathogenic bacterial cells; bacteriophage therapy against which bacteria develop less resistance; combination drugs that act on dissimilar targets in distinctive pathways; probiotics therapy by the secretion of antibacterial chemicals; blockage of quorum sensing signals stopping bacterial colonization, and vaccination against resistant bacterial strains along with virulence factors. All these techniques show us a promising future in the fight against MDR bacteria, which remains the greatest challenge in public health care.

Inflammatory Bowel Diseases: The Role of Gut Microbiota

Inflammatory bowel diseases (IBD) are chronic multifactorial diseases characterized by partially unclear pathogenic mechanisms including changes in intestinal microbiota. Despite the microbiota, alteration is well established in IBD patients, as reported by 16RNA sequencing analysis, an important goal is to define if it is just a consequence of the disease progression or a trigger factor of the disease itself. To date, gut microbiota composition and gut microbiota-related metabolites seem to affect the host healthy state both by modulating metabolic pathways or acting on the expression of different genes through epigenetic effects. Because of this, it has been suggested that intestinal microbiota might represent a promising therapeutic target for IBD patients. The aim of this review is to summarize both the most recent acquisitions in the field of gut microbiota and its involvement in intestinal inflammation together with the available strategies for the modulation of microbiota, such as prebiotics and/or probiotics administration or fecal microbiota transplantation.

Astaxanthin Alleviates Ochratoxin A-Induced Cecum Injury and Inflammation in Mice by Regulating the Diversity of Cecal Microbiota and TLR4/MyD88/NF-κB Signaling Pathway

Ochratoxin A (OTA) is a common environmental pollutant found in a variety of foods and grains, and excessive OTA consumption causes serious global health effects on animals and humans. Astaxanthin (AST) is a natural carotenoid that has anti-inflammatory, antiapoptotic, immunomodulatory, antitumor, antidiabetes, and other biological activities. The present study is aimed at investigating the effects of AST on OTA-induced cecum injury and its mechanism of action. Eighty C57 mice were randomly divided into four groups, including the control group, OTA group (5 mg/kg body weight), AST group (100 mg/kg body weight), and AST intervention group (100 mg/kg body weight AST+5 mg/kg body weight OTA). It was found that AST decreased the endotoxin content, effectively prevented the shortening of mouse cecum villi, and increased the expression levels of tight junction (TJ) proteins, consisting of occludin, claudin-1, and zonula occludens-1 (ZO-1). AST increased the number of goblet cells, the contents of mucin-2 (MUC2), and defensins (Defa5 and β-pD2) significantly, while the expression of mucin-1 (MUC1) decreased significantly. The 16S rRNA sequencing showed that AST affected the richness and diversity of cecum flora, decreased the proportion of lactobacillus, and also decreased the contents of short-chain fatty acids (SCFAs) (acetate and butyrate). In addition, AST significantly decreased the expression of TLR4, MyD88, and p-p65, while increasing the expression of p65. Meanwhile, the expression of inflammatory factors including TNF-α and INF-γ decreased, while the expression of IL-10 increased. In conclusion, AST reduced OTA-induced cecum injury by regulating the cecum barrier function and TLR4/MyD88/NF-κB signaling pathway.

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.

The roles and functions of Paneth cells in Crohn's disease: A critical review

Paneth cells (PCs) are located at the base of small intestinal crypts and secrete the α‐defensins, human α‐defensin 5 (HD‐5) and human α‐defensin 6 (HD‐6) in response to bacterial, cholinergic and other stimuli. The α‐defensins are broad‐spectrum microbicides that play critical roles in controlling gut microbiota and maintaining intestinal homeostasis. Inflammatory bowel disease, including ulcerative colitis and Crohn's disease (CD), is a complicated autoimmune disorder. The pathogenesis of CD involves genetic factors, environmental factors and microflora. Surprisingly, with regard to genetic factors, many susceptible genes and pathogenic pathways of CD, including nucleotide‐binding oligomerization domain 2 (NOD2), autophagy‐related 16‐like 1 (ATG16L1), immunity‐related guanosine triphosphatase family M (IRGM), wingless‐related integration site (Wnt), leucine‐rich repeat kinase 2 (LRRK2), histone deacetylases (HDACs), caspase‐8 (Casp8) and X‐box‐binding protein‐1 (XBP1), are relevant to PCs. As the underlying mechanisms are being unravelled, PCs are identified as the central element of CD pathogenesis, integrating factors among microbiota, intestinal epithelial barrier dysfunction and the immune system. In the present review, we demonstrate how these genes and pathways regulate CD pathogenesis via their action on PCs and what treatment modalities can be applied to deal with these PC‐mediated pathogenic processes.

The Role of Micronutrients in Support of the Immune Response against Viral Infections

Viral infections are a leading cause of morbidity and mortality worldwide, and the importance of public health practices including handwashing and vaccinations in reducing their spread is well established. Furthermore, it is well known that proper nutrition can help support optimal immune function, reducing the impact of infections. Several vitamins and trace elements play an important role in supporting the cells of the immune system, thus increasing the resistance to infections. Other nutrients, such as omega-3 fatty acids, help sustain optimal function of the immune system. The main aim of this manuscript is to discuss of the potential role of micronutrients supplementation in supporting immunity, particularly against respiratory virus infections. Literature analysis showed that in vitro and observational studies, and clinical trials, highlight the important role of vitamins A, C, and D, omega-3 fatty acids, and zinc in modulating the immune response. Supplementation with vitamins, omega 3 fatty acids and zinc appears to be a safe and low-cost way to support optimal function of the immune system, with the potential to reduce the risk and consequences of infection, including viral respiratory infections. Supplementation should be in addition to a healthy diet and fall within recommended upper safety limits set by scientific expert bodies. Therefore, implementing an optimal nutrition, with micronutrients and omega-3 fatty acids supplementation, might be a cost-effective, underestimated strategy to help reduce the burden of infectious diseases worldwide, including coronavirus disease 2019 (COVID-19).

Metaplastic Paneth Cells in Extra-Intestinal Mucosal Niche Indicate a Link to Microbiome and Inflammation

Paneth cells are residents of the intestinal epithelium. Abnormal appearance of Paneth cells has been widely documented in non-intestinal tissues within the digestive tract and even observed in non-gastrointestinal organs. Although metaplastic Paneth cells are part of the overarching pathology of intestinal metaplasia (IM), only a fraction of intestinal metaplastic lesions contain Paneth cells. We survey literature documenting metaplastic Paneth cells to gain insights into mechanism underlying their etiologic development as well as their potential relevance to human health. A synthesized view from this study suggests that the emergence of metaplastic Paneth cells at extra-intestinal mucosal sites likely represents a protective, anti-bacterial, and inflammatory response evoked by an altered microbial activity.

An engineering probiotic producing defensin-5 ameliorating dextran sodium sulfate-induced mice colitis via Inhibiting NF-kB pathway

Background

Human defensin-5 (HD-5) is a key antimicrobial peptide which plays an important role in host immune defense, while the short half-life greatly limits its clinical application. The purpose of this study was to investigate the effects of an engineering probiotic producing HD-5 on intestinal barrier and explore its underlying mechanism

Methods

We constructed the pN8148-SHD-5 vector, and transfected this plasmid into Lactococcus lactis (L. lactis) to create the recombinant NZ9000SHD-5 strain, which continuously produces mature HD-5. NZ9000SHD-5 was administrated appropriately in a dextran sodium sulfate (DSS)-induced colitis model. Alterations in the wounded intestine were analyzed by hematoxylin–eosin staining. The changes of intestinal permeability were detected by FITC-dextran permeability test, the tight junction (TJ) proteins ZO-1 and occludin and cytokines were analyzed by western blotting or enzyme linked immunosorbent assay. In Caco-2 cell monolayers, the permeability were analyzed by transepithelial electrical resistance, and the TJ proteins were detected by western blotting and immunofluorescence. In addition, NF-κB signaling pathway was investigated to further analyze the molecular mechanism of NZ9000SHD-5 treatment on inducing intestinal protection in vitro.

Results

We found oral administration with NZ9000SHD-5 significantly reduced colonic glandular structure destruction and inflammatory cell infiltration, downregulated expression of several inflammation-related molecules and preserved epithelial barrier integrity. The same protective effects were observed in in vitro experiments, and pretreatment of macrophages with NZ9000SHD-5 culture supernatants prior to LPS application significantly reduced the expression of phosphorylated nuclear transcription factor-kappa B (NF-κB) p65 and its inhibitor IκBα.

Conclusions

These results indicate the NZ9000SHD-5 can alleviate DSS-induced mucosal damage by suppressing NF-κB signaling pathway, and NZ9000SHD-5 may be a novel therapeutic means for ulcerative colitis.

CgRel involved in antibacterial immunity by regulating the production of CgIL17s and CgBigDef1 in the Pacific oyster Crassostrea gigas

The NF-κB/Rel transcription factors play essential roles in the induction and regulation of innate immune responses. In the present study, the full-length cDNA of CgRel from the Pacific oyster Crassostrea gigas was of 2,647 bp with an RHD and an IPT domain. The mRNA of CgRel was found to be constitutively expressed in all the tested tissues including gills, hepatopancreas, gonad, adductor muscle, labial palps, mantle, hemocytes, and ganglion. After lipopolysaccharide (LPS) stimulation, the expression level of CgRel mRNA in hemocytes was up-regulated to the first peak at 3 h (3.06-fold compared to the control group, p < 0.001) and second peak at 48 h (1.96-fold, p < 0.05). It increased significantly at 3 h (7.68-fold compared to the control group, p < 0.001), 24 h (3.63-fold, p < 0.05) and 48 h (1.99-fold, p < 0.05) post Vibrio splendidus stimulation, respectively. The protein of CgRel was translocated from cytoplasm into nucleus of oyster hemocytes after LPS stimulation. The mRNA expression levels of interleukin17s (CgIL17s) and big defensin (CgBigDef1) in hemocytes were examined after the expression of CgRel was silenced by RNAi. The transcripts of CgIL17-1 (0.25-fold of the control group, p < 0.01), CgIL17-2 (0.12-fold, p < 0.01), CgIL17-4 (0.33-fold, p < 0.01), CgIL17-6 (0.27-fold, p < 0.05) and CgBigDef1 (0.38-fold, p < 0.01) in CgRel-knockdown oysters decreased significantly at 12 h after LPS stimulation. The results indicated that CgRel played important roles in the immune defense against bacteria by regulating the expression of CgIL17 and CgBigDef1.

Dynamic Evolution of Antimicrobial Peptides Underscores Trade-Offs Between Immunity and Ecological Fitness

There is a developing interest in how immune genes may function in other physiological roles, and how traditionally non-immune peptides may, in fact, be active in immune contexts. In the absence of infection, the induction of the immune response is costly, and there are well-characterized trade-offs between immune defense and fitness. The agents behind these fitness costs are less understood. Here we implicate antimicrobial peptides (AMPs) as particularly costly effectors of immunity using an evolutionary framework. We describe the independent loss of AMPs in multiple lineages of Diptera (true flies), tying these observations back to life history. We then focus on the intriguing case of the glycine-rich AMP, Diptericin, and find several instances of loss, pseudogenization, and segregating null alleles. We suggest that Diptericin may be a particularly toxic component of the Dipteran immune response lost in flies either with reduced pathogen pressure or other environmental factors. As Diptericins have recently been described to have neurological roles, these findings parallel a developing interest in AMPs as potentially harmful neuropeptides, and AMPs in other roles beyond immunity.

Association of serum vitamin D levels and urinary tract infection in pregnant women: A case control study

OBJECTIVE

Urinary tract infection (UTI) is common during pregnancy and can cause serious complications for the mother and fetus. Vitamin D, is known to have an effect on the urothelium, with immunomodulatory capacity against bacterial infection. This study explored the association between serum vitamin D levels and urinary tract infections in pregnant women.

STUDY DESIGN

In this case control study, 187 participants including, 97 pregnant women diagnosed as a symptomatic UTI (case group) and 90 matched healthy pregnant women (control group) were consecutively enrolled from prenatal care clinic of Imam Reza Hospital in Urmia, North West of Iran. The two groups were matched for trimester and parity, and sexual intercourse. Blood samples were collected from both groups. Chemiluminescent immunoassay (CLIA) was used to evaluate the serum vitamin D levels. We used a binary multivariate unconditional logistic regression approach to evaluate the association between UTI and vitamin D and risk factor of the UTI.

RESULTS

Vitamin D deficiency (less than 20 ng/mL) was diagnosed in 85.7% of case group and 52.2% of control group. The serum vitamin D levels were significantly lower in pregnant women in the case group compared to the control group (12.7 ± 5.9 ng/ml vs 26.05 ± 10.37; p < 0.001). Pregnant women in case group with acute pyelonephritis had significantly lower serum vitamin D levels than those with Cystitis (p < 0.05). The serum vitamin D level of less than 20 ng/ml was the only factor associated with UTI after adjusting for all the confounders in multiple binary logistic regression modeling (AdjOR = 3.67; 95% of CI: 1.19-6.24; p < 0.001).

CONCLUSIONS

Women with vitamin D deficiencies are at increased risk of urinary tract infections during pregnancy. However, further studies are essential to confirm these observed results.

Taenia crassiceps-Excreted/Secreted Products Induce a Defined MicroRNA Profile that Modulates Inflammatory Properties of Macrophages

Helminth parasites modulate immune responses in their host to prevent their elimination and to establish chronic infections. Our previous studies indicate that Taenia crassiceps-excreted/secreted antigens (TcES) downregulate inflammatory responses in rodent models of autoimmune diseases, by promoting the generation of alternatively activated-like macrophages (M2) in vivo. However, the molecular mechanisms triggered by TcES that modulate macrophage polarization and inflammatory response remain unclear. Here, we found that, while TcES reduced the production of inflammatory cytokines (IL-6, IL-12, and TNFα), they increased the release of IL-10 in LPS-induced bone marrow-derived macrophages (BMDM). However, TcES alone or in combination with LPS or IL-4 failed to increase the production of the canonical M1 or M2 markers in BMDM. To further define the anti-inflammatory effect of TcES in the response of LPS-stimulated macrophages, we performed transcriptomic array analyses of mRNA and microRNA to evaluate their levels. Although the addition of TcES to LPS-stimulated BMDM induced modest changes in the inflammatory mRNA profile, it induced the production of mRNAs associated with the activation of different receptors, phagocytosis, and M2-like phenotype. Moreover, we found that TcES induced upregulation of specific microRNAs, including miR-125a-5p, miR-762, and miR-484, which are predicted to target canonical inflammatory molecules and pathways in LPS-induced BMDM. These results suggest that TcES can modulate proinflammatory responses in macrophages by inducing regulatory posttranscriptional mechanisms and hence reduce detrimental outcomes in hosts running with inflammatory diseases.

Thirty Years of Lactobacillus rhamnosus GG: A Review

Lactobacillus rhamnosus GG (LGG) was the first strain belonging to the genus Lactobacillus to be patented in 1989 thanks to its ability to survive and to proliferate at gastric acid pH and in medium containing bile, and to adhere to enterocytes. Furthermore LGG is able to produces both a biofilm that can mechanically protect the mucosa, and different soluble factors beneficial to the gut by enhancing intestinal crypt survival, diminishing apoptosis of the intestinal epithelium, and preserving cytoskeletal integrity. Moreover LGG thanks to its lectin-like protein 1 and 2 inhibits some pathogens such as Salmonella species. Finally LGG is able to promote type 1 immune-responsiveness by reducing the expression of several activation and inflammation markers on monocytes and by increasing the production of interleukin-10, interleukin-12 and tumor necrosis factor-α in macrophages. A large number of research data on Lactobacillus GG is the basis for the use of this probiotic for human health. In this review we have considered predominantly randomized controlled trials, meta-analysis, Cochrane Review, guide lines of Scientific Societies and anyway studies whose results were evaluated by means of relative risk, odds ratio, weighted mean difference 95% confidence interval. The effectiveness of LGG in gastrointestinal infections and diarrhea, antibiotic and Clostridium difficile associated diarrhea, irritable bowel syndrome, inflammatory bowel disease, respiratory tract infections, allergy, cardiovascular diseases, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, cystic fibrosis, cancer, elderly end sport were analyzed.

Reassessing the Host Defense Peptide Landscape

Current research has demonstrated that small cationic amphipathic peptides have strong potential not only as antimicrobials, but also as antibiofilm agents, immune modulators, and anti-inflammatories. Although traditionally termed antimicrobial peptides (AMPs) these additional roles have prompted a shift in terminology to use the broader term host defense peptides (HDPs) to capture the multi-functional nature of these molecules. In this review, we critically examined the role of AMPs and HDPs in infectious diseases and inflammation. It is generally accepted that HDPs are multi-faceted mediators of a wide range of biological processes, with individual activities dependent on their polypeptide sequence. In this context, we explore the concept of chemical space as it applies to HDPs and hypothesize that the various functions and activities of this class of molecule exist on independent but overlapping activity landscapes. Finally, we outline several emerging functions and roles of HDPs and highlight how an improved understanding of these processes can potentially be leveraged to more fully realize the therapeutic promise of HDPs.

Guts and Gall: Bile Acids in Regulation of Intestinal Epithelial Function in Health and Disease

Epithelial cells line the entire surface of the gastrointestinal tract and its accessory organs where they primarily function in transporting digestive enzymes, nutrients, electrolytes, and fluid to and from the luminal contents. At the same time, epithelial cells are responsible for forming a physical and biochemical barrier that prevents the entry into the body of harmful agents, such as bacteria and their toxins. Dysregulation of epithelial transport and barrier function is associated with the pathogenesis of a number of conditions throughout the intestine, such as inflammatory bowel disease, chronic diarrhea, pancreatitis, reflux esophagitis, and cancer. Driven by discovery of specific receptors on intestinal epithelial cells, new insights into mechanisms that control their synthesis and enterohepatic circulation, and a growing appreciation of their roles as bioactive bacterial metabolites, bile acids are currently receiving a great deal of interest as critical regulators of epithelial function in health and disease. This review aims to summarize recent advances in this field and to highlight how bile acids are now emerging as exciting new targets for disease intervention.

Emergent Behavior of IBD-Associated Escherichia coli During Disease

Inflammatory bowel diseases are becoming increasingly common throughout the world, both in developed countries and increasingly in rapidly developing countries. Multiple lines of evidence point to a role for the microbial composition of the gastrointestinal tract in the etiology of IBD, but to date, attempts to define a specific microbial cause for IBD have proved unsuccessful. Microbial 16S rRNA profiling shows that IBD patients have elevated levels of Enterobacteriaceae, in particular Escherichia coli, and reduced levels of Faecalibacterium prausnitzii. The observed E. coli have been assigned to a specific pathovar, adherent-invasive E. coli (AIEC). Adherent-invasive E. coli are a genomically heterogenous group, and whereas many groups have attempted to identify specific genetic markers that differentiate AIEC from non-AIEC strains, very few concrete genetic associations have been uncovered. Here, we highlight the advantages of applying a phenotyping approach to the study of these organisms, rather than solely depending on a sequencing or genomic-based screening strategy because virulence-associated phenotypes exhibit behaviors of emergent systems. In this respect, attempts at genetic reductionism are prone to failure because there are numerous metabolic, regulatory or genetic paths that can underlie these virulence-associated behaviors. Here, we review these IBD-associated phenotypes in E. coli and make recommendations for experimental approaches to advance our understanding of IBD-associated bacteria more generally. With advances in high-throughput screening and nongenetically based metabolomic characterization of IBD-associated bacteria, we anticipate a fuller understanding of how altered microbial communities contribute to the development of IBD.

Isolation and gene expression profiling of intestinal epithelial cells: crypt isolation by calcium chelation from in vivo samples

Aim

The epithelial layer within the colon represents a physical barrier between the luminal contents and its underlying mucosa. It plays a pivotal role in mucosal homeostasis, and both tolerance and anti-pathogenic immune responses. Identifying signals of inflammation initiation and responses to stimuli from within the epithelial layer is critical to understanding the molecular pathways underlying disease pathology. This study validated a method to isolate and analyze epithelial populations, enabling investigations of epithelial function and response in a variety of disease setting.

Materials and methods

Epithelial cells were isolated from whole mucosal biopsies harvested from healthy controls and patients with active ulcerative colitis by calcium chelation. The purity of isolated cells was assessed by flow cytometry. The expression profiles of a panel of epithelial functional genes were investigated by reverse transcription-polymerase chain reaction (PCR) in isolated epithelial cells and corresponding mucosal biopsies. The expression profiles of isolated cells and corresponding mucosal biopsies were evaluated and compared between healthy and inflamed colonic tissue.

Results

Flow cytometry identified 97% of cells isolated as intestinal epithelial cells (IECs). Comparisons of gene expression profiles between the mucosal biopsies and isolated IECs demonstrated clear differences in the gene expression signatures. Sixty percent of the examined genes showed contrasting trends of expression between sample types.

Conclusion

The calcium chelation isolation method provided a reliable method for the isolation of a pure population of cells with preservation of epithelial cell-specific gene expression. This demonstrates the importance of sample choice when investigating functions directly affecting the colonic epithelial layer.

Cryptdin-2 predicts intestinal injury during heatstroke in mice

Intestinal injury-induced bacterial translocation and endotoxemia are important in the pathophysiological process of heatstroke. However, the underlying mechanism remains to be fully elucidated. Previous studies using 2D-gel electrophoresis found that defensin-related cryptdin-2 (Cry-2), an intestinal α-defensin, is upregulated in intestinal tissues during heatstroke in mice, and that treatment with ulinastatin, a multivalent enzyme inhibitor, reduced heat-induced acute lung injury. To investigate the association between Cry-2 and heat stress (HS)-induced intestinal injury and the probable protective role of ulinastatin, the present study examined the intestinal expression of Cry-2 via histopathologic analysis and reverse transcription-quantitative polymerase chain reaction analysis in mice with heatstroke. The heat-stressed mice were exposed to different core temperatures and cooling treatments, and intestinal pathological changes and Chiu scores were determined. Chemical markers of intestinal injury, serum and intestinal concentrations of diamine oxidase (DAO) and D-lactic acid (D-Lac), and serum and intestinal concentrations of Cry-2 were also determined. Correlations were analyzed using Spearman's correlation analysis. It was found that HS upregulated the expression of Cry-2, and the serum and intestinal concentrations of Cry-2 were correlated with the severity of HS-induced intestinal damage, indicated by pathology scores and concentrations of DAO and D-lac. Ulinastatin protected the intestines from HS-induced injury and downregulated the expression of Cry-2, which was also correlated with the extent of intestinal injury. Therefore, ulinastatin administration may be beneficial for patients with heatstroke, and Cry-2 may be a novel predictor of HS-induced intestinal injury.

Fungal microbiota dysbiosis in IBD

OBJECTIVE

The bacterial intestinal microbiota plays major roles in human physiology and IBDs. Although some data suggest a role of the fungal microbiota in IBD pathogenesis, the available data are scarce. The aim of our study was to characterise the faecal fungal microbiota in patients with IBD.

DESIGN

Bacterial and fungal composition of the faecal microbiota of 235 patients with IBD and 38 healthy subjects (HS) was determined using 16S and ITS2 sequencing, respectively. The obtained sequences were analysed using the Qiime pipeline to assess composition and diversity. Bacterial and fungal taxa associated with clinical parameters were identified using multivariate association with linear models. Correlation between bacterial and fungal microbiota was investigated using Spearman's test and distance correlation.

RESULTS

We observed that fungal microbiota is skewed in IBD, with an increased Basidiomycota/Ascomycota ratio, a decreased proportion of Saccharomyces cerevisiae and an increased proportion of Candida albicans compared with HS. We also identified disease-specific alterations in diversity, indicating that a Crohn's disease-specific gut environment may favour fungi at the expense of bacteria. The concomitant analysis of bacterial and fungal microbiota showed a dense and homogenous correlation network in HS but a dramatically unbalanced network in IBD, suggesting the existence of disease-specific inter-kingdom alterations.

CONCLUSIONS

Besides bacterial dysbiosis, our study identifies a distinct fungal microbiota dysbiosis in IBD characterised by alterations in biodiversity and composition. Moreover, we unravel here disease-specific inter-kingdom network alterations in IBD, suggesting that, beyond bacteria, fungi might also play a role in IBD pathogenesis.

Mend Your Fences: The Epithelial Barrier and its Relationship With Mucosal Immunity in Inflammatory Bowel Disease

The intestinal epithelium can be easily disrupted during gut inflammation as seen in inflammatory bowel disease (IBD), such as ulcerative colitis or Crohn's disease. For a long time, research into the pathophysiology of IBD has been focused on immune cell-mediated mechanisms. Recent evidence, however, suggests that the intestinal epithelium might play a major role in the development and perpetuation of IBD. It is now clear that IBD can be triggered by disturbances in epithelial barrier integrity via dysfunctions in intestinal epithelial cell-intrinsic molecular circuits that control the homeostasis, renewal, and repair of intestinal epithelial cells. The intestinal epithelium in the healthy individual represents a semi-permeable physical barrier shielding the interior of the body from invasions of pathogens on the one hand and allowing selective passage of nutrients on the other hand. However, the intestinal epithelium must be considered much more than a simple physical barrier. Instead, the epithelium is a highly dynamic tissue that responds to a plenitude of signals including the intestinal microbiota and signals from the immune system. This epithelial response to these signals regulates barrier function, the composition of the microbiota, and mucosal immune homeostasis within the lamina propria. The epithelium can thus be regarded as a translator between the microbiota and the immune system and aberrant signal transduction between the epithelium and adjacent immune cells might promote immune dysregulation in IBD. This review summarizes the important cellular and molecular barrier components of the intestinal epithelium and emphasizes the mechanisms leading to barrier dysfunction during intestinal inflammation.

Exploration of Inflammatory Bowel Disease in Mice: Chemically Induced Murine Models of Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is a chronic multifactorial inflammatory disorder characterized by periods of activation and remission of intestinal inflammation, with potentially severe complications, that can lead to mortality. Experimental animal models of intestinal inflammation are crucial for understanding the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC), the two major human IBD phenotypes. Animal models have been instrumental in unveiling the molecular background of IBD, and although a single model is not able to capture the complexity of this disease, each of them provided valuable insight into its different aspects. Chemically induced models of intestinal inflammation, mainly dextran sodium sulfate (DSS)- and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis, are widely used. This article describes DSS- and TNBS-induced colitis models and their relevance to IBD pathophysiology and pre-clinical therapeutic management. © 2017 by John Wiley & Sons, Inc.

The Roles of Cathelicidin LL-37 in Inflammatory Bowel Disease

Human cathelicidin LL-37, the only member of the cathelicidin family of host defense peptides expressed in humans, plays a crucial role in host defense against pathogen invasion, as well as in regulating the functions of anti-inflammation, antitumorigenesis, and tissue repair. It is primarily produced by phagocytic leukocytes and epithelial cells, and mediates a wide range of biological responses. Emerging evidence from several studies indicates that LL-37 plays a prominent and complex role in inflammatory bowel disease (IBD). Although overexpression of LL-37 has been implicated in the inflamed and noninflamed colon mucosa in patients with ulcerative colitis, LL-37 expression was not changed in the inflamed or noninflamed colon or ileal mucosa in patients with Crohn's disease. Furthermore, studies in animal models and human patients further characterized the protective effect of cathelicidins both in ulcerative colitis and Crohn's disease. These data suggest the intricate functions of LL-37 in IBD. They will also create many strategies and opportunities for therapeutic intervention in IBD in the future. This review aims to elucidate the structure and bioactivity of LL-37 and also discuss the recent progress in understanding the relationship between LL-37 and IBD.

Protease inhibition as new therapeutic strategy for GI diseases

The GI tract is the most exposed organ to proteases, both in physiological and pathophysiological conditions. For digestive purposes, the lumen of the upper GI tract contains large amounts of pancreatic proteases, but studies have also demonstrated increased proteolytic activity into mucosal tissues (both in the upper and lower GI tract), associated with pathological conditions. This review aims at outlining the evidences for dysregulated proteolytic homeostasis in GI diseases and the pathogenic mechanisms of increased proteolytic activity. The therapeutic potential of protease inhibition in GI diseases is discussed, with a particular focus on IBDs, functional GI disorders and colorectal cancer.

Intestinal barrier dysfunction: implications for chronic inflammatory conditions of the bowel

The intestinal epithelium of adult humans acts as a differentially permeable barrier that separates the potentially harmful contents of the lumen from the underlying tissues. Any dysfunction of this boundary layer that disturbs the homeostatic equilibrium between the internal and external environments may initiate and sustain a biochemical cascade that results in inflammation of the intestine. Key to such dysfunction are genetic, microbial and other environmental factors that, singularly or in combination, result in chronic inflammation that is symptomatic of inflammatory bowel disease (IBD). The aim of the present review is to assess the scientific evidence to support the hypothesis that defective transepithelial transport mechanisms and the heightened absorption of intact antigenic proinflammatory oligopeptides are important contributing factors in the pathogenesis of IBD.

Calcitriol prevents inflammatory gene expression in macrovascular endothelial cells

BACKGROUND

Calcitriol (vitamin D) supplementation has been proposed for therapeutical use in vascular diseases due to its immunomodulatory activity, preventing inflammation and promoting angiogenesis. In the present study, we hypothesised whether calcitriol downregulates pro-inflammatory gene expression without affecting angiogenesis and anti-inflammatory gene expression in LPS-induced endothelial cells.

METHOD

In order to evaluate the effect of calcitriol in suppressing inflammatory gene expression in the endothelium, endothelial cells were exposed to the physiological concentration of calcitriol followed by stimulation with lipopolysaccharide (LPS). Gene expression of interleukin (IL)-1β, Transforming Growth Factor (TGF)-β, Human β-defensin (HBD)-2, angiogenin (ANG) and cathelicidin (LL-37) were quantified by quantitative polymerase chain reaction.

RESULTS

The results from six independent experiments conducted in duplicate, showed that calcitriol decreased IL-1β (p < 0.01) and HBD-2 expression (p < 0.01) when compared to non-treated cells. However, calcitriol treatment had no effect on TGF-β, ANG and LL-37 gene expression.

CONCLUSION

Calcitriol prevents inflammatory gene expression, but does not affect expression of angiogenic genes in endothelial cells, which suggest the potential use of calcitriol to prevent endothelial activation through the downregulation of IL-1β and HBD-2.

Epithelial IL-18 Equilibrium Controls Barrier Function in Colitis

The intestinal mucosal barrier controlling the resident microbiome is dependent on a protective mucus layer generated by goblet cells, impairment of which is a hallmark of the inflammatory bowel disease, ulcerative colitis. Here, we show that IL-18 is critical in driving the pathologic breakdown of barrier integrity in a model of colitis. Deletion of Il18 or its receptor Il18r1 in intestinal epithelial cells (Δ/EC) conferred protection from colitis and mucosal damage in mice. In contrast, deletion of the IL-18 negative regulator Il18bp resulted in severe colitis associated with loss of mature goblet cells. Colitis and goblet cell loss were rescued in Il18bp(-/-);Il18r(Δ/EC) mice, demonstrating that colitis severity is controlled at the level of IL-18 signaling in intestinal epithelial cells. IL-18 inhibited goblet cell maturation by regulating the transcriptional program instructing goblet cell development. These results inform on the mechanism of goblet cell dysfunction that underlies the pathology of ulcerative colitis.

Transcriptional regulation of cathelicidin genes in chicken bone marrow cells

Cathelicidins form a family of vertebrate-specific immune molecules with an evolutionarily conserved gene structure. We analyzed the expression patterns of cathelicidin genes (CAMP, CATH3, and CATHB1) in chicken bone marrow cells (BMCs) and chicken embryonic fibroblasts (CEFs). We found that CAMP and CATHB1 were significantly up-regulated in BMCs, whereas the expression of CATH3 did not differ significantly between BMCs and CEFs. To study the mechanism underlying the up-regulation of cathelicidin genes in BMCs, we predicted the transcription factors (TFs) that bind to the 5'-flanking regions of cathelicidin genes. CEBPA, EBF1, HES1, MSX1, and ZIC3 were up-regulated in BMCs compared to CEFs. Subsequently, when a siRNA-mediated knockdown assay was performed for MSX1, the expression of CAMP and CATHB1 was decreased in BMCs. We also showed that the transcriptional activity of the CAMP promoter was decreased by mutation of the MSX1-binding sites present within the 5'-flanking region of CAMP. These results increase our understanding of the regulatory mechanisms controlling cathelicidin genes in BMCs.

DNA Inversion Regulates Outer Membrane Vesicle Production in Bacteroides fragilis

Phase changes in Bacteroides fragilis, a member of the human colonic microbiota, mediate variations in a vast array of cell surface molecules, such as capsular polysaccharides and outer membrane proteins through DNA inversion. The results of the present study show that outer membrane vesicle (OMV) formation in this anaerobe is also controlled by DNA inversions at two distantly localized promoters, IVp-I and IVp-II that are associated with extracellular polysaccharide biosynthesis and the expression of outer membrane proteins. These promoter inversions are mediated by a single tyrosine recombinase encoded by BF2766 (orthologous to tsr19 in strain NCTC9343) in B. fragilis YCH46, which is located near IVp-I. A series of BF2766 mutants were constructed in which the two promoters were locked in different configurations (IVp-I/IVp-II = ON/ON, OFF/OFF, ON/OFF or OFF/ON). ON/ON B. fragilis mutants exhibited hypervesiculating, whereas the other mutants formed only a trace amount of OMVs. The hypervesiculating ON/ON mutants showed higher resistance to treatment with bile, LL-37, and human β-defensin 2. Incubation of wild-type cells with 5% bile increased the population of cells with the ON/ON genotype. These results indicate that B. fragilis regulates the formation of OMVs through DNA inversions at two distantly related promoter regions in response to membrane stress, although the mechanism underlying the interplay between the two regions controlled by the invertible promoters remains unknown.

Computational Systems Biology of Psoriasis: Are We Ready for the Age of Omics and Systems Biomarkers?

Computational biology and 'omics' systems sciences are greatly impacting research on common diseases such as cancer. By contrast, dermatology covering an array of skin diseases with high prevalence in society, has received relatively less attention from 'omics' and computational biosciences. We are focusing on psoriasis, a common and debilitating autoimmune disease involving skin and joints. Using computational systems biology and reconstruction, topological, modular, and a novel correlational analyses (based on fold changes) of biological and transcriptional regulatory networks, we analyzed and integrated data from a total of twelve studies from the Gene Expression Omnibus (sample size = 534). Samples represented a comprehensive continuum from lesional and nonlesional skin, as well as bone marrow and dermal mesenchymal stem cells. We identified and propose here a JAK/STAT signaling pathway significant for psoriasis. Importantly, cytokines, interferon-stimulated genes, antimicrobial peptides, among other proteins, were involved in intrinsic parts of the proposed pathway. Several biomarker and therapeutic candidates such as SUB1 are discussed for future experimental studies. The integrative systems biology approach presented here illustrates a comprehensive perspective on the molecular basis of psoriasis. This also attests to the promise of systems biology research in skin diseases, with psoriasis as a systemic component. The present study reports, to the best of our knowledge, the largest set of microarray datasets on psoriasis, to offer new insights into the disease mechanisms with a proposal of a disease pathway. We call for greater computational systems biology research and analyses in dermatology and skin diseases in general.

Are intact peptides absorbed from the healthy gut in the adult human?

For over 100 years it was believed that dietary protein must be completely hydrolysed before its constituent amino acids could be absorbed via specific amino acid transport systems. It is now known that the uptake of di- and tripeptides into the enterocyte is considerable, being transported across the intestinal endothelium by the PepT1 H+/peptide co-transporter. There is also evidence that some di- and tripeptides may survive cytosolic hydrolysis and be transported intact across the basolateral membrane. However, other than antigen sampling, the transport of larger intact macromolecules across the intestinal endothelium of the healthy adult human remains a controversial issue as there is little unequivocal in vivo evidence to support this postulation. The aim of the present review was to critically evaluate the scientific evidence that peptides/proteins are absorbed by healthy intestinal epithelia and pass intact into the hepatic portal system. The question of the absorption of oliogopeptides is paramount to the emerging science of food-derived bioactive peptides, their mode of action and physiological effects. Overall, we conclude that there is little unequivocal evidence that dietary bioactive peptides, other than di- and tripeptides, can cross the gut wall intact and enter the hepatic portal system in physiologically relevant concentrations.

Expression of TIM-3, Human β-defensin-2, and FOXP3 and Correlation with Disease Activity in Pediatric Crohn's Disease with Infliximab Therapy

BACKGROUND/AIMS

This study investigated the expression of T cell immunoglobulin- and mucin-domain-containing molecule 3 (TIM-3), human β-defensin (HBD)-2, forkhead box protein 3 (FOXP3), and the frequency of CD4(+) CD25(+) FOXP3(+) regulatory T cells (Tregs) in children with Crohn's disease (CD) during infliximab therapy.

METHODS

We enrolled 20 CD patients who received infliximab treatment for 1 year. Peripheral blood and colonic mucosal specimens were collected from all CD patients and from healthy control individuals.

RESULTS

A significant difference in TIM-3 mRNA expression was evident in peripheral blood mononuclear cells and colonic mucosa between CD patients before infliximab therapy and the healthy controls (p<0.001 and p=0.005, respectively). A significant difference in HBD-2 mRNA expression was found in colonic mucosa between CD patients before infliximab therapy and the healthy controls (p=0.013). In the active phase of CD, at baseline, the median percentage of T cells that were CD25(+) FOXP3(+) was 1.5% (range, 0.32% to 3.49%), which increased after inflixmab treatment for 1 year to 2.2% (range, 0.54% to 5.02%) (p=0.008).

CONCLUSIONS

Our study suggests that both the adaptive and innate immune systems are closely linked to each other in CD pathogenesis. And the results of our study indicate that it could be a useful therapeutic tool, where restoration of TIM-3, HBD-2 and the function of Tregs may repair the dysfunctional immunoregulation in CD.

Transcriptomic landscape of lncRNAs in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) is a complex multi-factorial inflammatory disease with Crohn's disease (CD) and ulcerative colitis (UC) being the two most common forms. A number of transcriptional profiling studies have provided compelling evidence that describe the role of protein-coding genes and microRNAs in modulating the immune responses in IBD.

METHODS

In the present study, we performed a genome-wide transcriptome profiling of lncRNAs and protein-coding genes in 96 colon pinch biopsies (inflamed and non-inflamed) extracted from multiple colonic locations from 45 patients (CD = 13, UC = 20, controls = 12) using an expression microarray platform.

RESULTS

In our study, we identified widespread dysregulation of lncRNAs and protein-coding genes in both inflamed and non-inflamed CD and UC compared to the healthy controls. In cases of inflamed CD and UC, we identified 438 and 745 differentially expressed lncRNAs, respectively, while in cases of the non-inflamed CD and UC, we identified 12 and 19 differentially expressed lncRNAs, respectively. We also observed significant enrichment (P-value <0.001, Pearson's Chi-squared test) for 96 differentially expressed lncRNAs and 154 protein-coding genes within the IBD susceptibility loci. Furthermore, we found strong positive expression correlations for the intersecting and cis-neighboring differentially expressed IBD loci-associated lncRNA-protein-coding gene pairs. The functional annotation analysis of differentially expressed genes revealed their involvement in the immune response, pro-inflammatory cytokine activity and MHC protein complex.

CONCLUSIONS

The lncRNA expression profiling in both inflamed and non-inflamed CD and UC successfully stratified IBD patients from the healthy controls. Taken together, the identified lncRNA transcriptional signature along with clinically relevant parameters suggest their potential as biomarkers in IBD.

Cathelicidin-BF, a Novel Antimicrobial Peptide from Bungarus fasciatus, Attenuates Disease in a Dextran Sulfate Sodium Model of Colitis

Antimicrobial peptides are molecules of innate immunity. Cathelicidin-BF is the first cathelicidin peptide found in reptiles. However, the immunoregulatory and epithelial barrier protective properties of C-BF have not been reported. Inflammatory bowel diseases, including ulcerative colitis and Crohn's disease, can lead to colon cancer, the third most common malignant tumor. The objective is to develop the new found cathelicidin-BF as a therapeutic to patients of ulcerative colitis. The morphology of the colon epithelium was observed by H&E staining; apoptosis index and infiltration of inflammatory cells in colonic epithelium were measured by TUNEL and immunohistochemistry; the expression level of endogenous mCRAMP was analyzed by immunofluorescence; and phosphorylation of the transcription factors c-jun and NF-κB in colon were analyzed by Western blot. Our results showed that the morphology of the colon epithelium in the C-BF+DSS group was improved compared with the DSS group. Apoptosis and infiltration of inflammatory cells in colonic epithelium were also significantly attenuated in the C-BF+DSS group compared with the DSS group, and the expression level of endogenous mCRAMP in the DSS group was significantly higher than other groups. DSS-induced phosphorylation level of c-jun and NF-κB while C-BF effectively inhibited phosphorylation of NF-κB (p65). The barrier protective effect of C-BF was still excellent. In conclusion, C-BF effectively attenuated inflammation and improved disrupted barrier function. Notably, this is the first report to demonstrate that C-BF attenuates DSS-induced UC both through the regulation of intestinal immune and retention of barrier function, and the exact pathway was through NF-κB.

Anti-endotoxic and antibacterial effects of a dermal substitute coated with host defense peptides

Biomaterials used during surgery and wound treatment are of increasing importance in modern medical care. In the present study we set out to evaluate the addition of thrombin-derived host defense peptides to human acellular dermis (hAD, i.e. epiflex(®)). Antimicrobial activity of the functionalized hAD was demonstrated using radial diffusion and viable count assays against Gram-negative Escherichia coli, Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria. Electron microscopy analyses showed that peptide-mediated bacterial killing led to reduced hAD degradation. Furthermore, peptide-functionalized hAD displayed endotoxin-binding activity in vitro, as evidenced by inhibition of NF-κB activation in human monocytic cells (THP-1 cells) and a reduction of pro-inflammatory cytokine production in whole blood in response to lipopolysaccharide stimulation. The dermal substitute retained its anti-endotoxic activity after washing, compatible with results showing that the hAD bound a significant amount of peptide. Furthermore, bacteria-induced contact activation was inhibited by peptide addition to the hAD. E. coli infected hAD, alone, or after treatment with the antiseptic substance polyhexamethylenebiguanide (PHMB), yielded NF-κB activation in THP-1 cells. The activation was abrogated by peptide addition. Thus, thrombin-derived HDPs should be of interest in the further development of new biomaterials with combined antimicrobial and anti-endotoxic functions for use in surgery and wound treatment.

Porcine β-defensin 2 attenuates inflammation and mucosal lesions in dextran sodium sulfate-induced colitis

Intestinal permeability plays a critical role in the etiopathogenesis of ulcerative colitis. Defensins, including porcine β-defensin (pBD)2, are crucial antimicrobial peptides for gut protection owing to their antibacterial and immunomodulatory activities. The purpose of this study was to investigate the protective effects of pBD2 on mucosal injury and the disruption of the epithelial barrier during the pathological process of dextran sodium sulfate (DSS)-induced colitis. The effects and mechanism of pBD2 were evaluated both using a DSS-induced C57BL/6 mouse model and, in vitro, using Caco-2 and RAW264.7 cells. DSS-induced colitis was characterized by higher disease activity index, shortened colon length, elevated activities of myeloperoxidase and eosinophil peroxidase, histologic evidence of inflammation, and increased expression levels of TNF-α, IL-6, and IL-8. pBD2 increased the expression of zonula occludens-1, zonula occludens-2, claudin-1, mucin-1, and mucin-2 mRNA and proteins, and it decreased permeability to FITC-D, as well as apoptosis, in DSS-treated mice. pBD2 also decreased inflammatory infiltrates of the colon epithelium. In Caco-2 cells, pBD2 increased transepithelial electrical resistance and mucin mRNA expression, and it decreased the permeability of FITC-D while preserving the structural integrity of the tight junctions. The effects of pBD2 appeared to be through upregulation of the expression of genes associated with tight junctions and mucins, and by suppressing DSS-induced increases in inflammation, inducible NO synthase, cyclooxygenase-2, and apoptosis. These results show that pBD2 improves DSS-induced changes in mucosal lesions and paracellular permeability, possibly by affecting the activation of NF-κB signaling. The present study demonstrates that intrarectal administration of pBD2 may be a novel preventive option for ulcerative colitis.

New role for human α-defensin 5 in the fight against hypervirulent Clostridium difficile strains

Clostridium difficile infection (CDI), one of the most common hospital-acquired infections, is increasing in incidence and severity with the emergence and diffusion of hypervirulent strains. CDI is precipitated by antibiotic treatment that destroys the equilibrium of the gut microbiota. Human α-defensin 5 (HD5), the most abundant enteric antimicrobial peptide, is a key regulator of gut microbiota homeostasis, yet it is still unknown if C. difficile, which successfully evades killing by other host microbicidal peptides, is susceptible to HD5. We evaluated, by means of viability assay, fluorescence-activated cell sorter (FACS) analysis, and electron microscopy, the antimicrobial activities of α-defensins 1 and 5 against a panel of C. difficile strains encompassing the most prevalent epidemic and hypervirulent PCR ribotypes in Europe (012, 014/020, 106, 018, 027, and 078). Here we show that (i) concentrations of HD5 within the intestinal physiological range produced massive C. difficile cell killing; (ii) HD5 bactericidal activity was mediated by membrane depolarization and bacterial fragmentation with a pattern of damage peculiar to C. difficile bacilli, compared to commensals like Escherichia coli and Enterococcus faecalis; and (iii) unexpectedly, hypervirulent ribotypes were among the most susceptible to both defensins. These results support the notion that HD5, naturally present at very high concentrations in the mucosa of the small intestine, could indeed control the very early steps of CDI by killing C. difficile bacilli at their germination site. As a consequence, HD5 can be regarded as a good candidate for the containment of hypervirulent C. difficile strains, and it could be exploited in the therapy of CDI and relapsing C. difficile-associated disease.

Immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of idiopathic, chronic and relapsing inflammatory conditions of the gastrointestinal tract. Familial and epidemiological studies have stressed the involvement of genetic factors and have also shown the critical role of environmental factors such as sanitation and hygiene in the development of IBD. However, the molecular mechanisms of intestinal inflammation in IBD have long remained unknown. In recent years, the study of susceptibility genes involved in the detection of bacterial components and in the regulation of the host immune response has shed light onto the potential role of intestinal pathogens and gut flora in IBD immunobiology. This review presents current knowledge on intestinal epithelial barrier alterations and on dysfunction of mucosal innate and acquired immune responses in IBD. The data support the etiological hypothesis which argues that pathogenic intestinal bacteria and/or infectious agents initiate and perpetuate the inflammation of the gut through disruption of tolerance towards the commensal microbiota in an individual with genetic vulnerability.

Regional specialization within the intestinal immune system

The intestine represents the largest compartment of the immune system. It is continually exposed to antigens and immunomodulatory agents from the diet and the commensal microbiota, and it is the port of entry for many clinically important pathogens. Intestinal immune processes are also increasingly implicated in controlling disease development elsewhere in the body. In this Review, we detail the anatomical and physiological distinctions that are observed in the small and large intestines, and we suggest how these may account for the diversity in the immune apparatus that is seen throughout the intestine. We describe how the distribution of innate, adaptive and innate-like immune cells varies in different segments of the intestine and discuss the environmental factors that may influence this. Finally, we consider the implications of regional immune specialization for inflammatory disease in the intestine.

Human cathelicidin LL-37 and its derivative IG-19 regulate interleukin-32-induced inflammation

Human cathelicidin LL-37 protects against infections and endotoxin-induced inflammation. In a recent study we have shown that IG-19, an LL-37-derived peptide, protects in a murine model of arthritis. Cytokine interleukin-32 (IL-32) is elevated and directly associated with the disease severity of inflammatory arthritis. Therefore, in this study we examined the effects of LL-37 and IG-19 on IL-32-induced responses in human peripheral blood-derived mononuclear cells (PBMC) and macrophages. We showed that CD14(+) monocytes are the primary cells that produce pro-inflammatory tumour necrosis factor-α (TNF-α) following stimulation of PBMC with IL-32. We demonstrated that LL-37 and IG-19 significantly suppress IL-32-induced production of pro-inflammatory cytokines, e.g. TNF-α and IL-1β, without altering chemokine production. In contrast, LL-37 and IG-19 enhance the production of the anti-inflammatory cytokine IL-1RA. Further mechanistic studies revealed that LL-37 and IG-19 suppress IL-32-mediated phosphorylation of Fyn (Y420) Src kinase. In contrast, IL-32-mediated phosphorylation of AKT-1 (T308) and MKP-1 (S359) is not suppressed by the peptides. LL-37 and IG-19 alone induce the phosphorylation of MKP-1 (S359), which is a known negative regulator of inflammation. Furthermore, the peptides induce the activity of p44/42 mitogen-activated protein kinase, which is known to phosphorylate MKP-1 (S359). This is the first study to demonstrate the regulation of IL-32-induced inflammation by LL-37 and its derivative peptide IG-19. The mechanistic results from this study suggest that regulation of immune-mediated inflammation by these peptides may be controlled by the dual phosphatase MKP-1. We speculate that LL-37 and its derivatives may contribute to the control of immune-mediated inflammatory diseases.

Serum antimicrobial peptides in patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is characterized by recurrent inflammation of serosal and synovial membranes. Despite the fact that it is a genetic disease, environmental factors, including infections, are shown to be triggering factors associated with the precipitation of attacks in FMF. Antimicrobial peptides (AMPs) are components of innate immunity which exert antimicrobial activity against many microorganisms. Human AMPs; cathelicidin (LL37) and defensins have immunomodulatory properties and are involved in the pathogenesis of many inflammatory disorders. Hence, we investigated serum AMPs in 23 newly diagnosed FMF patients. Blood samples were obtained at baseline, 6 months after initiation of colchicine and during an attack. Twenty-four healthy individuals constituted the control group. The concentrations of LL37, alpha-1, beta-1 and beta-2 defensins were determined by ELISA. Serum AMPs did not change during attacks and did not correlate with acute phase reactants. However, serum LL37 and defensins were found to be remarkably higher in FMF patients compared to healthy individuals both at baseline and 6 months after initiation of colchicine therapy which suggest that AMPs might have a role in the pathogenesis of FMF.

Construction of eukaryotic expression vector with mBD1-mBD3 fusion genes and exploring its activity against influenza A virus

Influenza (flu) pandemics have exhibited a great threat to human health throughout history. With the emergence of drug-resistant strains of influenza A virus (IAV), it is necessary to look for new agents for treatment and transmission prevention of the flu. Defensins are small (2–6 kDa) cationic peptides known for their broad-spectrum antimicrobial activity. Beta-defensins (β-defensins) are mainly produced by barrier epithelial cells and play an important role in attacking microbe invasion by epithelium. In this study, we focused on the anti-influenza A virus activity of mouse β-defensin 1 (mBD1) and β defensin-3 (mBD3) by synthesizing their fusion peptide with standard recombinant methods. The eukaryotic expression vectors pcDNA3.1(+)/mBD1-mBD3 were constructed successfully by overlap-PCR and transfected into Madin-Darby canine kidney (MDCK) cells. The MDCK cells transfected by pcDNA3.1(+)/mBD1-mBD3 were obtained by G₄₁₈ screening, and the mBD1-mBD3 stable expression pattern was confirmed in MDCK cells by RT-PCR and immunofluorescence assay. The acquired stable transfected MDCK cells were infected with IAV (A/PR/8/34, H1N1, 0.1 MOI) subsequently and the virus titers in cell culture supernatants were analyzed by TCID₅₀ 72 h later. The TCID₅₀ titer of the experimental group was clearly lower than that of the control group (p < 0.001). Furthermore, BALB/C mice were injected with liposome-encapsulated pcDNA3.1(+)/mBD1-mBD3 through muscle and then challenged with the A/PR/8/34 virus. Results showed the survival rate of 100% and lung index inhibitory rate of 32.6% in pcDNA3.1(+)/mBD1-mBD3group; the TCID₅₀ titer of lung homogenates was clearly lower than that of the control group (p < 0.001). This study demonstrates that mBD1-mBD3 expressed by the recombinant plasmid pcDNA3.1(+)/mBD1-mBD3 could inhibit influenza A virus replication both in vitro and in vivo. These observations suggested that the recombinant mBD1-mBD3 might be developed into an agent for influenza prevention and treatment.

Immune-epithelial crosstalk at the intestinal surface

The intestinal tract is one of the most complex organs of the human body. It has to exercise various functions including food and water absorption, as well as barrier and immune regulation. These functions affect not only the gut itself, but influence the overall health of the organism. Diseases involving the gastrointestinal tract such as inflammatory bowel disease and colorectal cancer therefore severely affect the patient's quality of life and can become life-threatening. Intestinal epithelial cells (IECs) play an important role in intestinal inflammation, infection, and cancer development. IECs not only constitute the first barrier in the gut against the lumen, they also constantly signal information about the gut lumen to immune cells, thereby influencing their behaviour. In contrast, by producing various antimicrobial peptides, IECs shape the microbial community within the gut. IECs also respond to cytokines and other mediators of immune cells in the lamina propria. Interactions between epithelial cells and immune cells in the intestine are responsible for gut homeostasis, and modulations of this crosstalk have been reported in studies of gut diseases. This review discusses the wide field of immune-epithelial interactions and shows the importance of immune-epithelial crosstalk in the intestine to gut homeostasis and the overall health status.