Paneth cell α-defensins and enteric microbiota in health and disease

Evaluation of Defensins as Markers of Gut Microbiota Disturbances in Children with Obesity and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

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

Food, Health, and Environmental Impact of Lactic Acid Bacteria: The Superbacteria for Posterity

Lactic acid bacteria (LAB) are Gram-positive cocci or rods that do not produce spores or respire. Their primary function is to ferment carbohydrates and produce lactic acid. The two primary forms of LAB that are currently recognized are homofermentative and heterofermentative. This review discusses the evolutionary diversity and the biochemical and biophysical conditions required by LAB for their metabolism. Next, it concentrates on the applications of these bacteria in gut health, cancer prevention, and overall well-being and food systems. There are numerous uses for LAB, including the food and dairy sectors, as probiotics to improve human and animal gut-health, as anti-carcinogenic agents, and in food safety as biopreservatives, pathogen inhibitors, and reducers of anti-nutrients in foods. The group included many genera, including Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Tetragenococcus, Vagococcus, and Weissella. Numerous species of Lactobacillus and Bifidobacterium genera as well as other microbes have been suggested as probiotic strains, or live microorganisms added to meals to improve health. LAB can colonize the intestine and take part in the host's physiological processes. This review briefly highlights the role of these bacteria in food safety and security as well as aspects of regulation and consumer acceptance. Finally, the recent innovations in LAB fermentations and the limitations and challenges of the applications of LAB in the food industry are discussed. Notwithstanding recent developments, the study of LAB and their functional components is still an emerging topic of study that has not yet realized its full potential.

Early-life antibiotic exposures: Paving the pathway for dysbiosis-induced disorders

Microbiota encompasses a diverse array of microorganisms inhabiting specific ecological niches. Gut microbiota significantly influences physiological processes, including gastrointestinal motor function, neuroendocrine signalling, and immune regulation. They play a crucial role in modulating the central nervous system and bolstering body defence mechanisms by influencing the proliferation and differentiation of innate and adaptive immune cells. Given the potential consequences of antibiotic therapy on gut microbiota equilibrium, there is a need for prudent antibiotic use to mitigate associated risks. Observational studies have linked increased antibiotic usage to various pathogenic conditions, including obesity, inflammatory bowel disease, anxiety-like effects, asthma, and pulmonary carcinogenesis. Addressing dysbiosis incidence requires proactive measures, including prophylactic use of β-lactamase drugs (SYN-004, SYN-006, and SYN-007), hydrolysing the β-lactam in the proximal GIT for maintaining intestinal flora homeostasis. Prebiotic and probiotic supplementations are crucial in restoring intestinal flora equilibrium by competing with pathogenic bacteria for nutritional resources and adhesion sites, reducing luminal pH, neutralising toxins, and producing antimicrobial agents. Faecal microbiota transplantation (FMT) shows promise in restoring gut microbiota composition. Rational antibiotic use is essential to preserve microflora and improve patient compliance with antibiotic regimens by mitigating associated side effects. Given the significant implications on gut microbiota composition, concerted intervention strategies must be pursued to rectify and reverse the occurrence of antibiotic-induced dysbiosis. Here, antibiotics-induced microbiota dysbiosis mechanisms and their systemic implications are reviewed. Moreover, proposed interventions to mitigate the impact on gut microflora are also discussed herein.

Ontogeny and function of the intestinal epithelial and innate immune cells during early development of chicks: to explore in ovo immunomodulatory nutrition

Intestinal epithelial cells (IECs) and innate immune cells in the gastrointestinal tract (GIT) of chickens play crucial roles in pathogens defense and maintaining gut health. However, their effectiveness influenced with their developmental and functional stages during pre and post hatch periods of chick. During embryonic development, differentiation and migration of these innate immune systems are tightly regulated by diverse cellular and molecular factors. The maturation and functionality of IECs are histologically evident starting embryonic day (ED) 14. Moreover, the innate immun cells, such as dendritic cells (DCs), macrophages, natural killer (NK) cells, and gamma-delta (γδ) T cells have showed developmental expression varation, while most identified by the 3rd days of incubation and capable of responsing to their cognate ligands of pathogens by ED 17, it may not efficient during posthatch period. In modern poultry production, in ovo feeding of bioactive substances is a topic of interest to maximize the protection capability of hatched chicks by enhancing improvement on the development of innate immune systems. However, their actions and effects on each distinct innate immune involved response are inconsistent and not clearly understood. Thus, summarizing the ontogeny and function of IECs, innate immunity systems, and interaction mechanisms of in ovo feeding of bioactive substances could provide baseline information for designing targeted in ovo feeding interventions to modulate cell waise specific innate immune systems.

Potential consequences of phototoxicity on cell function during live imaging of intestinal organoids

Live imaging visualizes the structure, dynamics, and function of cells and tissues to reveal the molecular mechanisms, and has contributed to the advancement of life science. In live imaging, it has been well known that there is a trade-off between higher-resolution analysis and cell damage caused by light illumination, i.e., phototoxicity. However, despite the risk of unknowingly distorting experimental results, phototoxicity is an unresolved issue in live imaging because overall consequences occurring inside cells due to phototoxicity remains unknown. Here, we determined the molecular process of phototoxicity-induced cell damage systematically under low- and high-dose light illumination conditions by analyzing differential gene expression using RNA-sequencing in a three-dimensional organoid of small intestinal epithelial cells, enteroid. The low-dose light illumination already induced various abnormalities in functional molecules involved in the response to reactive oxygen species generated by the excitation of fluorescent dyes, intracellular metabolism, mitosis, immune responses, etc., at mRNA expression level. Together with the behavior toward apoptosis caused by high-dose light illumination, the light dose-dependent progression of intracellular damage was revealed. About visible impairment of intestinal epithelial function, failures in both the structure-forming ability of enteroids and Paneth cell granule secretion were observed under high-dose light illumination, while the drug efflux was not disturbed despite abnormal drug efflux transporter mRNA expression. Based on the gene expression profiles, we comprehensively clarified phenomena in the cells at mRNA level that cannot be recognized both morphologically and functionally during live imaging, further providing a new insight into the risk of phototoxicity. This study warns from the aspect of mRNA expression that awareness of phototoxic artifacts is needed when analyzing cellular function and the mechanism in live imaging.

Heat-Killed Lactobacillus paracasei SMB092 Reduces Halitosis by Stimulating the Expression of β-Defensins in Oral Keratinocytes

The purpose of this study is to evaluate Lactobacillus paracasei SMB092 as a prophylactic agent for oral pathogens. We examined the physical interaction of SMB092 with a host by identifying the presence of mucus-binding (MuB) protein domains and the capacity of the mucin binding. We determined the role of heat-killed SMB092 in host oral immunity by quantifying the mRNA levels of β-defensins (BDs), Toll-like receptors (TLRs), and their cofactors (CD14/CD36) in normal human oral keratinocytes (HOK-16B cells). To assess the clinically relevant oral health effects of heat-killed SMB092, the growth of Porphyromonas (P.) gingivalis and the production of a volatile sulfur compound (H2S) were also measured in the filtered condition media (FCM) obtained from its cultures with HOK-16B cells. SMB092 possessed 14 putative MuB protein domains and was attached to mucin. Significant amounts of hBD1/2 and TLR2/6 were expressed in heat-killed SMB092-treated HOK-16B cells. The specific neutralization of TLR2 attenuated the expression of hBD1/2 and CD14/CD36. The FCM inhibited the growth of P. gingivalis and the production of H2S. Our data indicate that heat-killed SMB092 may contribute to a healthy oral microbiome as an immune stimulant in the production of BDs via the activation of the TLR2/6 signaling pathway.

Absence of Paneth Cell Metaplasia to Predict Clinical Relapse in Ulcerative Colitis with Endoscopically Quiescent Mucosa

BACKGROUND

Paneth cells play multiple roles in maintaining intestinal homeostasis. However, the clinical role of Paneth cell metaplasia (PCM) in ulcerative colitis (UC) remains unclear. We aimed to investigate the relationship between PCM and relapse in patients with UC and compare the usefulness of PCM with other histological indexes, including mucin depletion (MD) and basal plasmacytosis (BP).

METHODS

Patients with UC in clinical remission (CR) who underwent colonoscopy to confirm a Mayo endoscopic subscore (MES) ≦1 with biopsies from the distal colon were enrolled into this retrospective cohort study. Biopsy samples were evaluated for histological findings of PCM, MD, and BP. Clinical relapse was defined as partial Mayo score ≧3 or medication escalation. Multivariate analysis was performed to determine independent predictors of relapse among the three histological findings, MES, and patient background, and relapse prediction models were generated.

RESULTS

Eighty-three patients were enrolled in this study (MES 0, n = 47; MES 1, n = 36). The number of PCM cases was significantly higher in patients with prolonged CR than that in those with relapse (p = 0.01). Multivariate analysis showed that the absence of PCM and MD were related to relapse in all the patients. In patients with MES 1, the absence of PCM was the only risk factor significantly and independently associated with relapse (hazard ratio, 4.51 [1.15-17.7]; p = 0.03).

CONCLUSION

The absence of PCM was a histological risk factor for relapse in patients with MES 1, implying a protective role for PCM in remission and a new index for mucosal healing.

Reduced expression of central innate defense molecules in pancreatic biopsies from subjects with Type 1 diabetes

AIMS/HYPOTHESIS

Defensins play a crucial role in the innate immune system's first defense against microbial threats. However, little is known about the defensin system in the pancreas, especially in relation to Type 1 diabetes. We explore the expression of defensins in different disease stages of Type 1 diabetes and correlated obtained findings to the degree of inflammation, providing new insights into the disease and the innate immune system.

MATERIAL AND METHODS

Pancreases from non-diabetic human organ donors of different age groups and donors with Type 1 diabetes with different disease duration were examined. Sections from head, body and tail of the pancreas were stained for eight different defensins and for immune cells; CD3+, CD45+, CD68+ and NES+ (granulocytes).

RESULTS

In non-diabetic adult controls the level of expression for defensins Beta-1,Alpha-1, Cathelicidin and REG3A correlated with the level of inflammation. In contrast, individuals with Type  1 diabetes exhibit a reduction or absence of several central defensins regardless of the level of inflammation in their pancreas. The expression of Cathelicidin is present in neutrophils and macrophages but not in T-cells in subjects with Type 1 diabetes.

CONCLUSIONS

Obtained findings suggest a pancreatic dysfunction in the innate immune system and the bridging to the adaptive system in Type 1 diabetes. Further studies on the role of the local innate immune system in Type 1 diabetes is needed.

IL-22 promotes mucin-type O-glycosylation and MATH1+ cell-mediated amelioration of intestinal inflammation

The interleukin (IL)-22 cytokine can be protective or inflammatory in the intestine. It is unclear if IL-22 receptor (IL-22Ra1)-mediated protection involves a specific type of intestinal epithelial cell (IEC). By using a range of IEC type-specific Il22Ra1 conditional knockout mice and a dextran sulfate sodium (DSS) colitis model, we demonstrate that IL-22Ra1 signaling in MATH1+ cells (goblet and progenitor cells) is essential for maintaining the mucosal barrier and intestinal tissue regeneration. The IL-22Ra1 signaling in IECs promotes mucin core-2 O-glycan extension and induces beta-1,3-galactosyltransferase 5 (B3GALT5) expression in the colon. Adenovirus-mediated expression of B3galt5 is sufficient to rescue Il22Ra1IEC mice from DSS colitis. Additionally, we observe a reduction in the expression of B3GALT5 and the Tn antigen, which indicates defective mucin O-glycan, in the colon tissue of patients with ulcerative colitis. Lastly, IL-22Ra1 signaling in MATH1+ progenitor cells promotes organoid regeneration after DSS injury. Our findings suggest that IL-22-dependent protective responses involve O-glycan modification, proliferation, and differentiation in MATH1+ progenitor cells.

Effect of GVHD on the gut and intestinal microflora

Graft-versus-host disease (GVHD) is one of the most important cause of death in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). The gastrointestinal tract is one of the most common sites affected by GVHD. However, there is no gold standard clinical practice for diagnosing gastrointestinal GVHD (GI-GVHD), and it is mainly diagnosed by the patient's clinical symptoms and related histological changes. Additionally, GI-GVHD causes intestinal immune system disorders, damages intestinal epithelial tissue such as intestinal epithelial cells((IEC), goblet, Paneth, and intestinal stem cells, and disrupts the intestinal epithelium's physical and chemical mucosal barriers. The use of antibiotics and diet alterations significantly reduces intestinal microbial diversity, further reducing bacterial metabolites such as short-chain fatty acids and indole, aggravating infection, and GI-GVHD. gut microbe diversity can be restored by fecal microbiota transplantation (FMT) to treat refractory GI-GVHD. This review article focuses on the clinical diagnosis of GI-GVHD and the effect of GVHD on intestinal flora and its metabolites.

Viral Liver Disease and Intestinal Gut–Liver Axis

The intestinal microbiota is closely related to liver diseases via the intestinal barrier and bile secretion to the gut. Impairment of the barrier can translocate microbes or their components to the liver where they can contribute to liver damage and fibrosis. The components of the barrier are discussed in this review along with the other elements of the so-called gut–liver axis. This bidirectional relation has been widely studied in alcoholic and non-alcoholic liver disease. However, the involvement of microbiota in the pathogenesis and treatment of viral liver diseases have not been extensively studied, and controversial data have been published. Therefore, we reviewed data regarding the integrity and function of the intestinal barrier and the changes of the intestinal microbioma that contribute to progression of Hepatitis B (HBV) and Hepatitis C (HCV) infection. Their consequences, such as cirrhosis and hepatic encephalopathy, were also discussed in connection with therapeutic interventions such as the effects of antiviral eradication and the use of probiotics that may influence the outcome of liver disease. Profound alterations of the microbioma with significant reduction in microbial diversity and changes in the abundance of both beneficial and pathogenic bacteria were found.

Unusual or Uncommon Histology of Gastric Cancer

This review comprehensively examines the diverse spectrum of gastric cancers, focusing on unusual or uncommon histology that presents significant diagnostic and therapeutic challenges. While the predominant form, tubular adenocarcinoma, is well-characterized, this review focuses on lesser-known variants, including papillary adenocarcinoma, micropapillary carcinoma, adenosquamous carcinoma, squamous cell carcinoma (SCC), hepatoid adenocarcinoma, gastric choriocarcinoma, gastric carcinoma with lymphoid stroma, carcinosarcoma, gastroblastoma, parietal cell carcinoma, oncocytic adenocarcinoma, Paneth cell carcinoma, gastric adenocarcinoma of the fundic gland type, undifferentiated carcinoma, and extremely well-differentiated adenocarcinoma. Although these diseases have different nomenclatures characterized by distinct histopathological features, these phenotypes often overlap, making it difficult to draw clear boundaries. Furthermore, the number of cases was limited, and the unique histopathological nature and potential pathogenic mechanisms were not well defined. This review highlights the importance of understanding these rare variants for accurate diagnosis, effective treatment planning, and improving patient outcomes. This review emphasizes the need for ongoing research and case studies to enhance our knowledge of these uncommon forms of gastric cancer, which will ultimately contribute to more effective treatments and better prognostic assessments. This review aimed to broaden the pathological narrative by acknowledging and addressing the intricacies of all cancer types, regardless of their rarity, to advance patient care and improve prognosis.

[Infectious Gastric Diseases Other than Helicobacter]

In addition to Helicobacter pylori, the acute bacterial causes of infectious gastritis, include phlegmonous gastritis, gastric tuberculosis, and gastric syphilis. Bacterial gastritis often improves with appropriate broad-spectrum antibiotics, emphasizing the need for prompt diagnosis and treatment based on the clinical and endoscopic findings. Among viral gastritis, cytomegalovirus gastritis, primarily occurring in immunocompromised patients, necessitates antiviral intervention, while immunocompetent individuals typically achieve amelioration by administering proton pump inhibitors. In contrast, most gastric infections caused by the Epstein-Barr virus (EBV) are asymptomatic, but an EBV infection is a cause of stomach cancer. EBV-associated gastric cancer exhibits distinct clinical, pathological, genetic, and post-genetic mutation features, making it clinically significant. The colonization of Candida albicans in the stomach is uncommon, and typical antifungal treatment is unnecessary. Candida infections in gastric ulcers can be treated with anti-ulcer treatment alone. Lastly, anisakidosis in the stomach, which occurs when consuming raw seafood, can manifest in various clinical presentations and is typically treated through endoscopic removal of the nematode. This article aims to contribute to the rapid diagnosis and treatment of rare stomach infections beyond Helicobacter pylori in real clinical situations.

Murine fecal microRNAs alter the composition of cultured gut microbiota

Fecal microRNAs (miRNAs) derived from intestinal epithelial cells have been suggested to influence gut microbiota homeostasis. The present study examined whether fecal miRNAs alter the structure of cultured gut microbiota. Fecal bacteria isolated from murine cecal contents were cultured for 24 h under anaerobic conditions. Supplementation with fecal small RNAs isolated from cecal contents altered the structure of cultured fecal microbiota as assessed by 16S rRNA gene sequence analysis. In particular, fecal small RNAs increased Enterococcus spp. Fractionation of fecal small RNAs by ultrafiltration showed that small RNAs smaller than 10 kDa significantly increased enterococci compared to those larger than 10 kDa, as assessed by quantitative PCR, suggesting that the increase in enterococci by fecal small RNAs can mainly be attributed to miRNAs. Negative control miRNA that has low homology to miRNA sequences of human, mouse, and rat, failed to increase enterococci. Therefore, the findings from the present study employing cultured fecal bacteria suggest that fecal small RNAs, most likely host-derived miRNAs, alter gut microbiota structure by expanding enterococci in a sequence-dependent manner.

Paneth cell dysfunction in radiation injury and radio-mitigation by human α-defensin 5

Introduction

The mechanism underlying radiation-induced gut microbiota dysbiosis is undefined. This study examined the effect of radiation on the intestinal Paneth cell α-defensin expression and its impact on microbiota composition and mucosal tissue injury and evaluated the radio-mitigative effect of human α-defensin 5 (HD5).

Methods

Adult mice were subjected to total body irradiation, and Paneth cell α-defensin expression was evaluated by measuring α-defensin mRNA by RT-PCR and α-defensin peptide levels by mass spectrometry. Vascular-to-luminal flux of FITC-inulin was measured to evaluate intestinal mucosal permeability and endotoxemia by measuring plasma lipopolysaccharide. HD5 was administered in a liquid diet 24 hours before or after irradiation. Gut microbiota was analyzed by 16S rRNA sequencing. Intestinal epithelial junctions were analyzed by immunofluorescence confocal microscopy and mucosal inflammatory response by cytokine expression. Systemic inflammation was evaluated by measuring plasma cytokine levels.

Results

Ionizing radiation reduced the Paneth cell α-defensin expression and depleted α-defensin peptides in the intestinal lumen. α-Defensin down-regulation was associated with the time-dependent alteration of gut microbiota composition, increased gut permeability, and endotoxemia. Administration of human α-defensin 5 (HD5) in the diet 24 hours before irradiation (prophylactic) significantly blocked radiation-induced gut microbiota dysbiosis, disruption of intestinal epithelial tight junction and adherens junction, mucosal barrier dysfunction, and mucosal inflammatory response. HD5, administered 24 hours after irradiation (treatment), reversed radiation-induced microbiota dysbiosis, tight junction and adherens junction disruption, and barrier dysfunction. Furthermore, HD5 treatment also prevents and reverses radiation-induced endotoxemia and systemic inflammation.

Conclusion

These data demonstrate that radiation induces Paneth cell dysfunction in the intestine, and HD5 feeding prevents and mitigates radiation-induced intestinal mucosal injury, endotoxemia, and systemic inflammation.

HIV-1-Host Interaction in Gut-Associated Lymphoid Tissue (GALT): Effects on Local Environment and Comorbidities

HIV-1 replication in the gastrointestinal (GI) tract causes severe CD4+ T-cell depletion and disruption of the protective epithelial barrier in the intestinal mucosa, causing microbial translocation, the main driver of inflammation and immune activation, even in people living with HIV (PLWH) taking antiretroviral drug therapy. The higher levels of HIV DNA in the gut compared to the blood highlight the importance of the gut as a viral reservoir. CD4+ T-cell subsets in the gut differ in phenotypic characteristics and differentiation status from the ones in other tissues or in peripheral blood, and little is still known about the mechanisms by which the persistence of HIV is maintained at this anatomical site. This review aims to describe the interaction with key subsets of CD4+ T cells in the intestinal mucosa targeted by HIV-1 and the role of gut microbiome and its metabolites in HIV-associated systemic inflammation and immune activation that are crucial in the pathogenesis of HIV infection and related comorbidities.

Reg3α concentrations at day of allogeneic stem cell transplantation predict outcome and correlate with early antibiotic use

Intestinal microbiome diversity plays an important role in the pathophysiology of acute gastrointestinal (GI) graft-versus-host disease (GVHD) and influences the outcome of patients after allogeneic stem cell transplantation (ASCT). We analyzed clinical data and blood samples taken preconditioning and on the day of ASCT from 587 patients from 7 German centers of the Mount Sinai Acute GVHD International Consortium, dividing them into single-center test (n = 371) and multicenter validation (n = 216) cohorts. Regenerating islet-derived 3α (Reg3α) serum concentration of day 0 correlated with clinical data as well as urinary 3-indoxylsulfate (3-IS) and Clostridiales group XIVa, indicators of intestinal microbiome diversity. High Reg3α concentration at day 0 of ASCT was associated with higher 1-year transplant-related mortality (TRM) in both cohorts (P < .001). Cox regression analysis revealed high Reg3α at day 0 as an independent prognostic factor for 1-year TRM. Multivariable analysis showed an independent correlation of high Reg3α concentrations at day 0 with early systemic antibiotic (AB) treatment. Urinary 3-IS (P = .04) and Clostridiales group XIVa (P = .004) were lower in patients with high vs those with low day 0 Reg3α concentrations. In contrast, Reg3α concentrations before conditioning therapy correlated neither with TRM nor disease or treatment-related parameters. Reg3α, a known biomarker of acute GI GVHD correlates with intestinal dysbiosis, induced by early AB treatment in the period of pretransplant conditioning. Serum concentrations of Reg3α measured on the day of graft infusion are predictive of the risk for TRM of ASCT recipients.

From birth to death: The hardworking life of Paneth cell in the small intestine

Paneth cells are a group of unique intestinal epithelial cells, and they play an important role in host-microbiota interactions. At the origin of Paneth cell life, several pathways such as Wnt, Notch, and BMP signaling, affect the differentiation of Paneth cells. After lineage commitment, Paneth cells migrate downward and reside in the base of crypts, and they possess abundant granules in their apical cytoplasm. These granules contain some important substances such as antimicrobial peptides and growth factors. Antimicrobial peptides can regulate the composition of microbiota and defend against mucosal penetration by commensal and pathogenic bacteria to protect the intestinal epithelia. The growth factors derived from Paneth cells contribute to the maintenance of the normal functions of intestinal stem cells. The presence of Paneth cells ensures the sterile environment and clearance of apoptotic cells from crypts to maintain the intestinal homeostasis. At the end of their lives, Paneth cells experience different types of programmed cell death such as apoptosis and necroptosis. During intestinal injury, Paneth cells can acquire stem cell features to restore the intestinal epithelial integrity. In view of the crucial roles of Paneth cells in the intestinal homeostasis, research on Paneth cells has rapidly developed in recent years, and the existing reviews on Paneth cells have mainly focused on their functions of antimicrobial peptide secretion and intestinal stem cell support. This review aims to summarize the approaches to studying Paneth cells and introduce the whole life experience of Paneth cells from birth to death.

Decreased Paneth cell α-defensins promote fibrosis in a choline-deficient L-amino acid-defined high-fat diet-induced mouse model of nonalcoholic steatohepatitis via disrupting intestinal microbiota

Nonalcoholic steatohepatitis (NASH) is a chronic liver disease characterized by fibrosis that develops from fatty liver. Disruption of intestinal microbiota homeostasis, dysbiosis, is associated with fibrosis development in NASH. An antimicrobial peptide α-defensin secreted by Paneth cells in the small intestine is known to regulate composition of the intestinal microbiota. However, involvement of α-defensin in NASH remains unknown. Here, we show that in diet-induced NASH model mice, decrease of fecal α-defensin along with dysbiosis occurs before NASH onset. When α-defensin levels in the intestinal lumen are restored by intravenous administration of R-Spondin1 to induce Paneth cell regeneration or by oral administration of α-defensins, liver fibrosis is ameliorated with dissolving dysbiosis. Furthermore, R-Spondin1 and α-defensin improved liver pathologies together with different features in the intestinal microbiota. These results indicate that decreased α-defensin secretion induces liver fibrosis through dysbiosis, further suggesting Paneth cell α-defensin as a potential therapeutic target for NASH.

Efficient recombinant production of mouse-derived cryptdin family peptides by a novel facilitation strategy for inclusion body formation

BACKGROUND

A number of antimicrobial peptides (AMPs) hold promise as new drugs owing to their potent bactericidal activity and because they are often refractory to the development of drug resistance. Cryptdins (Crps) are a family of antimicrobial peptides found in the small intestine of mice, comprising six isoforms containing three sets of disulfide bonds. Although Crp4 is actively being investigated, there have been few studies to date on the other Crp isoforms. A prerequisite for detailed characterization of the other Crp isoforms is establishment of efficient sample preparation methods.

RESULTS

To avoid degradation during recombinant expression of Crps in E. coli, co-expression of Crps with the aggregation-prone protein human α-lactalbumin (HLA) was used to promote the formation of stable inclusion bodies. Using this method, the production of Crp4 and Crp6 by the BL21 strain was effective, but the expression of other Crp isoforms was not as efficient. The results of a cell-free system study suggested that Crps were degraded, even though a substantial amounts of Crps were synthesized. Therefore, using the Origami™ B strain, we were able to significantly increase the expression efficiency of Crps by promoting the formation of erroneous intermolecular disulfide bonds between HLA and Crps, thereby promoting protein aggregation and inclusion body formation, which prevented degradation. The various Crp isoforms were successfully refolded in vitro and purified using reversed-phase HPLC. In addition, the yield was further improved by deformylation of formyl-Crps. We measured the antibacterial activity of Crps against both Gram-positive and Gram-negative bacteria. Each Crp isoform exhibited a completely different trend in antimicrobial activity, although conformational analysis by circular dichroism did not reveal any significant steric differences.

CONCLUSION

In this study, we established a novel and efficient method for the production of the cryptdin family of cysteine-containing antimicrobial peptides. Additionally, we found that there were notable differences in the antibacterial activities of the various Crp family members. The expression system established in this study is expected to provide new insights regarding the mechanisms underlying the different antibacterial activities of the Crp family of peptides.

Shorter sleep time relates to lower human defensin 5 secretion and compositional disturbance of the intestinal microbiota accompanied by decreased short-chain fatty acid production

Sleep is essential for our health. Short sleep is known to increase disease risks via imbalance of intestinal microbiota, dysbiosis. However, mechanisms by which short sleep induces dysbiosis remain unknown. Small intestinal Paneth cell regulates the intestinal microbiota by secreting antimicrobial peptides including α-defensin, human defensin 5 (HD5). Disruption of circadian rhythm mediating sleep-wake cycle induces Paneth cell failure. We aim to clarify effects of short sleep on HD5 secretion and the intestinal microbiota. Fecal samples and self-reported sleep time were obtained from 35 healthy middle-aged Japanese (41 to 60-year-old). Shorter sleep time was associated with lower fecal HD5 concentration (r = 0.354, p = 0.037), lower centered log ratio (CLR)-transformed abundance of short-chain fatty acid (SCFA) producers in the intestinal microbiota such as [Ruminococcus] gnavus group (r = 0.504, p = 0.002) and Butyricicoccus (r = 0.484, p = 0.003), and lower fecal SCFA concentration. Furthermore, fecal HD5 positively correlated with the abundance of these genera and SCFA concentration. These findings suggest that short sleep relates to disturbance of the intestinal microbiota via decreased HD5 secretion.

Differentiated Epithelial Cells of the Gut

The intestine is a prime example of self-renewal where stem cells give rise to progenitor cells called transit-amplifying cells which differentiate into more specialized cells. There are two intestinal lineages: the absorptive (enterocytes and microfold cells) and the secretory (Paneth cells, enteroendocrine, goblet cells, and tuft cells). Each of these differentiated cell types has a role in creating an "ecosystem" to maintain intestinal homeostasis. Here, we summarize the main roles of each cell type.

FABP4 in Paneth cells regulates antimicrobial protein expression to reprogram gut microbiota

Antimicrobial proteins possess a broad spectrum of bactericidal activity and play an important role in shaping the composition of gut microbiota, which is related to multiple diseases such as metabolic syndrome. However, it is incompletely known for the regulation of defensin expression in the gut Paneth cells. Here, we found that FABP4 in the Paneth cells of gut epithelial cells and organoids can downregulate the expression of defensins. FABP4^fl/flpvillin^CreT mice were highly resistance to Salmonella Typhimurium (S.T) infection and had increased bactericidal ability to pathogens. The FABP4-mediated downregulation of defensins is through degrading PPARγ after K48 ubiquitination. We also demonstrate that high-fat diet (HFD)-mediated downregulation of defensins is through inducing a robust FABP4 in Paneth cells. Firmicutes/Bacteroidetes (F/B) ratio in FABP4^fl/flpvillin^CreT mice is lower than control mice, which is opposite to that in mice fed HFD, indicating that FABP4 in the Paneth cells could reprogram gut microbiota. Interestingly, FABP4-mediated downregulation of defensins in Paneth cells not only happens in mice but also in human. A better understanding of the regulation of defensins, especially HFD-mediated downregulation of defensin in Paneth cells will provide insights into factor(s) underlying modern diseases.Abbreviations: FABP4: Fatty acid binding protein 4; S. T: Salmonella Typhimurium; HFD: High-fat diet; Defa: α-defensin; 930 HD5: Human α-defensin 5; HD6: Human α-defensin 6; F/B: Firmicutes/Bacteroidetes; SFB: Segmental filamentous bacteria; AMPs: Antimicrobial peptides; PPARγ: Peroxisome proliferator-activated receptor γ; P-PPAR: Phosphorylated PPAR; Dhx15: DEAD-box helicase 15; 935 EGF: Epidermal growth factor; ENR: Noggin and R-spondin 1; CFU: Colony forming unit; Lyz1: Lysozyme 1; Saa1: Serum amyoid A 1; Pla2g2a: Phospholipase A2, group IIA; MMP-7: Matrix metalloproteinase; AU-PAGE: Acid-urea polyacrylamide gel electrophoresis; PA: Palmitic 940 acid; GPR40: G-protein-coupled receptor; GF: Germ-free; EGF: Epidermal growth factor; LP: Lamina propria; KO: Knock out; WT: Wild-type.

The Mechanism of Important Components in Canine Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is a potential treatment for many intestinal diseases. In dogs, FMT has been shown to have positive regulation effects in treating Clostridioides difficile infection (CDI), inflammatory bowel disease (IBD), canine parvovirus (CPV) enteritis, acute diarrhea (AD), and acute hemorrhagic diarrhea syndrome (AHDS). FMT involves transplanting the functional components of a donor's feces into the gastrointestinal tract of the recipient. The effective components of FMT not only include commensal bacteria, but also include viruses, fungi, bacterial metabolites, and immunoglobulin A (IgA) from the donor feces. By affecting microbiota and regulating host immunity, these components can help the recipient to restore their microbial community, improve their intestinal barrier, and induce anti-inflammation in their intestines, thereby affecting the development of diseases. In addition to the above components, mucin proteins and intestinal epithelial cells (IECs) may be functional ingredients in FMT as well. In addition to the abovementioned indications, FMT is also thought to be useful in treating some other diseases in dogs. Consequently, when preparing FMT fecal material, it is important to preserve the functional components involved. Meanwhile, appropriate fecal material delivery methods should be chosen according to the mechanisms these components act by in FMT.

Heat stress in pigs and broilers: role of gut dysbiosis in the impairment of the gut-liver axis and restoration of these effects by probiotics, prebiotics and synbiotics

Heat stress is one of the most challenging stressors for animal production due to high economic losses resulting from impaired animal’s productivity, health and welfare. Despite the fact that all farm animal species are susceptible to heat stress, birds and pigs are particularly sensitive to heat stress due to either lacking or non-functional sweat glands. Convincing evidence in the literature exists that gut dysbiosis, a term used to describe a perturbation of commensal gut microbiota, develops in broilers and pigs under heat stress. Owing to the protective role of commensal bacteria for the gut barrier, gut dysbiosis causes a disruption of the gut barrier leading to endotoxemia, which contributes to the typical characteristics of heat stressed broilers and growing and growing-finishing pigs, such as reduced feed intake, decreased growth and reduced lean carcass weight. A substantial number of studies have shown that feeding of probiotics, prebiotics and synbiotics is an efficacious strategy to protect broilers from heat stress-induced gut barrier disruption through altering the gut microbiota and promoting all decisive structural, biochemical, and immunological elements of the intestinal barrier. In most of the available studies in heat stressed broilers, the alterations of gut microbiota and improvements of gut barrier function induced by feeding of either probiotics, prebiotics or synbiotics were accompanied by an improved productivity, health and/or welfare when compared to non-supplemented broilers exposed to heat stress. These findings indicate that the restoration of gut homeostasis and function is a key target for dietary interventions aiming to provide at least partial protection of broilers from the detrimental impact of heat stress conditions. Despite the fact that the number of studies dealing with the same feeding strategy in heat stressed pigs is limited, the available few studies suggest that feeding of probiotics might also be a suitable approach to enhance productivity, health and welfare in pigs kept under heat stress conditions. 

Electroacupuncture promoted intestinal defensins and rescued the dysbiotic cecal microbiota of high-fat diet-induced obese mice

Obesity is currently one of the most important challenges to public health worldwide. Acupuncture has been widely used to treat obesity. However, whether acupuncture regulates intestinal innate immunity via intestinal microbiota against obesity remains to be elucidated. In this study, electroacupuncture (EA) effectively reduced body weight and fat accumulation in obese mice persistently fed a high-fat diet. Full-length 16S rDNA sequencing showed dysbiotic microbiota in the cecum of obese mice. The composition and function of the cecal microbiota of obese mice were markedly restored after EA treatment. After 21 d of EA intervention, the expression of defensin alpha 5 (Defa5) was restored to healthy controls, whereas fat digestion and absorption genes including fabp1 were markedly decreased in the jejunum of obese mice. The Defa5 levels were positively correlated with the family Lachnospiraceae and negatively correlated with obesity indexes. EA also reduced tissue inflammation, ameliorated misaligned glucose tolerance, and inhibited key genes for intestinal lipid absorption. In summary, EA exerted an anti-obesity effect by promoting intestinal defensins, rescuing dysbiotic cecal microbiota, and reducing lipid absorption in a synergistic mode. We present for the first time the key role of alpha defensins in the relationship between gut microbiota and disease during electroacupuncture treatment of obesity. The mucosal innate immunity seems to have a stronger ability to shape the microbiota than dietary factors.

[Paneth Cell Carcinoma of the Stomach]

Paneth cell carcinoma is a rare carcinoma composed predominantly or purely of malignant Paneth cells. An 83-year-old woman presented for evaluation of an elevated lesion in the stomach. On endoscopy, a 15 mm, discolored, elevated lesion with a central depression was found on the greater curvature of the gastric lower body. Endoscopic forceps biopsy revealed chronic gastritis with intestinal metaplasia. Magnifying endoscopy revealed an irregularly oval/tubular microsurface pattern and an irregular loop microvascular pattern with a demarcation line, suggestive of early gastric cancer. Therefore, endoscopic submucosal dissection was performed. Histopathological examination revealed a well-differentiated tubular adenocarcinoma limited to the muscularis mucosae and the tumor cells contained coarse eosinophilic granules in the cytoplasm. These tumor cells were diffusely and strongly stained for lysozyme, confirming the tumor diagnosis as Paneth cell carcinoma. Herein, we report a rare case of Paneth cell carcinoma and its endoscopic and histopathologic findings.

Intestinal Uptake and Tolerance to Food Antigens

Food allergy is a growing concern due to its increasing world-wide incidence. Strict avoidance of allergens is a passive treatment strategy. Since the mechanisms responsible for the occurrence and development of food allergy have not yet been fully elucidated, effective individualized treatment options are lacking. In this review, we summarize the pathways through which food antigens enter the intestine and review the proposed mechanisms describing how the intestine acquires and tolerates food antigens. When oral tolerance is not established, food allergy occurs. In addition, we also discuss the contribution of commensal bacteria of the gut in shaping tolerance to food antigens in the intestinal tract. Finally, we propose that elucidating the mechanisms of intestinal uptake and tolerance of food antigens will provide additional clues for potential treatment options for food allergy.

Antibiotic Exposure, Not Alloreactivity, Is the Major Driver of Microbiome Changes in Hematopoietic Cell Transplantation

Both autologous hematopoietic cell transplantation (auto-HCT) and allogeneic hematopoietic cell transplantation (allo-HCT) are associated with significant alterations in the intestinal microbiome. The relative contributions of antibiotic use and alloreactivity to microbiome dynamics have not yet been elucidated, however. There is a lack of data on the kinetics of microbiome changes beyond 30 days post-transplantation and how they might differ between different transplantation modalities. A direct comparison of the differential effects of auto-HCT and allo-HCT on the microbiome may shed light on these dynamics. This study was conducted to compare intestinal microbial diversity between auto-HCT recipients and allo-HCT recipients from pre-transplantation to 100 days post-transplantation, and to examine the effect of antibiotics, transplant type (auto versus allo), and conditioning regimens on the dynamics of microbiome recovery. We conducted a longitudinal analysis of changes in the intestinal microbiome in 35 patients undergoing HCT (17 auto-HCT, 18 allo-HCT) at 4 time points: pre-conditioning and 14, 28, and 100 days post-transplantation. Granular data on antibiotic exposure from day -30 pre-transplantation to day +100 post-transplantation were collected. Pre-transplantation, allo-HCT recipients had lower α-diversity in the intestinal microbiome compared with auto-HCT recipients, which correlated with greater pre-transplantation antibiotic use in allo-HCT recipients. The microbiome diversity declined at days +14 and +28 post-transplantation in both cohorts but generally returned to baseline by day +100. Conditioning regimen intensity did not significantly affect post-transplantation α-diversity. Through differential abundance analysis, we show that commensal bacterial taxa involved with maintenance of gut epithelial integrity and production of short-chain fatty acids were depleted after both auto-HCT and allo-HCT. In our dataset, antibiotic exposure was the major driver of post-transplantation microbiome changes rather than alloreactivity, conditioning intensity, or immunosuppression. Our findings also suggest that interventions to limit microbiome injury, such as limiting the use of broad-spectrum antibiotics, should target the pre-transplantation period and not only the peri-transplantation period.

The Intestinal Barrier Dysfunction as Driving Factor of Inflammaging

The intestinal barrier, composed of the luminal microbiota, the mucus layer, and the physical barrier consisting of epithelial cells and immune cells, the latter residing underneath and within the epithelial cells, plays a special role in health and disease. While there is growing knowledge on the changes to the different layers associated with disease development, the barrier function also plays an important role during aging. Besides changes in the composition and function of cellular junctions, the entire gastrointestinal physiology contributes to essential age-related changes. This is also reflected by substantial differences in the microbial composition throughout the life span. Even though it remains difficult to define physiological age-related changes and to distinguish them from early signs of pathologies, studies in centenarians provide insights into the intestinal barrier features associated with longevity. The knowledge reviewed in this narrative review article might contribute to the definition of strategies to prevent the development of diseases in the elderly. Thus, targeted interventions to improve overall barrier function will be important disease prevention strategies for healthy aging in the future.

Intestinal commensal microbiota and cytokines regulate Fut2+ Paneth cells for gut defense

Paneth cells are intestinal epithelial cells that release antimicrobial peptides, such as α-defensin as part of host defense. Together with mesenchymal cells, Paneth cells provide niche factors for epithelial stem cell homeostasis. Here, we report two subtypes of murine Paneth cells, differentiated by their production and utilization of fucosyltransferase 2 (Fut2), which regulates α(1,2)fucosylation to create cohabitation niches for commensal bacteria and prevent invasion of the intestine by pathogenic bacteria. The majority of Fut2- Paneth cells were localized in the duodenum, whereas the majority of Fut2+ Paneth cells were in the ileum. Fut2+ Paneth cells showed higher granularity and structural complexity than did Fut2- Paneth cells, suggesting that Fut2+ Paneth cells are involved in host defense. Signaling by the commensal bacteria, together with interleukin 22 (IL-22), induced the development of Fut2+ Paneth cells. IL-22 was found to affect the α-defensin secretion system via modulation of Fut2 expression, and IL-17a was found to increase the production of α-defensin in the intestinal tract. Thus, these intestinal cytokines regulate the development and function of Fut2+ Paneth cells as part of gut defense.

A bioinspired stimuli-responsive amino acid-based antibacterial drug delivery system in cancer therapy

Design of tyrosine based stimuli responsive antibacterial drug delivery system with potential application in cancer therapy.

Antimicrobial peptides: mechanism of action, activity and clinical potential

The management of bacterial infections is becoming a major clinical challenge due to the rapid evolution of antibiotic resistant bacteria. As an excellent candidate to overcome antibiotic resistance, antimicrobial peptides (AMPs) that are produced from the synthetic and natural sources demonstrate a broad-spectrum antimicrobial activity with the high specificity and low toxicity. These peptides possess distinctive structures and functions by employing sophisticated mechanisms of action. This comprehensive review provides a broad overview of AMPs from the origin, structural characteristics, mechanisms of action, biological activities to clinical applications. We finally discuss the strategies to optimize and develop AMP-based treatment as the potential antimicrobial and anticancer therapeutics.

Lower human defensin 5 in elderly people compared to middle-aged is associated with differences in the intestinal microbiota composition: the DOSANCO Health Study

Recently, aging is considered a risk factor for various diseases. Although changes in the intestinal microbiota along with aging are thought to associate with the increased disease risk, mechanisms that cause age-related transition of the intestinal microbiota remain unknown. This study aims to clarify relationships between the amount of human defensin 5 (HD5), a Paneth cell α-defensin, which is known to regulate the intestinal microbiota, and age-related differences of the intestinal microbiota composition. Fecal samples from 196 healthy Japanese (35 to 81 years old) were collected and measured HD5 concentration. HD5 concentration in the elderly group (age > 70 years old) was significantly lower than the middle-aged group (age ≤ 70 years old). Furthermore, individual age was negatively correlated with HD5 concentration (r =  - 0.307, p < 0.001). In β-diversity, the intestinal microbiota of the elderly showed a significantly different composition compared to the middle-aged. At the genus level, relative abundance of Collinsella, Alistipes, Peptococcaceae; unassigned, Lactobacillus, Lactococcus, Weissella, Christensenellaceae R-7 group, Megasphaera, and [Eubacterium] eligens group was significantly higher, and Lachnospiraceae; unassigned, Blautia, Anaerostipes, Fusicatenibacter, Dorea, and Faecalibacterium was significantly lower in the elderly compared to the middle-aged. In addition, HD5 concentration was negatively correlated with Alistipes, Peptococcaceae; unassigned, and Christensenellaceae R-7 group and positively correlated with Lachnospiraceae; unassigned and Dorea. These results provide novel insights into the immunosenescence of enteric innate immunity, indicating low HD5 is suggested to contribute to the age-related differences in the intestinal microbiota and may relate to increased risk of diseases in elderly people.

Decrease of α-defensin impairs intestinal metabolite homeostasis via dysbiosis in mouse chronic social defeat stress model

Psychological stress has been reported to relate to dysbiosis, imbalance of the intestinal microbiota composition, and contribute to the onset and exacerbation of depression, though, underlying mechanisms of psychological stress-related dysbiosis have been unknown. It has been previously established that α-defensins, which are effector peptides of innate enteric immunity produced by Paneth cells in the small intestine, play an important role in regulation of the intestinal microbiota. However, the relationship between disruption of intestinal ecosystem and α-defensin under psychological stress is yet to be determined. Here we show using chronic social defeat stress (CSDS), a mouse depression model that (1) the exposure to CSDS significantly reduces α-defensin secretion by Paneth cells and (2) induces dysbiosis and significant composition changes in the intestinal metabolites. Furthermore, (3) they are recovered by administration of α-defensin. These results indicate that α-defensin plays an important role in maintaining homeostasis of the intestinal ecosystem under psychological stress, providing novel insights into the onset mechanism of stress-induced depression, and may further contribute to discovery of treatment targets for depression.

Regulation of the gut barrier by carbohydrates from diet - Underlying mechanisms and possible clinical implications

The gut barrier has been recognized as being of relevance in the pathogenesis of multiple different diseases ranging from inflammatory bowel disease, irritable bowel syndrome, inflammatory joint disease, fatty liver disease, and cardiometabolic disorders. The regulation of the gut barrier is, however, poorly understood. Especially, the role of food components such as sugars and complex carbohydrates has been discussed controversially in this respect. More recently, the intestinal microbiota has been proposed as an important regulator of the gut barrier. Whether the microbiota affects the barrier by its own, or whether food components such as carbohydrates mediate their effects through alterations of the microbiota composition or its metabolites, is still not clear. In this review, we will summarize the current knowledge on this topic derived from both animal and human studies and discuss data for possible clinical impact.

Gut Microbial Dysbiosis in the Pathogenesis of Gastrointestinal Dysmotility and Metabolic Disorders

Of all microorganisms in the human body, the largest and most complex population resides in the gastrointestinal (GI) tract. The gut microbiota continuously adapts to the host environment and serves multiple critical functions for their hosts, including regulating host immunity, procuring energy from food, and preventing the colonization of pathogens. Mounting evidence has suggested gut microbial imbalance (dysbiosis) as a core pathophysiology in the development of GI motility and metabolic disorders, such as irritable bowel syndrome and diabetes. Current research has focused on discovering associations between these disorders and gut microbial dysbiosis; however, whether these associations are a consequence or cause is still mostly unexplored. State-of-the-art studies have investigated how gut microbes communicate with our body systems through microbiota-derived metabolites and how they are able to modulate host physiology. There is now mounting evidence that alterations in the composition of small intestinal microbes have an association with GI dysmotility and metabolic disorders. Although treatment options for gut microbial dysbiosis are currently limited, antibiotics, fecal microbiota transplantation, probiotics, and dietary interventions are currently the best options. However, treatment with broad-spectrum antibiotics has been viewed with skepticism due to the risk of developing antibiotic resistant bacteria. Studies are warranted to elucidate the cellular and molecular pathways underlying gut microbiota-host crosstalk and for the development of a powerful platform for future therapeutic approaches. Here, we review recent literature on gut microbial alterations and/or interactions involved in the pathophysiology of GI dysmotility and metabolic disorders.

Paneth cells: Maintaining dynamic microbiome-host homeostasis, protecting against inflammation and cancer

The human intestines are constantly under the influence of numerous pathological factors: enteropathogenic microorganisms, food antigens, physico-chemical stress associated with digestion and bacterial metabolism, therefore it must be provided with a system of protection against adverse impact. Recent studies have shown that Paneth cells play a crucial role in maintaining homeostasis of the small intestines. Paneth cells perform many vital functions aimed at maintaining a homeostatic balance between normal microbiota, infectious pathogens and the human body, regulate the qualitative composition and number of intestinal microorganisms, prevent the introduction of potentially pathogenic species, and protect stem cells from damage. Paneth cells take part in adaptive and protective-inflammatory reactions. Paneth cells maintain dynamic balance between microbial populations, and the macroorganism, preventing the development of intestinal infections and cancer. They play a crucial role in gastrointestinal homeostasis and may be key factors in the etiopathological progression of intestinal diseases.

Expression and Localization of Paneth Cells and Their α-Defensins in the Small Intestine of Adult Mouse

Paneth cells contribute to intestinal innate immunity by sensing bacteria and secreting α-defensin. In Institute of Cancer Research (ICR) mice, α-defensin termed cryptdin (Crp) in Paneth cells consists of six major isoforms, Crp1 to 6. Despite accumulating evidences that α-defensin functions in controlling the intestinal microbiota, topographical localization of Paneth cells in the small intestine in relation to functions of α-defensin remains to be determined. In this study, we examined the expression level of messenger RNA (mRNA) encoding six Crp-isoforms and Crp immunoreactivities using singly isolated crypts together with bactericidal activities of Paneth cell secretions from isolated crypts of duodenum, jejunum, and ileum. Here we showed that levels of Crp mRNAs in the single crypt ranged from 5 x 10³ to 1 x 10⁶ copies per 5 ng RNA. For each Crp isoform, the expression level in ileum was 4 to 50 times higher than that in duodenum and jejunum. Furthermore, immunohistochemical analysis of isolated crypts revealed that the average number of Paneth cell per crypt in the small intestine increased from proximal to distal, three to seven-fold, respectively. Both Crp1 and 4 expressed greater in ileal Paneth cells than those in duodenum or jejunum. Bactericidal activities in secretions of ileal Paneth cell exposed to bacteria were significantly higher than those of duodenum or jejunum. In germ-free mice, Crp expression in each site of the small intestine was attenuated and bactericidal activities released by ileal Paneth cells were decreased compared to those in conventional mice. Taken together, Paneth cells and their α-defensin in adult mouse appeared to be regulated topographically in innate immunity to control intestinal integrity.

Significant elevation of salivary human neutrophil peptides 1-3 levels by probiotic milk in preschool children with severe early childhood caries: a randomized controlled trial

OBJECTIVES

To determine salivary human neutrophil peptides 1-3 (HNP1-3) levels in caries-free preschool children and in those with early childhood caries (ECC) or severe-ECC, in a daily probiotic group, receiving reconstituted milk with the probiotic Lactobacillus paracasei SD1 once daily; a triweekly probiotic group, receiving the probiotic milk 3 days a week; and a placebo group.

MATERIALS AND METHODS

Oral examination and unstimulated whole saliva collection were conducted in 354 children at baseline, 6 months after intervention (T6), and after probiotic discontinuation (T12). Of the 354, adequate volume of saliva samples from 268 children were simultaneously analyzed for Streptococcus mutans and total lactobacilli levels using qPCR and for HNP1-3 levels using ELISA.

RESULTS

In the severe-ECC status, significant increases in the median HNP1-3 levels at T12 were found in both daily and triweekly probiotic groups (p < 0.001). The median S. mutans levels in the daily group were significantly decreased at T6 and T12 (p < 0.01), whereas the median total lactobacilli levels were significantly increased at T6 (p < 0.001). Significantly inverse correlations between altered HNP1-3 and S. mutans levels and significant decreases in caries progression were found in both probiotic groups (p < 0.05).

CONCLUSIONS

In the severe-ECC status, daily or triweekly consumption of L. paracasei SD1 significantly enhanced salivary HNP1-3 levels, but reduced S. mutans levels, possibly resulting in reduction of caries progression.

CLINICAL RELEVANCE

Significant enhancement of salivary HNP1-3 levels by probiotic consumption is associated with reduction in S. mutans levels, consistent with diminished caries progression in children with severe-ECC.

NOD2 receptor is crucial for protecting against the digestive form of Chagas disease

Digestive and cardiodigestive forms of Chagas’ disease are observed in 2% to 27% of the patients, depending on their geographic location, Trypanosoma cruzi strain and immunopathological responses. The aim of this work was to evaluate the role of NOD2 innate immune receptor in the pathogenesis of the digestive system in Chagas’ disease. Patients with digestive form of the disease showed lower mRNA expression of NOD2, higher expression of RIP2 and α-defensin 6, compared to indeterminate form, detected by Real-time PCR in peripheral blood mononuclear cells. In addition, there was a negative correlation between the expression of NOD2 and the degree of dilation of the esophagus, sigmoid and rectum in those patients. The infection of NOD2^-/- mice with T. cruzi strain isolated from the digestive patient induced a decrease in intestinal motility. Histopathological analysis of the colon and jejunum of NOD2^-/- and wild type C57BL/6 animals revealed discrete inflammatory foci during the acute phase of infection. Interestingly, during the chronic phase of the infection there was inflammation and hypertrophy of the longitudinal and circular muscular layer more pronounced in the colon and jejunum from NOD2^-/- animals, when compared to wild type C57BL/6 mice. Together, our results suggest that NOD2 plays a protective role against the development of digestive form of Chagas’ disease.

Chagas disease is caused by the protozoan Trypanosoma cruzi, during the chronic phase of infection 2–27% of patients develop digestive form of the disease (megaesophagus and megacolon) that contributes to patient morbidity and mortality, generating costs for public health services, and especially affecting significantly the life quality of the patients. Although is known that many factors inherent of the parasite (tropism, genetics, virulence and antigenicity), host (age, gender, nutritional status, genetics and immune response) and geographical distribution may influence the development of the different clinical forms of Chagas disease, the exact mechanism that leads to megacolon and megaesophagus development are unknown. Here we showed that patients with digestive form of Chagas’ disease do not express the innate immune receptor NOD2. By isolating a parasite from a digestive patient and infecting NOD2-deficient mice we observed a reduced intestinal motility, chronic development of colon and jejunum wall thickness associated with increased inflammatory mediators in the organ, when compared to wild type animals. Our results indicate that the NOD2 receptor protects against the development of the digestive form of Chagas disease and could be used as a biomarker for the development of gastrointestinal changes during T. cruzi infection in patients.

Enhanced Intestinal Immune Response in Mice after Oral Administration of Korea Red Ginseng-Derived Polysaccharide

(1) Background: The immunostimulatory role of the polysaccharide fraction (KRG-P) of Korea red ginseng (KRG) was studied in cells. However, its immunomodulatory activity is unknown. Therefore, we investigated the chemical properties of KRG-P and its intestinal immune responses in vitro and in vivo. (2) Methods: KRG-P monosaccharide composition and molecular weight were determined using high-performance liquid and size-exclusion chromatography systems. Immunoglobulin A (IgA) and α-defensin-1 transcript levels were measured using a SYBR Green qRT-PCR; defensin-1, Granulocyte-macrophage colony-stimulating factor (GM-CSF), and IgA protein levels were determined using Western blotting and ELISA kits. (3) Results: The molecular weight of KRG-P was estimated to be 106 kDa, and it contained neutral sugar (74.3%), uronic acid (24.6%), and proteins (1%). In vitro studies of intestinal immunomodulatory activity of KRG-P indicated that GM-CSF and IgA levels increased in Peyer’s patch cells to higher levels than those obtained with KRG and induced bone marrow cell proliferation. In in vivo study, oral KRG-P administration to mice upregulated the expression of α-defensin-1 and IgA in the small intestinal tissue and that of secreted IgA in the feces. (4) Conclusions: KRG-P contributed to the modulation of intestinal immunity and maintenance of intestinal homeostasis against intestinal infection.

Contribution of the Intestinal Microbiome and Gut Barrier to Hepatic Disorders

Intestinal barrier dysfunction and dysbiosis contribute to development of diseases in liver and other organs. Physical, immunologic, and microbiologic (bacterial, fungal, archaeal, viral, and protozoal) features of the intestine separate its nearly 100 trillion microbes from the rest of the human body. Failure of any aspect of this barrier can result in translocation of microbes into the blood and sustained inflammatory response that promote liver injury, fibrosis, cirrhosis, and oncogenic transformation. Alterations in intestinal microbial populations or their functions can also affect health. We review the mechanisms that regulate intestinal permeability and how changes in the intestinal microbiome contribute to development of acute and chronic liver diseases. We discuss individual components of the intestinal barrier and how these are disrupted during development of different liver diseases. Learning more about these processes will increase our understanding of the interactions among the liver, intestine, and its flora.

Analysis of Serotonin in Human Feces Using Solid Phase Extraction and Column-Switching LC-MS/MS

Serotonin, an important neurotransmitter, is produced mainly in intestines, and serotonin levels in feces can be an indicator of the intestinal environment. Human feces, however, contain a large amount of contaminants, which vary widely owing to food contents and the intestinal environment, and these contaminants would be expected to interfere with the determination of serotonin levels in human feces. To remove these contaminants and determine serotonin levels, we developed a new method using solid phase extraction (SPE) and column-switching LC-MS/MS. Serotonin, labeled with a stable isotope, was added to human feces samples prior to SPE as an internal standard to correct for individual differences in matrix effects. The recovery rate for SPE was 55.9–81.0% (intraday) and 56.5–78.1% (interday) for feces from two subjects. We analyzed 220 fecal samples from 96 subjects including 76 pregnant and post-delivery women. The endogenous serotonin content per unit weight of dried feces was 0.09–14.13 ng/mg for pregnant and post-delivery women and 0.30–9.93 ng/mg for the remaining subjects.

Paneth cell α-defensin misfolding correlates with dysbiosis and ileitis in Crohn's disease model mice

This study provides novel insight into Crohn’s disease where α-defensin misfolding resulting from excessive ER stress in Paneth cells induces dysbiosis and disease progression.

Crohn’s disease (CD) is an intractable inflammatory bowel disease, and dysbiosis, disruption of the intestinal microbiota, is associated with CD pathophysiology. ER stress, disruption of ER homeostasis in Paneth cells of the small intestine, and α-defensin misfolding have been reported in CD patients. Because α-defensins regulate the composition of the intestinal microbiota, their misfolding may cause dysbiosis. However, whether ER stress, α-defensin misfolding, and dysbiosis contribute to the pathophysiology of CD remains unknown. Here, we show that abnormal Paneth cells with markers of ER stress appear in SAMP1/YitFc, a mouse model of CD, along with disease progression. Those mice secrete reduced-form α-defensins that lack disulfide bonds into the intestinal lumen, a condition not found in normal mice, and reduced-form α-defensins correlate with dysbiosis during disease progression. Moreover, administration of reduced-form α-defensins to wild-type mice induces the dysbiosis. These data provide novel insights into CD pathogenesis induced by dysbiosis resulting from Paneth cell α-defensin misfolding and they suggest further that Paneth cells may be potential therapeutic targets.

The Paneth Cell: The Curator and Defender of the Immature Small Intestine

Paneth cells were first described in the late 19th century by Gustav Schwalbe and Josef Paneth as columnar epithelial cells possessing prominent eosinophilic granules in their cytoplasm. Decades later there is continued interest in Paneth cells as they play an integral role in maintaining intestinal homeostasis and modulating the physiology of the small intestine and its associated microbial flora. Paneth cells are highly specialized secretory epithelial cells located in the small intestinal crypts of Lieberkühn. The dense granules produced by Paneth cells contain an abundance of antimicrobial peptides and immunomodulating proteins that function to regulate the composition of the intestinal flora. This in turn plays a significant role in secondary regulation of the host microvasculature, the normal injury and repair mechanisms of the intestinal epithelial layer, and the levels of intestinal inflammation. These critical functions may have even more importance in the immature intestine of premature infants. While Paneth cells begin to develop in the middle of human gestation, they do not become immune competent or reach their adult density until closer to term gestation. This leaves preterm infants deficient in normal Paneth cell biology during the greatest window of susceptibility to develop intestinal pathology such as necrotizing enterocolitis (NEC). As 10% of infants worldwide are currently born prematurely, there is a significant population of infants contending with an inadequate cohort of Paneth cells. Infants who have developed NEC have decreased Paneth cell numbers compared to age-matched controls, and ablation of murine Paneth cells results in a NEC-like phenotype suggesting again that Paneth cell function is critical to homeostasis to the immature intestine. This review will provide an up to date and comprehensive look at Paneth cell ontogeny, the impact Paneth cells have on the host-microbial axis in the immature intestine, and the repercussions of Paneth cell dysfunction or loss on injury and repair mechanisms in the immature gut.

Marine Microalgae, Spirulina maxima-Derived Modified Pectin and Modified Pectin Nanoparticles Modulate the Gut Microbiota and Trigger Immune Responses in Mice

This study evaluated the modulation of gut microbiota, immune responses, and gut morphometry in C57BL/6 mice, upon oral administration of S. maxima-derived modified pectin (SmP, 7.5 mg/mL) and pectin nanoparticles (SmPNPs; 7.5 mg/mL). Metagenomics analysis was conducted using fecal samples, and mice duodenum and jejunum were used for analyzing the immune response and gut morphometry, respectively. The results of metagenomics analysis revealed that the abundance of Bacteroidetes in the gut increased in response to both modified SmP and SmPNPs (75%) as compared with that in the control group (66%), while that of Firmicutes decreased in (20%) as compared with that in the control group (30%). The mRNA levels of mucin, antimicrobial peptide, and antiviral and gut permeability-related genes in the duodenum were significantly (p < 0.05) upregulated (> 2-fold) upon modified SmP and SmPNPs feeding. Protein level of intestinal alkaline phosphatase was increased (1.9-fold) in the duodenum of modified SmPNPs feeding, evidenced by significantly increased goblet cell density (0.5 ± 0.03 cells/1000 µm2) and villi height (352 ± 10 µm). Our results suggest that both modified SmP and SmPNPs have the potential to modulate gut microbial community, enhance the expression of immune related genes, and improve gut morphology.

Expression and Function of Host Defense Peptides at Inflammation Sites

There is a growing interest in the complex role of host defense peptides (HDPs) in the pathophysiology of several immune-mediated inflammatory diseases. The physicochemical properties and selective interaction of HDPs with various receptors define their immunomodulatory effects. However, it is quite challenging to understand their function because some HDPs play opposing pro-inflammatory and anti-inflammatory roles, depending on their expression level within the site of inflammation. While it is known that HDPs maintain constitutive host protection against invading microorganisms, the inducible nature of HDPs in various cells and tissues is an important aspect of the molecular events of inflammation. This review outlines the biological functions and emerging roles of HDPs in different inflammatory conditions. We further discuss the current data on the clinical relevance of impaired HDPs expression in inflammation and selected diseases.