A Basic Study of the Effects of Mulberry Leaf Administration to Healthy C57BL/6 Mice on Gut Microbiota and Metabolites

Mulberry leaves contain α-glucosidase inhibitors, which have hypoglycemic effects and are considered functional foods. However, few reports have covered the effects of mulberry leaf components on normal gut microbiota and gut metabolites. Herein, gut microbiota analysis and NMR-based metabolomics were performed on the feces of mulberry leaf powder (MLP)-treated mice to determine the effects of long-term MLP consumption. Gut microbiota in the mouse were analyzed using 16S-rRNA gene sequencing, and no significant differences were revealed in the diversity and community structure of the gut microbiota in the C57BL/6 mice with or without MLP supplementation. Thirty-nine metabolites were identified via 1H-NMR analysis, and carbohydrates and amino acids were significantly (p < 0.01-0.05) altered upon MLP treatment. In the MLP-treated group, there was a marked increase and decrease in maltose and glucose concentrations, respectively, possibly due to the degradation inhibitory activity of oligosaccharides. After 5 weeks, all amino acid concentrations decreased. Furthermore, despite clear fluctuations in fecal saccharide concentrations, short-chain fatty acid production via intestinal bacterial metabolism was not strongly affected. This study provides the knowledge that MLP administration can alter the gut metabolites without affecting the normal gut microbiota, which is useful for considering MLP as a healthy food source.

Antimicrobial Properties and Mode of Action of Cryptdin-4, a Mouse α-Defensin Regulated by Peptide Redox Structures and Bacterial Cultivation Conditions

Cryptdin-4 (crp4) is an enteric α-defensin derived from mice, and is a main mediator of immunity to oral infections and a determinant of the composition of the intestinal microbiota. Structurally, crp4 exists in two states: the oxidized form (crp4oxi), constrained by three invariant disulfide bonds, and the reduced form (crp4red) with six free thiol groups, both of which exist in the intestinal tract. In this study, the antibacterial mechanisms of crp4 in both forms under aerobic and anaerobic conditions were investigated using Escherichia coli (E. coli), an anaerobic facultative bacterium, as a model. Fluorescent dye studies revealed that both crp4oxi and crp4red exhibited antimicrobial activity against cells cultured under aerobic conditions via rapid membrane depolarization. Furthermore, the antioxidant treatment experiments suggested that only crp4oxi exhibited antimicrobial activity by the induction and accumulation of reactive oxygen species (ROS). However, under anaerobic culture conditions, the ability of both forms to disrupt the function of bacterial membranes decreased and activity was greatly reduced, but crp4red maintained some antimicrobial activity. This activity may be due to the inhibition of intracellular functions by DNA binding. Altogether, these data indicate that, according to its redox structure and the environmental redox conditions, crp4 could perform different antimicrobial activities via different mechanisms.

Application of Benchtop NMR for Metabolomics Study Using Feces of Mice with DSS-Induced Colitis

Nuclear magnetic resonance (NMR)-based metabolomics, which comprehensively measures metabolites in biological systems and investigates their response to various perturbations, is widely used in research to identify biomarkers and investigate the pathogenesis of underlying diseases. However, further applications of high-field superconducting NMR for medical purposes and field research are restricted by its high cost and low accessibility. In this study, we applied a low-field, benchtop NMR spectrometer (60 MHz) employing a permanent magnet to characterize the alterations in the metabolic profile of fecal extracts obtained from dextran sodium sulfate (DSS)-induced ulcerative colitis model mice and compared them with the data acquired from high-field NMR (800 MHz). Nineteen metabolites were assigned to the 60 MHz ¹H NMR spectra. Non-targeted multivariate analysis successfully discriminated the DSS-induced group from the healthy control group and showed high comparability with high-field NMR. In addition, the concentration of acetate, identified as a metabolite with characteristic behavior, could be accurately quantified using a generalized Lorentzian curve fitting method based on the 60 MHz NMR spectra.

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.

Hemodynamic response to intestinal pH stimulation measured with spectroscopic video imaging

To investigate the relationship between the gut and skin (gut-skin axis), head skin hemodynamic responses to gut stimulation including the injection of acetic acid in nude mice were measured by spectroscopic video imaging, which was calculated using a modified Beer-Lambert formula. The relationship with blood proteins was also analyzed. The blood volume changes in three mice injected with acetic acid were highly reproducible in the mathematical model equation. Four proteins correlated with blood volume changes were all related to immunity. These results suggest that intestinal pH can alter the blood volume in the skin and induce immune-related responses.

Oral frailty and carriage of oral Candida in community-dwelling older adults (Check-up to discover Health with Energy for senior Residents in Iwamizawa; CHEER Iwamizawa)

OBJECTIVE

To examine the association between oral frailty and oral Candida carriage as a general indicator of deteriorating oral function in older adults.

BACKGROUND

Older adults exhibit an elevated risk of oral candidiasis caused by Candida. Although many studies have identified factors associated with oral Candida carriage, none have evaluated its relationship with oral function.

MATERIALS AND METHODS

This study included 210 community-dwelling older adults aged ≥60 years who participated in wellness checks. Fungal flora expression in saliva samples was evaluated to identify oral C. albicans and C. glabrata. Participants were categorised by detection of neither strain (group 1), either one of the strains (group 2), or both strains (group 3). The relationship between oral Candida carriage and oral frailty was evaluated by multinomial logistic regression analysis.

RESULTS

The participants included 58 men and 152 women with a mean age of 74.2 ± 6.1 years. A total of 88 (41.9%), 94 (44.8%) and 28 (13.3%) participants were assigned to groups 1, 2 and 3 respectively. In the multinomial logistic regression analysis, significant associations were observed between group 1 and group 2 for "Have you choked on your tea or soup recently?" and the number of applicable oral frailty items. Between group 1 and group 3, significant associations were observed for the number of remaining teeth, masticatory performance and the number of applicable oral frailty items.

CONCLUSION

We obtained basic data useful for intervention studies aimed at verifying whether oral function management prevents deterioration of the oral bacterial flora.

Ingestion of miso regulates immunological robustness in mice

In Japan, there is a long history of consumption of miso, a fermented soybean paste, which possesses beneficial effects on human health. However, the mechanism behind these effects is not fully understood. To clarify the effects of miso on immune cells, we evaluated its immunomodulatory activity in mice. Miso did not alter the percentage of B and T cells in the spleen; however, it increased CD69+ B cells, germinal center B cells and regulatory T cells. Anti-DNA immunoglobulin M antibodies, which prevent autoimmune disease, were increased following ingestion of miso. Transcriptome analysis of mouse spleen cells cultured with miso and its raw material revealed that the expression of genes, including interleukin (IL)-10, IL-22 and CD86, was upregulated. Furthermore, intravital imaging of the small intestinal epithelium using a calcium biosensor mouse line indicated that miso induced Ca2+ signaling in a manner similar to that of probiotics. Thus, ingestion of miso strengthened the immune response and tolerance in mice. These results appear to account, at least in part, to the salubrious effects of miso.

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.

Potent bactericidal activity of reduced cryptdin-4 derived from its hydrophobicity and mediated by bacterial membrane disruption

Defensin is a cysteine-rich antimicrobial peptide with three disulphide bonds under normal oxidative conditions. Cryptdin-4 (Crp4) is a defensin secreted by Paneth cells in the small intestine of mice, and only reduced Crp4 (Crp4_red) shows activity against enteric commensal bacteria, although both oxidised Crp4 (Crp4_ox) and Crp4_red can kill non-commensal bacteria. To investigate the molecular factors that affect the potent antimicrobial activity of Crp4_red, the bactericidal activities of Crp4_ox and Crp4_red, Crp4 with all Cys residues substituted with Ser peptide (6C/S-Crp4), and Crp4 with all thiol groups modified by N-ethylmaleimide (NEM-Crp4) were assessed. All peptides showed bactericidal activity against non-commensal bacteria, whereas Crp4_red and NEM-Crp4 showed bactericidal activity against commensal bacteria. These potent peptides exhibited high hydrophobicity, which was strongly correlated with membrane insertion. Intriguingly, Crp4_ox formed electrostatic interactions with the membrane surface of bacteria, even without exerting bactericidal activity. Moreover, the bactericidal activity of both oxidised and reduced forms of Crp4 was abolished by inhibition of electrostatic interactions; this finding suggests that Crp4_red targets bacterial membranes. Finally, a liposome leakage assay against lipids extracted from commensal bacteria demonstrated a correlation with bactericidal activity. These results suggest that the potent bactericidal activity of Crp4_red is derived from its hydrophobicity, and the bactericidal mechanism involves disruption of the bacterial membrane. Findings from this study provide a better understanding of the bactericidal mechanism of both Crp4_ox and Crp4_red.

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.

Simultaneous real-time analysis of Paneth cell and intestinal stem cell response to interferon-γ by a novel stem cell niche tracking method

Paneth cells and Lgr5+ intestinal stem cells (Lgr5+ ISCs) constitute the stem cell niche and maintain small intestinal epithelial integrity by recognizing various niche factors derived from subepithelial cells and external antigens. Although it has been known that interferon-γ (IFN-γ), a Th1 cytokine, is associated with intestinal epithelial disruption during inflammation as a niche factor, dynamics of Paneth cells and Lgr5+ ISCs in response to IFN-γ remain to be understood. Here we show that CAG-tdTomato;Lgr5-EGFP (CT-LE) mice generated in this study enable to identify Paneth cells and Lgr5+ ISCs separately by fluorescence signals. Lgr5+ ISCs underwent cell death a little earlier than Paneth cells in response to IFN-γ by simultaneous tracking using CT-LE mice. In addition, the timing of cell death in most Paneth cells overlapped with Lgr5+ ISCs, suggesting that Paneth cell depletion is induced directly by IFN-γ. Taken together, we established a novel simultaneous stem cell niche tracking method and clarified the involvement of both Paneth cells and Lgr5+ ISCs in stem cell niche damage induced by IFN-γ, further contribute to understanding the mechanism for maintaining intestinal homeostasis by stem cell niche.

Low prevalence of maternal microchimerism in peripheral blood of Japanese children with type 1 diabetes

AIM

To clarify the prevalence and degree of maternal microchimerism in Japanese children with type 1 diabetes, as well as its effect on phenotypic variation.

METHODS

We studied 153 Japanese children with type 1 diabetes, including 124 children positive for β-cell autoantibodies, and their 71 unaffected siblings. The number of circulating microchimeric cells per 10⁵ host cells was estimated by the use of quantitative-polymerase chain reaction targeting non-transmitted maternal human leukocyte antigen alleles. The results were compared to previous data from white European people. Phenotypic comparison was performed between maternal microchimerism carriers and non-carriers with diabetes.

RESULTS

Maternal microchimerism was detected in 15% of children with autoantibody-positive type 1 diabetes, 28% of children with autoantibody-negative type 1 diabetes, and 16% of unaffected siblings. There were no differences in the prevalence or levels of maternal microchimerism among the three groups or between the children with type 1 diabetes and their unaffected siblings. Furthermore, maternal microchimerism carriers and non-carriers exhibited similar phenotypes.

CONCLUSIONS

Maternal microchimerism appears to be less common in Japanese children with type 1 diabetes than in white European people. Our data indicate that maternal microchimerism is unlikely to be a major trigger or a phenotypic determinant of type 1 diabetes in Japanese children and that the biological significance of maternal microchimerism in type 1 diabetes may differ among ethnic groups.

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.

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.

Disease progression-associated alterations in fecal metabolites in SAMP1/YitFc mice, a Crohn's disease model

Crohn's disease (CD) is a chronic, relapsing inflammatory bowel disease affecting the gastrointestinal tract. Although its precise etiology has not been fully elucidated, an imbalance of the intestinal microbiota has been known to play a role in CD. Fecal metabolites derived from microbiota may be related to the onset and progression of CD OBJECTIVES: This study aimed to clarify the transition of gut microbiota and fecal metabolites associated with disease progression using SAMP1/YitFc mice, a model of spontaneous CD METHODS: The ileum tissues isolated from SAMP1/YitFc mice at different ages were stained with hematoxylin-eosin for histologic characterization with CD progression. Feces from control, Institute of Cancer Research (ICR; n = 6), and SAMP1/YitFc (n = 8) mice at different ages were subjected to microbial analysis and ¹H nuclear magnetic resonance (NMR) analysis to investigate fluctuations in gut microbiota and fecal metabolites with CD progression RESULTS: Relative abundance of the Lachnospiraceae, Ruminococcaceae, Bacteroidaceae, and Bacteroidales S24-7 at family-level gut microbiota and fecal metabolites, such as short-chain fatty acids, lactate, glucose, xylose, and choline, dramatically fluctuated with histologic progression of intestinal inflammation in SAMP1/YitFc mice. Unlike the other metabolites, fecal taurine concentration in SAMP1/YitFc mice was higher than ICR mice regardless of age CONCLUSION: The fecal metabolites showing characteristic fluctuations may help to understand the inflammatory mechanism associated with CD, and might be utilized as potential biomarkers in predicting CD pathology.

Butyric Acid and Leucine Induce α-Defensin Secretion from Small Intestinal Paneth Cells

The intestine not only plays a role in fundamental processes in digestion and nutrient absorption, but it also has a role in eliminating ingested pathogenic bacteria and viruses. Paneth cells, which reside at the base of small intestinal crypts, secrete α-defensins and contribute to enteric innate immunity through potent microbicidal activities. However, the relationship between food factors and the innate immune functions of Paneth cells remains unknown. Here, we examined whether short-chain fatty acids and amino acids induce α-defensin secretion from Paneth cells in the isolated crypts of small intestine. Butyric acid and leucine elicit α-defensin secretion by Paneth cells, which kills Salmonella typhimurium. We further measured Paneth cell secretion in response to butyric acid and leucine using enteroids, a three-dimensional ex vivo culture system of small intestinal epithelial cells. Paneth cells expressed short-chain fatty acid receptors, Gpr41, Gpr43, and Gpr109a mRNAs for butyric acid, and amino acid transporter Slc7a8 mRNA for leucine. Antagonists of Gpr41 and Slc7a8 inhibited granule secretion by Paneth cells, indicating that these receptor and transporter on Paneth cells induce granule secretion. Our findings suggest that Paneth cells may contribute to intestinal homeostasis by secreting α-defensins in response to certain nutrients or metabolites.

Associations of gut microbiota, dietary intake, and serum short-chain fatty acids with fecal short-chain fatty acids

In recent years, short-chain fatty acids (SCFAs) have been reported to play an important role in maintaining human health. Fecal SCFA concentrations correlate well with colonic SCFA status and gut microbiota composition. However, the associations with the gut microbiota functional pathway, dietary intake, blood SCFAs, and fecal SCFAs remain uncertain. To clarify these relationships, we collected fecal samples, blood samples, and dietary habit data from 12 healthy adults aged 22–51 years. The relative abundance of several SCFA-producing bacteria, gut microbiota diversity, and functional pathways related to SCFA biosynthesis were positively associated with fecal SCFAs even after adjusting for age and sex. Furthermore, fecal acetate was likely to be positively associated with serum acetate. By contrast, dietary intake was not associated with fecal SCFAs. Overall, the present study highlights the potential usefulness of fecal SCFAs as an indicator of the gut microbiota ecosystem and dynamics of SCFAs in the human body.

Myc-induced nuclear antigen constrains a latent intestinal epithelial cell-intrinsic anthelmintic pathway

Expulsion of parasitic gastrointestinal nematodes requires diverse effector mechanisms coordinated by a Th2-type response. The evolutionarily conserved JmjC protein; Myc Induced Nuclear Antigen (Mina) has been shown to repress IL4, a key Th2 cytokine, suggesting Mina may negatively regulate nematode expulsion. Here we report that expulsion of the parasitic nematode Trichuris muris was indeed accelerated in Mina deficient mice. Unexpectedly, this was associated not with an elevated Th2- but rather an impaired Th1-type response. Further reciprocal bone marrow chimera and conditional KO experiments demonstrated that retarded parasite expulsion and a normal Th1-type response both required Mina in intestinal epithelial cells (IECs). Transcriptional profiling experiments in IECs revealed anti-microbial α-defensin peptides to be the major target of Mina-dependent retention of worms in infected mice. In vitro exposure to recombinant α-defensin peptides caused cytotoxic damage to whipworms. These results identify a latent IEC-intrinsic anthelmintic pathway actively constrained by Mina and point to α-defensins as important effectors that together with Mina may be attractive therapeutic targets for the control of nematode infection.

Paneth cell granule dynamics on secretory responses to bacterial stimuli in enteroids

Paneth cells at the base of small intestinal crypts secrete granules containing α-defensins in response to bacteria and maintain the intestinal environment by clearing enteric pathogens and regulating the composition of the intestinal microbiota. However, Paneth cell secretory responses remain debatable and the mechanisms that regulate the secretion are not well understood. Although enteroids, three-dimensional cultures of small intestinal epithelial cells, have proven useful for analyzing intestinal epithelial cell functions including ion transport, their closed structures have imposed limitations to investigating interactions between Paneth cells and the intestinal microbiota. Here, we report that microinjection of bacteria or lipopolysaccharide (LPS) into the enteroid lumen provides an ex vivo system for studying Paneth cell secretion in real-time. The results show that Paneth cells released granules immediately when the apical surfaces of enteroid epithelial cells were exposed to LPS or live bacteria by microinjection. However, Paneth cells did not respond to LPS delivered in culture media to enteroid exterior basolateral surface, although they responded to basolateral carbamyl choline. In addition, Paneth cells replenished their granules after secretion, enabling responses to second stimulation. These findings provide new insight for apically-induced Paneth cell secretory responses in regulating the intestinal environment.

Essential role of IFN-γ in T cell-associated intestinal inflammation

Paneth cells contribute to small intestinal homeostasis by secreting antimicrobial peptides and constituting the intestinal stem cell (ISC) niche. Certain T cell-mediated enteropathies are characterized by extensive Paneth cell depletion coincident with mucosal destruction and dysbiosis. In this study, mechanisms of intestinal crypt injury have been investigated by characterizing responses of mouse intestinal organoids (enteroids) in coculture with mouse T lymphocytes. Activated T cells induced enteroid damage, reduced Paneth cell and Lgr5+ ISC mRNA levels, and induced Paneth cell death through a caspase-3/7-dependent mechanism. IFN-γ mediated these effects, because IFN-γ receptor-null enteroids were unaffected by activated T cells. In mice, administration of IFN-γ induced enteropathy with crypt hyperplasia, villus shortening, Paneth cell depletion, and modified ISC marker expression. IFN-γ exacerbated radiation enteritis, which was ameliorated by treatment with a selective JAK1/2 inhibitor. Thus, IFN-γ induced Paneth cell death and impaired regeneration of small intestinal epithelium in vivo, suggesting that IFN-γ may be a useful target for treating defective mucosal regeneration in enteric inflammation.

Protein-altering variants of PTPN2 in childhood-onset Type 1A diabetes

AIM

To examine the contribution of PTPN2 coding variants to the risk of childhood-onset Type 1A diabetes.

METHODS

PTPN2 mutation analysis was carried out for 169 unrelated Japanese people with childhood-onset Type 1A diabetes. We searched for coding variants that were absent or extremely rare in the general population and were scored as damaging by multiple in silico programs. We performed mRNA analysis and three-dimensional structural prediction of the detected variants, when possible. We also examined possible physical links between these variants and previously reported risk SNPs as well as clinical information from variant-positive children.

RESULTS

One frameshift variant (p.Q286Yfs*24) and two probably damaging missense substitutions (p.C232W and p.R350Q) were identified in one child each. Of these, p.Q286Yfs*24 and p.C232W were hitherto unreported, while p.R350Q accounted for 2/121,122 alleles of the exome datasets. The p.Q286Yfs*24 variant did not encode stable mRNA, and p.C232W appeared to affect the structure of the tyrosine-protein phosphatase domain. The three variants were physically unrelated to known risk SNPs. The variant-positive children manifested Type 1A diabetes without additional clinical features and invariably carried risk human leukocyte antigen alleles.

CONCLUSIONS

The results provide the first indication that PTPN2 variants contribute to the risk of Type 1A diabetes, independently of known risk SNPs. PTPN2 coding variants possibly induce non-specific Type 1A diabetes phenotypes in individuals with human leukocyte antigen-mediated disease susceptibility. Our findings warrant further validation.

R-Spondin1 expands Paneth cells and prevents dysbiosis induced by graft-versus-host disease

The intestinal microbial ecosystem is actively regulated by Paneth cell-derived antimicrobial peptides such as α-defensins. Various disorders, including graft-versus-host disease (GVHD), disrupt Paneth cell functions, resulting in unfavorably altered intestinal microbiota (dysbiosis), which further accelerates the underlying diseases. Current strategies to restore the gut ecosystem are bacteriotherapy such as fecal microbiota transplantation and probiotics, and no physiological approach has been developed so far. In this study, we demonstrate a novel approach to restore gut microbial ecology by Wnt agonist R-Spondin1 (R-Spo1) or recombinant α-defensin in mice. R-Spo1 stimulates intestinal stem cells to differentiate to Paneth cells and enhances luminal secretion of α-defensins. Administration of R-Spo1 or recombinant α-defensin prevents GVHD-mediated dysbiosis, thus representing a novel and physiological approach at modifying the gut ecosystem to restore intestinal homeostasis and host-microbiota cross talk toward therapeutic benefits.

FUT2 non-secretor status is associated with Type 1 diabetes susceptibility in Japanese children

AIM

To examine the contribution of the FUT2 gene and ABO blood type to the development of Type 1 diabetes in Japanese children.

METHODS

We analysed FUT2 variants and ABO genotypes in a total of 531 Japanese children diagnosed with Type 1 diabetes and 448 control subjects. The possible association of FUT2 variants and ABO genotypes with the onset of Type 1 diabetes was statistically examined.

RESULTS

The se2 genotype (c.385A>T) of the FUT2 gene was found to confer susceptibility to Type 1A diabetes in a recessive effects model [odds ratio for se2/se2, 1.68 (95% CI 1.20-2.35); corrected P value = 0.0075].

CONCLUSIONS

The FUT2 gene contributed to the development of Type 1 diabetes in the present cohort of Japanese children.

Variants associated with autoimmune Type 1 diabetes in Japanese children: implications for age-specific effects of cis-regulatory haplotypes at 17q12-q21

AIMS

The aim of this study was to clarify the significance of previously reported susceptibility variants in the development of autoimmune Type 1 diabetes in non-white children. Tested variants included rs2290400, which has been linked to Type 1 diabetes only in one study on white people. Haplotypes at 17q12-q21 encompassing rs2290400 are known to determine the susceptibility of early-onset asthma by affecting the expression of flanking genes.

METHODS

We genotyped 63 variants in 428 Japanese people with childhood-onset autoimmune Type 1 diabetes and 457 individuals without diabetes. Possible association between variants and age at diabetes onset was examined using age-specific quantitative trait locus analysis and ordered-subset regression analysis.

RESULTS

Ten variants, including rs2290400 in GSDMB, were more frequent among the people with Type 1 diabetes than those without diabetes. Of these, rs689 in INS and rs231775 in CTLA4 yielded particularly high odds ratios of 5.58 (corrected P value 0.001; 95% CI 2.15-14.47) and 1.64 (corrected P value 5.3 × 10^-5 ; 95% CI 1.34-2.01), respectively. Age-specific effects on diabetes susceptibility were suggested for rs2290400; heterozygosity of the risk alleles was associated with relatively early onset of diabetes, and the allele was linked to the phenotype exclusively in the subgroup of age at onset ≤ 5.0 years.

CONCLUSIONS

The results indicate that rs2290400 in GSDMB and polymorphisms in INS and CTLA4 are associated with the risk of Type 1 diabetes in Japanese children. Importantly, cis-regulatory haplotypes at 17q12-q21 encompassing rs2290400 probably determine the risk of autoimmune Type 1 diabetes predominantly in early childhood.

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

Antimicrobial peptides are major effectors of innate immunity of multicellular organisms including humans and play a critical role in host defense, and their importance is widely recognized. The epithelium of the intestine is the largest surface area exposed to the outer environment, including pathogens, toxins and foods. The Paneth cell lineage of intestinal epithelial cells produces and secretes α-defensin antimicrobial peptides and functions in innate enteric immunity by removing pathogens and living symbiotically with commensal microbiota to contribute to intestinal homeostasis. Paneth cells secrete α-defensins, HD5 and HD6 in humans and cryptdins in mice, in response to bacterial, cholinergic and other stimuli. The α-defensins have selective activities against bacteria, eliciting potent microbicidal activities against pathogenic bacteria but minimal or no bactericidal activity against commensal bacteria. Therefore, α-defensins regulate the composition of the intestinal microbiota in vivo and play a role in homeostasis of the entire intestine. Recently, relationships between dysbiosis, or abnormal composition of the intestinal microbiota, and diseases such as inflammatory bowel disease and lifestyle diseases including obesity and atherosclerosis have been reported. Because α-defensins regulate the composition of the intestinal microbiota, Paneth cells and their α-defensins may have a key role as one mechanism linking the microbiota and disease.

Decreased secretion of Paneth cell α-defensins in graft-versus-host disease

BACKGROUND

Intestinal microbial ecology is actively regulated by Paneth cell-derived antimicrobial peptides, α-defensins. Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (SCT). We previously demonstrated that Paneth cells are targeted by GVHD, and their expression of antimicrobial peptide α-defensins is impaired, leading to a loss of physiological diversity among the microflora and development of bloodstream infection. Herein, we evaluated whether fecal levels of α-defensins could be surrogate marker of intestinal dysbiosis.

METHODS

We directly measured α-defensin cryptdin-1 (Crp1) in fecal pellets of mice with GVHD by using a novel enzyme-linked immunosorbent assay.

RESULTS

Fecal levels of Crp1 were significantly decreased in mice with GVHD but unchanged in mice without GVHD after SCT. These were correlated with intestinal flora diversity.

CONCLUSION

We demonstrate a link between reduced secretion of Paneth cell α-defensins and dysbiosis of intestinal flora in GVHD. Fecal levels of α-defensins could be surrogate markers for intestinal microbial homeostasis.

Stiff substrates increase YAP-signaling-mediated matrix metalloproteinase-7 expression

Abnormally stiff substrates have been shown to trigger cancer progression. However, the detailed molecular mechanisms underlying this trigger are not clear. In this study, we cultured T84 human colorectal cancer cells on plastic dishes to create a stiff substrate or on collagen-I gel to create a soft substrate. The stiff substrate enhanced the expression of matrix metalloproteinase-7 (MMP-7), an indicator of poor prognosis. In addition, we used polyacrylamide gels (2, 67 and 126 kPa) so that the MMP-7 expression on the 126-kPa gel was higher compared with that on the 2-kPa gel. Next, we investigated whether yes-associated protein (YAP) affected the MMP-7 expression. YAP knockdown decreased MMP-7 expression. Treatment with inhibitors of epidermal growth factor receptor (EGFR) and myosin regulatory light chain (MRLC) and integrin-α2 or integrin-β1 knockdown downregulated MMP-7 expression. Finally, we demonstrated that YAP, EGFR, integrin-α2β1 and MRLC produced a positive feedback loop that enhanced MMP-7 expression. These findings suggest that stiff substrates enhanced colorectal cancer cell viability by upregulating MMP-7 expression through a positive feedback loop.

Bacterial cell wall components regulate adipokine secretion from visceral adipocytes

Recent studies suggest a relationship between intestinal microbiota and metabolic syndromes; however, the underlying mechanism remains unclear. To clarify this issue, we assessed the effects of bacterial cell wall components on adiponectin, leptin and resistin secretion from rat visceral adipocytes in vitro. We also measured the relative population of Firmicutes and Bacteroidetes in fecal microbiota and the amount of fecal mucin as an intestinal barrier function, when mice were fed a high-fat diet. In the present study, we demonstrated that bacterial cell wall components affect the secretion of adipokines, depending on the presence of antigens from gram-positive or gram-negative bacteria. Lipopolysaccharide markedly inhibited adiponectin, leptin, and resistin secretion, whereas peptidoglycan increased adiponectin secretion and decreased resistin secretion in vitro. In vivo experiments showed that the high-fat diet increased the population of Firmicutes and decreased that of Bacteroidetes. In contrast, the high-fat diet downregulated the stool output and fecal mucin content. These results demonstrate that bacterial cell wall components affect the onset of metabolic syndromes by mediating the secretion of adipokines from visceral adipose tissue. Furthermore, we believe that metabolic endotoxemia is not due to the increasing dominance of gram-negative bacteria, Bacteroidetes, but due to the depression of intestinal barrier function.

SuperNova, a monomeric photosensitizing fluorescent protein for chromophore-assisted light inactivation

Chromophore-assisted light inactivation (CALI) is a powerful technique for acute perturbation of biomolecules in a spatio-temporally defined manner in living specimen with reactive oxygen species (ROS). Whereas a chemical photosensitizer including fluorescein must be added to specimens exogenously and cannot be restricted to particular cells or sub-cellular compartments, a genetically-encoded photosensitizer, KillerRed, can be controlled in its expression by tissue specific promoters or subcellular localization tags. Despite of this superiority, KillerRed hasn't yet become a versatile tool because its dimerization tendency prevents fusion with proteins of interest. Here, we report the development of monomeric variant of KillerRed (SuperNova) by direct evolution using random mutagenesis. In contrast to KillerRed, SuperNova in fusion with target proteins shows proper localization. Furthermore, unlike KillerRed, SuperNova expression alone doesn't perturb mitotic cell division. Supernova retains the ability to generate ROS, and hence promote CALI-based functional analysis of target proteins overcoming the major drawbacks of KillerRed.

A monoclonal antibody-based sandwich enzyme-linked immunosorbent assay for detection of secreted α-defensin

Paneth cells at the base of small intestinal crypts secrete α-defensins, which contribute to innate immunity and shape composition of enteric microbiota. Efforts to establish a relationship between secreted α-defensins and disease have been hampered by a lack of sensitive assays to quantify luminal α-defensins. Here we report on a highly sensitive sandwich enzyme-linked immunosorbent assay (ELISA) for the mouse Paneth cell α-defensin cryptdin-4 (Crp4) in varied sources, including luminal contents rinsed from stomach to distal colon and fecal pellets. One pair of monoclonal antibodies (mAbs), selected from 10 rat hybridomas secreting Crp4-specific mAbs, was optimized for Crp4 detection and specificity in the sandwich ELISA. In CD1 mice, luminal Crp4 levels increased gradually from 6.8 ± 5.2 ng/ml in proximal small intestine to 54.3 ± 10.3 ng/ml in distal small intestine, and the peptide was detected in colonic lumen and feces. Secreted Crp4 was reduced significantly in feces of IL10 null mice, a model of inflammatory bowel disease (IBD) when compared with wild-type controls. This Crp4 sandwich ELISA enables accurate determinations of luminal α-defensins as biomarkers of Paneth cell function and enteric integrity in diverse disease states such as IBD, infectious disease, graft versus host disease, and obesity in association with dysbiosis of the intestinal microbiota.

Reciprocal expression of enteric antimicrobial proteins in intestinal graft-versus-host disease

We recently demonstrated that expression of α-defensins, the major antimicrobial peptides produced by Paneth cells, was severely suppressed in mice with graft-versus-host disease (GVHD). In this study, we found that antibacterial lectin, regenerating islet-derived IIIγ (RegIIIγ) was upregulated in villous enterocytes, thus demonstrating the reciprocal control of enteric antimicrobial proteins in GVHD. Upregulation of RegIIIγ was mediated by a mechanism independent upon radiation-induced intestinal tract damage. MyD88-mediated signaling in intestinal epithelium was required for RegIIIγ upregulation in GVHD and antibiotic therapy downregulated RegIIIγ expression. These results suggest that MyD88-mediated sensing of the intestinal microbes disregulated in GVHD induces RegIIIγ upregulation in GVHD and argue a role for RegIIIγ in the pathogenesis of GVHD.

46, XY gonadal dysgenesis: new SRY point mutation in two siblings with paternal germ line mosaicism

Familial recurrence risks are poorly understood in cases of de novo mutations. In the event of parental germ line mosaicism, recurrence risks can be higher than generally appreciated, with implications for genetic counseling and clinical practice. In the course of treating a female with pubertal delay and hypergonadotropic hypogonadism, we identified a new missense mutation in the SRY gene, leading to somatic feminization of this karyotypically normal XY individual. We tested a younger sister despite a normal onset of puberty, who also possessed an XY karyotype and the same SRY mutation. Imaging studies in the sister revealed an ovarian tumor, which was removed. DNA from the father's blood possessed the wild type SRY sequence, and paternity testing was consistent with the given family structure. A brother was 46, XY with a wild type SRY sequence strongly suggesting paternal Y-chromosome germline mosaicism for the mutation. In disorders of sexual development (DSDs), early diagnosis is critical for optimal psychological development of the affected patients. In this case, preventive karyotypic screening allowed early diagnosis of a gonadal tumor in the sibling prior to the age of normal puberty. Our results suggest that cytological or molecular diagnosis should be applied for siblings of an affected DSD individual.

Regulation of microbiota by antimicrobial peptides in the gut

The antimicrobial peptide is one of major effectors of the innate immunity, and is common in the entire multicellular organisms. In mammals, one family of antibacterial peptide named defensins plays a central role in host defense, especially in the epithelial surface such as oral cavity, skin and the intestine. Recently, the importance of the antimicrobial peptides has been widely recognized. The epithelium of the gut is a largest surface that is exposed to various pathogens in the environment. It is the Paneth cells that produce antimicrobial peptides, α-defensins in the small intestine. Paneth cells contribute to mucosal innate immunity by sensing bacteria and releasing microbicidal activities mostly from activated α-defensins. In mice, α-defensins, named cryptdins, consisted of six major isoforms (cryptdin-1 to cryptdin-6), and among those cryptdin-4 is the most microbicidal, suggesting that cryptdin-4 has a pivotal role in innate immunity. Paneth cell α-defensins have selective activities against commensal bacteria which may be associated with compositions of intestinal microbiota in vivo and homeostasis of the entire intestine. In addition, Paneth cell α-defensins appeared to be regulated topographically to control intestinal integrity.

Regulation of microbiota by antimicrobial peptides in the gut

The antimicrobial peptide is one of major effectors of the innate immunity, and is common in the entire multicellular organisms. In mammals, one family of antibacterial peptide named defensins plays a central role in host defense, especially in the epithelial surface such as oral cavity, skin and the intestine. Recently, the importance of the antimicrobial peptides has been widely recognized. The epithelium of the gut is a largest surface that is exposed to various pathogens in the environment. It is the Paneth cells that produce antimicrobial peptides, α-defensins in the small intestine. Paneth cells contribute to mucosal innate immunity by sensing bacteria and releasing microbicidal activities mostly from activated α-defensins. In mice, α-defensins, named cryptdins, consisted of six major isoforms (cryptdin-1 to cryptdin-6), and among those cryptdin-4 is the most microbicidal, suggesting that cryptdin-4 has a pivotal role in innate immunity. Paneth cell α-defensins have selective activities against commensal bacteria which may be associated with compositions of intestinal microbiota in vivo and homeostasis of the entire intestine. In addition, Paneth cell α-defensins appeared to be regulated topographically to control intestinal integrity.

Bactericidal activity of mouse α-defensin cryptdin-4 predominantly affects noncommensal bacteria

Mouse Paneth cell α-defensins, termed cryptdins, are secreted into the intestinal lumen, have microbicidal activity, and contribute to intestinal innate immunity. Among them, cryptdin-4 (Crp4) has the most potent microbicidal activity. In the intestinal lumen, commensal bacteria colonize and elicit beneficial effects in the host. However, the effects of Crp4 against commensal bacteria are poorly understood. Thus, we investigated the bactericidal activities of Crp4 against commensal bacteria compared to noncommensal bacteria. Oxidized Crp4 showed only minimal or no bactericidal activity against 8 out of 12 commensal bacterial species, including Bifidobacterium bifidum and Lactobacillus casei. We further addressed a role of the conserved disulfide bonds of Crp4 by analyzing reduced Crp4 (r-Crp4). r-Crp4 demonstrated significantly greater bactericidal activities against 7 of 12 commensal bacteria than did oxidized Crp4. Oxidized Crp4 and r-Crp4 elicited equivalently potent bactericidal activities against 11 of the 11 noncommensal bacteria tested, such as Salmonella enterica serovar Typhimurium,and against 5 of 12 commensal bacteria. Furthermore, when r-Crp4 was exposed to a processing enzyme of cryptdins, i.e. MMP-7, r-Crp4 was degraded and the bactericidal activities disappeared. These findings suggest that Crp4 has selective bactericidal activities against intestinal microbiota and that the activities are dependent on the disulfide bonds.

Carcinoembryonic antigen level in serum and pleural lavage fluid in non-small cell lung cancer

BACKGROUND

This study evaluates the tumor marker index (TMI) based on carcinoembryonic antigen (CEA) levels in serum and pleural lavage fluid as a potential prognostic determinant for patients with non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Three hundred and eighty-three consecutive NSCLC patients were reviewed retrospectively.

RESULTS

The 5-year survival of patients with normal and high serum CEA levels was 71.78% and 51.38%, respectively (P < 0.0001). The 5-year survival of patients with high CEA levels in pleural lavage fluid was 25.0%, which was significantly poorer compared with that of patients with normal lavage CEA levels (78.23%, P < 0.0001). There was a 5-year survival rate of 73.75% in patients with a TMI less than or equal to 1.0 compared to a rate of only 55.12% in patients with a TMI greater than 1.0 (P < 0.001). Both univariate and multivariate analyses indicated the independent prognostic impact of the TMI.

CONCLUSIONS

The TMI based on serum and lavage CEA levels might be useful for predicting the prognosis of NSCLC patients.

Expression of the antimicrobial peptide alpha-defensin/cryptdins in intestinal crypts decreases at the initial phase of intestinal inflammation in a model of inflammatory bowel disease, IL-10-deficient mice

BACKGROUND

The etiology of inflammatory bowel disease (IBD) is associated with an altered microflora due to a failure of the immune system. This study investigated the expression of the intestinal antimicrobial peptide alpha-defensin, which plays a pivotal role in the regulation of the intestinal microflora in a representative model of IBD, interleukin (IL)-10-deficient mice.

METHODS

The expression of alpha-defensin/cryptdins in IL-10-deficient mice was assessed by real-time polymerase chain reaction (PCR) and acid/urea polyacrylamide gel (AU-PAGE). The alteration of alpha-defensin/cryptdins expression was compared with the inflammatory grade of mice intestine at various weeks from birth.

RESULTS

The weight, length, and inflammation grade of the mouse intestines were assessed at 5, 7, 9, 11, 13, and 15 weeks from birth. While the weight of the large intestine was heavier at 15 weeks after birth in the IL-10-deficient mice than in the control mice, histological inflammation began from 7 weeks after birth. Real-time PCR and AU-PAGE identified a significant decrease in the expression of alpha-defensin/cryptdins at 7 weeks after birth in the IL-10 knockout mice, thus illustrating the involvement of alpha-defensin/cryptdins in the etiology of the intestinal inflammation in IBD. This study also identified the expression of alpha-defensin/cryptdins to be inversely proportional to age until 11 weeks, suggesting a relationship between the formation of the intestinal microflora and a reduction in the expression of alpha-defensin/cryptdins.

CONCLUSIONS

The altered expression of antimicrobial peptide alpha-defensin may cause the onset of intestinal inflammation due to a failure to regulate intestinal microflora.