Reduction of butyrate-producing bacteria in the gut microbiome of Japanese patients with pancreatic cancer.

BACKGROUND: The incidence of pancreatic cancer is on the rise, and its prognosis remains poor. Recent reports have established a link between the gut and oral microbiome and pancreatic cancer. However, the intricacies of this association within the Japanese population remain unclear. In this study, we investigated the gut and oral microbiomes of Japanese patients with pancreatic cancer, comparing them with those of healthy individuals. METHODS: We recruited 30 patients with untreated pancreatic cancer and 18 healthy controls at Kyoto University Hospital (2018-2022). We performed a comprehensive 16S rRNA gene sequencing to analyze their gut and oral microbiomes. RESULTS: Analysis revealed that the diversity of the gut and oral microbiomes of patients with pancreatic cancer was reduced compared to that of the healthy controls. Specifically, we observed an increase in the genus Streptococcus in both the gut and oral microbiomes and a significant decrease in several butyrate-producing bacteria in fecal samples. Moreover, bacteria such as Streptococcus mitis and Holdemanella biformis were present in pancreatic cancer tissues, suggesting that they might influence the carcinogenesis and progression of pancreatic cancer. CONCLUSIONS: The gut and oral microbiome differed between patients with pancreatic cancer and healthy controls, with a notable decrease in butyrate-producing bacteria in the gut microbiome of the patients. This suggests that there may be a distinct microbial signature associated with pancreatic cancer in the Japanese population. Further studies are required to elucidate the microbiome's causal role in this cancer and help develop prognostic markers or targeted therapies.

Comparative Analysis of Nutritional Advice and a Combined Approach for Addressing Impending Stunting in Infants: A Clinical Trial.

Weight faltering (WF) has been associated with stunting and with long-term adverse consequences for health and development. Nutritional care for managing WF may consist of giving nutritional advice (NA) and/or provision of oral nutrition supplements (ONSs). In this study, we aimed to evaluate practical management options in the community for infants with WF aged 6-12 months. This nonrandomized clinical trial was conducted in the community of Makassar, South Sulawesi, from March 2022 to March 2023. A total of 1013 infants were enrolled for screening. Anthropometric measures were performed in 913 infants, of which 170 showed WF below the 15th percentile of the WHO weight increment table without stunting. Infants with a weight increment below P5th were assigned to receive NA plus ONS, while infants between P5th and below P15th were assigned to receive only NA. At the second and third months, ONSs were administered to WF infants who were below P15th. One month after the intervention, 87/105 infants in the NA-plus-ONS group (82.8%) and 52/65 infants in the NA-only group (80%) were no longer WF. After 3 months, infants in the NA-plus-ONS group achieved greater weight gain than infants in the NA group (264.1 g vs. 137.4 g, p < 0.001) as well as greater length gain (2.35 cm vs. 2.14 cm, p < 0.001). WF management should be started at below P15th to achieve a better result. Infants with greater nutritional deficits should be assigned to receive the combination of NA plus ONSs to achieve a higher rate of resolution of growth.

Mechanisms of age-related Treg dysfunction in an arthritic environment.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by a polyarticular synovitis. In recent years, elderly onset rheumatoid arthritis (EORA) has been increasing. Treg cells in RA have been reported to be dysfunctional, but the relationship between aging and their functional changes is unclear. Here, we found that Treg cells from EORA patients had increased percentages, but decreased activity compared to those from younger onset RA (YORA) patients. In experiments using arthritis model mice, decreased suppressive function and oxygen consumption rate (OCR) were observed in Treg cells only from old arthritic mice. Furthermore, type I interferon (IFN) signaling was upregulated in Treg cells from old GIA mice, and IFN-ß decreased the suppressive function of Treg cells. Our findings demonstrate that increased type I IFN signaling in old Treg cells is induced only in the arthritic environment and relates to decreased suppressive function of Treg cells, gets involved in EORA.

Gut microbial factors predict disease severity in a mouse model of multiple sclerosis.

Gut bacteria are linked to neurodegenerative diseases but the risk factors beyond microbiota composition are limited. Here we used a pre-clinical model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE), to identify microbial risk factors. Mice with different genotypes and complex microbiotas or six combinations of a synthetic human microbiota were analysed, resulting in varying probabilities of severe neuroinflammation. However, the presence or relative abundances of suspected microbial risk factors failed to predict disease severity. Akkermansia muciniphila, often associated with MS, exhibited variable associations with EAE severity depending on the background microbiota. Significant inter-individual disease course variations were observed among mice harbouring the same microbiota. Evaluation of microbial functional characteristics and host immune responses demonstrated that the immunoglobulin A coating index of certain bacteria before disease onset is a robust individualized predictor of disease development. Our study highlights the need to consider microbial community networks and host-specific bidirectional interactions when aiming to predict severity of neuroinflammation.

Intestinal epithelium dysfunctions cause IgA deposition in the kidney glomeruli of intestine-specific Ap1m2-deficient mice.

BACKGROUND: Intestinal epithelial cells (IECs) serve as robust barriers against potentially hostile luminal antigens and commensal microbiota. Epithelial barrier dysfunction enhances intestinal permeability, leading to leaky gut syndrome (LGS) associated with autoimmune and chronic inflammatory disorders. However, a causal relationship between LGS and systemic disorders remains unclear. Ap1m2 encodes clathrin adaptor protein complex 1 subunit mu 2, which facilitates polarized protein trafficking toward the basolateral membrane and contributes to the establishment of epithelial barrier functions. METHODS: We generated IEC-specific Ap1m2-deficient (Ap1m2ΔIEC) mice with low intestinal barrier integrity as an LSG model and examined the systemic impact. FINDINGS: Ap1m2ΔIEC mice spontaneously developed IgA nephropathy (IgAN)-like features characterized by the deposition of IgA-IgG immune complexes and complement factors in the kidney glomeruli. Ap1m2 deficiency markedly enhanced aberrantly glycosylated IgA in the serum owing to downregulation and mis-sorting of polymeric immunoglobulin receptors in IECs. Furthermore, Ap1m2 deficiency caused intestinal dysbiosis by attenuating IL-22-STAT3 signaling. Intestinal dysbiosis contributed to the pathogenesis of IgAN because antibiotic treatment reduced aberrantly glycosylated IgA production and renal IgA deposition in Ap1m2ΔIEC mice. INTERPRETATION: IEC barrier dysfunction and subsequent dysbiosis by AP-1B deficiency provoke IgA deposition in the mouse kidney. Our findings provide experimental evidence of a pathological link between LGS and IgAN. FUNDING: AMED, AMED-CREST, JSPS Grants-in-Aid for Scientific Research, JST CREST, Fuji Foundation for Protein Research, and Keio University Program for the Advancement of Next Generation Research Projects.

Activation of chloride channels and promotion of bowel movements by heat-killed Bifidobacterium longum CLA8013.

Constipation is strongly associated with the deterioration of quality of life (QOL), and patients with constipation desire clear spontaneous defecation without the feeling of incomplete evacuation, rather than improved defecation frequency. The use of common osmotic or stimulant laxatives has not been shown to lead to a satisfactory improvement of bowel movements. In addition, softening of stools by increasing their water content has been reported to increase the frequency of spontaneous defecation and improve hard stools, straining during defecation, and abdominal symptoms, such as abdominal bloating, thereby leading to improvement of QOL deterioration caused by constipation. Thus, the present study screened bacterial strains in vitro using intestinal epithelial T84 cells, aiming to identify one that activates chloride channels involved in water secretion into the intestinal tract. As a result, the conditioned medium of Bifidobacterium longum CLA8013 was found to induce ion transport. Also, this effect was suppressed by cystic fibrosis transmembrane conductance regulator (CFTR) (inh)-172, a CFTR chloride channel inhibitor. Furthermore, both live and heat-killed CLA8013 similarly induced ion transport, suggesting that bacterial cell components are responsible for the effect. In addition, the administration of heat-killed CLA8013 to loperamide-induced constipation rats resulted in an increase in fecal water content and promoted defecation. These results suggest that the active components in CLA8013 act on CFTR chloride channels in the intestinal tract, promote water secretion into the intestinal tract, and soften stools, thereby promoting bowel movements.

Gut microbiota shifts from onset to remission in immune checkpoint inhibitor-induced enterocolitis: a case report.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are crucial in cancer treatment; however, they carry the risk of immune-related adverse events (irAEs), such as enteritis. CASE PRESENTATION: This study investigated the role of the gut microbiota during the onset and remission of irAE enteritis in a patient with stage IV melanoma undergoing anti-PD-1 and anti-CTLA-4 therapy. Following commencement of ICI treatment, the patient developed severe diarrhea and was diagnosed with grade 3 irAE enteritis. Steroid and probiotic treatments provided swift symptom relief and remission, as confirmed by reduced fecal calprotectin levels and gastrointestinal imaging. Microbiota diversity analysis conducted via 16S rRNA gene sequencing identified a decrease in Streptococcus prevalence with improvement in enteritis symptoms. Conversely, genera Fusobacterium, Faecalibacterium, Bacteroides, Prevotella, and Bifidobacterium showed increased representation after remission. These genera are associated with anti-inflammatory properties and fibrous substrate degradation, aiding gut health. Immunological assessment demonstrated fluctuations in cytokine expression and the modulation of costimulatory molecules, aligning with therapeutic interventions and microbiota alterations. CONCLUSIONS: Our findings indicate a significant correlation between gut microbiota and immune responses in irAE enteritis. This underscores the potential utility of microbiome profiling in predicting irAE occurrence and in providing treatment strategies, thereby promoting a more comprehensive approach to managing the adverse effects of ICIs.

Implications of Genetic Factors Underlying Mouse Hydronephrosis: Cautionary Considerations on Phenotypic Interpretation in Genetically Engineered Mice.

Hydronephrosis, the dilation of kidneys due to abnormal urine retention, occurs spontaneously in certain inbred mouse strains. In humans, its occurrence is often attributed to acquired urinary tract obstructions in adults, whereas in children, it can be congenital. However, the genetic factors underlying hydronephrosis pathogenesis remain unclear. We investigated the cause of hydronephrosis by analyzing tetraspanin 7 (Tspan7) gene-modified mice, which had shown a high incidence of hydronephrosis-like symptoms. We found that these mice were characterized by low liver weights relative to kidney weights and elevated blood ammonia levels, suggesting liver involvement in hydronephrosis. Gene expression analysis of the liver suggested that dysfunction of ornithine transcarbamylase (OTC), encoded by the X chromosome gene Otc and involved in the urea cycle, may contribute as a congenital factor in hydronephrosis. This OTC dysfunction may be caused by genomic mutations in X chromosome genes contiguous to Otc, such as Tspan7, or via the genomic manipulations used to generate transgenic mice, including the introduction of Cre recombinase DNA cassettes and cleavage of loxP by Cre recombinase. Therefore, caution should be exercised in interpreting the hydronephrosis phenotype observed in transgenic mice as solely a physiological function of the target gene.

Modulation of gut microbiota composition due to early weaning stress induces depressive behavior during the juvenile period in mice.

BACKGROUND: The gut microbiota plays an important role in the development of behavior and immunity in infants and juveniles. Early weaning (EW), a form of social stress in mice, leads to increased anxiety and an enhanced stress response in the hypothalamic-pituitary-adrenal axis during adulthood. Early life stress also modulates the immune system and increases vulnerability to infection. However, studies investigating the causal relationships among juvenile stress, microbiota changes, and immune and behavioral deficits are limited. Therefore, we hypothesized that EW alters gut microbiota composition and impairs the development of the nervous and immune systems. RESULTS: EW mice moved longer distances in the marble-burying test and had longer immobility times in the tail suspension test than normal weaning (NW) mice. In parallel, the gut microbiome composition differed between NW and EW mice, and the abundance of Erysipelotrichacea in EW mice at 8 weeks of age was lower than that in NW mice. In an empirical study, germ-free mice colonized with the gut microbiota of EW mice (GF-EW mice) demonstrated higher depressive behavior than GF mice colonized with normal weaning microbiota (GF-NW mice). Immune cell profiles were also affected by the EW microbiota colonization; the number of CD4 + T cells in the spleen was reduced in GF-EW mice. CONCLUSION: Our results suggest that EW-induced alterations in the gut microbiota cause depressive behaviors and modulate the immune system.

Microbial Metabolites and Gut Immunology.

The intestine is the largest peripheral lymphoid organ in animals, including humans, and interacts with a vast array of microorganisms called the gut microbiota. Comprehending the symbiotic relationship between the gut microbiota and our immune system is essential not only for the field of immunology but also for understanding the pathogenesis of various systemic diseases, including cancer, cardiometabolic disorders, and extraintestinal autoimmune conditions. Whereas microbe-derived antigens are crucial for activating the intestinal immune system, particularly T and B cells, as environmental cues, microbes and their metabolites play a critical role in directing the differentiation of these immune cells. Microbial metabolites are regarded as messengers from the gut microbiota, since bacteria have the ability to produce unique molecules that humans cannot, and many immune cells in the intestine express receptors for these molecules. This review highlights the distinct relationships between microbial metabolites and the differentiation and function of the immune system.

Lactobacillus paracasei subsp. paracasei 2004 improves health and lifespan in Caenorhabditis elegans.

Recent research has highlighted the importance of the gut microbiome in regulating aging, and probiotics are interventions that can promote gut health. In this study, we surveyed several novel lactic acid bacteria to examine their beneficial effect on organismal health and lifespan in C. elegans. We found that animals fed some lactic acid bacteria, including L. acidophilus 1244 and L. paracasei subsp. paracasei 2004, grew healthy. Supplementation with the lactic acid bacterial strains L. acidophilus 1244 or L. paracasei subsp. paracasei 2004 significantly improved health, including food consumption, motility, and resistance to oxidative stressor, hydrogen peroxide. Our RNA-seq analysis showed that supplementation with L. paracasei subsp. paracasei 2004 significantly increased the expression of daf-16, a C. elegans FoxO homolog, as well as genes related to the stress response. Furthermore, daf-16 deletion inhibited the longevity effect of L. paracasei subsp. paracasei 2004 supplementation. Our results suggest that L. paracasei subsp. paracasei 2004 improves health and lifespan in a DAF-16-dependent manner.

A lipidome landscape of aging in mice.

Understanding the molecular mechanisms of aging is crucial for enhancing healthy longevity. We conducted untargeted lipidomics across 13 biological samples from mice at various life stages (2, 12, 19 and 24 months) to explore the potential link between aging and lipid metabolism, considering sex (male or female) and microbiome (specific pathogen-free or germ-free) dependencies. By analyzing 2,704 molecules from 109 lipid subclasses, we characterized common and tissue-specific lipidome alterations associated with aging. For example, the levels of bis(monoacylglycero)phosphate containing polyunsaturated fatty acids increased in various organs during aging, whereas the levels of other phospholipids containing saturated and monounsaturated fatty acids decreased. In addition, we discovered age-dependent sulfonolipid accumulation, absent in germ-free mice, correlating with Alistipes abundance determined by 16S ribosomal RNA gene amplicon sequencing. In the male kidney, glycolipids such as galactosylceramides, galabiosylceramides (Gal2Cer), trihexosylceramides (Hex3Cer), and mono- and digalactosyldiacylglycerols were detected, with two lipid classes-Gal2Cer and Hex3Cer-being significantly enriched in aged mice. Integrated analysis of the kidney transcriptome revealed uridine diphosphate galactosyltransferase 8A (UGT8a), alkylglycerone phosphate synthase and fatty acyl-coenzyme A reductase 1 as potential enzymes responsible for the male-specific glycolipid biosynthesis in vivo, which would be relevant to sex dependency in kidney diseases. Inhibiting UGT8 reduced the levels of these glycolipids and the expression of inflammatory cytokines in the kidney. Our study provides a valuable resource for clarifying potential links between lipid metabolism and aging.

A Bcl11bN797K variant isolated from an immunodeficient patient inhibits early thymocyte development in mice.

BCL11B is a transcription factor with six C2H2-type zinc-finger domains. Studies in mice have shown that Bcl11b plays essential roles in T cell development. Several germline heterozygous BCL11B variants have been identified in human patients with inborn errors of immunity (IEI) patients. Among these, two de novo mis-sense variants cause asparagine (N) to lysine (K) replacement in distinct zinc-finger domains, BCL11BN441K and BCL11BN807K. To elucidate the pathogenesis of the BCL11BN807K variant, we generated a mouse model of BCL11BN807K by inserting the corresponding mutation, Bcl11bN797K, into the mouse genome. In Bcl11b+/N797K mice, the proportion of immature CD4-CD8+ single-positive thymocytes was increased, and the development of invariant natural killer cells was severely inhibited in a T-cell-intrinsic manner. Under competitive conditions, γδT cell development was outcompeted by control cells. Bcl11bN797K/N797K mice died within one day of birth. Recipient mice reconstituted with Bcl11bN797K/N797K fetal liver cells nearly lacked CD4+CD8+ double-positive thymocytes, which was consistent with the lack of their emergence in culture from Bcl11bN797K/N797K fetal liver progenitors. Interestingly, Bcl11bN797K/N797K progenitors gave rise to aberrant c-Kit+ and CD44+ cells both in vivo and in vitro. The increase in the proportion of immature CD8 single-positive thymocytes in the Bcl11bN797K mutants is caused, in part, by the inefficient activation of the Cd4 gene due to the attenuated function of the two Cd4 enhancers via distinct mechanisms. Therefore, we conclude that immunodeficient patient-derived Bcl11bN797K mutant mice elucidated a novel role for Bcl11b in driving the appropriate transition of CD4-CD8- into CD4+CD8+ thymocytes.

Genetic and Functional Analyses of Patients with Marked Hypo-High-Density Lipoprotein Cholesterolemia.

AIM: This study aimed to analyze two cases of marked hypo-high-density lipoprotein (HDL) cholesterolemia to identify mutations in ATP-binding cassette transporter A1 (ABCA1) and elucidate the molecular mechanism by which these novel pathological mutations contribute to hypo-HDL cholesterolemia in Tangier disease. METHODS: Wild type and mutant expression plasmids containing a FLAG tag inserted at the C-terminus of the human ABCA1 gene were generated and transfected into HEK293T cells. ABCA1 protein expression and cholesterol efflux were evaluated via Western blotting and efflux assay. The difference in the rate of change in protein expression was evaluated when proteolytic and protein-producing systems were inhibited. RESULTS: In case 1, a 20-year-old woman presented with a chief complaint of gait disturbance. Her HDL-C level was only 6.2 mg/dL. Tangier disease was suspected because of muscle weakness, decreased nerve conduction velocity, and splenomegaly. Whole-exome analysis showed compound heterozygosity for a W484* nonsense mutation and S1343I missense mutation, which confirmed Tangier disease. Cholesterol efflux decreased by a mixture of W484* and S1343I mutations. The S1343I mutation decreased the protein production rate but increased the degradation rate, decreasing the protein levels. This patient also had Krabbe disease. The endogenous ABCA1 protein level of macrophage cell decreased by knocking down its internal galactocerebrosidase. Case 2, a 51-year-old woman who underwent tonsillectomy presented with peripheral neuropathy, corneal opacity, and HDL-C of 3.4 mg/dL. Whole-exome analysis revealed compound heterozygosity for R579* and R1572* nonsense mutations, which confirmed Tangier disease. CONCLUSION: Case 1 is a new ABCA1 mutation with complex pathogenicity, namely, a W484*/S1343I compound heterozygote with marked hypo-HDL cholesterolemia. Analyses of the compound heterozygous mutations indicated that decreases in ABCA1 protein levels and cholesterol efflux activity caused by the novel S1343I mutation combined with loss of W484* protein activity could lead to marked hypo-HDL cholesterolemia. Galactocerebrosidase dysfunction could also be a potential confounding factor for ABCA1 protein function.

Alteration of shoaling behavior and dysbiosis in the gut of medaka (Oryzias latipes) exposed to 2-µm polystyrene microplastics.

There is global concern that microplastics may harm aquatic life. Here, we examined the effects of fine polystyrene microplastics (PS-MPs, 2-µm diameter, 0.1 mg/L, 2.5 × 107 particles/L) on the behavior and the microbiome (linked to brain-gut interaction) of a fish model using medaka, Oryzias latipes. We found that shoaling behavior was reduced in PS-MP-exposed medaka compared with control fish during the exposure period, but it recovered during a depuration period. There was no difference in swimming speed between the PS-MP-exposed and control groups during the exposure period. Analysis of the dominant bacterial population (those comprising ≥1% of the total bacterial population) in the gut of fish showed that exposure to PS-MPs tended to increase the relative abundance of the phylum Fusobacteria and the genus Vibrio. Furthermore, structural-equation modeling of gut bacteria on the basis of machine-learning data estimated strong relationship involved in the reduction of the functional bacterial species of minority (<1% of the total bacterial population) such as the genera Muribaculum (an undefined role), Aquaspirillum (a candidate for nitrate metabolism and magnetotactics), and Clostridium and Phascolarctobacterium (potential producers of short-chain fatty acids, influencing behavior by affecting levels of neurotransmitters) as a group of gut bacteria in association with PS-MP exposure. Our results suggest that fish exposure to fine microplastics may cause dysbiosis and ultimately cause social behavior disorders linked to brain-gut interactions. This effect could be connected to reduction of fish fitness in the ecosystem and reduced fish survival.

Focus-free single-pixel color-mapping of a reflectance direction field.

A single-pixel optical system, equipped with a multicolor filter, is proposed for the screening inspection of the surfaces of objects in manufacturing processes. The optical system can identify sub-microscale roughness and detect a microscale defect in a focus-free setting through the color-mapping of reflectance direction fields, as validated by experiments.

Disease pathogenesis and barrier functions regulated by group 3 innate lymphoid cells.

The mucosal surface is in constant contact with foreign antigens and is regulated by unique mechanisms that are different from immune responses in the peripheral organs. For the last several decades, only adaptive immune cells such as helper T (Th) cells, Th1, Th2, or Th17 were targeted to study a wide variety of immune responses in the mucosal tissues. However, since their discovery, innate lymphoid cells (ILCs) have been attracting attention as a unique subset of immune cells that provide border defense with various functions and tissue specificity. ILCs are classified into different groups based on cell differentiation and functions. Group 3 innate lymphoid cells (ILC3s) are particularly in close proximity to mucosal surfaces and therefore have the opportunity to be exposed to a variety of bacteria including pathogenic bacteria. In recent years, studies have also provided much evidence that ILC3s contribute to disease pathogenesis as well as the defense of mucosal surfaces by rapidly responding to pathogens and coordinating other immune cells. As the counterpart of helper T cells, ILC3s together with other ILC subsets establish the immune balance between adaptive and innate immunity in protecting us from invasion or encounter with non-self-antigens for maintaining a complex homeostasis. In this review, we summarize recent advances in our understanding of ILCs, with a particular focus on the function of ILC3s in their involvement in bacterial infection and disease pathogenesis.

Genetic mutation in Escherichia coli genome during adaptation to the murine intestine is optimized for the host diet.

Mammalian gut microbes colonize the intestinal tract of their host and adapt to establish a microbial ecosystem. The host diet changes the nutrient profile of the intestine and has a high impact on microbiota composition. Genetic mutations in Escherichia coli, a prevalent species in the human gut, allow for adaptation to the mammalian intestine, as reported in previous studies. However, the extent of colonization fitness in the intestine elevated by genetic mutation and the effects of diet change on these mutations in E. coli are still poorly known. Here, we show that notable mutations in sugar metabolism-related genes (gatC, araC, and malI) were detected in the E. coli K-12 genome just 2 weeks after colonization in the germ-free mouse intestine. In addition to elevated fitness by deletion of gatC, as previously reported, deletion of araC and malI also elevated E. coli fitness in the murine intestine in a host diet-dependent manner. In vitro cultures of medium containing nutrients abundant in the intestine (e.g., galactose, N-acetylglucosamine, and asparagine) also showed increased E. coli fitness after deletion of the genes-of-interest associated with their metabolism. Furthermore, the host diet was found to influence the developmental trajectory of gene mutations in E. coli. Taken together, we suggest that genetic mutations in E. coli are selected in response to the intestinal environment, which facilitates efficient utilization of nutrients abundant in the intestine under laboratory conditions. Our study offers some insight into the possible adaptation mechanisms of gut microbes.IMPORTANCEThe gut microbiota is closely associated with human health and is greatly impacted by the host diet. Bacteria such as Escherichia coli live in the gut all throughout the life of a human host and adapt to the intestinal environment. Adaptive mutations in E. coli are reported to enhance fitness in the mammalian intestine, but to what extent is still poorly known. It is also unknown whether the host diet affects what genes are mutated and to what extent fitness is affected. This study suggests that genetic mutations in the E. coli K-12 strain are selected in response to the intestinal environment and facilitate efficient utilization of abundant nutrients in the germ-free mouse intestine. Our study provides a better understanding of these intestinal adaptation mechanisms of gut microbes.

Gut microbiota and fecal metabolites in sustained unresponsiveness by oral immunotherapy in school-age children with cow's milk allergy.

BACKGROUND: Oral immunotherapy (OIT) can ameliorate cow's milk allergy (CMA); however, the achievement of sustained unresponsiveness (SU) is challenging. Regarding the pathogenesis of CMA, recent studies have shown the importance of gut microbiota (Mb) and fecal water-soluble metabolites (WSMs), which prompted us to determine the change in clinical and gut environmental factors important for acquiring SU after OIT for CMA. METHODS: We conducted an ancillary cohort study of a multicenter randomized, parallel-group, delayed-start design study on 32 school-age children with IgE-mediated CMA who underwent OIT for 13 months. We defined SU as the ability to consume cow's milk exceeding the target dose in a double-blind placebo-controlled food challenge after OIT followed by a 2-week-avoidance. We longitudinally collected 175 fecal specimens and clustered the microbiome and metabolome data into 29 Mb- and 12 WSM-modules. RESULTS: During OIT, immunological factors improved in all participants. However, of the 32 participants, 4 withdrew because of adverse events, and only 7 were judged SU. Gut environmental factors shifted during OIT, but only in the beginning, and returned to the baseline at the end. Of these factors, milk- and casein-specific IgE and the Bifidobacterium-dominant module were associated with SU (milk- and casein-specific IgE; OR for 10 kUA/L increments, 0.67 and 0.66; 95%CI, 0.41-0.93 and 0.42-0.90; Bifidobacterium-dominant module; OR for 0.01 increments, 1.40; 95%CI, 1.10-2.03), and these associations were observed until the end of OIT. CONCLUSIONS: In this study, we identified the clinical and gut environmental factors associated with SU acquisition in CM-OIT.