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Objectives We aimed to assess the unmet medical needs of young adult patients with juvenile idiopathic arthritis by evaluating real-world treatment data. Methods We analyzed data on juvenile idiopathic arthritis in the 20-29 age group from the National Database of Designated Incurable Diseases of Japan, which records severe cases or those requiring high-cost medical care registered between April 2018 and March 2020. Results Overall, 322 patients with juvenile idiopathic arthritis transitioning to adulthood were included. A high frequency of methotrexate use was observed among all juvenile idiopathic arthritis subtypes. The frequency of methotrexate use at registration was significantly higher in patients with rheumatoid factor-positive polyarthritis and those with oligoarthritis or polyarthritis than in those with systemic arthritis. The historical use percentage of any biological disease-modifying antirheumatic drug was ≥85% for all juvenile idiopathic arthritis subtypes. The proportion of patients with ≥2 biological disease-modifying antirheumatic drug prescriptions was significantly higher in patients with rheumatoid factor-positive polyarthritis than in those with systemic arthritis. Conclusions High-cost drugs were necessary for many patients with juvenile idiopathic arthritis transitioning to young adulthood and registered in the database. Further studies on the medical interventions and support for these patients are needed.

BACKGROUND: This study aimed to clarify the diagnostic and predictive factors for perennial allergic rhinitis (PAR) onset in children by analyzing the results of the Chiba High-risk Birth Cohort for Allergy study, which examined newborns with a family history of allergies. METHODS: Overall, 306 pregnant women were recruited. Their newborns were examined by otolaryngologists and pediatric allergists at 1, 2, and 5 years of age. Participants with clinical and laboratory data available at all consultation points were considered eligible. RESULTS: Among 187 eligible participants, the prevalence rates of PAR were 2.1%, 4.3%, and 24.1% at 1, 2, and 5 years of age, respectively. AR-specific nasal local findings and eosinophils in nasal smear were observed in a substantial number of patients with PAR at 1 and 2 years of age. Factors present up to 2 years of age that were associated with PAR onset at 5 years of age, in descending order, were as follows: sensitization to house dust mites (HDM), nasal eosinophilia, and sensitization to cat dander. In 44 cases with HDM sensitization, nasal eosinophilia up to 2 years of age achieved a sensitivity of 76.0% and a specificity of 73.7% for predicting PAR onset at 5 years. CONCLUSIONS: Rhinitis findings and nasal eosinophilia are useful auxiliary diagnostic items for pediatric PAR. Sensitization to HDM and nasal eosinophilia were the most influential factors associated with future PAR onset. A combination of these factors may facilitate the prediction of PAR onset.

Constipation is common in children and can significantly affect quality of life. Prebiotics are reportedly helpful for constipation in adults, but few studies have examined their use in young children. In this study, the effect of 1-kestose (kestose), which has excellent bifidobacterial growth properties, on constipation in kindergarten children (n = 11) was compared with that of maltose (n = 12) in a randomized, double-blind study. Three grams of kestose per day for 8 weeks did not affect stool properties, but significantly increased the number of defecations per week (Median; 3 → 4 times/week, p = 0.017, effect size = 0.53). A significant decrease in Intestinibacter, a trend toward increased bifidobacteria, and a trend toward decreased Clostridium sensu stricto were observed after kestose ingestion, while concentrations of short-chain fatty acids in stools were unchanged.

BACKGROUND: Early identification of infants at high risk of allergies can improve the efficacy of preventive interventions. However, an established quantifiable risk assessment method in the early postnatal period does not exist. TARC (or CCL17) is a Th2 chemokine used as an activity marker for atopic dermatitis (AD). Therefore, we evaluated the association between cord blood TARC (cTARC) and the development of allergic diseases in childhood. METHODS: This is a high-risk birth cohort for allergy, consisting of children with a family history of allergy. We collected 263 pairs of maternal and child cord blood samples perinatally and child blood samples at ages 1, 2, and 5 years. TARC and allergen-specific immunoglobulin E levels were measured, and the relationship between allergic diseases was analyzed. RESULTS: The median cTARC was 989 pg/mL (interquartile range [IQR]: 667-1430 pg/mL). The cTARC levels in children who developed AD were higher than those in children who did not develop AD, and the association strengthened with younger age (median [IQR] at 1 year: 1285 [816-1965] vs. 933 [662-1330] pg/mL, p < 0.01; at 2 years: 1114 [787-1753] vs. 950 [660-1373] pg/mL, p = 0.02). In the multivariate analysis, cTARC was associated with AD, egg white sensitization, food allergy, allergic rhinitis, and Japanese cedar pollen sensitization. CONCLUSIONS: cTARC was associated with the development of allergic diseases and allergen sensitization in early childhood. These results suggest that, infantile AD-mediated atopic march starts during fetal life, and this immune status is reflected in the cTARC at birth.

Milk cytokines play a vital role in mucosal immunity during infancy by supporting immune development and functions. Although the maternal background characteristics influence milk cytokines, changes in cytokine levels across generations remain unclear. Colostrum (C, n = 48) and mature milk (MM, n = 49) samples were collected from lactating Japanese women in 1989 (2727 samples) and 2013 (1408 samples). Milk cytokines were comprehensively measured using a suspension array and immunosorbent assays. The positive rates and cytokine concentrations were compared between the two generations using logistic and multiple regression analyses. Twenty-eight cytokines tested positive in all sample groups (1989-C, 1989-MM, 2013-C, and 2013-MM). The median osteopontin (OPN) level was significantly higher in the 1989-C group than in the 2013-C group (318.1 vs. 137.5 μg/mL; p = 0.0016) but did not differ between the MM groups. The median TGF-β1 level was significantly lower in the 1989-MM group than in the 2013-MM group (1056.2 vs. 1330.8 pg/mL; p = 0.008) but did not differ between the C groups. Most cytokines were comparable between generations, except for potential variation in the C-OPN and TGF-β1 levels. Milk cytokine secretion may reflect temporal changes in maternal background characteristics; however, the results from the analysis of 30-year-old samples may have influenced the milk cytokine levels. Further studies are needed with a larger number of milk samples collected from the same individuals at multiple time points over a wide lactation period, with detailed data on the maternal and infant background characteristics and diets.

Evidence has accumulated that gut microbiota and its metabolites, in particular the short-chain fatty acid propionate, are significant contributors to the pathogenesis of a variety of diseases. However, little is known regarding its impact on pediatric bronchial asthma, one of the most common allergic diseases in childhood. This study aimed to elucidate whether, and if so how, intestinal propionate during lactation is involved in the development of bronchial asthma. We found that propionate intake through breast milk during the lactation period resulted in a significant reduction of airway inflammation in the offspring in a murine house dust mite-induced asthma model. Moreover, GPR41 was the propionate receptor involved in suppressing this asthmatic phenotype, likely through the upregulation of Toll-like receptors. In translational studies in a human birth cohort, we found that fecal propionate was decreased one month after birth in the group that later developed bronchial asthma. These findings indicate an important role for propionate in regulating immune function to prevent the pathogenesis of bronchial asthma in childhood.

OBJECTIVE: Guillain-Barré syndrome (GBS), Fisher syndrome (FS), and Bickerstaff brainstem encephalitis (BBE) are immune-mediated neuropathies presenting with symptoms such as weakness, ophthalmoplegia, ataxia, and consciousness disturbances. Although the epidemiology of GBS and BBE in patients of all ages has been reported, childhood data have not been well-investigated. We aimed to determine the clinical features, therapeutics, and prognoses of childhood GBS, FS, and BBE in Japan. METHODS: We sent questionnaires to 1068 pediatric neurologists in Japan from 2014 to 2016 to determine the number of children less than 15 years old with GBS, FS, or BBE and their age and sex. We subsequently performed a secondary survey to investigate the clinical features, laboratory data, treatment, and prognosis. RESULTS: Five-hundred thirty-eight pediatric neurology specialists (50.4%) responded to the first survey. The total number of children with GBS, FS, and BBE in Japan from 2014 to 2016 were 87, 10, and 6, respectively. GBS was classified as acute inflammatory demyelinating neuropathy (35.6%), acute motor axonal neuropathy (20.7%), or acute motor-sensory axonal neuropathy (10.3%), with a male-to-female ratio of 1.29:1.0 and a wide distribution of onset ages. The disease severities of GBS, FS, and BBE were variable, but all children could walk within one year. CONCLUSION: The prognoses of childhood GBS, FS, and BBE were generally favorable, as long as the patient was promptly treated with either intravenous immunoglobulin or plasma exchange.

Cardio-facio-cutaneous syndrome (CFC) (OMIM 115150) is a congenital disease caused by constitutive activation of the Raf/MEK/ERK signaling cascade. Unlike aspects of morphological anomalies, metabolic functions related to the disease have garnered little attention. We present severe neuroglycopenic symptoms due to nonketotic hypoglycemia in two children with CFC (Case 1, a 4-year-old male with c.389A > G heterozygous variant in MAP2K1; Case 2, a 3-year-old male with c.770A > G heterozygous variant in BRAF). Case 1 exhibited a nonketotic hypoglycemic coma and clustered left-hemispheric convulsions despite receiving infusion therapy, leading to severe sequelae with choreoathetosis. Brain magnetic resonance imaging of Case 1 showed T2-elongation with restricted diffusion on the bilateral basal ganglia and thalamus, with the dominance of the right putamen. Case 2 presented a prolonged generalized seizure as an initial clinical symptom but fully recovered. The presence of growth hormone and cortisol deficiency was ruled out in both cases. Blood spots acylcarnitine profiles excluded the co-occurrence of mitochondrial HMG-CoA synthase deficiency and HMG-CoA lyase deficiency. These cases demonstrate the potential vulnerability to nonketotic hypoglycemia, especially during lipid shortages. As children with CFC frequently have difficulties feeding, we suggest great attention should be paid to the potential risk of severe nonketotic hypoglycemia.

Background: Eosinophils are major effector cells of allergic disease and excellent markers of eosinophilic inflammation. Accurate and reliable biomarkers are helpful in the diagnosis, treatment, and control of allergic disease. Objective: This study aimed to investigate an alternate marker of eosinophilic inflammation, eosinophil-derived neurotoxin (EDN), in a number of allergic diseases. Methods: Three hundred ninety-six elementary school-age children with various allergic conditions were recruited for this study. Subgroups included food allergies (FAs), atopic dermatitis (AD), bronchial asthma (BA), and allergic rhinitis (AR). EDN levels in these groups were compared to those in 93 healthy controls (HC). Results: All subjects with allergic disease had elevated levels of serum EDN (median [interquartile range]: FA, 124.2 ng/mL [59.13-160.5 ng/mL]; AD, 110.8 ng/mL [57.52-167.9 ng/mL]; BA, 131.5 ng/mL [60.60-171.0 ng/mL]; AR, 91.32 ng/mL [46.16-145.0 ng/mL]) compared to HC (38.38 ng/mL [32.40-55.62 ng/mL]) (p < 0.0001). These elevated levels were consistent throughout the age range (6-12 years) of the healthy study subjects (p = 0.0679). EDN levels also correlated well with total immunoglobulin E (Rs = 0.5599, p < 0.0001). Looking at all individuals with an allergic disease, the area under the curve was 0.790. Conclusions: Direct measures of eosinophilic inflammation are needed for accurate diagnosis, treatment, and monitoring of allergic diseases. EDN may be a worthy biomarker of eosinophil activity and a useful screening tool for allergic diseases including FA, AD, BA, and AR.

Existing evidence on the correlation between maternal vitamin D concentrations and birth outcomes is conflicting. Investigation of these associations requires accurate assessment of vitamin D status, especially in individuals with low 25-hydroxyvitamin D (25(OH)D) concentrations. This study examined the correlations between birth outcomes and the maternal vitamin D metabolite ratio (VMR) 1 (defined as the ratio of 24,25(OH)2D3 to 25(OH)D) and VMR2 (defined as the ratio of 3-epi-25(OH)D3 to 25(OH)D) using data from the Japan Environment and Children's Study at Chiba Regional Center. A total of 297 mother-neonate pairs were analyzed. Using liquid chromatography-tandem mass spectrometry, we measured 25(OH)D2, 25(OH)D3, 24,25(OH)2D3, and 3-epi-25(OH)D3 concentrations in maternal serum samples. These data were analyzed in relation to birth anthropometric data using multivariable linear regression. Of the study participants, 85.2% showed insufficient vitamin D concentrations. VMR1 was strongly correlated with 25(OH)D concentrations, whereas VMR2 showed a weak correlation. Only VMR2 was associated with all anthropometric data. VMR2 in pregnant women with low vitamin D blood concentrations is a useful marker for neonatal anthropometric data and is independent of 25(OH)D. Accurate measurement of vitamin D metabolites could help better understand the effects of vitamin D on birth outcomes.

小児に対して、漢方医学に基づいた診断(証)も含めての効果検証は少ない。我々は現代医学での治療に抵抗性のあり、慢性化した小児に対して、漢方治療を専門に行う医師が処方した漢方薬併用療法の効果の後ろ向き観察研究をした。過去10年間に千葉大学医学部附属病院和漢診療科を受診した小児98(未就学児(PS)21、小学生(ES)37、中学生(JS)40)人に対して、診療録から患者背景、主訴、紹介元の科、漢方薬の有効性を検討した。効果判定は症状の変化から分類した。75人(76%)に症状の改善を認め、悪化は無かった。PSは皮膚疾患、ESは消化器疾患、JSは循環器疾患の主訴が多かった。全群で小児科からの紹介が多く、JSの3割は精神科からの紹介だった。PS・ESはJSに比べ有意に効果を認めた(p=0.025)。現代医学に治療抵抗性がある小児に対する証も含めた漢方薬併用は有用であった。(著者抄録)

小児に対して、漢方医学に基づいた診断(証)も含めての効果検証は少ない。我々は現代医学での治療に抵抗性のあり、慢性化した小児に対して、漢方治療を専門に行う医師が処方した漢方薬併用療法の効果の後ろ向き観察研究をした。過去10年間に千葉大学医学部附属病院和漢診療科を受診した小児98(未就学児(PS)21、小学生(ES)37、中学生(JS)40)人に対して、診療録から患者背景、主訴、紹介元の科、漢方薬の有効性を検討した。効果判定は症状の変化から分類した。75人(76%)に症状の改善を認め、悪化は無かった。PSは皮膚疾患、ESは消化器疾患、JSは循環器疾患の主訴が多かった。全群で小児科からの紹介が多く、JSの3割は精神科からの紹介だった。PS・ESはJSに比べ有意に効果を認めた(p=0.025)。現代医学に治療抵抗性がある小児に対する証も含めた漢方薬併用は有用であった。(著者抄録)

Behçet's disease (BD) is often associated with neutrophilic dermatosis. However, BD is rarely associated with aseptic abscesses in the spleen or liver. A 2-year-old girl presented to our hospital with a two-week history of fever, abdominal pain, and a skin ulcer on her leg. Each time her skin was punctured with a needle for a blood test or spinal fluid test, she developed intractable aseptic abscesses on her skin. She was diagnosed with intestinal BD based on gastrointestinal endoscopy findings and was treated with prednisolone, mesalazine, and elemental diet therapy. Although these were effective for her colon ulcers, low-grade fever and mild abdominal pain persisted. Abdominal computed tomography revealed a low-density area in the spleen. Although it is recommended to check the contents with puncture drainage, it was difficult due to the risk of bleeding and pathergy. The abscess expanded despite antimicrobial therapy. We discontinued antimicrobial therapy and switched to intensified immunosuppressive therapy for BD (intravenous infliximab [IFX]). After administration of IFX, the splenic abscess gradually disappeared, and all her symptoms improved. In cases of BD with splenic abscesses resistant to antimicrobial therapy, intensifying immunosuppressive therapy can be expected to shrink the abscesses and avoid splenectomy.

Hematological malignancy and solid tumor are major risks for invasive pneumococcal disease. Thirteen-valent pneumococcal conjugate vaccine (PCV13) is recommended for immunocompromised patients aged 6 years and older and adults who had not received the vaccine previously. However, vaccination for these individuals is not publicly subsidized in Japan. We measured pneumococcal serotype-specific IgGs (Pn-IgGs) and opsonophagocytic activities (Pn-OPAs) against PCV13 serotypes (1, 3, 5, 6A, 7F, and 19A) in patients with hematological malignancies and solid tumors who were outside the recommended age range for routine vaccination at baseline and at 1 and 6 months after the first dose of PCV13. Pneumococcal serotype-specific memory B cells (Pn-MBCs) against serotype 3 were measured from a portion of the study samples. Thirty-seven patients (30 in the young patient group and 7 in the adult patient group) completed the study. Pn-IgGs were significantly elevated at 1 month post-vaccination and persisted in protection level for 6 months after the first vaccination against all six serotypes measured except serotype 3. Pn-OPAs were significantly elevated and persisted as well against all six serotypes. Pn-MBCs were measured in 10 patients, and 90% of them had at least one detectable Pn-MBC, and 70% of them showed an increased frequency of Pn-MBCs against serotype 3. No serious adverse events were observed up to 1 month after vaccination. PCV13 is thus safe and immunogenic, including against serotype 3, in patients with hematological malignancies and solid tumors outside the recommended age range for routine vaccination.

Cryopyrin-associated periodic syndrome (CAPS) is a rare inherited autoinflammatory disease caused by gain-of-function mutations in the NLRP3 gene, with a genotype-phenotype correlation. The clinical presentation of each mutation has been previously studied. However, very few studies have reported on the clinical characteristics and treatment effectiveness across different generations within a family with the same mutation. A detailed investigation of family members of patients with CAPS may help in the appropriate diagnosis and treatment of undiagnosed CAPS. Herein, we report a 2-year-old boy (proband), his father, and his grandmother who presented with several symptoms of CAPS, such as persistently positive inflammatory reactions and hearing impairment. All three patients had the same pathogenic mutation in the NLRP3 gene (c.1049C>T (p.Thr350Met) heterozygous mutation) and were diagnosed with CAPS. With canakinumab treatment, the laboratory data of all three patients improved, the proband and father's skin rash disappeared, and his grandmother's arthropathy improved. The proband's hearing also showed slight improvement, but not in his father or grandmother. Among the various non-specific symptoms associated with CAPS, chronic ocular hyperemia is a finding that can be easily identified by non-ophthalmologists. Diagnosis of CAPS should be considered when eye symptoms are present in a combination of hyperinflammatory response, arthropathy, or skin symptoms. Thorough family history records, physical examinations, and close collaboration between pediatricians and adult rheumatologists are important for prompt diagnosis and appropriate treatment of inherited autoinflammatory diseases.

【はじめに】日本小児アレルギー学会は,小児アレルギー学を学び続けたいと考える学会員に対し支援を行うことを目的にワーキンググループを設立した.今回,現状把握を目的に学会員を対象にアンケート調査を行った.【結果】回答数は668人(男/女353/315)で,アレルギー専門医資格を340人(54.8%)の医師が取得(男/女56.6/52.5%)していた.勤務形態は常勤医が男性93.5%,女性77.3%であった.仕事の中断を男性の11.0%,女性の75.6%が経験していた.男女ともキャリア形成のために専門分野の研鑽が最も重要と回答した.学会のさらなるダイバーシティ推進が必要と回答したのは男性の85.6%,女性の92.1%であった.自由記載では,子育て中のキャリア継続や復職支援を求める声がある一方,「キャリア支援=女性支援」と捉えることへの反対意見もあった.【結論】本学会が考えるキャリア支援は性別にとどまらない支援であることを学会員と共有し,学会員の多様な立場や価値観を踏まえた支援を行なっていく.(著者抄録)

<title>Abstract</title>Maternal tobacco smoke exposure during pregnancy impairs fetal body size, including head circumference (HC) at birth; however, the mechanism still remains unclear. This analysis using a large prospective cohort study evaluated the impact of maternal tobacco exposure on their offspring’s HC and the relationship with placental weight ratio (PWR) and placental abnormalities. Parents-children pairs (n = 84,856) were included from the 104,065 records of the Japan Environmental and Children’s Study. Maternal perinatal clinical and social information by self-administered questionnaires, offspring’s body size, and placental information were collected. Data were analyzed with binominal logistic regression analysis and path analysis. Logistic regression showed significantly elevated adjusted odds ratio (aOR) (1.653, 95% CI 1.387–1.969) for the impact of maternal smoking during pregnancy on their offspring’s smaller HC at birth. Maternal exposure to environmental tobacco smoke in the non-smoking group did not increase aOR for the smaller HC. Path analysis showed that maternal smoking during pregnancy decreased the offspring’s HC directly, but not indirectly via PWR or placental abnormalities. The quitting smoking during pregnancy group did not increase aOR for the smaller HC than the non-smoking group, suggesting that quitting smoking may reduce their offspring’s neurological impairment even after pregnancy.

Patients with asplenia are at high risks of severe infections caused by encapsulated bacteria, particularly Streptococcus pneumoniae. Thirteen-valent pneumococcal conjugate vaccine (PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPSV23) are recommended for invasive pneumococcal disease prevention; however, little is known about the immunity to pneumococci in young patients with asplenia. We measured pneumococcal serotype-specific IgG (Pn-IgG) levels and pneumococcal opsonophagocytic activity (Pn-OPA) against some PCV13-contained serotypes (1, 3, 5, 6A, 7 F, 19A) in 23 young patients with asplenia using surplus serum samples. In this study, 5 and 13 patients had received PCV13 during routine immunizations and PPSV23, respectively; however, >5 years had passed since the last dose in most cases. The geometric mean concentrations (GMCs) of Pn-IgG in all study patients were not under the cutoff level against six serotypes, but they were lower than the those of age-matched healthy controls, as we have previously published. The patients who had received only PPSV23 had significantly lower GMCs against four serotypes (serotypes 1, 6A, 7 F, and 19A) than that of the patients who had received at least one PCV13 vaccination. The patients who had received only PPSV23 also had significantly lower geometric mean titers (GMTs) of Pn-OPA against all three serotypes we measured (serotypes 3, 5, and 19A) than that of the patients who had received at least one PCV13 vaccination. Our findings are useful data that can indicate insufficient immunity in young patients with asplenia against some PCV13 pneumococci serotypes and suggest the need for appropriate vaccinations in the post-PCV13 era.

Chemokine (C-C motif) ligand 17 (CCL17) is a pro-allergic factor: high CCL17 levels in cord blood (CB) precede later allergic predisposition. Short-chain fatty acid (SCFA) treatment during pregnancy has been shown to protect mouse pups against allergic diseases. The maternal microbial metabolome during pregnancy may affect fetal allergic immune responses. We therefore examined the associations between CB CCL17 and gut SCFA levels in healthy pregnant Japanese women. CB CCL17 serum levels at birth, and maternal non-specific IgE levels in maternal sera at 32 weeks of gestation were measured. Maternal stool samples were collected at 12 (n = 59) and 32 (n = 58) weeks of gestation for gut microbiota analysis, based on barcoded 16S rRNA sequencing and metabolite levels. The CB CCL17 levels correlated negatively with butyrate concentrations and positively with isobutyrate at 12 weeks; CB CCL17 correlated positively with valerate and lactate at 32 weeks. Similarly, butyrate levels correlated negatively with maternal non-specific IgE levels, whereas the lactate concentration correlated positively with IgE levels. At 32 weeks, the Shannon diversity index (SDI) of Firmicutes and Proteobacteria correlated negatively with CB CCL17 levels, while those of the total microbiota correlated positively with the CB CCL17 levels. These metabolites may alter fetal immune responses. This study provides the first link between maternal metabolites during pregnancy and the risk of allergic diseases in human offspring.

In the present study, we report a human-inherited, impaired, adaptive immunity disorder, which predominantly manifested as a B cell differentiation defect, caused by a heterozygous IKZF3 missense variant, resulting in a glycine-to-arginine replacement within the DNA-binding domain of the encoded AIOLOS protein. Using mice that bear the corresponding variant and recapitulate the B and T cell phenotypes, we show that the mutant AIOLOS homodimers and AIOLOS-IKAROS heterodimers did not bind the canonical AIOLOS-IKAROS DNA sequence. In addition, homodimers and heterodimers containing one mutant AIOLOS bound to genomic regions lacking both canonical motifs. However, the removal of the dimerization capacity from mutant AIOLOS restored B cell development. Hence, the adaptive immunity defect is caused by the AIOLOS variant hijacking IKAROS function. Heterodimeric interference is a new mechanism of autosomal dominance that causes inborn errors of immunity by impairing protein function via the mutation of its heterodimeric partner.

Breastfeeding influences the immune system development in infants and may even affect various immunological responses later in life. Breast milk provides a rich source of early nutrition for infant growth and development. However, the presence of certain compounds in breast milk, related to an unhealthy lifestyle or the diet of lactating mothers, may negatively impact infants. Based on a cohort study of atopic dermatitis (AD), we find the presence of damage-associated molecular patterns (DAMPs) activity in the mother's milk. By non-targeted metabolomic analysis, we identify the long-chain saturated fatty acids (LCSFA) as a biomarker DAMPs (+) breast milk samples. Similarly, a mouse model in which breastfed offspring are fed milk high in LCSFA show AD onset later in life. We prove that LCSFA are a type of damage-associated molecular patterns, which initiate a series of inflammatory events in the gut involving type 3 innate lymphoid cells (ILC3s). A remarkable increase in inflammatory ILC3s is observed in the gut, and the migration of these ILC3s to the skin may be potential triggers of AD. Gene expression analysis of ILC3s isolated from the gut reveal upregulation of genes that increase ILC3s and chemokines/chemokine receptors, which may play a role in ILC migration to the skin. Even in the absence of adaptive immunity, Rag1 knockout mice fed a high-LCSFA milk diet develop eczema, accompanied by increased gut ILC3s. We also present that gut microbiota of AD-prone PA milk-fed mice is different from non-AD OA/ND milk-fed mice. Here, we propose that early exposure to LCSFAs in infants may affect the balance of intestinal innate immunity, inducing a highly inflammatory environment with the proliferation of ILC3s and production of interleukin-17 and interleukin-22, these factors may be potential triggers or worsening factors of AD.