Many studies reported the influence of infants' gut microbiota on atopic dermatitis (AD) postnatally, yet the role of maternal gut microbiota and plasma metabolites in infants’ AD remains largely unexplored. Sixty-three pregnant mother-infants were enrolled and followed after childbirth in Guangzhou, China. Demographic information, maternal stool and plasma samples, and records for infants’ AD were collected. Maternal gut microbiota/metabolome and plasma metabolome were profiled using shotgun metagenomics and non-targeted metabolomics. Logistic regression and multi-omics analysis were used to explore characteristic maternal gut microbiota in the AD and health groups. The α-diversity of maternal gut microbiota in health group was significantly higher than AD group (Shannon diversity P = 0.02, Simpson diversity P = 0.04). Short-chain fatty acids (SCFAs) producing microorganisms, including Faecalibacterium, Roseburia, Butyricicoccus, and Ruminococcus, as well as the abundance of phenylalanine, tyrosine, and tryptophan biosynthesis pathway, were enriched in health group (LDA>2 and P < 0.05). Virulent factors (VFs) involved in immune modulation were enriched in the health group, while VFs involving in adhesin were enriched in the AD group (P < 0.05). Metabolomic analysis showed that a polyunsaturated fatty acid/linoleic acid, 13S-hydroxyoctadecadienoic, were negatively associated with AD in both the gut and plasma samples (FDR<0.05). Several other linoleic acids and flavonoids were negatively associated with AD (FDR<0.05). Neural network analysis revealed that microorganisms enriched in health group may produce these protective fatty acids. Our findings show that maternal gut microorganisms/metabolites and plasma metabolites during pregnancy impact subsequent pathogenesis of infants AD. This illuminates new strategies against early AD in offspring.

Background: The role of the indoor microbiome in sick building syndrome (SBS) is well-recognized, yet prior studies have been limited to single-center analyses, limiting a broader understanding and applicability of their findings. Methods: We conducted a multicenter indoor microbiome and metabolome investigation for SBS, involving 1139 middle school students across three regions in Malaysia (Johor Bahru, Terengganu, and Penang). Using high-throughput amplicon sequencing and untargeted LC-MS, indoor microbiome and metabolites were characterized from classroom dust samples. Results: The study found that the prevalence of SBS symptoms was high across all three centers (51.0% to 54.6%). Environmental characteristics, including indoor NO₂ and CO₂ concentrations and total weight of indoor dust, were positively associated with SBS (p < 0.01, linear regression). Curtobacterium in Terengganu was negatively associated with SBS, and Clostridium perfringens in Johor Bahru was positively associated with SBS (p < 0.01, FDR < 0.05). Whereas all identified fungal taxa, including an uncharacterized uc_f_Auriculariaceae_sp., Duportella kuehneroides, and Wallemia mellicola, were positively associated with SBS (p < 0.01, FDR < 0.05) in Johor Bahru and Terengganu. Mediation analysis revealed that the adverse health effects of NO₂ on SBS were partially mediated by the increased abundance of uc_f_Auriculariaceae_sp. (p < 0.05, total effect mediated 51.40%). Additionally, potential protective metabolites (S-adenosylmethionine, N-acetylserotonin, sphinganine, 4-hydroxy-2-quinolone, and (2E,4Z,8E)-Colneleic acid) were mainly derived from environmental microorganisms, conferring protective effects against nasal symptoms and tiredness. In contrast, synthetic chemicals were associated with higher SBS symptoms, inducing eye and nasal symptoms. Conclusions: This study emphasizes both the significance of fostering a balanced indoor microbiome/metabolite and the necessity to reduce exposure to deleterious substances, providing new insights for future targeted intervention strategies.

Nocardia, a rare but life-threatening pathogen, can invade multiple tissues and organs, such as lungs, brain, skin and soft tissue. In this study, we determined whether nitric oxide (NO) contributes to the severity of experimental pulmonary nocardiosis. BALB/c mice with or without aminoguanidine (AG) treatment were infected with N. farcinica through intranasal or intraperitoneal routes. Over experimental period, weight and mortality were monitored, and lung tissues were collected for NO production, cytokines detection, histopathological analysis, and bacterial load assessment. Next, alveolar MH-S macrophages were treated with various inhibitors to explore the impacts of NO, MAPK, and NF-κB against N. farcinica infection. AG treatment improved weight loss, lowered pulmonary bacterial load, and attenuated inflammatory response in infected mice. Similar effects were observed in alveolar MH-S macrophages. And all AG-treated mice survived infection. Furthermore, we suggest that NO is induced by N. farcinica through MAPK JNK and NF-κB signaling. Our study demonstrates the causative role of inducible NO on the severity of N. farcinica infection.

Nocardia, an easily missed but potentially fatal opportunistic pathogen, can lead to serious infections like lung and brain abscesses. Intranasal inoculation (IN) is the traditional approach for constructing a Nocardia-induced pneumonia mice model, while it usually only results in limited local bacterial infection in the lungs. To comprehensively assess infection dynamics across distinct pulmonary inoculation routes in mice models, this study compared the pathogenicity of three different Nocardia farcinica pneumonia models established via IN, intratracheal aerosolization (ITA), and intratracheal instillation (ITI). C57BL/6J mice were infected with N. farcinica through IN, ITA and ITI with comparative analyses of bacterial distribution in lungs, survival rate, weight, bacterial load, inflammatory cytokines, histopathological characteristics and transcriptome differences. The findings suggest that ITA N. farcinica infections caused severer clinical symptoms, higher mortality, pulmonary bacterial load, levels of inflammatory cytokines in bronchoalveolar lavage fluid, and more significant histopathological damage to lungs than IN and ITI. Furthermore, ITA resulted in better lung bacterial distribution and delivery efficiency than ITI and IN. Transcriptome analysis of lungs from N. farcinica infected mice via IN, ITA and ITI revealed significant differential gene expression, whereas ITA route resulted in a larger fold change. ITA provides a more consistent and severe model of N. farcinica pneumonia in mice than IN and ITI, which can make the bacteria more evenly distributed in the lungs, leading to more severe pathological damage and higher mortality rates. In conclusion, ITA is an optimal route for developing animal models of N. farcinica pneumonia infections.