Takumi Tochio

Feline atopic skin syndrome (FASS) is a chronic inflammatory skin disease characterized by itching and dermatitis. While the relationship between the gut microbiota and atopic dermatitis (AD) has been highlighted, exploring gut-targeted therapies for FASS remain limited. This study aimed to evaluate the effects of a parasynbiotic containing 1-kestose and heat-killed Lactobacillus plantarum FM8 on clinical symptoms and gut microbiota in cats with FASS. Eleven FASS cats were treated with a parasynbiotic containing 1-kestose (400 mg/day) and heat-killed FM8 (2.0 × 1010 CFU/day) for 8 weeks. Clinical symptoms were assessed using the SCORing Feline Allergic Dermatitis (SCORFAD), investigator pruritus score (IPS), and rating of global assessment of improvement (GAI). Fecal microbiota composition was analyzed through 16S rRNA sequencing, with 16 healthy cats serving as controls. Parasynbiotic intervention significantly reduced SCORFAD and IPS scores. GAI scores improved in 10 of 11 cats, with the most severe case maintaining a score of 3. The β-diversity analysis showed no significant differences; however, a trend toward variation was observed between the healthy control cats and the baseline group of FASS cats, as well as between the healthy control cats and post- intervention groups. The abundance of Collinsella stercoris was significantly higher in FASS cats than in healthy controls, and it significantly decreased after parasynbiotic intervention, suggesting potential improvements in gut health and inflammation. This study is the first to demonstrate the potential benefits of parasynbiotic administration in FASS, showing improvements in clinical symptoms and partial modulation of the gut microbiota. These findings highlight parasynbiotic administration as a compelling therapeutic approach for FASS, offering new possibilities for innovative interventions aimed at the gut–skin axis.

As the global population continues to grow, so too does the demand for poultry meat. However, the concurrent increase in the prevalence of drug-resistant bacteria has stimulated interest in the search for alternatives to antibiotics in poultry and livestock agriculture. One potential strategy is the use of probiotics. In this study, we showed that prophylactic oral administration of Limosilactobacillus ingluviei C37 (LIC37) reduced Campylobacter jejuni colonization of the cecum in cage-raised chicks, without causing significant changes in the overall diversity of gut bacteria. Further, the abundance of Blautia, another genus of probiotic bacteria, increased in the gastrointestinal tract following ingestion of LIC37 by chicks. These findings suggest that LIC37 could potentially be used as a novel probiotic agent against C. jejuni in livestock production.

Recent studies have linked Ruminococcus gnavus to inflammatory bowel disease and Fusobacterium nucleatum to various cancers. Agarooligosaccharides (AOS), derived from the acid hydrolysis of agar, have shown significant inhibitory effects on the growth of R. gnavus and F. nucleatum at concentrations of 0.1 and 0.2%, respectively. RNA sequencing and quantitative reverse-transcription PCR analyses revealed the downregulation of fatty acid biosynthesis genes (fab genes) in these bacteria when exposed to 0.1% AOS. Furthermore, AOS treatment altered the fatty acid composition of R. gnavus cell membranes, increasing medium-chain saturated fatty acids (C8, C10) and C18 fatty acids while reducing long-chain fatty acids (C14, C16). In contrast, no significant growth inhibition was observed in several strains of Bifidobacteria and Lactobacillales at AOS concentrations of 0.2 and 2%, respectively. Co-culture experiments with R. gnavus and Bifidobacterium longum in 0.2% AOS resulted in B. longum dominating the population, constituting over 96% post-incubation. In vivo studies using mice demonstrated a significant reduction in the Lachnospiraceae family, to which R. gnavus belongs, following AOS administration. Quantitative PCR also showed lower levels of the nan gene, potentially associated with immune disorders, in the AOS group. These findings suggest that AOS may introduce a novel concept in prebiotics by selectively inhibiting potentially pathogenic bacteria while preserving beneficial bacteria such as Bifidobacteria and Lactobacillales.

Aim: This study aimed to establish a non-invasive, rapid, and cost-effective method to assess the potential risk of immune and psychiatric disorders by quantifying nan gene levels in gut microbiota, specifically focusing on Ruminococcus gnavus and other Lachnospiraceae species associated with mucin degradation. Methodology: We first designed a primer set targeting the consensus sequence of the nanA gene, which is highly conserved within nan gene clusters. To validate this primer set, we performed Next-Generation Sequencing (NGS) on the PCR-amplified fragments. To explore the association between nan levels and immune or psychiatric disorders, we conducted qPCR to quantify nan levels in the intestines, analyzing intestinal DNA from both allergy-induced mice with or without fructan treatment, and dogs with or without aggressive behavior. Additionally, to assess whether nan levels reflect the clinical status of immune disorders, fecal samples were collected from 45 patients with ulcerative colitis (UC) and analyzed for nan levels. Results: NGS analysis of DNA fragments amplified from various intestinal samples using the nan primer set confirmed the presence of nanA sequences from R. gnavus and other members of the Lachnospiraceae family, including Blautia and Dorea species. The qPCR quantification of nan levels using this primer set revealed that allergy-induced mice treated with fructans, which are known to be associated with lower allergy scores compared to untreated mice, exhibited significantly reduced nan levels. Additionally, the nan levels of aggressive dogs were substantially higher than those of non-aggressive dogs. Notably, nan levels were also substantially elevated in patients with UC in comparison to the healthy control individuals. Conclusion: qPCR-based measurement of nan levels in gut microbiota shows potential for selectively detecting pathogenic nan-harboring strains and may reflect the clinical status of immune and psychiatric disorders. This approach could provide a non-invasive, rapid, and cost-effective method for assessing the risk of these disorders.