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Background: Nasopharyngeal Bordetella pertussis (BP) colonization is common, with about 5% of individuals having PCR evidence of subclinical BP infection on nasal swab, even in countries with high vaccination rates. BP secretes pertussis toxin (PTx). PTx is an adjuvant commonly used to induce autoimmunity in multiple animal models of human disease. Colocalization of PTx and myelin from myelinated nerves in the nasopharynx may lead to host sensitization to myelin with subsequent autoimmune pathology. Methods: C57BL/6J female adult mice were given varied doses and schedules of intranasal PTx, MOG35-55 antigen, or controls to test whether intranasal administration of PTx and myelin oligodendrocyte peptide (MOG35-55) could induce experimental autoimmune encephalomyelitis (EAE) in mice. While we observed systemic cell-mediated immunity against MOG35-55, we did not observe EAE. Unexpectedly, many mice developed alopecia. We systematically investigated this finding. Results: Patchy alopecia developed in 36.4% of mice with the optimized protocol. Pathology consistent with alopecia areata was confirmed histologically by documenting concomitant reduced anagen phase and increased telogen phase hair follicles (HFs) in biopsies from patches of hair loss in mice with alopecia. We also found reduced CD200 staining and increased CD3+T cells surrounding the HFs of mice with alopecia compared to the mice without alopecia, indicating HF Immune Privilege (HFIP) collapse. Systemic immune responses were also found, with increased proportions of activated T cells and B cells, as well as MHCII+ dendritic cells in peripheral blood and/or splenocytes. Finally, in mice initially exposed to intranasal MOG35-55 and PTx in combination, but not to either agent alone, splenocytes were shown to proliferate after in vitro stimulation by MOG35-55. Consistent with prior investigations, PTx exhibited a dose-response effect on immune cell induction and phenotype, with the lowest PTx dose failing to induce autoimmunity, the highest PTx dose suppressing autoimmunity, and intermediate doses optimizing autoimmunity. Conclusions: We propose that this is the first report of an autoimmune disease in an animal model triggered by colocalization of intranasal PTx and autoantigen. This model parallels a natural exposure and potential intranasal sensitization-topathology paradigm and supports the plausibility that nasopharyngeal subclinical BP colonization is a cause of alopecia areata. [ABSTRACT FROM AUTHOR]

Treg deficiency causes a lethal, CD4+ T cell-driven autoimmune disease called IPEX syndrome (immunodysregulation, polyendocrinopathy, and enteropathy, with X-linked inheritance) in humans and in the scurfy (SF) mouse, a mouse model of the disease. Feeding Limosilactobacillus reuteri DSM 17938 (LR 17938, LR) to SF mice reprograms the gut microbiota, reduces disease progression, and prolongs lifespan. However, the efficacy and mechanism of LR, compared with other probiotics, in producing these effects is unknown. We compared LR with Lacticaseibacillus rhamnosus GG (LGG), an extensively investigated probiotic. LR was more effective than LGG in prolonging survival. Both probiotics restored the fecal microbial alpha diversity, but they produced distinct fecal bacterial clusters and differentially modulated microbial relative abundance (RA). LR increased the RA of phylum_Firmicutes, genus_Oscillospira whereas LR reduced phylum_Bacteroidetes, genus_Bacteroides and genus_Parabacteroides, reversing changes attributed to the SF phenotype. LGG primarily reduced the RA of genus_Bacteroides. Both LR and LGG reduced the potentially pathogenic taxon class_cproteobacteria. Plasma metabolomics revealed substantial differences among 696 metabolites. We observed similar changes of many clusters of metabolites in SF mice associated with treatment with either LR or LGG. However, a unique effect of LR was to increase the abundance of plasma adenosine metabolites such as inosine, which we previously showed had immune modulatory effects. In conclusion: 1) different probiotics produce distinct signatures in the fecal microbial community in mice with Treg deficiency; and 2) when comparing different probiotics, there are strain-specific microbial products with different anti-inflammatory properties, reinforcing the concept that “one size does not fit all” in the treatment of autoimmune disease. [ABSTRACT FROM AUTHOR]

Early administration of Lactobacillus reuteri DSM 17938 (LR) prevents necrotizing enterocolitis and inhibits regulatory T-cell (Treg)-deficiency-associated autoimmunity in mice. In humans, LR reduces crying time in breastfed infants with colic, modifies severity in infants with acute diarrheal illnesses, and improves pain in children with functional bowel disorders. In healthy breastfed newborns with evolving microbial colonization, it is unclear if early administration of LR can modulate gut microbiota and their metabolites in such a way as to promote homeostasis. We gavaged LR (107 colony-forming units/day, daily) to C57BL/6J mice at age of day 8 for 2 wk. Both male and female mice were investigated in these experiments. We found that feeding LR did not affect clinical phenotype or inflammatory biomarkers in plasma and stool, but LR increased the proportion of Foxp3+ regulatory T cells (Tregs) in the intestine. LR also increased bacterial diversity and the relative abundance of p_Firmicutes, f_Lachnospiraceae, f_Ruminococcaceae, and genera Clostridium and Candidatus arthromitus, while decreasing the relative abundance of p_Bacteriodetes, f_Bacteroidaceae, f_Verrucomicrobiaceae, and genera Bacteroides, Ruminococcus, Akkermansia, and Sutterella. Finally, LR exerted a major impact on the plasma metabolome, upregulating amino acid metabolites formed via the urea, tricarboxylic acid, and methionine cycles and increasing tryptophan metabolism. In conclusion, early oral administration of LR to healthy breastfed mice led to microbial and metabolic changes which could be beneficial to general health. [ABSTRACT FROM AUTHOR]

Background: Nasopharyngeal Bordetella pertussis (BP) colonization is common, with about 5% of individuals having PCR evidence of subclinical BP infection on nasal swab, even in countries with high vaccination rates. BP secretes pertussis toxin (PTx). PTx is an adjuvant commonly used to induce autoimmunity in multiple animal models of human disease. Colocalization of PTx and myelin from myelinated nerves in the nasopharynx may lead to host sensitization to myelin with subsequent autoimmune pathology., Methods: C57BL/6J female adult mice were given varied doses and schedules of intranasal PTx, MOG 35-55 antigen, or controls to test whether intranasal administration of PTx and myelin oligodendrocyte peptide (MOG 35-55 ) could induce experimental autoimmune encephalomyelitis (EAE) in mice. While we observed systemic cell-mediated immunity against MOG 35-55 , we did not observe EAE. Unexpectedly, many mice developed alopecia. We systematically investigated this finding., Results: Patchy alopecia developed in 36.4% of mice with the optimized protocol. Pathology consistent with alopecia areata was confirmed histologically by documenting concomitant reduced anagen phase and increased telogen phase hair follicles (HFs) in biopsies from patches of hair loss in mice with alopecia. We also found reduced CD200 staining and increased CD3 + T cells surrounding the HFs of mice with alopecia compared to the mice without alopecia, indicating HF Immune Privilege (HFIP) collapse. Systemic immune responses were also found, with increased proportions of activated T cells and B cells, as well as MHCII + dendritic cells in peripheral blood and/or splenocytes. Finally, in mice initially exposed to intranasal MOG 35-55 and PTx in combination, but not to either agent alone, splenocytes were shown to proliferate after in vitro stimulation by MOG 35-55. Consistent with prior investigations, PTx exhibited a dose-response effect on immune cell induction and phenotype, with the lowest PTx dose failing to induce autoimmunity, the highest PTx dose suppressing autoimmunity, and intermediate doses optimizing autoimmunity., Conclusions: We propose that this is the first report of an autoimmune disease in an animal model triggered by colocalization of intranasal PTx and autoantigen. This model parallels a natural exposure and potential intranasal sensitization-to-pathology paradigm and supports the plausibility that nasopharyngeal subclinical BP colonization is a cause of alopecia areata., Competing Interests: KR and SG are employed by ILiAD Biotechnologies LLC, which is developing a vaccine for the prevention of Bordetella pertussis infection. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Author YL declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision. The authors declare that this study received funding from ILiAD Biotechnologies LLC (P00427002 to JR). The funder had the following involvement in the study: the study design and the writing of this article (review and edit)., (Copyright © 2024 Liu, Freeborn, Okeugo, Armbrister, Saleh, Fadhel Alvarez, Hoang, Park, Lindsey, Rapini, Glazer, Rubin and Rhoads.)

Treg deficiency causes a lethal, CD4 + T cell-driven autoimmune disease called IPEX syndrome (immunodysregulation, polyendocrinopathy, and enteropathy, with X-linked inheritance) in humans and in the scurfy (SF) mouse, a mouse model of the disease. Feeding Limosilactobacillus reuteri DSM 17938 (LR 17938, LR) to SF mice reprograms the gut microbiota, reduces disease progression, and prolongs lifespan. However, the efficacy and mechanism of LR, compared with other probiotics, in producing these effects is unknown. We compared LR with Lacticaseibacillus rhamnosus GG (LGG), an extensively investigated probiotic. LR was more effective than LGG in prolonging survival. Both probiotics restored the fecal microbial alpha diversity, but they produced distinct fecal bacterial clusters and differentially modulated microbial relative abundance (RA). LR increased the RA of phylum_Firmicutes, genus_Oscillospira whereas LR reduced phylum_Bacteroidetes, genus_Bacteroides and genus_Parabacteroides , reversing changes attributed to the SF phenotype. LGG primarily reduced the RA of genus_Bacteroides . Both LR and LGG reduced the potentially pathogenic taxon class_γ-proteobacteria . Plasma metabolomics revealed substantial differences among 696 metabolites. We observed similar changes of many clusters of metabolites in SF mice associated with treatment with either LR or LGG. However, a unique effect of LR was to increase the abundance of plasma adenosine metabolites such as inosine, which we previously showed had immune modulatory effects. In conclusion: 1 ) different probiotics produce distinct signatures in the fecal microbial community in mice with Treg deficiency; and 2 ) when comparing different probiotics, there are strain-specific microbial products with different anti-inflammatory properties, reinforcing the concept that "one size does not fit all" in the treatment of autoimmune disease. NEW & NOTEWORTHY In the treatment of Treg-deficiency-induced autoimmunity, Limosilactobacillus reuteri DSM 17938 (LR) showed greater efficacy than Lacticaseibacillus rhamnosus GG (LGG). The study demonstrated that two different probiotics produce distinct signatures in the fecal microbial community in mice with Treg deficiency, but with many similarities in global plasma metabolites in general. However, there are strain-specific microbial products with different anti-inflammatory properties, reinforcing the concept that "one size does not fit all" in the treatment of autoimmune disease.

Early administration of Lactobacillus reuteri DSM 17938 (LR) prevents necrotizing enterocolitis and inhibits regulatory T-cell (Treg)-deficiency-associated autoimmunity in mice. In humans, LR reduces crying time in breastfed infants with colic, modifies severity in infants with acute diarrheal illnesses, and improves pain in children with functional bowel disorders. In healthy breastfed newborns with evolving microbial colonization, it is unclear if early administration of LR can modulate gut microbiota and their metabolites in such a way as to promote homeostasis. We gavaged LR (10 7 colony-forming units/day, daily) to C57BL/6J mice at age of day 8 for 2 wk. Both male and female mice were investigated in these experiments. We found that feeding LR did not affect clinical phenotype or inflammatory biomarkers in plasma and stool, but LR increased the proportion of Foxp3 + regulatory T cells (Tregs) in the intestine. LR also increased bacterial diversity and the relative abundance of p_Firmicutes, f_Lachnospiraceae , f_Ruminococcaceae , and genera Clostridium and Candidatus arthromitus , while decreasing the relative abundance of p_Bacteriodetes, f_Bacteroidaceae , f_Verrucomicrobiaceae , and genera Bacteroides , Ruminococcus, Akkermansia , and Sutterella . Finally, LR exerted a major impact on the plasma metabolome, upregulating amino acid metabolites formed via the urea, tricarboxylic acid, and methionine cycles and increasing tryptophan metabolism. In conclusion, early oral administration of LR to healthy breastfed mice led to microbial and metabolic changes which could be beneficial to general health. NEW & NOTEWORTHY Oral administration of Lactobacillus reuteri DSM 17938 (LR) to healthy breastfed mice promotes intestinal immune tolerance and is linked to proliferation of beneficial gut microbiota. LR upregulates plasma metabolites that are involved in the urea cycle, the TCA cycle, methionine methylation, and the polyamine pathway. Herein, we show that LR given to newborn mice specifically increases levels of tryptophan metabolites and the purine nucleoside adenosine that are known to enhance tolerance to inflammatory stimuli.