The MS-Associated Gut Microbiome

Category: Microbiome Background: An essential function of the gut microbiota is to regulate immune responses, including T lymphocyte functions in health and disease. Objectives: We hypothesized that gut microbiota contribute to the pathogenesis of MS. Methods: We analyzed the microbiome of stool samples from 64 treatment-naïve MS patients and 68 healthy controls using amplicon sequencing of the 16S V4 region of the rRNA gene. We characterized immune profiles of cultured PBMC in response to specific bacteria harbored by MS patients. Results: We found that MS patients exhibited impaired in-vitro Treg differentiation in response to their own microbiota. No major shifts in microbial community structure were observed. However, we were able to identify individual microbial taxa that were significantly associated with MS and studied their ability to regulate primary human T lymphocyte differentiation in vitro. We next conducted in-vitro assays to characterize the functional properties of the MS gut microbiota. We found that MS-associated Acinetobacter calcoaceticus was sufficient to reduce Treg differentiation and increase both Th1 and Th2 differentiation. The expansion of Th1 lymphocytes was recapitulated by Akkermansia muciniphila, which was also more abundant in MS patients. In contrast, Parabacteroidesdistasonis, which was significantly reduced in MS microbiomes, stimulated CD4+ T lymphocyte differentiation into a CD25+ IL-10+ regulatory phenotype. Our results suggest that MS-associated changes in microbiota alter T lymphocyte differentiation in a complex fashion and likely through multiple mechanisms. Finally, microbiota transplants from MS patients into germ-free mice results in more severe experimental autoimmune encephalomyelitis and reduced Tregs compared to controls. Conclusion: This study identifies specific human gut bacteria that regulate adaptive autoimmune responses, suggesting therapeutic targeting of the microbiota as a novel treatment for MS

Effects of ceftiofur and chlortetracycline treatment strategies on antimicrobial susceptibility and on tet(A), tet(B), and bla[subscript CMY-2] resistance genes among E. coli isolated from the feces of feedlot cattle

A randomized controlled field trial was conducted to evaluate the effects of two sets of treatment strategies on ceftiofur and tetracycline resistance in feedlot cattle. The strategies consisted of ceftiofur crystalline-free acid (CCFA) administered to either one or all of the steers within a pen, followed by feeding or not feeding a therapeutic dose of chlortetracycline (CTC). Eighty-eight steers were randomly allocated to eight pens of 11 steers each. Both treatment regimens were randomly assigned to the pens in a two-way full factorial design. Non-type-specific (NTS) E. coli (n = 1,050) were isolated from fecal samples gathered on Days 0, 4, 12, and 26. Antimicrobial susceptibility profiles were determined using a microbroth dilution technique. PCR was used to detect tet(A), tet(B), and bla[subscript CMY-2] genes within each isolate. Chlortetracycline administration greatly exacerbated the already increased levels of both phenotypic and genotypic ceftiofur resistance conferred by prior CCFA treatment (P<0.05). The four treatment regimens also influenced the phenotypic multidrug resistance count of NTS E. coli populations. Chlortetracycline treatment alone was associated with an increased probability of selecting isolates that harbored tet(B) versus tet(A) (P<0.05); meanwhile, there was an inverse association between finding tet(A) versus tet(B) genes for any given regimen (P<0.05). The presence of a tet(A) gene was associated with an isolate exhibiting reduced phenotypic susceptibility to a higher median number of antimicrobials (n = 289, median = 6; 95% CI = 4–8) compared with the tet(B) gene (n = 208, median = 3; 95% CI = 3–4). Results indicate that CTC can exacerbate ceftiofur resistance following CCFA therapy and therefore should be avoided, especially when considering their use in sequence. Further studies are required to establish the animal-level effects of co-housing antimicrobial-treated and non-treated animals together

Low-Dose Anti-Thymocyte Globulin (ATG) Preserves β-Cell Function and Improves HbA1c in New-Onset Type 1 Diabetes

ObjectiveA pilot study suggested that combination therapy with low-dose anti-thymocyte globulin (ATG) and pegylated granulocyte colony-stimulating factor (GCSF) preserves C-peptide in established type 1 diabetes (T1D) (duration 4 months to 2 years). We hypothesized that 1) low-dose ATG/GCSF or 2) low-dose ATG alone would slow the decline of β-cell function in patients with new-onset T1D (duration &lt;100 days).Research design and methodsA three-arm, randomized, double-masked, placebo-controlled trial was performed by the Type 1 Diabetes TrialNet Study Group in 89 subjects: 29 subjects randomized to ATG (2.5 mg/kg intravenously) followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for 6 doses), 29 to ATG alone (2.5 mg/kg), and 31 to placebo. The primary end point was mean area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test 1 year after initiation of therapy. Significance was defined as one-sided P value &lt; 0.025.ResultsThe 1-year mean AUC C-peptide was significantly higher in subjects treated with ATG (0.646 nmol/L) versus placebo (0.406 nmol/L) (P = 0.0003) but not in those treated with ATG/GCSF (0.528 nmol/L) versus placebo (P = 0.031). HbA1c was significantly reduced at 1 year in subjects treated with ATG and ATG/GCSF, P = 0.002 and 0.011, respectively.ConclusionsLow-dose ATG slowed decline of C-peptide and reduced HbA1c in new-onset T1D. Addition of GCSF did not enhance C-peptide preservation afforded by low-dose ATG. Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of the disease