The dual role of short fatty acid chains in the pathogenesis of autoimmune disease models

<div><p>Autoimmune diseases are influenced by both genetic and environmental factors. The gut environment has attracted much attention as an essential component that modulates immune responses, and therefore immune-mediated disorders, such as autoimmune diseases. Growing evidence suggests that microbiota and their metabolites are critical factors for immune modulation. Recently, we reported that the microbiome in patients with multiple sclerosis, an autoimmune disease targeting the myelin sheath of the central nervous system, is characterized by a reduction of bacteria belonging to <i>Clostridia</i> clusters IV and XIVa, which are potent producers of short-chain fatty acids (SCFAs) by fermentation of indigestible carbohydrates. In the present study, we investigated the role of SCFAs in the regulation of inflammation. We demonstrated that oral administration of SCFAs ameliorated the disease severity of systemic autoimmune inflammatory conditions mediated by lymphocytes such as experimental autoimmune encephalitis and collagen-induced arthritis. Amelioration of disease was associated with a reduction of Th1 cells and an increase in regulatory T cells. In contrast, SCFAs contributed to the exaggeration of K/BxN serum transfer arthritis, representing the effector phase of inflammation in rheumatoid arthritis. An increased understanding of the effect of microbiota metabolites will lead to the effective treatment and prevention of systemic inflammatory disorders.</p></div

Effect of SCFAs on K/BxN mouse serum–induced arthritis.

<p>(A) Clinical scores of K/BxN mouse serum–induced arthritis in B6 mice treated with orally administrated SCFAs 3 weeks before K/BxN mouse serum–induced arthritis induction and throughout the study. *<i>P</i><0.05, **<i>P</i><0.005, control versus acetate group. †<i>P</i><0.05, control versus propionate group. Results shown are the mean + SEM of 10 mice per group. The data shown are pooled from two similar experiments. (B) Representative histological features of joints in control and SCFAs-treated mice. (H&E stained; original magnification ×40). Scale bar = 500 μm. (C) Quantification of histological assessment of joints 10 days after induction of K/BxN mouse serum–induced arthritis is shown in A. Results shown are the mean + SEM of 3 mice per group. *<i>P</i><0.05 control versus acetate group.</p

Effect of a high-fiber diet on K/BxN mouse serum–induced arthritis.

<p>(A) Clinical scores of K/BxN mouse serum–induced arthritis in B6 mice fed a high-fiber, low-fiber, or control diet 2 weeks before the transfer of serum of K/BxN mouse and throughout the study. *<i>P</i><0.05, **<i>P</i><0.005, low-fiber versus high-fiber group. †<i>P</i><0.05, ††<i>P</i><0.005, control diet versus high-fiber group. Results shown are the mean + SEM of 10 mice per group. The data shown are pooled from two similar experiments. (B) Representative histological features of joints in control, low- or high-fiber diet mice (H&E stained; original magnification ×40). Scale bar = 500 μm. (C) Quantification of histological assessment of joints 10 days after induction of K/BxN mouse serum–induced arthritis is shown in A. Results shown are the mean + SEM of 3 mice per group. **<i>P</i><0.005, low-fiber versus high-fiber group. ††<i>P</i><0.005, control diet versus high-fiber group.</p

Oral administration of SCFAs ameliorates the disease severity of CIA.

<p>(A) Clinical scores of CIA in DBA1/J mice with orally administrated SCFAs 3 weeks before immunization with CII and throughout the study. The data shown are pooled from two similar experiments. Data are expressed as the means ± SEM of 10 mice per group. ** <i>P</i><0.005, control versus butyrate group. (B) Representative histological features of joints in control and SCFAs-treated mice (H&E stained; original magnification ×40). Scale bar = 500 μm. (C) Quantification of histological assessment of joints 46–48 days after induction of CIA. Result shown is the mean + SEM of 5 mice per group. *<i>P</i><0.05, ** <i>P</i><0.005, versus control group.</p

T cell responses in mice orally administrated with SCFAs.

<p>(A) B6 mice were administrated with SCFAs and then immunized with MOG_35–55. Then, 10–11 days after immunization, draining lymph node cells were incubated with MOG_35–55. Supernatants were collected from the culture and measured for the concentrations of IFN-γ and IL-17 by ELISA. Data represent the mean ± SEM of samples pooled from four similar experiments (n = 13 mice). *<i>P</i><0.05, ** <i>P</i>< 0.01, control versus butyrate group. (B) The frequency of Tregs in spleen (SPN) and draining lymph node (LN) obtained from mice treated with SCFAs were measured using flow cytometry.*<i>P</i><0.05, ** <i>P</i>< 0.005 versus control.</p

High-fiber diet ameliorates the disease severity of MOG-induced EAE.

<p>(<b>A</b>) EAE was induced in B6 mice by immunization with MOG_35–55. Mice were fed a high-fiber, low-fiber or control diet 2 weeks before immunization and throughout the study. *<i>P</i><0.05, **<i>P</i><0.005, low-fiber versus high-fiber group. †<i>P</i><0.05, control versus high-fiber group. Data are expressed as the means ± SEM of 9–10 mice per group. <b>(B)</b> Histopathological assessment of the CNS in EAE-induced mice. Cellular infiltration of the spinal cord of mice on day 30 is shown. Paraffin-embedded spinal cords were stained with hematoxylin and eosin (H&E). Scale bar = 200 μm (upper panels) or 50 μm (lower panels). <b>(C)</b> HPLC quantification of SCFA levels in the cecal contents.</p

Additional file 1: Table S1. of Enhanced IFN-Îą production is associated with increased TLR7 retention in the lysosomes of palasmacytoid dendritic cells in systemic lupus erythematosus

Characteristics of HC and lupus patients for confocal microscopic analysis. Values are n or median [interquartile range]. (DOCX 30 kb

Additional file 1: Figure S1. of MicroRNA-101a regulates microglial morphology and inflammation

The expression level of miR-101a in MG6 cells cultured with each miRNA was analyzed by quantitative real-time PCR. Figure S2. Neither miR-101a nor its inhibitor exhibited any influence on the viability of MG6 cells as measured by MTT assay. (PPTX 52 kb

Additional file 2: Figure S3. of MicroRNA-101a regulates microglial morphology and inflammation

Predicted miR-101a target genes included in MAPK signaling pathway. Asterisks indicate miR-101a targets. (TIF 101 kb

A Trifluoromethyl Analogue of Celecoxib Exerts Beneficial Effects in Neuroinflammation

<div><p>Celecoxib is a selective cyclooxygenase-2 (COX2) inhibitor. We have previously shown that celecoxib inhibits experimental autoimmune encephalomyelitis (EAE) in COX-2-deficient mice, suggestive for a mode of action involving COX2-independent pathways. In the present study, we tested the effect of a trifluoromethyl analogue of celecoxib (TFM-C) with 205-fold lower COX-2 inhibitory activity in two models of neuroinflammation, i.e. cerebellar organotypic cultures challenged with LPS and the EAE mouse model for multiple sclerosis. TFM-C inhibited secretion of IL-1β, IL-12 and IL-17, enhanced that of TNF-α and RANTES, reduced neuronal axonal damage and protected from oxidative stress in the organotypic model. TFM-C blocked TNF-α release in microglial cells through a process involving intracellular retention, but induced TNF-α secretion in primary astrocyte cultures. Finally, we demonstrate that TFM-C and celecoxib ameliorated EAE with equal potency. This coincided with reduced secretion of IL-17 and IFN-γ by MOG-reactive T-cells and of IL-23 and inflammatory cytokines by bone marrow-derived dendritic cells. Our study reveals that non-coxib analogues of celecoxib may have translational value in the treatment of neuro-inflammatory conditions.</p> </div