Dimethyl fumarate (DMF), a new drug for multiple sclerosis (MS) treatment, acts against neuroinflammation via mechanisms that are triggered by adduct formation with thiol redox switches. Ethyl pyruvate (EP), an off-the-shelf agent, appears to be a redox analog of DMF, but its immunomodulatory properties have not been put into the context of MS therapy. In this article, we examined and compared the effects of EP and DMF on MS-relevant activity/functions of T cells, macrophages, microglia, and astrocytes. EP efficiently suppressed the release of MS signature cytokines, IFN-γ and IL-17, from human PBMCs. Furthermore, the production of these cytokines was notably decreased in encephalitogenic T cells after in vivo application of EP to rats. Production of two other proinflammatory cytokines, IL-6 and TNF, and NO was suppressed by EP in macrophages and microglia. Reactive oxygen species production in macrophages, microglia activation, and the development of Ag-presenting phenotype in microglia and macrophages were constrained by EP. The release of IL-6 was reduced in astrocytes. Finally, EP inhibited the activation of transcription factor NF-κB in microglia and astrocytes. Most of these effects were also found for DMF, implying that EP and DMF share common targets and mechanisms of action. Importantly, EP had in vivo impact on experimental autoimmune encephalomyelitis, an animal model of MS. Treatment with EP resulted in delay and shortening of the first relapse, and lower clinical scores, whereas the second attack was annihilated. Further studies on the possibility to use EP as an MS therapeutic are warranted.

Two Balkan Peninsula endemics, Nepeta rtanjensis and N. argolica subsp. argolica, both characterized by specialized metabolite profiles predominated by iridoids and phenolics, are differentiated according to the stereochemistry of major iridoid aglycone nepetalactone (NL). For the first time, the present study provides a comparative analysis of antimicrobial and immunomodulating activities of the two Nepeta species and their major iridoids isolated from natural sources—cis,trans-NL, trans,cis-NL, and 1,5,9-epideoxyloganic acid (1,5,9-eDLA), as well as of phenolic acid rosmarinic acid (RA). Methanol extracts and pure iridoids displayed excellent antimicrobial activity against eight strains of bacteria and seven strains of fungi. They were especially potent against food-borne pathogens such as L. monocytogenes, E. coli, S. aureus, Penicillium sp., and Aspergillus sp. Targeted iridoids were efficient agents in preventing biofilm formation of resistant P. aeruginosa strain, and they displayed additive antimicrobial interaction. Iridoids are, to a great extent, responsible for the prominent antimicrobial activities of the two Nepeta species, although are probably minor contributors to the moderate immunomodulatory effects. The analyzed iridoids and RA, individually or in mixtures, have the potential to be used in the pharmaceutical industry as potent antimicrobials, and in the food industry to increase the shelf life and safety of food products.

Gut microbiota dysbiosis has been considered the essential element in the pathogenesis of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). Antibiotics were administered orally to Dark Agouti (DA) rats early in their life with the aim of perturbing gut microbiota and investigating the effects of such intervention on the course of EAE. As a result, the diversity of the gut microbiota was reduced under the influence of antibiotics. Mainly, Firmicutes and Actinobacteria were replaced by Proteobacteria and Bacteroidetes, while decreased proportions of Clostridia and Bacilli classes were accompanied by an increase in Gamma-Proteobacteria in antibiotic-treated animals. Interestingly, a notable decrease in the Helicobacteraceae, Spirochaetaceae and Turicibacteriaceae was scored in antibiotic-treated groups. Also, levels of short chain fatty acids were reduced in the faeces of antibiotic-treated rats. Consequently, aggravation of EAE, paralleled with stronger immune response in lymph nodes draining the site of immunization, and increased inflammation within the CNS, were observed in antibiotic-treated DA rats. Thus, the alteration of gut microbiota leads to an escalation of CNS-directed autoimmunity in DA rats. The results of this study indicate that antibiotic use in early life may have subsequent unfavourable effects on the regulation of the immune system.

Gut microbiota and gut-associated lymphoid tissue have been increasingly appreciated as important players in pathogenesis of various autoimmune diseases, including multiple sclerosis. Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis that can be induced with an injection of spinal cord homogenate emulsified in complete Freund’s adjuvant in Dark Agouti (DA) rats, but not in Albino Oxford (AO) rats. In this study, mesenteric lymph nodes (MLN), Peyer’s patches (PP) and gut microbiota were analysed in these two rat strains. There was higher proportion of CD4⁺T cells and regulatory T cells in non-immunised DA rats in comparison to AO rats. Also, DA rat MLN and PP cells were higher producers of pro-inflammatory cytokines interferon-γ and interleukin-17. Finally, microbial analyses showed that uncultivated species ofTuricibacterandAtopostipesgenus were exclusively present in AO rats, in faeces and intestinal tissue, respectively. Thus, it is clear that in comparison of an EAE-susceptible with an EAE-resistant strain of rats, various discrepancies at the level of gut associated lymphoid tissue, as well as at the level of gut microbiota can be observed. Future studies should determine if the differences have functional significance for EAE pathogenesis.

Albino Oxford (AO) rats are extremely resistant to induction of experimental autoimmune encephalomyelitis (EAE). EAE is an animal model of multiple sclerosis, a chronic inflammatory disease of the central nervous system (CNS), with established autoimmune pathogenesis. The autoimmune response against the antigens of the CNS is initiated in the peripheral lymphoid tissues after immunization of AO rats with CNS antigens. Subsequently, limited infiltration of the CNS occurs, yet without clinical sequels. It has recently become increasingly appreciated that gut-associated lymphoid tissues (GALT) and gut microbiota play an important role in regulation and propagation of encephalitogenic immune response. Therefore, modulation of AO gut microbiota by antibiotics was performed in this study. The treatment altered composition of gut microbiota in AO rats and led to a reduction in the proportion of regulatory T cells in Peyer’s patches, mesenteric lymph nodes, and in lymph nodes draining the site of immunization. Upregulation of interferon-γ and interleukin (IL)-17 production was observed in the draining lymph nodes. The treatment led to clinically manifested EAE in AO rats with more numerous infiltrates and higher production of IL-17 observed in the CNS. Importantly, transfer of AO gut microbiota into EAE-prone Dark Agouti rats ameliorated the disease. These results clearly imply that gut microbiota is an important factor in AO rat resistance to EAE and that gut microbiota transfer is an efficacious way to treat CNS autoimmunity. These findings also support the idea that gut microbiota modulation has a potential as a future treatment of multiple sclerosis.