Proximity-enabled covalent binding of IL-2 to IL-2Rα selectively activates regulatory T cells and suppresses autoimmunity

Interleukin-2(IL-2)is a pleiotropic cytokine that orchestrates bidirectional immune responses via regulatory T cells(Tregs)and effector cells,leading to paradoxical consequences.Here,we report a strategy that exploited genetic code expansion-guided incorporation of the latent bioreactive artificial amino acid fluorosulfate-L-tyrosine(FSY)into IL-2 for proximity-enabled covalent binding to IL-2Rαto selectively promote Treg activation.We found that FSY-bearing IL-2 variants,such as L72-FSY,covalently bound to IL-2Rαvia sulfur-fluoride exchange when in proximity,resulting in persistent recycling of IL-2 and selectively promoting the expansion of Tregs but not effector cells.Further assessment of L72-FSY-expanded Tregs demonstrated that L72-FSY maintained Tregs in a central memory phenotype without driving terminal differentiation,as demonstrated by simultaneously attenuated expression of lymphocyte activation gene-3(LAG-3)and enhanced expression of programmed cell death protein-1(PD-1).Subcutaneous administration of L72-FSY in murine models of pristane-induced lupus and graft-versus-host disease(GvHD)resulted in enhanced and sustained therapeutic efficacy compared with wild-type IL-2 treatment.The efficacy of L72-FSY was further improved by N-terminal PEGylation,which increased its circulatory retention for preferential and sustained effects.This proximity-enabled covalent binding strategy may accelerate the development of pleiotropic cytokines as a new class of immunomodulatory therapies.

A high-fiber diet synergizes with Prevotella copri and exacerbates rheumatoid arthritis

Both preclinical and established rheumatoid arthritis(RA)patients display alterations in the gut microbiome.Prevotella spp.are preferentially enriched in a subset of RA patients.Here,we isolated a Prevotella strain,P.copri RA,from the feces of RA patients and showed that colonization of P.copri RA exacerbated arthritis in a collagen-induced arthritis(CIA)model.With the presence of P.copri RA colonization,a high-fiber diet exacerbated arthritis via microbial alterations and intestinal inflammation.Colonization of P.copri together with a high-fiber diet enabled the digestion of complex fiber,which led to the overproduction of organic acids,including fumarate,succinate and short-chain fatty acids.Succinate promoted proinflammatory responses in macrophages,and supplementation with succinate exacerbated arthritis in the CIA model.Our findings highlight the importance of dysbiosis when evaluating the effects of dietary interventions on RA pathogenesis and provide new insight into dietary interventions or microbiome modifications to improve RA management.

Helicobacter pylori may participate in the development of inflammatory bowel disease by modulating the intestinal microbiota

Inflammatory bowel disease(IBD)is a non-specific inflammatory disease of the gastrointestinal(GI)tract that is generally accepted to be closely related to intestinal dysbiosis in the host.GI infections contribute a key role in the pathogenesis of IBD;however,although the results of recent clinical studies have revealed an inverse correlation between Helicobacter pylori(H.pylori)infection and IBD,the exact mechanism underlying the development of IBD remains unclear.H.pylori,as a star microorganism,has been a focus for decades,and recent preclinical and real-world studies have demonstrated that H.pylori not only affects the changes in the gastric microbiota and microenvironment but also influences the intestinal microbiota,indicating a potential correlation with IBD.Detailed analysis revealed that H.pylori infection increased the diversity of the intestinal microbiota,reduced the abundance of Bacteroidetes,augmented the abundance of Firmicutes,and produced short-chain fatty acid-producing bacteria such as Akkermansia.All these factors may decrease vulnerability to IBD.Further studies investigating the H.pylori-intestinal microbiota metabolite axis should be performed to understand the mechanism underlying the development of IBD.

Molecular mechanism of mureidomycin biosynthesis activated by introduction of an exogenous regulatory gene ssa A into Streptomyces roseosporus

Mureidomycins(MRDs), a group of unique uridyl-peptide antibiotics, exhibit antibacterial activity against the highly refractory pathogen Pseudomonas aeruginosa. Our previous study showed that the cryptic MRD biosynthetic gene cluster(BGC) mrd in Streptomyces roseosporus NRRL 15998 could not be activated by its endogenous regulator 02995 but activated by an exogenous activator Ssa A from sansanmycin’s BGC ssa of Streptomyces sp. strain SS. Here we report the molecular mechanism for this inexplicable regulation. EMSAs and footprinting experiments revealed that Ssa A could directly bind to a 14-nt palindrome sequence of 5′-CTGRCNNNNGTCAG-3′ within six promoter regions of mrd. Disruption of three representative target genes(SSGG-02981, SSGG-02987 and SSGG-02994) showed that the target genes directly controlled by Ssa Awere essential for MRD production. The regulatory function was further investigated by replacing six regions of SSGG-02995 with those of ssa A.Surprisingly, only the replacement of 343–450 nt fragment encoding the 115–150 amino acids(AA) of Ssa A could activate MRD biosynthesis. Further bioinformatics analysis showed that the 115–150 AA situated between two conserved domains of Ssa A.Our findings significantly demonstrate that constitutive expression of a homologous exogenous regulatory gene is an effective strategy to awaken cryptic biosynthetic pathways in Streptomyces.