Single-Cell RNA Sequencing Identifies WARS1+ Mesenchymal Stem Cells with Enhanced Immunomodulatory Capacity and Improved Therapeutic Efficacy.

Psoriasis is a common inflammatory skin disorder with no cure. Mesenchymal stem cells (MSCs) have immunomodulatory properties for psoriasis, but the therapeutic efficacies varied, and the molecular mechanisms were unknown. In this study, we improved the efficacy by enhancing the immunomodulatory effects of umbilical cord-derived MSCs (UC-MSCs). UC-MSCs stimulated by TNF-α and IFN-γ exhibited a better therapeutic effect in a mouse model of psoriasis. Single-cell RNA sequencing revealed that the stimulated UC-MSCs overrepresented a subpopulation expressing high tryptophanyl-tRNA synthetase 1 (WARS1). WARS1-overexpressed UC-MSCs treat psoriasis-like skin inflammation more efficiently than control UC-MSCs by restraining the proinflammatory macrophages. Mechanistically, WARS1 maintained a RhoA-Akt axis and governed the immunomodulatory properties of UC-MSCs. Together, we identify WARS1 as a master regulator of UC-MSCs with enhanced immunomodulatory capacities, which paves the way for the directed modification of UC-MSCs for escalated therapeutic efficacy.

A lncRNA Dleu2-encoded peptide relieves autoimmunity by facilitating Smad3-mediated Treg induction.

Micropeptides encoded by short open reading frames (sORFs) within long noncoding RNAs (lncRNAs) are beginning to be discovered and characterized as regulators of biological and pathological processes. Here, we find that lncRNA Dleu2 encodes a 17-amino-acid micropeptide, which we name Dleu2-17aa, that is abundantly expressed in T cells. Dleu2-17aa promotes inducible regulatory T (iTreg) cell generation by interacting with SMAD Family Member 3 (Smad3) and enhancing its binding to the Foxp3 conserved non-coding DNA sequence 1 (CNS1) region. Importantly, the genetic deletion of Dleu2-17aa in mice by start codon mutation impairs iTreg generation and worsens experimental autoimmune encephalomyelitis (EAE). Conversely, the exogenous supplementation of Dleu2-17aa relieves EAE. Our findings demonstrate an indispensable role of Dleu2-17aa in maintaining immune homeostasis and suggest therapeutic applications for this peptide in treating autoimmune diseases.

Targeting the transcription factor HES1 by L-menthol restores protein phosphatase 6 in keratinocytes in models of psoriasis.

Protein Phosphatase 6 down-regulation in keratinocytes is a pivotal event that amplifies the inflammatory circuits in psoriasis, indicating that restoration of protein phosphatase 6 can be a rational strategy for psoriasis treatment. Through the phenotypic screen, we here identify L-menthol that ameliorates psoriasis-like skin inflammation by increasing protein phosphatase 6 in keratinocytes. Target identification approaches reveal an indispensable role for the transcription factor hairy and enhancer of split 1 in governing the protein phosphatase 6-upregulating function of L-menthol in keratinocytes. The transcription factor hairy and enhancer of split 1 is diminished in the epidermis of psoriasis patients and imiquimod-induced mouse model, while L-menthol upregulates the transcription factor hairy and enhancer of split 1 by preventing its proteasomal degradation. Mechanistically, the transcription factor hairy and enhancer of split 1 transcriptionally activates the expression of immunoglobulin-binding protein 1 which promotes protein phosphatase 6 expression and inhibits its ubiquitination. Collectively, we discover a therapeutic compound, L-menthol, for psoriasis, and uncover the dysfunctional the transcription factor hairy and enhancer of split 1- immunoglobulin-binding protein 1- protein phosphatase 6 axis that contributes to psoriasis pathology by using L-menthol as a probe.

Protein phosphatase 6 (Pp6) is crucial for regulatory T cell function and stability in autoimmunity.

Regulatory T (Treg) cells constitute a dynamic population that is critical in autoimmunity. Treg cell therapies for autoimmune diseases are mainly focused on enhancing their suppressive activities. However, recent studies demonstrated that certain inflammatory conditions induce Treg cell instability with diminished FoxP3 expression and convert them into pathogenic effector cells. Therefore, the identification of novel targets crucial to both Treg cell function and plasticity is of vital importance to the development of therapeutic approaches in autoimmunity. In this study, we found that conditional Pp6 knockout (cKO) in Treg cells led to spontaneous autoinflammation, immune cell activation, and diminished levels of FoxP3 in CD4+ T cells in mice. Loss of Pp6 in Treg cells exacerbated two classical mouse models of Treg-related autoinflammation. Mechanistically, Pp6 deficiency increased CpG motif methylation of the FoxP3 locus by dephosphorylating Dnmt1 and enhancing Akt phosphorylation at Ser473/Thr308, leading to impaired FoxP3 expression in Treg cells. In summary, our study proposes Pp6 as a critical positive regulator of FoxP3 that acts by decreasing DNA methylation of the FoxP3 gene enhancer and inhibiting Akt signaling, thus maintaining Treg cell stability and preventing autoimmune diseases.

Lidocaine Ameliorates Psoriasis by Obstructing Pathogenic CGRP Signaling‒Mediated Sensory Neuron‒Dendritic Cell Communication.

Psoriasis is a chronic immune-mediated skin disorder with the nervous system contributing to its pathology. The neurogenic mediators of psoriasis are elusive, and whether the intervention of the cutaneous nervous system can treat psoriasis remains to be determined. In this study, we conducted a pilot study using an epidural injection of lidocaine to treat patients with psoriasis. Lidocaine treatment markedly reduced patients' clinical scores and improved an imiquimod-induced rat model of psoriasis as competent as systemic delivery of a TNF-α antibody. Imiquimod application elicited aberrant cutaneous nerve outgrowth and excessive generation of neuropeptide calcitonin gene-related peptide from dorsal root ganglion neurons, both of which were inhibited by epidural lidocaine treatment. Single-cell RNA sequencing unveiled the overrepresentation of calcitonin gene-related peptide receptors in dermal dendritic cell populations of patients with psoriasis. Through disturbing calcitonin gene-related peptide signaling, lidocaine inhibited IL-23 production by dendritic cells cocultured with dorsal root ganglion neurons. Thus, epidural nerve block with lidocaine demonstrates an effective therapy for psoriasis, which suppresses both inordinate sensory nerve growth in the inflamed skin and calcitonin gene-related peptide-mediated IL-23 production from psoriatic dendritic cells.

SZB120 Exhibits Immunomodulatory Effects by Targeting eIF2α to Suppress Th17 Cell Differentiation.

IL-17-secreting Th17 cells play an important role in the pathogenesis of various inflammatory and autoimmune diseases. IL-17-targeted biologics and small molecules are becoming promising treatments for these diseases. In this study, we report that SZB120, a derivative of the natural compound 3-acetyl-ß-boswellic acid, inhibits murine Th17 cell differentiation by interacting with the α-subunit of eukaryotic initiation factor 2 (eIF2α). We showed that SZB120 directly interacts with eIF2α and contributes to serine 51 phosphorylation of eIF2α. The suppressive effect of SZB120 on Th17 cell differentiation was reversed by GSK2606414, an inhibitor of eIF2α phosphokinase. Phosphorylation of eIF2α induced by SZB120 decreased the protein expression of IκBζ, which is important for Th17 cell differentiation. Notably, interaction with eIF2α by SZB120 also impaired glucose uptake and glycolysis in T cells. In vivo, SZB120 treatment of C57BL/6 mice significantly attenuated IL-17/Th17-mediated autoimmune disease. Our study indicates that SZB120 is a promising drug candidate for IL-17/Th17-mediated inflammatory diseases.

A micropeptide encoded by lncRNA MIR155HG suppresses autoimmune inflammation via modulating antigen presentation.

Many annotated long noncoding RNAs (lncRNAs) harbor predicted short open reading frames (sORFs), but the coding capacities of these sORFs and the functions of the resulting micropeptides remain elusive. Here, we report that human lncRNA MIR155HG encodes a 17-amino acid micropeptide, which we termed miPEP155 (P155). MIR155HG is highly expressed by inflamed antigen-presenting cells, leading to the discovery that P155 interacts with the adenosine 5'-triphosphate binding domain of heat shock cognate protein 70 (HSC70), a chaperone required for antigen trafficking and presentation in dendritic cells (DCs). P155 modulates major histocompatibility complex class II-mediated antigen presentation and T cell priming by disrupting the HSC70-HSP90 machinery. Exogenously injected P155 improves two classical mouse models of DC-driven auto inflammation. Collectively, we demonstrate the endogenous existence of a micropeptide encoded by a transcript annotated as "non-protein coding" and characterize a micropeptide as a regulator of antigen presentation and a suppressor of inflammatory diseases.

Persistence and Transcription of Paternal mtDNA Dependent on the Delivery Strategy Rather than Mitochondria Source in Fish Embryos.

BACKGROUND/AIMS: Mitochondria (MT) and mitochondrial DNA (mtDNA) show maternal inheritance in most eukaryotic organisms; the sperm mtDNA is usually delivered to the egg during fertilization and then rapidly eliminated to avoid heteroplasmy, which can affect embryogenesis. In our previous study, fertilization-delivered sperm mtDNA exhibited late elimination and transcriptional quiescence in cyprinid fish embryos. However, the mechanisms underlying elimination and transcriptional quiescence of paternal mtDNA are unclear. METHODS: Goldfish and zebrafish were used to investigate the fate of mtDNAs with different parental origins delivered by fertilization or microinjection in embryos. Goldfish MT from heart, liver and spermatozoa were microinjected into zebrafish zygotes, respectively. Specific PCR primers were designed so that the amplicons have different sizes to characterize goldfish and zebrafish cytb genes or their cDNAs. RESULTS: The MT injection-delivered paternal mtDNA from sperm, as well as those from the heart and liver, was capable of persistence and transcription until birth, in contrast to the disappearance and transcriptional quiescence at the heartbeat stage of fertilization-delivered sperm mtDNA. In addition, the exogenous MT-injected zebrafish embryos have normal morphology during embryonic development. CONCLUSIONS: The fate of paternal mtDNA in fishes is dependent on the delivery strategy rather than the MT source, suggesting that the presence of sperm factor(s) is responsible for elimination and transcriptional quiescence of fertilization-delivered sperm mtDNA. These findings provide insights into the mechanisms underlying paternal mtDNA fate and heteroplasmy in cyprinid fishes.