IL17/IL17RA as a Novel Signaling Axis Driving Mesenchymal Stem Cell Therapeutic Function in Experimental Autoimmune Encephalomyelitis

Re-establishing immune tolerance in multiple sclerosis: focusing on novel mechanisms of mesenchymal stem cell regulation of Th17/Treg balance

The T-helper 17 (Th17) cell and regulatory T cell (Treg) axis plays a crucial role in the development of multiple sclerosis (MS), which is regarded as an immune imbalance between pro-inflammatory cytokines and the maintenance of immune tolerance. Mesenchymal stem cell (MSC)-mediated therapies have received increasing attention in MS research. In MS and its animal model experimental autoimmune encephalomyelitis, MSC injection was shown to alter the differentiation of CD4+T cells. This alteration occurred by inducing anergy and reduction in the number of Th17 cells, stimulating the polarization of antigen-specific Treg to reverse the imbalance of the Th17/Treg axis, reducing the inflammatory cascade response and demyelination, and restoring an overall state of immune tolerance. In this review, we summarize the mechanisms by which MSCs regulate the balance between Th17 cells and Tregs, including extracellular vesicles, mitochondrial transfer, metabolic reprogramming, and autophagy. We aimed to identify new targets for MS treatment using cellular therapy by analyzing MSC-mediated Th17-to-Treg polarization.

Lactate: an alternative pathway for the immunosuppressive properties of mesenchymal stem/stromal cells

BACKGROUND

The metabolic reprogramming of mesenchymal stem/stromal cells (MSC) favoring glycolysis has recently emerged as a new approach to improve their immunotherapeutic abilities. This strategy is associated with greater lactate release, and interestingly, recent studies have proposed lactate as a functional suppressive molecule, changing the old paradigm of lactate as a waste product. Therefore, we evaluated the role of lactate as an alternative mediator of MSC immunosuppressive properties and its contribution to the enhanced immunoregulatory activity of glycolytic MSCs.

MATERIALS AND METHODS

Murine CD4+ T cells from C57BL/6 male mice were differentiated into proinflammatory Th1 or Th17 cells and cultured with either L-lactate, MSCs pretreated or not with the glycolytic inductor, oligomycin, and MSCs pretreated or not with a chemical inhibitor of lactate dehydrogenase A (LDHA), galloflavin or LDH siRNA to prevent lactate production. Additionally, we validated our results using human umbilical cord-derived MSCs (UC-MSCs) in a murine model of delayed type 1 hypersensitivity (DTH).

RESULTS

Our results showed that 50 mM of exogenous L-lactate inhibited the proliferation rate and phenotype of CD4+ T cell-derived Th1 or Th17 by 40% and 60%, respectively. Moreover, the suppressive activity of both glycolytic and basal MSCs was impaired when LDH activity was reduced. Likewise, in the DTH inflammation model, lactate production was required for MSC anti-inflammatory activity. This lactate dependent-immunosuppressive mechanism was confirmed in UC-MSCs through the inhibition of LDH, which significantly decreased their capacity to control proliferation of activated CD4+ and CD8+ human T cells by 30%.

CONCLUSION

These findings identify a new MSC immunosuppressive pathway that is independent of the classical suppressive mechanism and demonstrated that the enhanced suppressive and therapeutic abilities of glycolytic MSCs depend at least in part on lactate production.

Mesenchymal stromal cell-derived secretome-based therapy for neurodegenerative diseases: overview of clinical trials

BACKGROUND

Over the past few years, mesenchymal stromal cells (MSCs) have attracted a great deal of scientific attention owing to their promising results in the treatment of incurable diseases. However, there are several concerns about their possible side effects after direct cell transplantation, including host immune response, time-consuming cell culture procedures, and the dependence of cell quality on the donor, which limit the application of MSCs in clinical trials. On the other hand, it is well accepted that the beneficial effects of MSCs are mediated by secretome rather than cell replacement. MSC secretome refers to a variety of bioactive molecules involved in different biological processes, specifically neuro-regeneration.

MAIN BODY

Due to the limited ability of the central nervous system to compensate for neuronal loss and relieve disease progress, mesenchymal stem cell products may be used as a potential cure for central nervous system disorders. In the present study, the therapeutic effects of MSC secretome were reviewed and discussed the possible mechanisms in the three most prevalent central nervous system disorders, namely Alzheimer's disease, multiple sclerosis, and Parkinson's disease. The current work aimed to help discover new medicine for the mentioned complications.

CONCLUSION

The use of MSC-derived secretomes in the treatment of the mentioned diseases has encouraging results, so it can be considered as a treatment option for which no treatment has been introduced so far.

Oxidative stress-triggered pyroptosis mediates Candida albicans susceptibility in diabetic foot

An accumulating trend of research demonstrates that diabetic patients are susceptible to skin infections with Candida albicans, but the mechanism still remains unclear. The intense oxidative stress (OS) responses were occurred in the lesion of diabetic mice footpads after C. albicans infection. Localised skin infections would lead to more severe complications while the severity of the condition worsens or the inadequate treatment. Notably, in this study, through the investigation of murine diabetic footpad C. albicans infection model and molecular biotechnology, including histopathological staining, immunofluorescence (IF) staining, quantitative real-time PCR (qPCR), western blot (WB), flow cytometry (FCM), sandwich enzyme-linked immunosorbent assay (ELISA) assays, we found that intense OS responses in the footpad tissue not only mediated the activation of NF-κB protein complex, but also triggered downstream pyroptosis and apoptosis through NLRP3 inflammasome, which is one of the potential reasons for the severe condition of infectious skin injuries in diabetic mice. Caspase-1, a classical signal pathway protein in pyroptosis, could promote pore formation on cell membranes and the release of the cytokine after NLRP3 inflammasome activation. With intense immune-inflammatory responses, the organism also stimulates immune organs such as the spleen and lymph nodes to produce negative feedback regulation and generate CD4⁺CD25⁺Foxp3⁺ Treg cells to rectify the process. Therefore, combined with the results of this work, it is possible to design and screen relevant drugs for NLRP3 inflammasomes as core targets to keep the OS response at a low level in the footpad tissues.

Potential Utility of Natural Products against Oxidative Stress in Animal Models of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune-mediated degenerative disease of the central nervous system (CNS) characterized by immune cell infiltration, demyelination and axonal injury. Oxidative stress-induced inflammatory response, especially the destructive effect of immune cell-derived free radicals on neurons and oligodendrocytes, is crucial in the onset and progression of MS. Therefore, targeting oxidative stress-related processes may be a promising preventive and therapeutic strategy for MS. Animal models, especially rodent models, can be used to explore the in vivo molecular mechanisms of MS considering their similarity to the pathological processes and clinical signs of MS in humans and the significant oxidative damage observed within their CNS. Consequently, these models have been used widely in pre-clinical studies of oxidative stress in MS. To date, many natural products have been shown to exert antioxidant effects to attenuate the CNS damage in animal models of MS. This review summarized several common rodent models of MS and their association with oxidative stress. In addition, this review provides a comprehensive and concise overview of previously reported natural antioxidant products in inhibiting the progression of MS.

IL-17A Increases Doxorubicin Efficacy in Triple Negative Breast Cancer

Due to lack of targetable receptors and intertumoral heterogeneity, triple negative breast cancer (TNBC) remains particularly difficult to treat. Doxorubicin (DOX) is typically used as nonselective neoadjuvant chemotherapy, but the diversity of treatment efficacy remains unclear. Comparable to variability in clinical response, an experimental model of TNBC using a 4T1 syngeneic mouse model was found to elicit a differential response to a seven-day treatment regimen of DOX. Single-cell RNA sequencing identified an increase in T cells in tumors that responded to DOX treatment compared to tumors that continued to grow uninhibited. Additionally, compared to resistant tumors, DOX sensitive tumors contained significantly more CD4 T helper cells (339%), γδ T cells (727%), Naïve T cells (278%), and activated CD8 T cells (130%). Furthermore, transcriptional profiles of tumor infiltrated T cells in DOX responsive tumors revealed decreased exhaustion, increased chemokine/cytokine expression, and increased activation and cytotoxic activity. γδ T cell derived IL-17A was identified to be highly abundant in the sensitive tumor microenvironment. IL-17A was also found to directly increase sensitivity of TNBC cells in combination with DOX treatment. In TNBC tumors sensitive to DOX, increased IL-17A levels lead to a direct effect on cancer cell responsiveness and chronic stimulation of tumor infiltrated T cells leading to improved chemotherapeutic efficacy. IL-17A’s role as a chemosensitive cytokine in TNBC may offer new opportunities for treating chemoresistant breast tumors and other cancer types.

Parthenolide Suppresses T Helper 17 and Alleviates Experimental Autoimmune Encephalomyelitis

T helper (Th) cells play crucial roles in inflammation and adaptive immune system. Importantly, Th17 cells, a major pathogenic Th cell subset, are involved in the pathogenesis of multiple sclerosis (MS) and its classical animal modal experimental autoimmune encephalomyelitis (EAE). Previous studies have shown that parthenolide (PTL), a sesquiterpene lactone, possesses potent anti-cancer and anti-inflammatory activities. However, the immunosuppressive effect of PTL on the pathogenic Th17 cell and MS is unclear. In this study, we showed that PTL treatment could alleviate clinical symptoms by inhibiting inflammatory cell infiltration, reducing inflammation and demyelination of CNS. In addition, the mRNA expression of cytokines and inflammatory factors in CD4⁺ T cells, especially Th1 and Th17 cells, reduced in both CNS and peripheral immune tissue of EAE mice. Furthermore, PTL could inhibit the reactivation of MOG-specific T cells and the differentiation of naïve CD4⁺ T cells into Th17 cells in vitro. We also found that PTL inhibited nuclear factor kappa B (NF-κB) signaling and retinoid-related orphan receptor-γt (RORγt) in mouse Th17 cell and human Jurkat cell line. Taken together, our data demonstrated a critical immune-suppressive effect of PTL on autoimmune inflammation through regulating Th17 cells and the NF-κB/RORγt pathway.

Autoantibodies against cytoskeletons and lysosomal trafficking discriminate sarcoidosis from healthy controls, tuberculosis and lung cancers

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Hypergammaglobulinemia and the presence of autoantibodies in sarcoidosis suggest active humoral immunity to unknown antigen(s). We developed a complex cDNA library derived from tissues of sarcoidosis patients. Using a high throughput method, we constructed a microarray platform from this cDNA library containing large numbers of sarcoidosis clones. After selective biopanning, 1070 sarcoidosis-specifc clones were arrayed and immunoscreend with 152 sera from patients with sarcoidosis and other pulmonary diseases. To identify the sarcoidosis classifiers two statistical approaches were conducted: First, we identified significant biomarkers between sarcoidosis and healthy controls, and second identified markers comparing sarcoidosis to all other groups. At the threshold of an False Discovery Rate (FDR) < 0.01, we identified 14 clones in the first approach and 12 clones in the second approach discriminating sarcoidosis from other groups. We used the classifiers to build a naïve Bayes model on the training-set and validated it on an independent test-set. The first approach yielded an AUC of 0.947 using 14 significant clones with a sensitivity of 0.93 and specificity of 0.88, whereas the AUC of the second option was 0.92 with a sensitivity of 0.96 and specificity of 0.83. These results suggest robust classifier performance. Furthermore, we characterized the informative phage clones by sequencing and homology searches. Large numbers of classifier-clones were peptides involved in cellular trafficking and cytoskeletons. These results show that sarcoidosis is associated with a specific pattern of immunoreactivity that can discriminate it from other diseases.

Endothelial nitric oxide synthase-engineered mesenchymal stromal cells induce anti-inflammation in experimental immune models

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) remain an area of interest in the field of regenerative medicine. Although there is clear evidence of safety, a lack of substantial efficacy has led to many MSC-based clinical trials to stall in phase 1. Therefore, potentiating MSCs with biologically relevant messenger RNA (mRNA) transcripts presents a relatively safe and efficient way to increase functionality.

METHODS

In this study, human bone marrow-derived MSCs were transfected with endothelial nitric oxide synthase (eNOS) mRNA and evaluated for transfection efficiency and immunosuppressive ability. To assess MSC-eNOS functionality, T-cell proliferation assays and mouse models of experimental autoimmune encephalomyelitis and graft-versus-host disease were used.

RESULTS

The authors found that MSC-eNOS retained MSC characteristics and exhibited significantly enhanced immunosuppressive effects compared with naive MSCs in both in vitro and in vivo models.

CONCLUSIONS

It is feasible to pursue eNOS mRNA transfection to potentiate the immunomodulatory capacity of MSCs for clinical applications in the future.

Crotalphine Attenuates Pain and Neuroinflammation Induced by Experimental Autoimmune Encephalomyelitis in Mice

Multiple sclerosis (MS) is a demyelinating disease of inflammatory and autoimmune origin, which induces sensory and progressive motor impairments, including pain. Cells of the immune system actively participate in the pathogenesis and progression of MS by inducing neuroinflammation, tissue damage, and demyelination. Crotalphine (CRO), a structural analogue to a peptide firstly identified in Crotalus durissus terrificus snake venom, induces analgesia by endogenous opioid release and type 2 cannabinoid receptor (CB2) activation. Since CB2 activation downregulates neuroinflammation and ameliorates symptoms in mice models of MS, it was presently investigated whether CRO has a beneficial effect in the experimental autoimmune encephalomyelitis (EAE). CRO was administered on the 5th day after immunization, in a single dose, or five doses starting at the peak of disease. CRO partially reverted EAE-induced mechanical hyperalgesia and decreased the severity of the clinical signs. In addition, CRO decreases the inflammatory infiltrate and glial cells activation followed by TNF-α and IL-17 downregulation in the spinal cord. Peripherally, CRO recovers the EAE-induced impairment in myelin thickness in the sciatic nerve. Therefore, CRO interferes with central and peripheral neuroinflammation, opening perspectives to MS control.

Association of IL-17A Polymorphism with Chronic Periodontitis in Type 1 Diabetic Patients

STATEMENT OF THE PROBLEM

The association of genetic polymorphisms with periodontitis has been studied extensively. The interleukin -17 (IL-17) is a group of cytokines, which comprises six different molecules (IL-17A, B, C, D, E & F). Among these, IL-17A & F are the most commonly understood cytokine, which plays a critical role in inflammatory diseases and periodontal inflammation.

PURPOSE

To evaluate whether IL-17A gene polymorphism is associated with increased risk of chronic periodontitis in type 1 diabetes patients.

MATERIALS AND METHOD

This quantitative case- control study was carried out in 60 subjects in 4 groups. The study groups included group A: 15 type 1 diabetes patients (T1DM) with chronic periodontitis (CP), group B: 15 T1DM patients without CP, group C: 15 Non-diabetic patients with CP, group D: 15 Non-diabetic patients without CP. Blood samples were drawn from the subjects and analyzed for IL-17A polymorphism by using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

There was no statistical significant difference seen in the genotype distribution among CP patients with or without T1DM and healthy controls. Odds ratio and p value indicated that increased risks for CP were associated with IL-17A allele (G) in patients with T1DM. This allele was correlated with worse clinical parameters of CP in T1DM patients.

CONCLUSION

The present study revealed that IL-17A (rs2275913) polymorphism was not associated with increased risk for CP in T1DM patients.

From Messengers to Receptors in Psoriasis: The Role of IL-17RA in Disease and Treatment

The paradigm of psoriasis as a Th17-driven disease has evolved in the last years towards a much deeper knowledge of the complex pathways, mechanisms, cells, and messengers involved, highlighting the crucial role played by the IL-17 family of cytokines. All IL-17 isoforms signal through IL-17R. Five subunits of IL-17R have been described to date, which couple to form a homo- or hetero-receptor complex. Characteristically, IL-17RA is a common subunit in all hetero-receptors. IL-17RA has unique structural—containing a SEFIR/TILL domain—and functional—requiring ACT-1 for signaling—properties, enabling Th17 cells to act as a bridge between innate and adaptive immune cells. In psoriasis, IL-17RA plays a key role in pathogenesis based on: (a) IL-17A, IL-17F, and other IL-17 isoforms are involved in disease development; and (b) IL-17RA is essential for signaling of all IL-17 cytokines but IL-17D, whose receptor has not been identified to date. This article reviews current evidence on the biology and role of the IL-17 family of cytokines and receptors, with focus on IL-17RA, in psoriasis and some related comorbidities, and puts them in context with current and upcoming treatments.

Dynamic stromal cellular reaction throughout human colorectal adenoma-carcinoma sequence: A role of TH17/IL-17A

BACKGROUND

Accumulating data suggest that the tumour stroma rapidly undergoes dynamic mechanical and cellular changes by which creates a supportive milieu to promote disease progression and metastasis. Cytokines are reported to play a key role in the modulation of tumour stromal response.

METHODS

The activation of TH17/interleukin (IL)-17A network in association with tumour stromal proliferative and cellular response in samples from 50 patients with colorectal adenoma, 45 with colorectal cancer (CRCs) were elucidated with quantitative real-time PCR (q-PCR), immunohistochemistry and double immunofluorescence.

RESULTS

q-PCR results showed that retinoic acid-receptor-related orphan receptor-C, a critical transcriptional factor for TH17 cell differentiation, was significantly increased at the adenoma stage and slightly decreased at the CRC stage, but was still higher than that at normal controls. The level of TH17 signature cytokine IL-17A was shown in an increasing gradient throughout the adenoma-carcinoma sequence. Immunohistochemistry revealed an activated proliferative rate evaluated by Ki67 and population expansion of myofibroblasts in the adenoma/CRC stroma. Notably, densities of IL-17A-expressing cells were associated with populations of Ki67-positive cells and myofibroblasts in the adenoma/CRC stroma. Finally, CD146-positive stromal cells are an important participator for stroma remodelling, double immunofluorescence image demonstrated that IL-17 receptor C, one of the key elements for IL-17 receptor complex, was highly expressed in CD146-positive adenoma/CRC stromal cells.

CONCLUSIONS

An activated TH17/IL-17A network in the tumour microenvironment is significantly associated with dynamic stromal cellular response throughout the adenoma-carcinoma sequence, which might provide a supportive environment for the initiation and progression of CRC.

IL-17A expressed on neutrophil extracellular traps promotes mesenchymal stem cell differentiation toward bone-forming cells in ankylosing spondylitis

Ankylosing spondylitis (AS) is an inflammatory disease characterized by excessive bone formation. We investigated the presence of neutrophil extracellular traps (NETs) in AS and how they are involved in the osteogenic capacity of bone marrow mesenchymal stem cells (MSCs) through interleukin-17A (IL-17A). Peripheral neutrophils and sera were obtained from patients with active AS and healthy controls. NET formation and neutrophil/NET-associated proteins were studied using immunofluorescence, immunoblotting, qPCR, and ELISA. In vitro co-culture systems of AS NET structures and MSCs isolated from controls were deployed to examine the role of NETs in the differentiation of MSCs toward osteogenic cells. Analysis was performed using specific staining and qPCR. Neutrophils from patients with AS were characterized by enhanced formation of NETs carrying bioactive IL-17A and IL-1β. IL-17A-enriched AS NETs mediated the differentiation of MSCs toward bone-forming cells. The neutrophil expression of IL-17A was positively regulated by IL-1β. Blocking IL-1β signaling on neutrophils with anakinra or dismantling NETs using DNase-I disrupted osteogenesis driven by IL-17A-bearing NETs. These findings propose a novel role of neutrophils in AS-related inflammation, linking IL-17A-decorated NETs with the differentiation of MSCs toward bone-forming cells. Moreover, IL-1β triggers the expression of IL-17A on NETs offering an additional therapeutic target in AS.

The ATP synthase inhibition induces an AMPK-dependent glycolytic switch of mesenchymal stem cells that enhances their immunotherapeutic potential

Objectives: Mesenchymal Stem/Stromal Cells (MSC) are promising therapeutic tools for inflammatory diseases due to their potent immunoregulatory capacities. Their suppressive activity mainly depends on inflammatory cues that have been recently associated with changes in MSC bioenergetic status towards a glycolytic metabolism. However, the molecular mechanisms behind this metabolic reprogramming and its impact on MSC therapeutic properties have not been investigated.

Methods: Human and murine-derived MSC were metabolically reprogramed using pro-inflammatory cytokines, an inhibitor of ATP synthase (oligomycin), or 2-deoxy-D-glucose (2DG). The immunosuppressive activity of these cells was tested in vitro using co-culture experiments with pro-inflammatory T cells and in vivo with the Delayed-Type Hypersensitivity (DTH) and the Graph versus Host Disease (GVHD) murine models.

Results: We found that the oligomycin-mediated pro-glycolytic switch of MSC significantly enhanced their immunosuppressive properties in vitro. Conversely, glycolysis inhibition using 2DG significantly reduced MSC immunoregulatory effects. Moreover, in vivo, MSC glycolytic reprogramming significantly increased their therapeutic benefit in the DTH and GVHD mouse models. Finally, we demonstrated that the MSC glycolytic switch effect partly depends on the activation of the AMPK signaling pathway.

Conclusion: Altogether, our findings show that AMPK-dependent glycolytic reprogramming of MSC using an ATP synthase inhibitor contributes to their immunosuppressive and therapeutic functions, and suggest that pro-glycolytic drugs might be used to improve MSC-based therapy.

Mesenchymal Stem Cells in Multiple Sclerosis: Recent Evidence from Pre-Clinical to Clinical Studies

Multiple sclerosis (MS) is an autoimmune, demyelinating disease of the central nervous system. Nowadays, available therapies for MS can help to manage MS course and symptoms, but new therapeutic approaches are required. Stem cell therapy using mesenchymal stem cells (MSCs) appeared promising in different neurodegenerative conditions, thanks to their beneficial capacities, including the immunomodulation ability, and to their secretome. The secretome is represented by growth factors, cytokines, and extracellular vesicles (EVs) released by MSCs. In this review, we focused on studies performed on in vivo MS models involving the administration of MSCs and on clinical trials evaluating MSCs administration. Experimental models of MS evidenced that MSCs were able to reduce inflammatory cell infiltration and disease score. Moreover, MSCs engineered to express different genes, preconditioned with different compounds, differentiated or in combination with other compounds also exerted beneficial actions in MS models, in some cases also superior to native MSCs. Secretome, both conditioned medium and EVs, also showed protective effects in MS models and appeared promising to develop new approaches. Clinical trials highlighted the safety and feasibility of MSC administration and reported some improvements, but other trials using larger cohorts of patients are needed.

Burns Impair Blood-Brain Barrier and Mesenchymal Stem Cells Can Reverse the Process in Mice

Neurological syndromes are observed in numerous patients who suffer burns, which add to the economic burden of societies and families. Recent studies have implied that blood-brain barrier (BBB) dysfunction is the key factor that induces these central nervous system (CNS) syndromes in peripheral traumatic disease, e.g., surgery and burns. However, the effect of burns on BBB and the underlying mechanism remains, largely, to be determined. The present study aimed to investigate the effect of burns on BBB and the potential of umbilical cord-derived mesenchymal stem cells (UC-MSCs), which have strong anti-inflammatory and repairing ability, to protect the integrity of BBB. BBB permeability was evaluated using dextran tracer (immunohistochemistry imaging and spectrophotometric quantification) and western blot, interleukin (IL)-6, and IL-1β levels in blood and brain were measured by enzyme-linked immunosorbent assay. Furthermore, transmission electron microscopy (TEM) was used to detect transcellular vesicular transport (transcytosis) in BBB. We found that burns increased mouse BBB permeability to both 10-kDa and 70-kDa dextran. IL-6 and IL-1β levels increased in peripheral blood and CNS after burns. In addition, burns decreased the level of tight junction proteins (TJs), including claudin-5, occludin, and ZO-1, which indicated increased BBB permeability due to paracellular pathway. Moreover, increased vesicular density after burns suggested increased transcytosis in brain microvascular endothelial cells. Finally, administering UC-MSCs at 1 h after burns effectively reversed these adverse effects and protected the integrity of BBB. These results suggest that burns increase BBB permeability through both paracellular pathway and transcytosis, the potential mechanism of which might be through increasing IL-6 and IL-1β levels and decreasing Mfsd2a level, and appropriate treatment with UC-MSCs can reverse these effects and protect the integrity of BBB after burns.

Microarray-based transcriptional profiling of a mouse model of autoimmune hepatitis

Long noncoding RNAs (lncRNAs) are RNA molecules longer than 200 nucleotides that do not typically code for a protein. lncRNAs have regulatory roles in many physiological processes, and their dysregulation can contribute to cancer, cardiovascular and neurodegenerative diseases, as well as the onset of autoimmune diseases, including systemic lupus erythematosus and rheumatoid arthritis. However, lncRNA expression changes in autoimmune hepatitis (AIH), a form of inflammation induced by immunological tolerance disorders, are poorly understood. Here, for the first time to our knowledge, we used microarrays to profile 1161 differentially expressed lncRNAs (DELs; 608 up‐ and 553 down‐regulated) and 11 512 differentially expressed mRNAs (DEMs; 5189 up‐ and 6323 down‐ regulated) in a concanavalin A‐induced AIH mouse model. We used quantitative real‐time PCR to confirm the expression of eight DELs and DEMs, and analyzed the coexpression relationship between them. Potential biological functions of screened DELs and DEMs were predicted with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. DEL‐DEM interaction networks were also constructed. Our study revealed the roles of DELs and DEMs in the pathogenesis of AIH. We also provided potential candidate biomarkers that may have potential for future development into possible diagnostics or as a treatment for this disorder.

Immunocytometric analysis of COVID patients: A contribution to personalized therapy?

AIMS

This study aims to cast light on immunocytometric alterations in COVID-19, a potentially fatal viral infection with heterogeneous clinical expression and a not completely defined pathophysiology.

METHODS

We studied 35 COVID patients at hospital admission testing by cytofluorimetry a large panel of lymphocyte subpopulations and serum tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-17A and the soluble receptor of IL-17A (IL-17RA).

KEY FINDINGS

At hospital admission, total lymphocytes and most T and B subpopulations were reduced in 50-80% of patients, with close relationship to disease severity. While activated T helper 1 (TH1) and TH17 cells resulted normal or higher. Serum IL-6 was increased in all patients, while TNF-α and IL-17A were higher in advanced stages. A patient subset with low severity had very high IL-17RA levels. Tocilizumab treatment caused an increase of IL-17A in 3/6 patients and a reduction in 3 others, while the lymphocyte number increased in 3 patients and did not change in the others.

SIGNIFICANCE

Cytofluorimetry revealed a functional exhaustion of most lymphocyte populations in COVID patients not involving activated TH1 and TH17. Consequently, there was a relevant cytokines production that contributes to impair the respiratory inflammation. The increase of TH17 and IL-17 in a subset of cases and the evidence of a significant increase of IL-17RA (that prevents the interaction of IL-17 with the cell receptor) in patients with low severity suggest that some patients could benefit from monoclonal antibodies treatment targeting IL-17 pathway. Immunocytofluorimetric markers may contribute to a personalized therapy in COVID patients.

Mechanisms behind the Immunoregulatory Dialogue between Mesenchymal Stem Cells and Th17 Cells

Mesenchymal stem cells (MSCs) exhibit potent immunoregulatory abilities by interacting with cells of the adaptive and innate immune system. In vitro, MSCs inhibit the differentiation of T cells into T helper 17 (Th17) cells and repress their proliferation. In vivo, the administration of MSCs to treat various experimental inflammatory and autoimmune diseases, such as rheumatoid arthritis, type 1 diabetes, multiple sclerosis, systemic lupus erythematosus, and bowel disease showed promising therapeutic results. These therapeutic properties mediated by MSCs are associated with an attenuated immune response characterized by a reduced frequency of Th17 cells and the generation of regulatory T cells. In this manuscript, we review how MSC and Th17 cells interact, communicate, and exchange information through different ways such as cell-to-cell contact, secretion of soluble factors, and organelle transfer. Moreover, we discuss the consequences of this dynamic dialogue between MSC and Th17 well described by their phenotypic and functional plasticity.

PPARβ/δ-dependent MSC metabolism determines their immunoregulatory properties

Mesenchymal stem cell (MSC)-based therapy is being increasingly considered a powerful opportunity for several disorders based on MSC immunoregulatory properties. Nonetheless, MSC are versatile and plastic cells that require an efficient control of their features and functions for their optimal use in clinic. Recently, we have shown that PPARβ/δ is pivotal for MSC immunoregulatory and therapeutic functions. However, the role of PPARβ/δ on MSC metabolic activity and the relevance of PPARβ/δ metabolic control on MSC immunosuppressive properties have never been addressed. Here, we demonstrate that PPARβ/δ deficiency forces MSC metabolic adaptation increasing their glycolytic activity required for their immunoregulatory functions on Th1 and Th17 cells. Additionally, we show that the inhibition of the mitochondrial production of ATP in MSC expressing PPARβ/δ, promotes their metabolic switch towards aerobic glycolysis to stably enhance their immunosuppressive capacities significantly. Altogether, these data demonstrate that PPARβ/δ governs the immunoregulatory potential of MSC by dictating their metabolic reprogramming and pave the way for enhancing MSC immunoregulatory properties and counteracting their versatility.

HIF1α-dependent metabolic reprogramming governs mesenchymal stem/stromal cell immunoregulatory functions

Hypoxia-inducible factor 1 α (HIF1α), a regulator of metabolic change, is required for the survival and differentiation potential of mesenchymal stem/stromal cells (MSC). Its role in MSC immunoregulatory activity, however, has not been completely elucidated. In the present study, we evaluate the role of HIF1α on MSC immunosuppressive potential. We show that HIF1α silencing in MSC decreases their inhibitory potential on Th1 and Th17 cell generation and limits their capacity to generate regulatory T cells. This reduced immunosuppressive potential of MSC is associated with a metabolic switch from glycolysis to OXPHOS and a reduced capacity to express or produce some immunosuppressive mediators including Intercellular Adhesion Molecule (ICAM), IL-6, and nitric oxide (NO). Moreover, using the Delayed-Type Hypersensitivity murine model (DTH), we confirm, in vivo, the critical role of HIF1α on MSC immunosuppressive effect. Indeed, we show that HIF1α silencing impairs MSC capacity to reduce inflammation and inhibit the generation of pro-inflammatory T cells. This study reveals the pivotal role of HIF1α on MSC immunosuppressive activity through the regulation of their metabolic status and identifies HIF1α as a novel mediator of MSC immunotherapeutic potential.

Progressive multiple sclerosis: from pathophysiology to therapeutic strategies

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that involves demyelination and axonal degeneration. Although substantial progress has been made in drug development for relapsing-remitting MS, treatment of the progressive forms of the disease, which are characterized clinically by the accumulation of disability in the absence of relapses, remains unsatisfactory. This unmet clinical need is related to the complexity of the pathophysiological mechanisms involved in MS progression. Chronic inflammation, which occurs behind a closed blood-brain barrier with activation of microglia and continued involvement of T cells and B cells, is a hallmark pathophysiological feature. Inflammation can enhance mitochondrial damage in neurons, which, consequently, develop an energy deficit, further reducing axonal health. The growth-inhibitory and inflammatory environment of lesions also impairs remyelination, a repair process that might protect axons from degeneration. Moreover, neurodegeneration is accelerated by the altered expression of ion channels on denuded axons. In this Review, we discuss the current understanding of these disease mechanisms and highlight emerging therapeutic strategies based on these insights, including those targeting the neuroinflammatory and degenerative aspects as well as remyelination-promoting approaches.