The effects of Cyclosporine A and azathioprine on human T cells activated by different costimulatory signals

Cyclosporine: Immunosuppressive effects, entwined toxicity, and clinical modulations of an organ transplant drug

The discovery and use of cyclosporine since its inception into the clinics in the '70s and up have played a crucial role in advancing transplant therapy, and containment of the immune-based rejections. The drug has improved the high rates of acute rejections and has supported early graft survival. However, the long-term survival of renal allografts is still less prevalent, and an in-depth analysis, as well as reported findings led us to believe that there is a chronic irreversible component to the drug, that is tackled through its metabolites, and that causes toxicity, which has led to new therapies, including monoclonal antibody-based medications. A recap of the immunosuppressive effects, and entwined toxicity of the drug, now relegated primarily to bone marrow early transplants, is being overviewed for the past protocols that were used to minimize, and avoid, or use this calcineurin inhibitor class of drug, cyclosporine, in combination with other drugs. The current review circumvents the cyclosporine's mechanism of action, pathophysiology, cytochrome roles, and other factors associated with acute and chronic toxicity developments. The review also attempts to find conclusive strategies reported in the recent studies to avoid its toxic side effects, and develop a safe-use strategy for the drug. Gastrointestinal decontamination, supporting the airway, monitoring for signs of respiratory insufficiency, monitoring for severe reactions, such as seizures, need for administration of oxygen, and avoiding the administration of drugs, that increase the blood levels of the cyclosporine, are beneficial interventions, when encountering cyclosporine toxicity cases. The constrained therapeutic outcomes have also led to redesign, and making use of combined formulations to reassess the pharmacokinetics of the drug.

Nonspecific Orbital Inflammation (NSOI): Unraveling the Molecular Pathogenesis, Diagnostic Modalities, and Therapeutic Interventions

Nonspecific orbital inflammation (NSOI), colloquially known as orbital pseudotumor, sometimes presents a diagnostic and therapeutic challenge in ophthalmology. This review aims to dissect NSOI through a molecular lens, offering a comprehensive overview of its pathogenesis, clinical presentation, diagnostic methods, and management strategies. The article delves into the underpinnings of NSOI, examining immunological and environmental factors alongside intricate molecular mechanisms involving signaling pathways, cytokines, and mediators. Special emphasis is placed on emerging molecular discoveries and approaches, highlighting the significance of understanding molecular mechanisms in NSOI for the development of novel diagnostic and therapeutic tools. Various diagnostic modalities are scrutinized for their utility and limitations. Therapeutic interventions encompass medical treatments with corticosteroids and immunomodulatory agents, all discussed in light of current molecular understanding. More importantly, this review offers a novel molecular perspective on NSOI, dissecting its pathogenesis and management with an emphasis on the latest molecular discoveries. It introduces an integrated approach combining advanced molecular diagnostics with current clinical assessments and explores emerging targeted therapies. By synthesizing these facets, the review aims to inform clinicians and researchers alike, paving the way for molecularly informed, precision-based strategies for managing NSOI.

Systemic Inflammatory Disorders, Immunosuppressive Treatment and Increase Risk of Head and Neck Cancers-A Narrative Review of Potential Physiopathological and Biological Mechanisms

Head and neck cancers (HNCs) are known to present multiple factors likely to influence their development. This review aims to provide a comprehensive overview of the current scientific literature on the interplay between systemic inflammatory disorders, immunosuppressive treatments and their synergistic effect on HNC risk. Both cell-mediated and humoral-mediated systemic inflammatory disorders involve dysregulated immune responses and chronic inflammation and these inflammatory conditions have been associated with an increased risk of HNC development, primarily in the head and neck region. Likewise, the interaction between systemic inflammatory disorders and immunosuppressive treatments appears to amplify the risk of HNC development, as chronic inflammation fosters a tumor-promoting microenvironment, while immunosuppressive therapies further compromise immune surveillance and anti-tumor immune responses. Understanding the molecular and cellular mechanisms underlying this interaction is crucial for developing targeted prevention strategies and therapeutic interventions. Additionally, the emerging field of immunotherapy provides potential avenues for managing HNCs associated with systemic inflammatory disorders, but further research is needed to determine its efficacy and safety in this specific context. Future studies are warranted to elucidate the underlying mechanisms and optimize preventive strategies and therapeutic interventions.

Intermittent administration of tacrolimus enhances anti-tumor immunity in melanoma-bearing mice

One key reason for T cell exhaustion is continuous antigen exposure. Early exhausted T cells can reverse exhaustion and differentiate into fully functional memory T cells if removed from persisting antigen stimulation. Therefore, this study viewed T cell exhaustion as an over-activation status induced by chronic antigen stimuli. This study hypothesized that blocking TCR signal intermittently to terminate over-activation signal can defer the developmental process of T cell exhaustion. In this study, melanoma-bearing mice were treated with tacrolimus (FK506) every five days. The tumor size and tumor-infiltrating lymphocytes (TILs) were analyzed. We found that intermittent administration of tacrolimus significantly inhibited tumor growth, and this effect was mediated by CD8+T cells. Intermittent tacrolimus treatment facilitated the infiltration of CD8+TILs. RNA-seq and quantitative RT-PCR of sorted CD8+TILs showed the expression of Nr4a1 (an exhaustion-related transcription factor) and Ctla4 (a T cell inhibitory receptor) was remarkably downregulated. These results indicated that intermittently blocking TCR signal by tacrolimus can promote anti-tumor immunity and inhibit the tumor growth in melanoma-bearing mice, inhibiting the transcription of several exhaustion-related genes, such as Nr4a1 and Ctla4.

Improving Right Ventricular Function by Increasing BMP Signaling with FK506

Right ventricular (RV) function is the predominant determinant of survival in patients with pulmonary arterial hypertension (PAH). In preclinical models, pharmacological activation of BMP (bone morphogenetic protein) signaling with FK506 (tacrolimus) improved RV function by decreasing RV afterload. FK506 therapy further stabilized three patients with end-stage PAH. Whether FK506 has direct effects on the pressure-overloaded right ventricle is yet unknown. We hypothesized that increasing cardiac BMP signaling with FK506 improves RV structure and function in a model of fixed RV afterload after pulmonary artery banding (PAB). Direct cardiac effects of FK506 on the microvasculature and RV fibrosis were studied after surgical PAB in wild-type and heterozygous Bmpr2 mutant mice. RV function and strain were assessed longitudinally via cardiac magnetic resonance imaging during continuous FK506 infusion. Genetic lineage tracing of endothelial cells (ECs) was performed to assess the contribution of ECs to fibrosis. Molecular mechanistic studies were performed in human cardiac fibroblasts and ECs. In mice, low BMP signaling in the right ventricle exaggerated PAB-induced RV fibrosis. FK506 therapy restored cardiac BMP signaling, reduced RV fibrosis in a BMP-dependent manner independent from its immunosuppressive effect, preserved RV capillarization, and improved RV function and strain over the time course of disease. Endothelial mesenchymal transition was a rare event and did not significantly contribute to cardiac fibrosis after PAB. Mechanistically, FK506 required ALK1 in human cardiac fibroblasts as a BMPR2 co-receptor to reduce TGFβ1-induced proliferation and collagen production. Our study demonstrates that increasing cardiac BMP signaling with FK506 improves RV structure and function independent from its previously described beneficial effects on pulmonary vascular remodeling.

The evolving role of allogeneic haematopoietic cell transplantation in the era of chimaeric antigen receptor T-cell therapy

Chimaeric antigen receptor T-cell (CAR T) therapy has revolutionized the management of many haematological malignancies. It is associated with impressive disease responses in relapsed or refractory high-grade B-cell non-Hodgkin lymphoma (B-NHL) and acute lymphoblastic leukaemia (B-ALL) with durable remissions in a subset of patients. Historically, haematopoietic cell transplantation (HCT) has been the standard consolidation strategy for many of these patients who are now being treated with CAR T. Relapses are frequent after CD19 CAR T therapy in B-ALL and consolidation with allogeneic HCT (allo-HCT) may improve survival of patients with high-risk disease. There appears to be a clear difference in B-ALL outcomes between paediatric and adult patients, with the latter having a much higher risk of relapse after CAR T therapy. Late relapses are infrequent in patients with B-NHL and consolidation with allo-HCT may not be needed in patients who achieve a complete remission after CAR T therapy. Future registry-based and prospective studies will hopefully provide the needed data in the future to risk-stratify the recipients of CAR T therapy. Meanwhile, we provide guidance on patient selection and practical issues with performing allo-HCT after CAR T therapy.

Impact of immunosuppressive and antifungal drugs on PBMC- and whole blood-based flow cytometric CD154+ Aspergillus fumigatus specific T-cell quantification

Flow cytometric quantification of CD154⁺ mould specific T-cells in antigen-stimulated peripheral blood mononuclear cells (PBMCs) or whole blood has been described as a supportive biomarker to diagnose invasive mould infections and to monitor therapeutic outcomes. As patients at risk frequently receive immunosuppressive and antifungal medication, this study compared the matrix-dependent impact of representative drugs on CD154⁺ T-cell detection rates. PBMCs and whole blood samples from healthy adults were pre-treated with therapeutic concentrations of liposomal amphotericin B, voriconazole, posaconazole, cyclosporine A (CsA) or prednisolone. Samples were then stimulated with an Aspergillus fumigatus lysate or a viral antigen cocktail (CPI) and assessed for CD154⁺ T-helper cell frequencies. Specific T-cell detection rates and technical assay properties remained largely unaffected by exposure of both matrices to the studied antifungals. By contrast, CsA and prednisolone pre-treatment of isolated PBMCs and whole blood adversely impacted specific T-cell detection rates and caused elevated inter-replicate variation. Unexpectedly, the whole blood-based protocol that uses additional α-CD49d co-stimulation was less susceptible to CsA and prednisolone despite prolonged drug exposure in the test tube. Accordingly, addition of α-CD49d during PBMC stimulation partially attenuated the impact of immunosuppressive drugs on test performance. Translating these results into the clinical setting, false-negative results of CD154⁺ antigen-specific T-cell quantification need to be considered in patients receiving T-cell-active immunosuppressive medication. Optimized co-stimulation regimes with α-CD49d could contribute to an improved feasibility of functional T-cell assays in immunocompromised patient populations.

Risk of tuberculosis reactivation associated with traditional disease modifying anti-rheumatic drugs and non-anti-tumor necrosis factor biologics in patients with rheumatic disorders and suggestion for clinical practice

INTRODUCTION

Two classes of biologics, anti-tumor necrosis factor (TNF) and non-anti-TNF targeted, are currently available for the treatment of rheumatic diseases.

AREAS COVERED

Discussion on the need for LTBI diagnosis in rheumatic patients treated csDMARDs and non-anti-TNFs through a review of the literature. The literature, updated to 15 April 2019, on tuberculosis (TB) reactivation risk in patients exposed to conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and non-anti-TNF biologics was reviewed.

EXPERT OPINION

An increased risk of TB reactivation in patients receiving csDMARDs (except sulphasalazine) resulted, while a review of clinical trials, and Periodic Safety Update Reports from pharmaceutical Companies evidenced a very low or absent risk for non-anti-TNF biologics. Hence, a contradiction emerges considering that latent TB infection (LTBI) screening is recommended for non-anti-TNF candidates but not for csDMARDs. Concerning the low TB incidence countries, several actions could be undertaken, including to screen all patients independently on the treatment, to omit the procedure in non-anti-TNF candidates, or to perform the LTBI investigations only in high-risk patients. According to WHO guidelines, LTBI screening in low TB risk countries seems unnecessary, except in high TB risk subjects.

Transplantation of Human Neural Progenitor Cells Reveals Structural and Functional Improvements in the Spastic Han-Wistar Rat Model of Ataxia

The use of regenerative medicine to treat nervous system disorders like ataxia has been proposed to either replace or support degenerating neurons. In this study, we assessed the ability of human neural progenitor cells (hNPCs) to repair and restore the function of dying neurons within the spastic Han-Wistar rat (sHW), a model of ataxia. The sHW rat suffers from neurodegeneration of specific neurons, including cerebellar Purkinje cells and hippocampal CA3 pyramidal cells leading to the observed symptoms of forelimb tremor, hind-leg rigidity, gait abnormality, motor incoordination, and a shortened life span. To alleviate the symptoms of neurodegeneration and to replace or augment dying neurons, neuronal human progenitor cells were implanted into the sHW rats. At 30 d of age, male sHW mutant rats underwent subcutaneous implantation of an Alzet osmotic pump that infused cyclosporine (15 mg/kg/d) used to suppress the rat's immune system. At 40 d, sHW rats received bilateral injections (500,000 cells in 5 µL media) of live hNPCs, dead hNPCs, live human embryonic kidney cells, or growth media either into the cerebellar cortex or into the hippocampus. To monitor results, motor activity scores (open-field testing) and weights of the animals were recorded weekly. The sHW rats that received hNPC transplantation into the cerebellum, at 60 d of age, displayed significantly higher motor activity scores and sustained greater weights and longevities than control-treated sHW rats or any hippocampal treatment group. In addition, cerebellar histology revealed that the transplanted hNPCs displayed signs of migration and signs of neuronal development in the degenerated Purkinje cell layer. This study revealed that implanted human progenitor cells reduced the ataxic symptoms in the sHW rat, identifying a future clinical use of these progenitor cells against ataxia and associated neurodegenerative diseases.

Description of the immune microenvironment of chondrosarcoma and contribution to progression

Chondrosarcoma (CHS) is a rare bone malignancy characterized by its resistance to conventional systemic and radiation therapies. Whether immunotherapy targeting immune checkpoints may be active in these tumors remains unknown. To explore the role of the immune system in this tumor, we analyzed the immune environment of chondrosarcomas both in human sample, and in a syngeneic rat model, and tested the contribution of T lymphocytes and macrophages in chondrosarcoma progression. Immunohistochemical stainings were performed on human chondrosarcoma samples and on Swarm rat chondrosarcoma (SRC) model. Selective immunodepletion assays were performed in SRC to evaluate immune population's involvement in tumor progression. In human and rat chondrosarcoma, immune infiltrates composed of lymphocytes and macrophages were identified in the peritumoral area. Immune infiltrates composition was found correlated with tumors characteristics and evolution (grade, invasiveness and size). In SRC, selective depletion of T lymphocytes resulted in an accelerated growth rates, whereas depletion of CD163⁺ macrophages slowed down tumor progression. Splenocytes isolated from CHS-bearing SRC showed a specific cytotoxicity directed against chondrosarcoma cells (27%), which significantly decreased in CD3-depleted SRC (11%). The immune environment contributes to CHS progression in both human and animal models, suggesting that immunomodulatory approaches could be tested in bone chondrosarcoma.

Psoriasis, psoriatic arthritis, and rheumatoid arthritis: Is all inflammation the same?

OBJECTIVES

To review the pathophysiology, co-morbidities, and therapeutic options for psoriasis, psoriatic arthritis and rheumatoid arthritis in order to further understand the similarities and differences in treatment paradigms in the management of each disease. New targets for individualized therapeutic decisions are also identified with the aim of improving therapeutic outcome and reducing toxicity.

SEARCH STRATEGY

Using the PubMed database, we searched literature published from 2000 to 2015 using combinations of the key words "psoriasis," "psoriatic arthritis," "rheumatoid arthritis," "pathogenesis," "immunomodulation," and "treatment."

INCLUSION AND EXCLUSION CRITERIA

This was a non-systematic review and there were no formal inclusion and exclusion criteria.

DATA EXTRACTION

Abstracts identified in the search were screened for relevance and articles considered appropriate evaluated further. References within these selected articles were also screened. Information was extracted from 198 articles for inclusion in this report.

DATA SYNTHESIS

There was no formal data synthesis. Articles were reviewed and summarized according to disease area (psoriasis, psoriatic arthritis, and rheumatoid arthritis).

HEADLINE RESULTS

The pathophysiology of psoriasis, psoriatic arthritis, and rheumatoid arthritis involves chronic inflammation mediated by pro-inflammatory cytokines. Dysfunction in integrated signaling pathways affecting different constituents of the immune system result in varying clinical features in the three diseases. Co-morbidities, including cardiovascular disease, malignancies, and non-alcoholic fatty liver disease are increased. Increased understanding of the immunopathogenesis allowed development of targeted treatments; however, despite a variety of potentially predictive genetic, protein and cellular biomarkers, there is still significant unmet need in these three inflammatory disorders.

Efficacy of Two Delivery Routes for Transplanting Human Neural Progenitor Cells (NPCs) Into the Spastic Han-Wistar Rat, a Model of Ataxia

An emerging avenue for recalcitrant neurodegenerative disease treatment is neural progenitor cell (NPC) transplantation. In this study, we investigated the effectiveness of two different delivery routes of human-derived NPC inoculation: injection into the common carotid artery or unilateral stereotactic implantation into the degenerating cerebellum and hippocampus of spastic Han-Wistar (sHW) rats, a model of ataxia. At 30 days of age, sHW mutants were implanted with osmotic pumps preloaded with cyclosporine. Ten days after pump implantation, the animals were given either 3,000,000 live human-derived NPCs (hNPCs; n = 12) or 3,000,000 dead NPCs (dNPCs; n = 12) injected into the common carotid artery, or were given two unilateral implantations of 500,000 hNPCs into the cerebellum and 500,000 hNPCs into the hippocampus of each sHW rat (n = 12) or 500,000 dNPCs by unilateral implantation into the cerebellum and hippocampus (n = 12). We also compared treated sHW rats to untreated sHW rats: normal rats (n = 12) and sibling sHW rats (n = 12). Motor activity and animal weights were monitored every 5 days to ascertain effectiveness of the two types of delivery methods compared to the untreated mutant and normal animals. Mutant rats with hNPC implantations, but not dNPC or carotid artery injections, showed significant deceleration of motor deterioration (p < 0.05). These mutants with hNPC implantations also retained weight longer than dNPC mutants did (p < 0.05). At the end of the experiment, animals were sacrificed for histological evaluation. Using fluorescent markers (Qtracker) incorporated into the hNPC prior to implantation and human nuclear immunostaining, we observed few hNPCs in the brains of carotid artery-injected mutants. However, significant numbers of surviving hNPCs were seen using these techniques in mutant cerebellums and hippocampi implanted with hNPC. Our results show that direct implantation of hNPCs reduced ataxic symptoms in the sHW rat, demonstrating that stereotactic route of stem cell delivery correlates to improved clinical outcomes.

Assessment of costimulation and coinhibition in a triple parameter T cell reporter line: Simultaneous measurement of NF-κB, NFAT and AP-1

Engagement of the T cell receptor complex reprograms T cells for proliferation, cytokine production and differentiation towards effector cells. This process depends on activating costimulatory signals and is counteracted by coinhibitory molecules. Three transcription factors, namely NF-κB, NFAT and AP-1, have a major role in inducing the transcriptional program that is required for T cell activation and differentiation. Here we describe the generation of a triple parameter reporter based on the human Jurkat T cell line, where response elements for NF-κB, NFAT and AP-1 drive the expression of the fluorescent proteins CFP, eGFP and mCherry, respectively. The emission spectra of these proteins allow simultaneous assessment of NF-κB, NFAT and AP-1 activity in response to stimulation. Ligation of the TCR complex induced moderate reporter activity, which was strongly enhanced upon coengagement of the costimulatory receptors CD2 or CD28. Moreover, we have generated and tested triple parameter reporter cells that harbor costimulatory and inhibitory receptors not endogenously expressed in the Jurkat cells. In these experiments we could show that engagement of the costimulatory molecule 4-1BB enhances NF-κB and AP-1 activity, whereas coinhibition via PD-1 or BTLA strongly reduced the activation of NF-κB and NFAT. Engagement of BTLA significantly inhibited AP-1, whereas PD-1 had little effect on the activation of this transcription factor. Our triple parameter reporter T cell line is an excellent tool to assess the effect of costimulatory and coinhibitory receptors on NF-κB, NFAT and AP-1 activity and has a wide range of applications beyond the evaluation of costimulatory pathways.

Phenotype modifications of T-cells and their shift toward a Th2 response in patients with systemic lupus erythematosus supplemented with different monthly regimens of vitamin D

BACKGROUND

Vitamin D receptor is constitutively expressed on the lymphocyte surface. Recent studies highlight that vitamin D may exert actions on T-cells, inhibiting Th1 and Th17 response and enhancing Th2 and T-regulatory (T-reg) function.

METHODS

Thirty-four patients with systemic lupus erythematosus (SLE) were randomly enrolled in a two-year prospective study. In the first year, 16 patients were supplemented with an intensive regimen of cholecalciferol (IR) (300.000 UI of cholecalciferol at baseline and 50.000 UI/monthly as maintenance, 850.000 UI annually), whereas 18 with a standard regimen (SR) (25.000 UI of cholecalciferol monthly, 300.000 UI annually). During the second year, patients were switched to the other arm of treatment. Phenotypic analysis of peripheral T lymphocyte and the quantification of cytokine production from peripheral blood mononuclear cells (PBMCs) were evaluated by flow cytometry.

RESULTS

At baseline, no significant difference between the two groups emerged among main T-cell subtypes. Over two years of treatment, we saw an increase in the number of T-reg cells, in the total amount of CD4+CD45RA+CCR7- T-cells, whereas a significant reduction of CD8+CD28- T-cells was observed. In addition, the analysis of PBMCs from eight patients following the IR showed the reduction of the IFN-γ/IL-4 ratio (p = 0.01) among CD8+ T-cells after 12 months.

CONCLUSIONS

After a long-term of monthly treatment with vitamin D in SLE patients, an enhancement of T-reg cells and the production of Th2 cytokines should be expected.

The tryptophan metabolite picolinic acid suppresses proliferation and metabolic activity of CD4+ T cells and inhibits c-Myc activation

Tryptophan metabolites, including kynurenine, 3-hydroxyanthranilic acid, and picolinic acid, are key mediators of immunosuppression by cells expressing the tryptophan-catabolizing enzyme indoleamine2,3-dioxygenase. In this study, we assessed the influence of picolinic acid on cell viability and effector functions of CD4(+)T cells following in vitro activation with agonistic anti-CD3/anti-CD28 antibodies. In contrast to kynurenine and 3-hydroxyanthranilic acid, exposure of T cells with picolinic acid did not affect cell viability, whereas proliferation and metabolic activity were suppressed in a dose-dependent manner. On the other hand, cytokine secretion and up-regulation of cell surface activation markers were not or only weakly inhibited by picolinic acid. Picolinic acid exposure induced a state of deep anergy that could not be overcome by the addition of exogenous IL-2 and inhibited Th cell polarization. On the molecular level, important upstream signaling molecules, such as the MAPKs ERK and p38 and the mammalian target of rapamycin target protein S6 ribosomal protein, were not affected by picolinic acid. Likewise, NFAT, NF-κB, and AP-1 promoter activity in Jurkat T cells was not influenced by exposure to picolinic acid. Whereas transcriptional levels of v-myc avian myelocytomatosis viral oncogene homolog were not affected by picolinic acid, phosphorylation at Ser62 was strongly reduced in picolinic acid-exposed T cells following activation. In conclusion, picolinic acid mediates a unique immunosuppressive program in T cells, mainly inhibiting cell cycle and metabolic activity, while leaving other effector functions intact. These functional features are accompanied by reduced phosphorylation of v-myc avian myelocytomatosis viral oncogene homolog. It remains to be determined whether this effect is mediated by direct inhibition of ERK activity or whether indirect mechanisms apply.

Cyclosporine A increases hair follicle growth by suppressing apoptosis-inducing factor nuclear translocation: a new mechanism

Cyclosporine A (CsA) enhances hair growth through caspase-dependent pathways by retarding anagen-to-catagen phase transition in the hair follicle growth cycle. Whether apoptosis-inducing factor (AIF), a protein that induces caspase-independent apoptosis, can regulate the hair follicle cycle in response to CsA is currently unclear. Here, we show that the pro-hair growth properties of CsA are in part due to blockage of AIF nuclear translocation. We first isolate hair follicles from murine dorsal skin. We then used Western blot, immunohistochemistry and immunofluorescence to evaluate the expression and localization of AIF in hair follicles. We also determined whether modulation of AIF was responsible for the effects of CsA at the anagen-to-catagen transition. AIF was expressed in hair follicles during the anagen, catagen and telogen phases. There was significant nuclear translocation of AIF as hair follicles transitioned from anagen to late catagen phase; this was inhibited by CsA, likely due to reduced cyclophilin A expression and attenuated AIF release from mitochondria. However, we note that AIF translocation was not completely eliminated, which likely explains why the transition to catagen phase was severely retarded by CsA, rather than being completely inhibited. We speculate that blockade of the AIF signalling pathway is a critical event required for CsA-dependent promotion of hair growth in mice. The study of AIF-related signalling pathways may provide insight into hair diseases and suggest potential novel therapeutic strategies.

Experimental evidence that mutated-self peptides derived from mitochondrial DNA somatic mutations have the potential to trigger autoimmunity

Autoimmune disease is a critical health concern, whose etiology remains enigmatic. We hypothesized that immune responses to somatically mutated self proteins could have a role in the development of autoimmune disease. IFN-γ secretion by T cells stimulated with mitochondrial peptides encoded by published mitochondrial DNA was monitored to test the hypothesis. Human peripheral blood mononuclear cells (PBMCs) of healthy controls and autoimmune patients were assessed for their responses to the self peptides and mutated-self peptides differing from self by one amino acid. None of the self peptides but some of the mutated-self peptides elicited an immune response in healthy controls. In some autoimmune patients, PBMCs responded not only to some of the mutated-self peptides, but also to some of the self peptides, suggesting that there is a breach of self-tolerance in these patients. Although PBMCs from healthy controls failed to respond to self peptides when stimulated with self, the mutated-self peptide could elicit a response to the self peptide upon re-stimulation in vitro, suggesting that priming with mutated-self peptides elicits a cross-reactive response with self. The data raise the possibility that DNA somatic mutations are one of the events that trigger and/or sustain T cell responses in autoimmune diseases.

New perspective on dextran sodium sulfate colitis: antigen-specific T cell development during intestinal inflammation

CD4+ T cell responses against oral antigens can develop in inflammatory bowel disease (IBD) patients, which may modulate disease. Dextran sodium sulfate (DSS) colitis is commonly used to study IBD, however, it is not considered the best model in which to study T cell involvement in intestinal disease. Our aim was to determine if antigen-specific T cells could be induced during DSS colitis and if they could be detected after disease resolution. To induce antigen-specific T cells, the tracking antigen, ovalbumin (OVA), was administered orally during colitis initiation. Disease severity was monitored, and the antigen-reactivity of CD4+ T cells examined using CD69 expression. While OVA-directed, CD4+ Foxp3+ regulatory T cells could be detected in the spleens of both OVA-treated control and DSS mice, OVA-reactive, CD4+ Foxp3-T cells were only found in the OVA and DSS-treated mice. These results indicate that during DSS colitis T cells develop that are specific against oral antigens, and they are found systemically after colitis resolution. This gives added depth and utility to the DSS model as well as a way to track T cells that are primed against luminal antigens.

Thiopurine treatment in patients with Crohn's disease leads to a selective reduction of an effector cytotoxic gene expression signature revealed by whole-genome expression profiling

Crohn's disease (CD) is characterized by chronic inflammation of the gastrointestinal tract, as a result of aberrant activation of the innate immune system through TLR stimulation by bacterial products. The conventional immunosuppressive thiopurine derivatives (azathioprine and mercaptopurine) are used to treat CD. The effects of thiopurines on circulating immune cells and TLR responsiveness are unknown. To obtain a global view of affected gene expression of the immune system in CD patients and the treatment effect of thiopurine derivatives, we performed genome-wide transcriptome analysis on whole blood samples from 20 CD patients in remission, of which 10 patients received thiopurine treatment, compared to 16 healthy controls, before and after TLR4 stimulation with LPS. Several immune abnormalities were observed, including increased baseline interferon activity, while baseline expression of ribosomal genes was reduced. After LPS stimulation, CD patients showed reduced cytokine and chemokine expression. None of these effects were related to treatment. Strikingly, only one highly correlated set of 69 genes was affected by treatment, not influenced by LPS stimulation and consisted of genes reminiscent of effector cytotoxic NK cells. The most reduced cytotoxicity-related gene in CD was the cell surface marker CD160. Concordantly, we could demonstrate an in vivo reduction of circulating CD160(+)CD3(-)CD8(-) cells in CD patients after treatment with thiopurine derivatives in an independent cohort. In conclusion, using genome-wide profiling, we identified a disturbed immune activation status in peripheral blood cells from CD patients and a clear treatment effect of thiopurine derivatives selectively affecting effector cytotoxic CD160-positive cells.