IL-9 induces differentiation of TH17 cells and enhances function of FoxP3+ natural regulatory T cells

The development of T helper (T(H))17 and regulatory T (T(reg)) cells is reciprocally regulated by cytokines. Transforming growth factor (TGF)-beta alone induces FoxP3(+) T(reg) cells, but together with IL-6 or IL-21 induces T(H)17 cells. Here we demonstrate that IL-9 is a key molecule that affects differentiation of T(H)17 cells and T(reg) function. IL-9 predominantly produced by T(H)17 cells, synergizes with TGF-beta1 to differentiate naïve CD4(+) T cells into T(H)17 cells, while IL-9 secretion by T(H)17 cells is regulated by IL-23. Interestingly, IL-9 enhances the suppressive functions of FoxP3(+) CD4(+) T(reg) cells in vitro, and absence of IL-9 signaling weakens the suppressive activity of nT(regs) in vivo, leading to an increase in effector cells and worsening of experimental autoimmune encephalomyelitis. The mechanism of IL-9 effects on T(H)17 and T(regs) is through activation of STAT3 and STAT5 signaling. Our findings highlight a role of IL-9 as a regulator of pathogenic versus protective mechanisms of immune responses.

CD4(+) T cells prevent spontaneous experimental autoimmune encephalomyelitis in anti-myelin basic protein T cell receptor transgenic mice

Autoimmune diseases result from a failure of tolerance. Although many self-reactive T cells are present in animals and humans, their activation appears to be prevented normally by regulatory T cells. In this study, we show that regulatory CD4(+) T cells do protect mice against the spontaneous occurrence of experimental autoimmune encephalomyelitis (EAE), a mouse model for multiple sclerosis. Anti-myelin basic protein (MBP) TCR transgenic mice (T/R+) do not spontaneously develop EAE although many self-reactive T cells are present in their thymi and peripheral lymphoid organs. However, the disease develops in all crosses of T/R+ mice with recombination-activating gene (RAG)-1 knockout mice in which transgenic TCR-expressing cells are the only lymphocytes present (T/R- mice). In this study, crosses of T/R+ mice with mice deficient for B cells, CD8(+) T cells, NK1.1 CD4(+) T (NKT) cells, gamma/delta T cells, or alpha/beta T cells indicated that alpha/beta CD4(+) T cells were the only cell population capable of controlling the self-reactive T cells. To confirm the protective role of CD4(+) T cells, we performed adoptive transfer experiments. CD4(+) T cells purified from thymi or lymph nodes of normal mice prevented the occurrence of spontaneous EAE in T/R- mice. To achieve full protection, the cells had to be transferred before the recipient mice manifested any symptoms of the disease. Transfer of CD4(+) T cells after the appearance of symptoms of EAE had no protective effect. These results indicate that at least some CD4(+) T cells have a regulatory function that prevent the activation of self-reactive T cells.

A defect in interleukin 12-induced activation and interferon gamma secretion of peripheral natural killer T cells in nonobese diabetic mice suggests new pathogenic mechanisms for insulin-dependent diabetes mellitus

The function of natural killer T (NKT) cells in the immune system has yet to be determined. There is some evidence that their defect is associated with autoimmunity, but it is still unclear how they play a role in regulating the pathogenesis of T cell-mediated autoimmune diseases. It was originally proposed that NKT cells could control autoimmunity by shifting the cytokine profile of autoimmune T cells toward a protective T helper 2 cell (Th2) type. However, it is now clear that the major function of NKT cells in the immune system is not related to their interleukin (IL)-4 secretion. In fact, NKT cells mainly secrete interferon (IFN)-gamma and, activated in the presence of IL-12, acquire a strong inflammatory phenotype and cytotoxic function.

Near-infrared photoimmunotherapy of cancer: a new approach that kills cancer cells and enhances anti-cancer host immunity

Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed hybrid cancer therapy that directly kills cancer cells as well as producing a therapeutic host immune response. Conventional immunotherapies, such as immune-activating cytokine therapy, checkpoint inhibition, engineered T cells and suppressor cell depletion, do not directly destroy cancer cells, but rely exclusively on activating the immune system. NIR-PIT selectively destroys cancer cells, leading to immunogenic cell death that initiates local immune reactions to released cancer antigens from dying cancer cells. These are characterized by rapid maturation of dendritic cells and priming of multi-clonal cancer-specific cytotoxic T cells that kill cells that escaped the initial direct effects of NIR-PIT. The NIR-PIT can be applied to a wide variety of cancers either as monotherapy or in combination with conventional immune therapies to further activate anti-cancer immunity. A global Phase 3 clinical trial (https://clinicaltrials.gov/ct2/show/NCT03769506) of NIR-PIT targeting the epidermal growth factor receptor (EGFR) in patients with recurrent head and neck cancer is underway, employing RM1929/ASP1929, a conjugate of anti-EGFR antibody (cetuximab) plus the photo-absorber IRDye700DX (IR700). NIR-PIT has been given fast-track recognition by regulators in the USA and Japan. A variety of imaging methods, including direct IR700 fluorescence imaging, can be used to monitor NIR-PIT. As experience with NIR-PIT grows, additional antibodies will be employed to target additional antigens on other cancers or to target immune-suppressor cells to enhance host immunity. NIR-PIT will be particularly important in patients with localized and locally advanced cancers and may help such patients avoid side-effects associated with surgery, radiation and chemotherapy.

CD38, a Receptor with Multifunctional Activities: From Modulatory Functions on Regulatory Cell Subsets and Extracellular Vesicles, to a Target for Therapeutic Strategies

CD38 is a multifunctional cell surface protein endowed with receptor/enzymatic functions. The protein is generally expressed at low/intermediate levels on hematological tissues and some solid tumors, scoring the highest levels on plasma cells (PC) and PC-derived neoplasia. CD38 was originally described as a receptor expressed by activated cells, mainly T lymphocytes, wherein it also regulates cell adhesion and cooperates in signal transduction mediated by major receptor complexes. Furthermore, CD38 metabolizes extracellular NAD+, generating ADPR and cyclic ADPR. This ecto-enzyme controls extra-cellular nucleotide homeostasis and intra-cellular calcium fluxes, stressing its relevance in multiple physiopathological conditions (infection, tumorigenesis and aging). In clinics, CD38 was adopted as a cell activation marker and in the diagnostic/staging of leukemias. Quantitative surface CD38 expression by multiple myeloma (MM) cells was the basic criterion used for therapeutic application of anti-CD38 monoclonal antibodies (mAbs). Anti-CD38 mAbs-mediated PC depletion in autoimmunity and organ transplants is currently under investigation. This review analyzes different aspects of CD38's role in regulatory cell populations and how these effects are obtained. Characterizing CD38 functional properties may widen the extension of therapeutic applications for anti-CD38 mAbs. The availability of therapeutic mAbs with different effects on CD38 enzymatic functions may be rapidly translated to immunotherapeutic strategies of cell immune defense.

The role of HLA-G in immunity and hematopoiesis

The non-classical HLA class I molecule HLA-G was initially shown to play a major role in feto-maternal tolerance. Since this discovery, it has been established that HLA-G is a tolerogenic molecule which participates to the control of the immune response. In this review, we summarize the recent advances on (1) the multiple structures of HLA-G, which are closely associated with their role in the inhibition of NK cell cytotoxicity, (2) the factors that regulate the expression of HLA-G and its receptors, (3) the mechanism of action of HLA-G at the immunological synapse and through trogocytosis, and (4) the generation of suppressive cells through HLA-G. Moreover, we also review recent findings on the non-immunological functions of HLA-G in erythropoiesis and angiogenesis.

Role of Regulatory Cells in Oral Tolerance

The immune system is continuously exposed to great amounts of different antigens from both food and intestinal microbes. Immune tolerance to these antigens is very important for intestinal and systemic immune homeostasis. Oral tolerance is a specific type of peripheral tolerance induced by exposure to antigen via the oral route. Investigations on the role of intestinal immune system in preventing hypersensitivity reactions to innocuous dietary and microbial antigens have been intensively performed during the last 2 decades. In this review article, we discuss how food allergens are recognized by the intestinal immune system and draw attention to the role of regulatory T (Treg) and B (Breg) cells in the establishment of oral tolerance and tolerogenic features of intestinal dendritic cells. We also emphasize the potential role of tonsils in oral tolerance induction because of their anatomical location, cellular composition, and possible usage to develop novel ways of specific immunotherapy for the treatment of allergic diseases.

Colorectal cancer-derived microvesicles modulate differentiation of human monocytes to macrophages

BACKGROUND

Tumour-derived microvesicles (TMVs) are important players in tumour progression, modulating biological activity of immune cells e.g. lymphocytes, monocytes and macrophages. This phenomenon is particularly interesting in the progression of colon cancer, as macrophages in this type of tumour are relevant for the recovery processes. In the present study, the role of colon cancer cell-derived microvesicles in monocyte differentiation and activity profile (polarization) was investigated.

METHODS

Monocyte-derived macrophages (MDM) were differentiated in vitro in the presence of TMVs obtained from colon cancer: Caco-2, SW620, LoVo or SW480 cell lines and analysed according to their morphology and biological functions, as defined by cytokine secretion, reactive oxygen intermediate (ROI) production and cytotoxic activity against respective colon cancer cells.

RESULTS

Monocytes differentiated with TMVs exhibited morphological and phenotypical characteristics of macrophages. An early contact (beginning with the first day of the in vitro culture) of monocytes with TMVs resulted in increased IL-10 secretion and only slightly elevated TNF release. Early, or prolonged contact resulted in low ROI production and low cytotoxicity against tumour cells. On the other hand, late contact of MDM with TMVs, stimulated MDM to significant TNF and IL-12 secretion, ROI production and enhanced cytotoxicity against tumour cells in vitro. In addition, differences in MDM response to TMVs from different cell lines were observed (according to cytokine secretion, ROI production and cytotoxicity against tumour cells in vitro). Biological activity, STATs phosphorylation and microRNA profiling of MDMs indicated differences in their polarization/activation status which may suggest mixed polarization type M1/M2 with the predominance of proinflammatory cells after late contact with TMVs.

CONCLUSIONS

Macrophage activity (polarization status) may be regulated by contact with not only tumour cells but also with TMVs. Their final polarization status depends on the contact time, and probably on the vesicle "cargo", as signified by the distinct impact of TMVs which enabled the switching of MDM maturation to regulatory macrophages.

The Role of IgG4 in the Fine Tuning of Tolerance in IgE-Mediated Allergy and Cancer

Among the four immunoglobulin G (IgG) subclasses, IgG4 is the least represented in serum of a healthy human and it is considered an “odd” antibody. The IgG4 antibody has unique structural features that affect its biological function. These include the ability to undergo antigen-binding fragment (Fab)-arm exchange, to create fragment crystallizable (Fc) – Fc binding with other IgG4 and other IgG subclass antibodies, have a unique affinity profile for Fc gamma receptors (FcγRs) and no binding to complement component C1q. Altogether, these characteristics support anti-inflammatory roles of IgG4 leading to immune tolerance. Under conditions of chronic antigenic stimulation and Th2-type inflammation, both tissue and serum IgG4 levels are increased. This review seeks to highlight how in allergen immunotherapy IgG4 can confer a protective role as a “blocking” antibody and safeguard from subsequent allergen exposure, while IgG4 can confer immunomodulatory functions to support malignancy. While Th2 conditions drive polarization of macrophages to the M2a subtype, chronic antigen stimulation drives B cell class switching to IgG4 to further support phenotypical macrophage changes towards an M2b-like state. M2b-like macrophages can secrete chemokine (C-C motif) ligand 1 (CCL1) and interleukin-10 (IL-10) to support regulatory cell recruitment and to further shape a tolerogenic microenvironment. Thereby, IgG4 have a Janus-faced role, favorable in allergy but detrimental in cancer.

Safety and patient response as indicated by biomarker changes to binding immunoglobulin protein in the phase I/IIA RAGULA clinical trial in rheumatoid arthritis

OBJECTIVES

Binding immunoglobulin protein (BiP) is a human endoplasmic reticulum-resident stress protein. In pre-clinical studies it has anti-inflammatory properties due to the induction of regulatory cells. This randomized placebo-controlled, dose ascending double blind phase I/IIA trial of BiP in patients with active RA, who had failed accepted therapies, had the primary objective of safety. Potential efficacy was measured by DAS28-ESR and changes in biomarkers.

METHODS

Twenty-four patients with active RA who had failed one or more DMARDs were sequentially assigned to three groups each of eight patients randomly allocated to receive placebo (two patients) or BiP (six patients), 1, 5 or 15 mg. Patients received a single i.v. infusion over 1 h and were observed as inpatients overnight. A 12-week follow-up for clinical, rheumatological and laboratory assessments for safety, efficacy (DAS28-ESR) and biomarker analysis was performed.

RESULTS

No infusion reactions or serious adverse drug reactions were noted. Adverse events were evenly distributed between placebo and BiP groups with no BiP-related toxicities. Haematological, renal and metabolic parameters showed no drug-related toxicities. Remission was only achieved by patients in the 5 and 15 mg groups, and not patients who received placebo or 1 mg BiP. Good DAS28-ESR responses were achieved in all treatment groups. The BiP responding patients showed significantly lower serum concentrations of CRP, 2 weeks post-infusion compared with pre-infusion levels, and of VEGF and IL-8 from the placebo group.

CONCLUSION

BiP (⩽15 mg) is safe in patients with active RA. Some patients had clinical and biological improvements in RA activity. BiP merits further study.

TRIAL REGISTRATION

ISRCTN registry, http://isrctn.com, ISRCTN22288225 and EudraCT, https://eudract.ema.europa.eu, 2011-005831-19.

Autoimmunity and Cancer-Two Sides of the Same Coin

Autoimmune disease results from the immune response against self-antigens, while cancer develops when the immune system does not respond to malignant cells. Thus, for years, autoimmunity and cancer have been considered as two separate fields of research that do not have a lot in common. However, the discovery of immune checkpoints and the development of anti-cancer drugs targeting PD-1 (programmed cell death receptor 1) and CTLA-4 (cytotoxic T lymphocyte antigen 4) pathways proved that studying autoimmune diseases can be extremely helpful in the development of novel anti-cancer drugs. Therefore, autoimmunity and cancer seem to be just two sides of the same coin. In the current review, we broadly discuss how various regulatory cell populations, effector molecules, genetic predisposition, and environmental factors contribute to the loss of self-tolerance in autoimmunity or tolerance induction to cancer. With the current paper, we also aim to convince the readers that the pathways involved in cancer and autoimmune disease development consist of similar molecular players working in opposite directions. Therefore, a deep understanding of the two sides of immune tolerance is crucial for the proper designing of novel and selective immunotherapies.

HLA-G Expressing Immune Cells in Immune Mediated Diseases

HLA-G is a HLA class Ib antigen that possesses immunomodulatory properties. HLA-G-expressing CD4+ and CD8+ T lymphocytes, NK cells, monocytes, and dendritic cells with immunoregulatory functions are present in small percentages of patients with physiologic conditions. Quantitative and qualitative derangements of HLA-G+ immune cells have been detected in several conditions in which the immune system plays an important role, such as infectious, neoplastic, and autoimmune diseases as well as in complications from transplants and pregnancy. These observations strongly support the hypothesis that HLA-G+ immune cells may be implicated in the complex mechanisms underlying the pathogenesis of these disorders.

Immune regulation by non-lymphoid cells in transplantation

Regulatory cells play a crucial role in the induction and maintenance of tolerance by controlling T cell as well as B and natural killer (NK) cell-mediated immunity. In transplantation, CD4+CD25+forkhead box P3+ T regulatory cells are instrumental in the maintenance of immunological tolerance, as are several other T cell subsets such as NK T cells, double negative CD3+ T cells, gammadelta T cells, interleukin-10-producing regulatory type 1 cells, transforming growth factor-beta-producing T helper type 3 cells and CD8+CD28(-) cells. However, not only T cells have immunosuppressive properties, as it is becoming increasingly clear that both T and non-T regulatory cells co-operate and form a network of cellular interactions controlling immune responses. Non-T regulatory cells include tolerogenic dendritic cells, plasmacytoid dendritic cells, mesenchymal stem cells, different types of stem cells, various types of alternatively activated macrophages and myeloid-derived suppressor cells. Here, we review the mechanism of action of these non-lymphoid regulatory cells as they relate to the induction or maintenance of tolerance in organ transplantation.

Immune tolerance induction by integrating innate and adaptive immune regulators

A diversity of immune tolerance mechanisms have evolved to protect normal tissues from immune damage. Immune regulatory cells are critical contributors to peripheral tolerance. These regulatory cells, exemplified by the CD4(+)Foxp3(+) regulatory T (Treg) cells and a recently identified population named myeloid-derived suppressor cells (MDSCs), regulate immune responses and limiting immune-mediated pathology. In a chronic inflammatory setting, such as allograft-directed immunity, there may be a dynamic "cross-talk" between the innate and adaptive immunomodulatory mechanisms for an integrated control of immune damage. CTLA4-B7-based interaction between the two branches may function as a molecular "bridge" to facilitate such "cross-talk." Understanding the interplays among Treg cells, innate suppressors, and pathogenic effector T (Teff) cells will be critical in the future to assist in the development of therapeutic strategies to enhance and synergize physiological immunosuppressive elements in the innate and adaptive immune system. Successful development of localized strategies of regulatory cell therapies could circumvent the requirement for very high number of cells and decrease the risks associated with systemic immunosuppression. To realize the potential of innate and adaptive immune regulators for the still elusive goal of immune tolerance induction, adoptive cell therapies may also need to be coupled with agents enhancing endogenous tolerance mechanisms.

Modulation of B Cells and Homing Marker on NK Cells Through Extracorporeal Photopheresis in Patients With Steroid-Refractory/Resistant Graft-Vs.-Host Disease Without Hampering Anti-viral/Anti-leukemic Effects

Graft-vs.-host disease (GvHD), a severe complication of allogeneic hematopoietic stem cell transplantation, significantly affects the post-transplant morbidity and mortality. Systemic steroids remain the gold standard for the initial management of GvHD. However, up to 60% of patients will not sufficiently respond to steroids. Extracorporeal photopheresis (ECP), a cell-based immunotherapy, has shown good clinical results in such steroid-refractory/resistant GvHD patients. Given its immunomodulatory, but not global immunosuppressive and steroid-sparing capacity, ECP constitutes an attractive option. In the case of GvHD, the balance of immune cells is destroyed: effector cells are not any longer efficiently controlled by regulatory cells. ECP therapy may restore this balance. However, the precise mechanism and the impact of ECP on anti-viral/anti-leukemic function remain unclear. In this study, 839 ECP treatments were performed on patients with acute GvHD (aGvHD) and chronic GvHD (cGvHD). A comprehensive analysis of effector and regulatory cells in patients under ECP therapy included multi-parametric flow cytometry and tetramer staining, Luminex^TM-based cytokine, interferon-γ enzyme-linked immunospot, and chromium-51 release assays. Gene profiling of myeloid-derived suppressor cells (MDSCs) was performed by microarray analysis. Immunologically, modulations of effector and regulatory cells as well as proinflammatory cytokines were observed under ECP treatment: (1) GvHD-relevant cell subsets like CD62L⁺ NK cells and newly defined CD19^hiCD20^hi B cells were modulated, but (2) quantity and quality of anti-viral/anti-leukemic effector cells were preserved. (3) The development of MDSCs was promoted and switched from an inactivated subset (CD33^-CD11b⁺) to an activated subset (CD33⁺CD11b⁺). (4) The frequency of Foxp3⁺CD4⁺ regulatory T cells (Tregs) and CD24⁺CD38^hi regulatory B cells was considerably increased in aGvHD patients, and Foxp3⁺CD8⁺ Tregs in cGvHD patients. (5) Proinflammatory cytokines like IL-1β, IL-6, IL-8, and TNF-α were significantly reduced. In summary, ECP constitutes an effective immunomodulatory therapy for patients with steroid-refractory/resistant GvHD without impairment of anti-viral/leukemia effects.

Successful TB treatment induces B-cells expressing FASL and IL5RA mRNA

Activated B-cells increase T-cell behaviour during autoimmune disease and other infections by means of cytokine production and antigen-presentation. Functional studies in experimental autoimmune encephalomyelitis (EAE) indicate that B-cell deficiencies, and a lack of IL10 and IL35 leads to a poor prognosis. We hypothesised that B-cells play a role during tuberculosis. We evaluated B-cell mRNA expression using real-time PCR from healthy community controls, individuals with other lung diseases and newly diagnosed untreated pulmonary TB patients at three different time points (diagnosis, month 2 and 6 of treatment).

We show that FASLG, IL5RA, CD38 and IL4 expression was lower in B-cells from TB cases compared to healthy controls. The changes in expression levels of CD38 may be due to a reduced activation of B-cells from TB cases at diagnosis. By month 2 of treatment, there was a significant increase in the expression of APRIL and IL5RA in TB cases. Furthermore, after 6 months of treatment, APRIL, FASLG, IL5RA and CD19 were upregulated in B-cells from TB cases. The increase in the expression of APRIL and CD19 suggests that there may be restored activation of B-cells following anti-TB treatment. The upregulation of FASLG and IL5RA indicates that B-cells expressing regulatory genes may play an important role in the protective immunity against M.tb infection. Our results show that increased activation of B-cells is present following successful TB treatment, and that the expression of FASLG and IL5RA could potentially be utilised as a signature to monitor treatment response.

Characterization and antiproliferative activity of glioma-derived extracellular vesicles

Aim: To characterize a method to isolate glioma-derived extracellular vesicles (GEVs) and understand their role in immune system modulation and glioma progression. Materials & methods: GEVs were isolated by differential centrifugation from C6 cell supernatant and characterized by size and expression of CD9, HSP70, CD39 and CD73. The glioma model was performed by injecting C6 glioma cells into the right striatum of Wistar rats in the following groups: controls (C6 cells alone), coinjection (C6 cells + GEVs) and GEVs by intranasal administration followed by immune cells, tumor size and cells proliferation analyses. Results: GEVs presented uniform size (175 nm), expressed CD9, HSP70, CD39, CD73 and produced adenosine. In vivo, we observed a reduction in tumor size, in cell proliferation (Ki-67) and in a regulatory cell marker (FoxP3). Conclusion: GEVs, administered before or at tumor challenge, have antiproliferative properties and reduce regulatory cells in the glioma microenvironment.

Resisting Resistance to Immune Checkpoint Therapy: A Systematic Review

The treatment landscape in oncology has witnessed a major revolution with the introduction of checkpoint inhibitors: anti-PD1, anti-PDL1 and anti-CTLA-4. These agents enhance the immune response towards cancer cells instead of targeting the tumor itself, contrary to standard chemotherapy. Although long-lasting durable responses have been observed with immune checkpoints inhibitors, the response rate remains relatively low in many cases. Some patients respond in the beginning but then eventually develop acquired resistance to treatment and progress. Other patients having primary resistance never respond. Multiple studies have been conducted to further elucidate these variations in response in different tumor types and different individuals. This paper provides an overview of the mechanisms of resistance to immune checkpoint inhibitors and highlights the possible therapeutic approaches under investigation aiming to overcome such resistance in order to improve the clinical outcomes of cancer patients.

Regulatory and Effector Cell Disequilibrium in Patients with Acute Cellular Rejection and Chronic Lung Allograft Dysfunction after Lung Transplantation: Comparison of Peripheral and Alveolar Distribution

Background: The immune mechanisms occurring during acute rejection (AR) and chronic lung allograft dysfunction are a challenge for research and the balance between effector and regulatory cells has not been defined completely. In this study, we aimed to elucidate the interaction of effector cells, mainly Th17, Th1 and Th2, and regulatory cells including (CD4⁺CD25⁺CD127^low/−) T reg cells and phenotypes of B regs, CD19⁺CD24^hiCD38^hi, CD19⁺CD24^hiCD27^hi and CD19⁺CD5⁺CD1d⁺. Methods: Bronchoalveolar lavage cells (BAL) and peripheral blood mononuclear cells (PBMCs) from stable lung transplanted (LTx )subjects (n = 4), AR patients (n = 6) and bronchiolitis obliterans syndrome (BOS) (n = 6) were collected at the same time. Cellular subsets were detected through flow cytometry. Results: A predominance of Th17 cells subtypes in the PBMCs and BAL and a depletion of Tregs, that resulted in decrease Treg/Th17 ratio, was observed in the AR group. CD19⁺CD24^hiCD38^hi Bregs resulted increased in BAL of AR patients. Th1 cells predominance and a reduction of Tregs cells was observed in BAL from AR patients. Moreover, multivariate analysis showed interdependences within studied variables revealing that effector cells and regulatory cells can effectively discriminate patients’ immunological status. Conclusions: In AR, BOS and stable lung transplant, regulatory and effector cells clearly demonstrated different pathways of activation. Understanding of the balance of T cells and T and B regulatory cells can offers insights into rejection.

Modulation of CD39 and Exogenous APT102 Correct Immune Dysfunction in Experimental Colitis and Crohn's Disease

BACKGROUND AND AIMS

CD39/ENTPD1 scavenges pro-inflammatory nucleotides, to ultimately generate immunosuppressive adenosine, which has a central role in immune homeostasis. Global deletion of Cd39 increases susceptibility to experimental colitis while single nucleotide polymorphisms within the human CD39 promoter, and aberrant patterns of expression during experimental hypoxia, predispose to Crohn's disease. We aimed to define the impact of transgenic human CD39 [hTG] overexpression in experimental colitis and to model therapeutic effects using the recombinant apyrase APT102 in vivo. We also determined the in vitro effects of APT102 on phenotypic and functional properties of regulatory T-lymphocytes derived from patients with Crohn's disease.

METHODS

Colitis was induced by administration of dextran sulfate sodium in wild-type [WT] or hTG mice, and, in another model, by adoptive transfer of CD45RBhigh cells with or without WT or hTG regulatory T cells [Treg]. In additional experiments, mice were treated with APT102. The effects of APT102 on phenotype and function of Treg and type-1 regulatory T [Tr1] cells were also evaluated, after purification from peripheral blood and lamina propria of Crohn's disease patients [n = 38].

RESULTS

Overexpression of human CD39 attenuated experimental colitis and protected from the deleterious effects of systemic hypoxia, pharmacologically induced by deferoxamine. Administration of APT102 in vivo enhanced the beneficial effects of endogenous Cd39 boosted by the administration of the aryl hydrocarbon receptor [AhR] ligand unconjugated bilirubin [UCB]. Importantly, supplemental APT102 restored responsiveness to AhR stimulation by UCB in Treg and Tr1 cells, obtained from Crohn's disease patients.

CONCLUSIONS

hCD39 overexpression ameliorated experimental colitis and prevented hypoxia-related damage in vivo. Exogenous administration of APT102 boosted AhR-mediated regulatory effects in vivo while enhancing Treg functions in Crohn's disease in vitro.

Manipulating Immune Tolerance with Micro-RNA Regulated Gene Therapy

The success of in vivo gene therapy greatly depends on the ability to control the immune response toward the therapeutic transgene. Over the last decade several vector-based and pharmacological approaches have been explored to control the immune-mediated clearance of transgene-expressing cells after viral delivery. One important outcome from these studies is the concept that expression of a transgene in tolerance-promoting organs, such as the liver and tolerogenic antigen-presenting cells, can help safeguard transgene-expressing cells from immune-mediated clearance. Gene therapists are now manipulating vectors to target naturally occurring tolerogenic properties of the body by: (i) incorporating tissue/cell specific promoters for targeted expression, (ii) using viral-capsid engineering to alter tropism and avoid pre-existing immunity, and (iii) regulating cell and activation dependent expression by including micro-RNA (miR) targets into expression cassettes. The combination of these three layers of vector regulation greatly enhances the targeting of tolerogenic cells and limits off-target expression of the transgene, which can lead to the induction of transgene-specific pathogenic effector T cells. In this review, we discuss the application of using miR transgene regulation to generate tolerogenic responses and speculate on possible mechanisms used by the liver to induce the transgene-specific regulatory T cells.

Mesenchymal Stromal Cell Therapy in Solid Organ Transplantation

Transplantation is the gold-standard treatment for the failure of several solid organs, including the kidneys, liver, heart, lung and small bowel. The use of tailored immunosuppressive agents has improved graft and patient survival remarkably in early post-transplant stages, but long-term outcomes are frequently unsatisfactory due to the development of chronic graft rejection, which ultimately leads to transplant failure. Moreover, prolonged immunosuppression entails severe side effects that severely impact patient survival and quality of life. The achievement of tolerance, i.e., stable graft function without the need for immunosuppression, is considered the Holy Grail of the field of solid organ transplantation. However, spontaneous tolerance in solid allograft recipients is a rare and unpredictable event. Several strategies that include peri-transplant administration of non-hematopoietic immunomodulatory cells can safely and effectively induce tolerance in pre-clinical models of solid organ transplantation. Mesenchymal stromal cells (MSC), non-hematopoietic cells that can be obtained from several adult and fetal tissues, are among the most promising candidates. In this review, we will focus on current pre-clinical evidence of the immunomodulatory effect of MSC in solid organ transplantation, and discuss the available evidence of their safety and efficacy in clinical trials.

Adaptive immune system in pulmonary sarcoidosis-Comparison of peripheral and alveolar biomarkers

Sarcoidosis is a multi‐systemic granulomatous disease of unknown origin. Recent research has focused upon the role of autoimmunity in its development and progression. This study aimed to determine and define the disturbance and distribution of T and B cell subsets in the alveolar and peripheral compartments. Thirteen patients were selected for the study [median age, interquartile range (IQR) = 57 years (48–59); 23% were male]. Twelve healthy controls [median age, IQR = 53 years (52–65); 16% male] were also enrolled into the study. Cellular and cytokine patterns were measured using the cytofluorimetric approach. Peripheral CD8 percentages were higher in sarcoidosis patients (SP) than healthy controls (HC) (p = 0.0293), while CD4 percentages were lower (p = 0.0305). SP showed low bronchoalveolar lavage (BAL) percentages of CD19 (p = 0.0004) and CD8 (p = 0.0035), while CD19⁺CD5⁺CD27⁻ percentages were higher (p = 0.0213); the same was found for CD4 (p = 0.0396), follicular regulatory T cells (T_reg) (p = 0.0078) and T_reg (p < 0.0001) cells. Low T helper type 17 (Th17) percentages were observed in BAL (p = 0.0063) of SP. Peripheral CD4⁺ C‐X‐C chemokine receptor (CXCR)5⁺CD45RA⁻) percentages and follicular T helper cells (Tfh)‐like Th1 (Tfh1) percentages (p = 0.0493 and p = 0.0305, respectively) were higher in the SP than HC. Tfh1 percentages and Tfh‐like Th2 percentages were lower in BAL than in peripheral blood (p = 0.0370 and p = 0.0078, respectively), while CD4⁺ C‐X‐C motif CXCR5⁺CD45RA⁻ percentages were higher (p = 0.0011). This is the first study, to our knowledge, to demonstrate a link between an imbalance in circulating and alveolar Tfh cells, especially CCR4‐, CXCR3‐ and CXCR5‐expressing Tfh subsets in the development of sarcoidosis. These findings raise questions about the pathogenesis of sarcoidosis and may provide new directions for future clinical studies and treatment strategies.

A paragon of self-tolerance: CD25+CD4+ regulatory T cells and the control of immune responses

The interest in naturally arising regulatory T (TR) cells as a paradigm for maintaining immunological self-tolerance has undergone an explosive re-emergence in recent years. This renaissance was triggered by several key experimental observations and the identification of specific molecular markers that have enabled the isolation and experimental manipulation of these cells. Although their existence was once controversial, a large body of evidence now highlights the critical roles of TR cells in maintaining immunological self-tolerance. Furthermore, abnormality of natural TR cells can be a primary cause of autoimmune and other inflammatory diseases in humans.