Production of the effector cytokine interleukin-17, rather than interferon-γ, is more strongly associated with autoimmune hemolytic anemia

Regulatory T-cell dysfunctions are associated with increase in tumor necrosis factor α in autoimmune hemolytic anemia and participate in Th17 polarization

Warm autoimmune hemolytic anemia (wAIHA) is a rare acquired autoimmune disease mediated by antibodies targeting red blood cells. The involvement of CD4 T-helper cells has been scarcely explored, with most findings extrapolated from animal models. Here, we performed quantification of both effector T lymphocytes (Teff) and regulatory T cells (Treg), associated with functional and transcriptomic analyses of Treg in human wAIHA. We observed a shift of Teff toward a Th17 polarization concordant with an increase in serum interleukin-17 concentration that correlates with red blood cell destruction parameters, namely lactate dehydrogenase and bilirubin levels. A decrease in circulating Treg, notably effector Treg, associated with a functional deficiency, as represented by their decrease capability to inhibit Teff proliferation, were also observed. Treg deficiency was associated with a reduced expression of Foxp3, the master transcription factor known to maintain the Treg phenotype stability and suppressive functions. Transcriptomic profiling of Treg revealed activation of the tumor necrosis facto (TNF)-α pathway, which was linked to increased serum TNF-α concentrations that were twice as high as in controls. Treg transcriptomic profiling also suggested that post-translational mechanisms possibly accounted for Foxp3 downregulation and Treg dysfunctions. Since TNF-α participates in the rupture of immune tolerance during wAIHA, its inhibition could be of interest. To this end, the effects of fostamatinib, a SYK inhibitor, were investigated in vitro, and we showed that besides the inhibition of erythrocyte phagocytosis by monocytes, fostamatinib is also able to dampen TNF-α production, thus appearing as a promising multitargeting therapy in wAIHA (clinicaltrials gov. Identifier: NCT02158195).

Is Th17-Targeted Therapy Effective in Systemic Lupus Erythematosus?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a broad spectrum of clinical manifestations. The proposed pathophysiological hypotheses of SLE are numerous, involving both innate and adaptive abnormal immune responses. SLE is characterized by the overproduction of different autoantibodies that form immune complexes, which cause damage in different organs. Current therapeutic modalities are anti-inflammatory and immunosuppressive. In the last decade, we have witnessed the development of many biologicals targeting different cytokines and other molecules. One of them is interleukin-17 (IL-17), a central cytokine of a proinflammatory process that is mediated by a group of helper T cells called Th17. Direct inhibitors of IL-17 are used in psoriatic arthritis, spondyloarthritis, and other diseases. Evidence about the therapeutic potential of Th17-targeted therapies in SLE is scarce, and probably the most promising is related to lupus nephritis. As SLE is a complex heterogeneous disease with different cytokines involved in its pathogenesis, it is highly unlikely that inhibition of only one molecule, such as IL-17, will be effective in the treatment of all clinical manifestations. Future studies should identify SLE patients that are eligible for Th17-targeted therapy.

In vitro Immunomodulatory Effects of Human Umbilical Cord-Derived Mesenchymal Stem Cells on Peripheral Blood Cells from Warm Autoimmune Hemolytic Anemia Patients

INTRODUCTION

Autoimmune hemolytic anemia is a potentially lethal disease characterized by autoimmune hemolysis. Although human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have been reported as a promising therapy, there is limited evidence regarding warm autoimmune hemolytic anemia (wAIHA) patients. This study aimed to investigate the potential therapeutic effects of hUC-MSCs via immune regulation in wAIHA patients.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 10 wAIHA patients and 8 healthy controls were isolated from peripheral blood and cultured for 3 days with or without the presence of hUC-MSCs; PBMCs were co-cultured with hUC-MSCs using Transwell assays. The supernatant cytokine levels were measured after culture through AimPlex Multiple Immunoassays for Flow, including IL-2, IL-4, IL-10, IFN-γ, TNF-α, and IL-17A. The percentages of regulatory T cells, regulatory B cells, and Th1/Th2 in PBMCs were also assessed before and after culturing.

RESULTS

In the wAIHA group, hUC-MSCs could upregulate the Treg and Breg proportions after culturing for 3 days, and the Treg and Breg percentages increased after co-culturing with hUC-MSCs in the wAIHA group compared with PBMC cultured alone for 3 days (8.29 ± 8.59 vs. 6.82 ± 1.32, 3.82 ± 1.87 vs. 1.75 ± 1.20, respectively). Compared with the PBMC wAIHA group, the levels of TNF-α (2.13 ± 2.07 vs. 16.20 ± 21.13 pg/mL, p = 0.019) and IL-10 (10.51 ± 18.42 vs. 37.78 ± 44.20 pg/mL, p = 0.012) were significantly elevated in the PBMC + hUC-MSCs wAIHA group.

CONCLUSION

The hUC-MSCs contributed to the increasing proportion of regulatory cell populations in PBMCs of wAIHA patients, thereby potentially regulating autoimmune response; thus, hUC-MSCs may be a promising approach for wAIHA treatment.

Serum interleukin 17 concentrations in dogs with immune-mediated hemolytic anemia

Background

Increased serum interleukin 17 (IL‐17) concentration has been associated with the immunopathogenesis of autoimmune hemolytic anemia in humans. No data are available about IL‐17 in immune‐mediated hemolytic anemia (IMHA) of dogs.

Objectives

Monitor changes in serum IL‐17 concentration during the acute stages of IMHA in dogs, compared with results in healthy dogs, and its relationship with outcome.

Animals

Thirty‐one client‐owned dogs with primary IMHA and 27 healthy dogs.

Methods

Quantification of serum IL‐17 concentration using a commercially available ELISA kit at the time of admission (D0), after 48 hours (D2) and after 96 hours (D4) as compared to concentration in healthy dogs. The IMHA dogs were classified as survivors if discharged from hospital, or nonsurvivors for any cause of in‐hospital mortality.

Results

Mean serum IL‐17 concentration was higher in dogs with IMHA on admission compared with healthy dogs (D0), but this difference was not significant (mean, 19.52 pg/mL vs 10.52 pg/mL, respectively, P = .17). Throughout hospitalization, serum IL‐17 concentration significantly decreased in survivors. Serum IL‐17 concentration at D0 was not different between survivors and nonsurvivors, but surviving dogs had significantly lower serum IL‐17 concentration at D2 and D4 (P = .04 and P = .004, respectively) compared with nonsurviving dogs. No correlation was found between serum IL‐17 concentration and serum total bilirubin or lactate concentrations or CBC parameters.

Conclusion and Clinical Importance

Serum IL‐17 concentration remained significantly higher in nonsurviving IMHA dogs whereas it significantly decreased during hospitalization in survivors, making serum IL‐17 concentration a potential biomarker for severity and response to treatment in IMHA.

Pro- and anti-inflammatory cytokines in children with malaria in Franceville, Gabon

Severe Plasmodium falciparum malaria anemia (SMA) is a major cause of mortality in pediatric wards. Variations in inflammatory mediator production play an essential role in disease outcomes. Indeed, several studies have shown the involvement of pro- and anti-inflammatory cytokines such as IFN-γ, IL-6, TNF-α and IL-10 in malaria immunopathology. In other hand the exact role of Th17 cytokines such as IL-17, IL-22 and IL-21 in malaria remains poorly documented. Here, we investigated IFN-γ, TNF-α, IL-6, IL-12, IL-10, IL-4, IL-13, IL-17, IL-22 and IL-21 circulating levels and their association with malaria anemia and parasitemia in Gabonese children. Levels of IFN-γ (500 ± 100.2 pg/ml), IL-6 (64 ± 14.2 pg/ml), IL-10 (505 ± 35 pg/ml), IL-13 (30.6 ± 5.6 pg/ml) were significantly higher (P < 0.03) in infected children than in uninfected controls (210 ± 20 pg/ml, 17.5 pg/ml, 50 ± 25.9, pg/ml, 17.48 pg/ml, respectively). IFN-γ levels were significantly lower (P = 0.04) in children with SMA (400 ± 200 pg/ml) than in those with uncomplicated malaria (900 ± 450 pg/ml) and higher in those with parasitemia (P = 0.019). Levels of IL-6 and IL-10 were significantly higher in children with malarial anemia (P < 0.001) and hyperparasitemia (P < 0.0001). A significant association between IL-10 levels and parasite density was observed (P < 0.00001). IL-22 levels were significantly higher (P = 0.01) in infected children (72.57 ± 7.5 pg/ml) than in the controls (54.96 ± 1.93 pg/ml). IL-21 levels (44.46 ± 17.27 pg/ml) decreased with the severity of anemia (P < 0.05), whereas IL-17 levels increased in children with SMA (12.25 ± 1.25 pg/ml) than in those with mild malaria anemia (MMA: 6.2 ± 5.25 pg/ml, P = 0.002). Data suggest possible role of IFN-γ in the protection against SMA and parasite clearance. However, IL-6 and IL-10 could play a role in inflammatory response and pathophysiology of severe malaria anemia. Also, the role of IL-22 and IL-17 in P. falciparum malaria infection should be investigated.

Characterisation of the Immunophenotype of Dogs with Primary Immune-Mediated Haemolytic Anaemia

Background

Immune-mediated haemolytic anaemia (IMHA) is reported to be the most common autoimmune disease of dogs, resulting in significant morbidity and mortality in affected animals. Haemolysis is caused by the action of autoantibodies, but the immunological changes that result in their production have not been elucidated.

Aims

To investigate the frequency of regulatory T cells (Tregs) and other lymphocyte subsets and to measure serum concentrations of cytokines and peripheral blood mononuclear cell expression of cytokine genes in dogs with IMHA, healthy dogs and dogs with inflammatory diseases.

Animals

19 dogs with primary IMHA, 22 dogs with inflammatory diseases and 32 healthy control dogs.

Methods

Residual EDTA-anti-coagulated blood samples were stained with fluorophore-conjugated monoclonal antibodies and analysed by flow cytometry to identify Tregs and other lymphocyte subsets. Total RNA was also extracted from peripheral blood mononuclear cells to investigate cytokine gene expression, and concentrations of serum cytokines (interleukins 2, 6 10, CXCL-8 and tumour necrosis factor α) were measured using enhanced chemiluminescent assays. Principal component analysis was used to investigate latent variables that might explain variability in the entire dataset.

Results

There was no difference in the frequency or absolute numbers of Tregs among groups, nor in the proportions of other lymphocyte subsets. The concentrations of pro-inflammatory cytokines were greater in dogs with IMHA compared to healthy controls, but the concentration of IL-10 and the expression of cytokine genes did not differ between groups. Principal component analysis identified four components that explained the majority of the variability in the dataset, which seemed to correspond to different aspects of the immune response.

Conclusions

The immunophenotype of dogs with IMHA differed from that of dogs with inflammatory diseases and from healthy control dogs; some of these changes could suggest abnormalities in peripheral tolerance that permit development of autoimmune disease. The frequency of Tregs did not differ between groups, suggesting that deficiency in the number of these cells is not responsible for development of IMHA.

Emergence of long-lived autoreactive plasma cells in the spleen of primary warm auto-immune hemolytic anemia patients treated with rituximab

Primary warm autoimmune hemolytic anemia (wAIHA) is a rare autoimmune disease in which red blood cells are eliminated by IgG autoantibodies. We analyzed the antibody-secreting cells in the spleen and the peripheral blood of wAIHA patients in various contexts of treatment. Plasmablasts were observed in peripheral blood of newly diagnosed wAIHA patients and, accordingly, active germinal center reactions were present in the spleen of patients receiving short-term corticosteroid therapy. Long-term corticosteroid regimens markedly reduced this response while splenic plasma cells were able to persist, a fraction of them secreting anti-red blood cell IgG in vitro. In wAIHA patients treated by rituximab and who underwent splenectomy because of treatment failure, plasma cells were still present in the spleen, some of them being autoreactive. By using a set of diagnostic genes that allowed us to assess the plasma cell maturation stage, we observed that these cells displayed a long-lived program, differing from the one of plasma cells from healthy donors or from wAIHA patients with various immunosuppressant treatments, and more similar to the one of normal long-lived bone-marrow plasma cells. Interestingly, an increased level of B-cell activating factor (BAFF) was observed in the supernatant of spleen cell cultures from such rituximab-treated wAIHA patients. These results suggest, in line with our previous report on primary immune thrombocytopenia, that the B-cell depletion induced by rituximab promoted a suitable environment for the maturation and survival of auto-immune long-lived plasma cells in the spleen.

Human interleukin-27: wide individual variation in plasma levels and complex inter-relationships with interleukin-17A

Although it is widely believed that interleukin (IL)-27 is anti-inflammatory, its role in controlling human immune responses is not fully established. In particular, its interactions with T helper type 17 (Th)17 cytokines are unclear. Our aims were to establish the relationships between IL-27 and proinflammatory cytokines, including IL-17A, in human sera and cultures of peripheral blood mononuclear cells. Plasma IL-27 levels in 879 healthy humans from 163 families varied widely, but with relatively low heritability (19%). Despite IL-27 including a subunit encoded by Epstein-Barr virus-induced gene 3 (EBI3), there was no correlation of levels with serological evidence of infection with the virus. Although IL-27 has been reported to inhibit IL-17A production, we demonstrated a strong positive correlation in sera, but lower correlations of IL-27 with other proinflammatory cytokines. We verified that IL-27 inhibited IL-17A production by human peripheral blood T cells in vitro, but not that it stimulated IL-10 secretion. Importantly, addition of IL-17A decreased IL-27 production by stimulated T cells but had the opposite effect on resting T cells. Together, these data suggest a model whereby IL-27 and IL-17A exerts complex reciprocal effects to boost inflammatory responses, but restrain resting cells to prevent inappropriate activation.

Combination peptide immunotherapy suppresses antibody and helper T-cell responses to the RhD protein in HLA-transgenic mice

The offspring from pregnancies of women who have developed anti-D blood group antibodies are at risk of hemolytic disease of the newborn. We have previously mapped four peptides containing immunodominant T-helper cell epitopes from the RhD protein and the purpose of the work was to develop these into a product for suppression of established anti-D responses. A panel of each of the four immunodominant RhD peptides was synthesized with modifications to improve manufacturability and solubility, and screened for retention of recognition by human T-helper cells. A selected version of each sequence was combined in a mixture (RhDPmix), which was tested for suppressive ability in a humanized murine model of established immune responses to RhD protein. After HLA-DR15 transgenic mice had been immunized with RhD protein, a single dose of RhDPmix, given either intranasally (P=0.008, Mann-Whitney rank sum test) or subcutaneously (P=0.043), rapidly and significantly suppressed the ongoing antibody response. This was accompanied by reduced T-helper cell responsiveness, although this change was less marked for subcutaneous RhDPmix delivery, and by the recruitment of cells with a regulatory T-cell phenotype. The results support human trials of RhDPmix peptide immunotherapy in women with established antibody responses to the RhD blood group.

Immunotherapy treatments of warm autoimmune hemolytic anemia

Warm autoimmune hemolytic anemia (WAIHA) is one of four clinical types of autoimmune hemolytic anemia (AIHA), with the characteristics of autoantibodies maximally active at body temperature. It produces a variable anemia—sometimes mild and sometimes severe. With respect to the absence or presence of an underlying condition, WAIHA is either idiopathic (primary) or secondary, which determines the treatment strategies in practice. Conventional treatments include immune suppression with corticosteroids and, in some cases, splenectomy. In recent years, the number of clinical studies with monoclonal antibodies and immunosuppressants in the treatment of WAIHA increased as the knowledge of autoimmunity mechanisms extended. This thread of developing new tools of treating WAIHA is well exemplified with the success in using anti-CD20 monoclonal antibody, Rituximab. Following this success, other treatment methods based on the immune mechanisms of WAIHA have emerged. We reviewed these newly developed immunotherapy treatments here in order to provide the clinicians with more options in selecting the best therapy for patients with WAIHA, hoping to stimulate researchers to find more novel immunotherapy strategies.

Epigenetics, autoimmunity and hematologic malignancies: a comprehensive review

The relationships between immunological dysfunction, loss of tolerance and hematologic malignancies have been a focus of attention in attempts to understand the appearance of a higher degree of autoimmune disease and lymphoma in children with congenital immunodeficiency. Although multiple hypotheses have been offered, it is clear that stochastic processes play an important role in the immunopathology of these issues. In particular, accumulating evidence is defining a role of epigenetic mechanisms as being critical in this continuous spectrum between autoimmunity and lymphoma. In this review, we focus attention predominantly on the relationships between T helper 17 (Th17) and T regulatory populations that alter local microenvironments and ultimately the expression or transcription factors involved in cell activation and differentiation. Abnormal expression in any of the molecules involved in Th17 and/or Treg development alter immune homeostasis and in genetically susceptible hosts may lead to the appearance of autoimmunity and/or lymphoma. These observations have clinical significance in explaining the discordance of autoimmunity in identical twins. They are also particularly important in the relationships between primary immune deficiency syndromes, immune dysregulation and an increased risk of lymphoma. Indeed, defining the factors that determine epigenetic alterations and their relationships to immune homeostasis will be a challenge greater or even equal to the human genome project.