IL-4 and IL-10 modulate autoimmune haemolytic anaemia in NZB mice

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).

Differential bicistronic gene translation mediated by the internal ribosome entry site element of encephalomyocarditis virus

Background

Internal ribosome entry sites (IRESs) allow the translation of a transcript independent of its cap structure. They are distributed in some viruses and cellular RNA. The element is applied in dual gene expression in a single vector. Although it appears the lower efficiency of IRES-mediated translation than that of cap-dependent translation, it is with the crucial needs to know the precise differences in translational efficacy between upstream cistrons (cap-dependent) and downstream cistrons (IRES-mediate, cap-independent) before applying the bicistronic vector in biomedical applications.

Methods

This study aimed to provide real examples and showed the precise differences for translational efficiency dependent upon target gene locations. We generated various bicistronic constructs with quantifiable reporter genes as upstream and downstream cistrons of the encephalomyocarditis virus (EMCV) IRES to precisely evaluate the efficacy of IRES-mediated translation in mammalian cells.

Results

There was no significant difference in protein production when the reporter gene was cloned as an upstream cistron. However, lower levels of protein production were obtained when the reporter gene was located downstream of the IRES. Moreover, in the presence of an upstream cistron, a markedly reduced level of protein production was observed.

Conclusion

Our findings demonstrate the version of the EMCV IRES that is provided in many commercial vectors is relatively less efficient than cap-dependent translation and provide valuable information regarding the utilization of IRES to facilitate the expression of more than one protein from a transcript.

Interleukin-4 Supports the Suppressive Immune Responses Elicited by Regulatory T Cells

Interleukin-4 (IL-4) has been considered as one of the tolerogenic cytokines in many autoimmune animal models and clinical settings. Despite its role in antagonizing pathogenic Th1 responses, little is known about whether IL-4 possesses functions that affect regulatory T cells (Tregs). Tregs are specialized cells responsible for the maintenance of peripheral tolerance through their immune modulatory capabilities. Interestingly, it has been suggested that IL-4 supplement at a high concentration protects responder T cells (Tresps) from Treg-mediated immune suppression. In addition, such supplement also impedes TGF-β-induced Treg differentiation in vitro. However, these phenomena may contradict the tolerogenic role of IL-4, and the effects of IL-4 on Tregs are therefore needed to be further elucidated. In this study, we utilized IL-4 knockout (KO) mice to validate the role of IL-4 on Treg-mediated immune suppression. Although IL-4 KO and control animals harbor similar frequencies of Tregs, Tregs from IL-4 KO mice weakly suppressed autologous Tresp activation. In addition, IL-4 deprivation impaired the ability of Tregs to modulate immune response, whereas IL-4 supplementation reinforced IL-4 KO Tregs in their function in suppressing Tresps. Finally, the presence of IL-4 was associated with increased cell survival and granzyme expression of Tregs. These results suggest the essential role of IL-4 in supporting Treg-mediated immune suppression, which may benefit the development of therapeutic strategies for autoimmune diseases.

Induction of IL-10 cytokine and the suppression of T cell proliferation by specific peptides from red cell band 3 and in vivo effects of these peptides on autoimmune hemolytic anemia in NZB mice

PURPOSE

The anion channel protein band 3 is the main target of the pathogenic red blood cells (RBC) autoantibodies in New Zealand black (NZB) mice. CD4 T cells from NZB mice with autoimmune hemolytic anemia respond to band 3. Previously, we have shown that IL-10 and peptides containing a dominant T cell epitope from red cell band 3 modulate autoimmune hemolytic anemia in NZB mice. Because of the immunoregulatory role of IL-10 in autoimmune diseases, we aim to identify individual band 3 peptides that induce high IL-10 production and simultaneously suppress CD4 T cell proliferation and to investigate the effect intranasal administration of IL-10 producing band 3 peptides on autoantibody responses of NZB mice.

METHODS

Splenic CD4 T cells of NZB mice were isolated and stimulated by co-culture of T cells with individual band 3 peptides. IL-10 production was measured by enzyme-linked immunosorbent assay and proliferative response of CD4 T cells was estimated by incorporation of [³H] thymidine assay. NZB mice were given either PBS, or peptides 25 (241-251) and 29 (282-296) or both peptides intranasally on three occasions at 2-day intervals. The mice were bled at 6, 10 and 18 weeks after peptide inhalation, and the number of RBC auto-antibodies was measured by DELAT and hematocrit values were assessed.

RESULTS

Peptides 25 (241-251) and 29 (282-296) induced the highest IL-10 production by CD4 T cells. These peptides also inhibited the peak T cell proliferative response. 6 and 10 weeks after peptide inhalation, the total IgG, IgG1 and IgG2a in mice treated with both peptides 241-251 and 282-296 were significantly higher than control (P < 0.05). However, no significant difference in the mean hematocrit between of the peptide-treated mice and the control group was found.

CONCLUSIONS

Although band 3 peptides 241-251 and 282-296 induced to the highest IL-10 production by CD4 T cells in vitro but fail to reverse the RBC autoantibody response in vivo. Modifications to improve solubility these peptides might help to modulate the immune response toward a T helper-2 profile and decrease the severity of anemia.

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.

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

BACKGROUND

Interleukin-17A is the signature cytokine of the Th17 subset and drives inflammatory pathology, but its relevance to autoantibody-mediated diseases is unclear. Th1 cells secreting interferon-γ have been implicated in autoimmune hemolytic anemia, so the aim was to determine which cytokine is more closely associated with disease severity.

DESIGN AND METHODS

Interferon-γ and interleukin-17A were measured in the sera of patients with autoimmune hemolytic anemia and healthy donors, and in peripheral blood mononuclear cell cultures stimulated with autologous red blood cells, or a panel of peptides spanning red blood cell autoantigen.

RESULTS

Serum interleukin-17A, but not interferon-γ, was significantly raised in patients with autoimmune hemolytic anemia (P<0.001), and correlated with the degree of anemia. Interleukin-17A was also more prominent in the responses of peripheral blood mononuclear cells from patients with autoimmune hemolytic anemia to red blood cells, and, again unlike interferon-γ, significantly associated with more severe anemia (P<0.005). There were no interleukin-17A responses to red blood cells by peripheral blood mononuclear cells from healthy donors. Specific autoantigenic peptides were identified that elicit patients' interleukin-17A responses.

CONCLUSIONS

Interleukin-17A makes a previously unrecognized contribution to the autoimmune response in autoimmune hemolytic anemia, challenging the model that the disease is driven primarily by Th1 cells. This raises the possibility that Th17, rather than Th1, cells should be the target for therapy.

Adenovirus-mediated gene delivery of interleukin-10, but not transforming growth factor beta, ameliorates the induction of Graves' hyperthyroidism in BALB/c mice

Interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) are well known anti-inflammatory cytokines. We have studied the effect of adenovirus-mediated IL-10 and TGF-beta gene delivery on the induction of Graves' hyperthyroidism in our mouse model that involves repeated injections of adenovirus expressing the thyrotropin receptor A subunit (AdTSHR). We first constructed adenoviruses encoding the two cytokines (AdIL10 and AdTGF(beta)) and confirmed expression by in vitro infection of COS cells. Susceptible BALB/c mice were injected twice with AdTSHR alone or together with AdIL10 or AdTGF(beta), and bled two weeks after the second immunization. Significantly elevated serum thyroxine levels were seen in 26% of mice immunized with AdTSHR and AdIL10 versus 61% with AdTSHR alone. Levels of thyroid stimulating antibody, but not nonstimulating antibody, were also decreased, and TSHR-specific splenocyte secretion of interferon-gamma in recall assays was impaired in mice treated with AdIL10. In contrast, AdTGF(beta) had little effect on hyperthyroidism. Overall, our findings demonstrate that gene delivery of IL-10, but not TGF-beta, suppresses the induction of Graves' hyperthyroidism in a mouse model. However, the effect of IL-10 is less powerful than we observed previously with T helper type 2-inducers including adenovirus expressing IL-4, Shistosoma mansoni infection or alpha-galactosylceramide.