Increased T regulatory cells lead to development of Th2 immune response in male SJL mice

Dissecting the causal role of immunophenotypes in primary sclerosing cholangitis risk: A Mendelian randomization study

Primary sclerosing cholangitis (PSC), a chronic cholestatic liver condition, is frequently associated with inflammatory bowel disease. Specific immune cells have been implicated in PSC pathogenesis with the emergence of the "microbiota" and "gut lymphocyte homing" hypotheses, albeit their identities remain controversial. The first genome-wide association analysis leveraged nonoverlapping data from 3757 Europeans to evaluate 731 immunophenotypes. A genome-wide association analysis comprising 2871 cases and 12,019 controls yielded summary statistics for PSC. An inverse-variance weighted (IVW) analysis was performed to identify immunophenotypes causally related to PSC, and the results were validated using weighted mode, MR-Egger, and weighted median methods. Comprehensive sensitivity analyses were performed to verify the robustness, heterogeneity, and horizontal pleiotropy of the results. IVW analysis revealed 26 immune traits exhibiting causal associations with PSC. CD3 on HLA-DR+ CD4+ (IVW odds ratio [OR]: 0.904; 95% confidence interval [CI]: 0.828-0.986, P = .023) and CD3 on secreting Treg (IVW OR: 0.893; 95% CI: 0.823-0.969, P = .007) were negatively associated with PSC susceptibility and demonstrated high consistency across the 3 validation methods. Moreover, 7 other immune traits, including CD39+ resting Treg absolute cell (IVW OR = 1.083, 95% CI: 1.013-1.157, P = .019), CD39+ secreting Treg absolute cell (IVW OR = 1.063, 95% CI: 1.012-1.118, P = .015), CD3 on naive CD8br (IVW OR = 0.907, 95% CI: 0.835-0.986, P = .022), CD3 on CD39+ activated Treg (IVW OR = 0.927, 95% CI: 0.864-0.994, P = .034), CD28 on resting Treg (IVW OR = 0.724, 95% CI: 0.630-0.833, P = 5.95E-06), and CD39 on CD39+ CD4+ (IVW OR = 1.055, 95% CI: 1.001-1.112, P = .044) exhibited consistent results in the Weighted Median and Weighted Mode validation methods. Moreover, no significant heterogeneity or horizontal pleiotropy was observed across the single nucleotide polymorphisms. The leave-one-out results revealed that sequentially eliminating each single nucleotide polymorphism had no significant influence on model effect estimates or qualitative inference. This study evaluated potential causal links between 731 immune traits and PSC susceptibility. Twenty-six immune traits were identified using the IVW method. Verification across multiple methods revealed 9 immune traits with a plausible causal connection to PSC. These findings may uncover mechanistic pathways and novel therapeutic approaches.

Mechanisms and consequences of sex differences in immune responses

Biological sex differences refer to differences between males and females caused by the sex chromosome complement (that is, XY or XX), reproductive tissues (that is, the presence of testes or ovaries), and concentrations of sex steroids (that is, testosterone or oestrogens and progesterone). Although these sex differences are binary for most human individuals and mice, transgender individuals receiving hormone therapy, individuals with genetic syndromes (for example, Klinefelter and Turner syndromes) and people with disorders of sexual development reflect the diversity in sex-based biology. The broad distribution of sex steroid hormone receptors across diverse cell types and the differential expression of X-linked and autosomal genes means that sex is a biological variable that can affect the function of all physiological systems, including the immune system. Sex differences in immune cell function and immune responses to foreign and self antigens affect the development and outcome of diverse diseases and immune responses.

Inbred SJL mice recapitulate human resistance to Cryptococcus infection due to differential immune activation

IMPORTANCE

Cryptococcosis studies often utilize the common C57BL/6J mouse model. Unfortunately, infection in these mice fails to replicate the basic course of human disease, particularly hampering immunological studies. This work demonstrates that SJL/J mice can recapitulate human infection better than other mouse strains. The immunological response to Cryptococcus infection in SJL/J mice was markedly different from C57BL/6J and much more productive in combating this infection. Characterization of infected mice demonstrated strain-specific genetic linkage and differential regulation of multiple important immune-relevant genes in response to Cryptococcus infection. While our results validate many of the previously identified immunological features of cryptococcosis, we also demonstrate limitations from previous mouse models as they may be less translatable to human disease. We concluded that SJL/J mice more faithfully recapitulate human cryptococcosis serving as an exciting new animal model for immunological and genetic studies.

Immune Cell Contributors to the Female Sex Bias in Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic, autoimmune, demyelinating disease of the central nervous system (CNS) that leads to axonal damage and accumulation of disability. Relapsing-remitting MS (RR-MS) is the most frequent presentation of MS and this form of MS is three times more prevalent in females than in males. This female bias in MS is apparent only after puberty, suggesting a role for sex hormones in this regulation; however, very little is known of the biological mechanisms that underpin the sex difference in MS onset. Experimental autoimmune encephalomyelitis (EAE) is an animal model of RR-MS that presents more severely in females in certain mouse strains and thus has been useful to study sex differences in CNS autoimmunity. Here, we overview the immunopathogenesis of MS and EAE and how immune mechanisms in these diseases differ between a male and female. We further describe how females exhibit more robust myelin-specific T helper (Th) 1 immunity in MS and EAE and how this sex bias in Th cells is conveyed by sex hormone effects on the T cells, antigen presenting cells, regulatory T cells, and innate lymphoid cell populations.

Is there a window of opportunity for the therapeutic use of vitamin D in multiple sclerosis?

Multiple sclerosis is an autoimmune treatable but not curable disease. There are a multiplicity of medications for multiple sclerosis therapy, including a class entitled disease-modifying drugs that are mainly indicated to reduce the number and severity of disease relapses. Not all patients respond well to these therapies, and minor to severe adverse effects have been reported. Vitamin D, called sunshine vitamin, is being studied as a possible light at the end of the tunnel. In this review, we recapitulated the similar immunopathogenesis of multiple sclerosis and experimental autoimmune encephalomyelitis, the immunomodulatory and neuroprotective potential of vitamin D and the state-of-art concerning its supplementation to multiple sclerosis patients. Finally, based on our and other groups’ experimental findings, we analyzed the need to consider the relevance of the route and the different time-point administration aspects for a more rational indication of this vitamin to multiple sclerosis patients.

Animal models of congenital zika syndrome provide mechanistic insight into viral pathogenesis during pregnancy

In utero Zika virus (ZIKV; family Flaviviridae) infection causes a distinct pattern of birth defects and disabilities in the developing fetus and neonate that has been termed congenital zika syndrome (CZS). Over 8,000 children were affected by the 2016 to 2017 ZIKV outbreak in the Americas, many of whom developed CZS as a result of in utero exposure. To date, there is no consensus about how ZIKV causes CZS; animal models, however, are providing mechanistic insights. Using nonhuman primates, immunocompromised mice, immunocompetent mice, and other animal models (e.g., pigs, sheep, guinea pigs, and hamsters), studies are showing that maternal immunological responses, placental infection and inflammation, as well as viral genetic factors play significant roles in predicting the downstream consequences of in utero ZIKV infection on the development of CZS in offspring. There are thousands of children suffering from adverse consequences of CZS. Therefore, the animal models developed to study ZIKV-induced adverse outcomes in offspring could provide mechanistic insights into how other viruses, including influenza and hepatitis C viruses, impact placental viability and fetal growth to cause long-term adverse outcomes in an effort to identify therapeutic treatments.

Determination of cytokine levels in multiple sclerosis patients and their relevance with patients' response to Cinnovex

Multiple sclerosis (MS) is a heterogeneous chronic immune-mediated disorder of the central nervous system (CNS) with several environmental and genetic factors participating in its development and disease course. Interferon (IFN)-β therapy is considered as the first line treatment in this disorder. The present study enrolled 231 relapsing-remitting MS patients who were diagnosed as IFN-β responders (n=146) and non-responders (n=85). Serum cytokine levels were analyzed by commercially available ELISA kits in distinct groups based on HLA-A, -B and -DRB1 alleles. IFN-γ levels were significantly higher in responders compared with non-responders, whereas IL-17A and IL-6 had the opposite trend. The levels of IL-10 and IL-4 were not significantly different between two groups. IFN-γ and IL-17A levels were associated with response to IFN-β. Comparison of cytokine levels revealed higher IFN-γ levels in HLA-DRB1∗04 positive patients (n=72) compared with HLA-DRB1∗04 negative patients (n=159). In responder group, patients who were positive for HLA-DRB1∗15 had significantly higher levels of IL-6 compared to HLA-DRB1∗15 negative patients. IL-17A levels tend to be higher in responder patients who were positive for HLA-DRB1∗04 compared with those were negative for the same allele. This study suggests that the serum levels of pro- and anti-inflammatory cytokines are different among IFN-β responders and non-responders. Future studies are needed to confirm their efficiency in determination of response to IFN-β in MS patients.

Regulatory CD4+CD25+ T Cells Dampen Inflammatory Disease in Murine Mycoplasma Pneumonia and Promote IL-17 and IFN-γ Responses

Mycoplasmas cause respiratory diseases characterized by persistent infection and chronic airway inflammation. Mycoplasma lung disease is immunopathologic, with CD4⁺ Th cells determining both disease severity and resistance to infection. Th2 cell responses promote immunopathology, while Th1 cells confer resistance to infection. However, regulatory CD4⁺ T cells may also have a role in the pathogenesis of mycoplasma respiratory diseases. We hypothesized Treg cells control the severity of the inflammatory lesions and may also promote persistence of infection. To examine this, BALB/c mice were depleted of CD25⁺ cells, and had increased disease severity due to Mycoplasma pulmonis infection. Increases in mycoplasma antibody responses and lymphocyte infiltration into lungs also occurred after CD25⁺ cell depletion. CD4⁺CD25⁺ regulatory T cells promoted IFN-γ and IL-17 mycoplasma-specific CD4⁺ T cell responses in vitro and in vivo, while dampening IL-13⁺ Th responses. Neither IL-10 nor TGF-ß expression was detected in CD4⁺CD25⁺ T cells from lymph nodes. Thus, a regulatory T cell population plays an important role in controlling damaging immune responses in mycoplasma respiratory disease but does not contribute to persistence of infection. It appears that a regulatory T cell population preferentially dampens Th2 cell-mediated inflammatory responses to mycoplasma through a mechanism independent of IL-10 or TGF-ß characteristic of “classic” Treg cells.

Sex-Based Differences in Multiple Sclerosis (Part I): Biology of Disease Incidence

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease that leads to neuron damage and progressive disability. One major feature of multiple sclerosis (MS) is that it affects women three times more often than men. In this chapter, we overview the evidence that the autoimmune component of MS, which predominates in the early stages of this disease, is more robust in women than in men and undergoes a sharp increase with the onset of puberty. In addition, we discuss the common rodent models of MS that have been used to study the sex-based differences in the development of central nervous system (CNS) autoimmunity. We then address the biological underpinnings of this enhanced MS risk in women by first reviewing the autoimmune mechanisms that are thought to lead to the initiation of this disease and then honing in on how these mechanisms differ between the sexes. Finally, we review what is known about the hormonal and genetic basis of these sex differences in CNS autoimmunity.

The selective impact of transgenically expressed glucocorticoid receptor on T cells

Glucocorticoids (GCs) strongly impact on different T cell subsets inducing generally immunosuppressive effects, whereas much less is known about the effect of GC on natural killer (NK) cells. The aims of this study were to investigate the effects of GC on T cell functions, including T cell-mediated anti-tumor immune response, and on NK cells. We have used lck-GR mice, which overexpress a transgenic rat GR in both T and NK cells. These mice were found to have decreased both CD4(+) and CD8(+) T cell populations in the periphery. In contrast, both NK and NKT cells were found in normal numbers in lck-GR mice. To identify genes and pathways affected by GR overexpression in our system in T cells, we have compared gene expression profiles in wild-type and lck-GR T cells. Among the genes upregulated in T cells from lck-GR mice, the microarray analysis has identified genes regulating expansion of regulatory T cells. The analysis of genes downregulated in lck-GR mice has identified genes and gene associated with the regulation of immune response. With regard to the effects on T cell functions in lck-GR mice, transgenic expression of GR had a suppressive effect on killer cell activity in vitro. In addition, lck-GR mice showed an increased tumor growth in murine tumor model in vivo, which may be a possible consequence of reduced T cell numbers and activity. We conclude that an increased expression of the GR strongly affects numbers and possibly functions of T cell subsets, but has little effect on NK cells.

Autoimmunity in 2012

The initiation and perpetuation of autoimmunity recognize numerous checkpoints, from the genomic susceptibility to the breakdown of tolerance. This latter phenomenon includes the loss of B cell anergy and T regulatory cell failure, as well as the production of autoantibodies and autoreactive T cells. These mechanisms ultimately lead to tissue injury via different mechanisms that span from the production of proinflammatory cytokines to the chemotaxis of immune cells to the target sites. The pathways to autoimmunity have been widely investigated over the past year and resulted in a number of articles in peer-reviewed journals that has increased by nearly 10 % compared to 2011. We herein follow on the attempt to provide a brief discussion of the majority of articles on autoimmune diseases that were published in the major immunology journals in the previous solar year. The selection is necessarily arbitrary and may thus not be seen as comprehensive but reflects current research trends. Indeed, 2012 articles were mostly dedicated to define new and old mechanisms with potential therapeutic implications in autoimmunity in general, though based on specific clinical conditions or animal models. As paradigmatic examples, the environmental influence on autoimmunity, Th17 changes modulating the autoimmune response, serum autoantibodies and B cell changes as biomarkers and therapeutic targets were major issues addressed by experimental articles in 2012. Further, a growing number of studies investigated the sex bias of autoimmunity and supported different working hypotheses to explain the female predominance, including sex chromosome changes and reproductive life factors. In conclusion, the resulting scenario illustrates that common factors may underlie different autoimmune diseases and this is well represented by the observed alterations in interferon-α and TGFβ or by the shared signaling pathways.

Autoimmunity in 2011

The mechanisms leading to the onset and perpetuation of systemic and tissue-specific autoimmune diseases are complex, and numerous hypotheses have been proposed or confirmed over the past 12 months. It is particularly of note that the number of articles published during 2011 in the major immunology and autoimmunity journals increased by 3 % compared to the previous year. The present article is dedicated to a brief review of the reported data and, albeit not comprehensive of all articles, is aimed at identifying common and future themes. First, clinical researchers were particularly dedicated to defining refractory forms of diseases and to discuss the use and switch of therapeutic monoclonal antibodies in everyday practice. Second, following the plethora of genome-wide association studies reported in most multifactorial diseases, it became clear that genomics cannot fully explain the individual susceptibility and additional environmental or epigenetic factors are necessary. Both these components were widely investigated, both in organ-specific (i.e., type 1 diabetes) and systemic (i.e., systemic lupus erythematosus) diseases. Third, a large number of 2011 works published in the autoimmunity area are dedicated to dissect pathogenetic mechanisms of tolerance breakdown in general or in specific conditions. While our understanding of T regulatory and Th17 cells has significantly increased in 2011, it is of note that most of the proposed lines of evidence identify potential targets for future treatments and should not be overlooked.

Prenatal and Postnatal Epigenetic Programming: Implications for GI, Immune, and Neuronal Function in Autism

Although autism is first and foremost a disorder of the central nervous system, comorbid dysfunction of the gastrointestinal (GI) and immune systems is common, suggesting that all three systems may be affected by common molecular mechanisms. Substantial systemic deficits in the antioxidant glutathione and its precursor, cysteine, have been documented in autism in association with oxidative stress and impaired methylation. DNA and histone methylation provide epigenetic regulation of gene expression during prenatal and postnatal development. Prenatal epigenetic programming (PrEP) can be affected by the maternal metabolic and nutritional environment, whereas postnatal epigenetic programming (PEP) importantly depends upon nutritional support provided through the GI tract. Cysteine absorption from the GI tract is a crucial determinant of antioxidant capacity, and systemic deficits of glutathione and cysteine in autism are likely to reflect impaired cysteine absorption. Excitatory amino acid transporter 3 (EAAT3) provides cysteine uptake for GI epithelial, neuronal, and immune cells, and its activity is decreased during oxidative stress. Based upon these observations, we propose that neurodevelopmental, GI, and immune aspects of autism each reflect manifestations of inadequate antioxidant capacity, secondary to impaired cysteine uptake by the GI tract. Genetic and environmental factors that adversely affect antioxidant capacity can disrupt PrEP and/or PEP, increasing vulnerability to autism.