H2 control of natural T regulatory cell frequency in the lymph node correlates with susceptibility to day 3 thymectomy-induced autoimmune disease

The role of maternal T cell and macrophage activation in preterm birth: Cause or consequence?

The role of the immune system in term (TL) and preterm labor (PTL) is unknown. Despite the fact that globally, PTL remains the most important cause of childhood mortality. Infection, typically of the fetal membranes, termed chorioamnionitis, is the best-understood driver of PTL, but the mechanisms underpinning other causes, including idiopathic and stretch-induced PTL, are unclear, but may well involve activation of the maternal immune system. The final common pathway of placental dysfunction, fetal membrane rupture, cervical dilation and uterine contractions are highly complex processes. At term, choriodecidual rather than myometrial inflammation is thought to drive the onset of labor and similar findings are present in different types of PTL including idiopathic PTL. Although accumulated data has confirmed an association between the immune response and preterm birth, there is yet a need to understand if this response is an initiator or a consequence of tissue-level dysregulation. This review focuses on the potential role of macrophages and T cells in innate and adaptive immunity relevant to preterm birth in humans and animal models.

Low expression of a Ddm7/Ldm7-hybrid mutant (D/Ldm7) in the novel haplotype H-2nc identified in atopic dermatitis model NC/Nga mice

Environmental factors and the major histocompatibility complex (MHC) are involved in the pathogenesis of atopic dermatitis (AD). However, MHC type (H2 haplotype) of AD model mice NC/Nga is poorly understood. Alloreactive CD8⁺ or CD4⁺ T cells in NC/Nga strongly responded to each antigen-presenting cells (A/J: H-2^a, C57BL/6: H-2^b, BALB/c: H-2^d, or C3H/HeJ: H-2^k), suggesting that NC/Nga has other H2 haplotype. Polymorphic microsatellite (CA)ⁿ repeats in TNF-α gene differ based on the H2 haplotype at present. NC/Nga's (CA)ⁿ repeats (n = 19) were different from other examined strains, A/J (n = 14), BALB/c (n = 14), C3H/HeJ (n = 16), and C57BL/6 (n = 20). Using flow cytometry and genotyping, we demonstrated the NC/Nga H2 haplotype had a unique phenotype (K^d, I-A^k, and I-E^k) in which D^d and L^d lacked as protein despite sensitive mRNA detection. The loss of D^d and L^d was caused by forming a unique D^dm7/L^dm7-hybrid mutant (D/L^dm7). We propose to call this novel H2 haplotype the "H-2^nc," and provide the important information regarding the AD research using NC/Nga mice.

Alternative theories: Pregnancy and immune tolerance

For some time, reproductive immunologists have worked to understand the balance between maternal tolerance of the fetus, maternal health, and fetal protection which leads to successful pregnancy in mammalian species. We have always understood the potential importance of multiple factors, including nutrition, genetics, anatomy, hormonal regulation, environmental insult and many others. Yet, we still struggle to combine our knowledge of these factors and immunology to finally understand complex diseases of pregnancy, such as preeclampsia. Data, and potentially other factors (e.g. politics, economics), support the work to fit pregnancy into classical immune theory driven by the concept of self-non-self-discrimination. However, based on data, many classical theorists call pregnancy "a special case." This review is a first-pass suggestion to attempt to view three models of immune system activation and tolerance as potential alternatives to classical self-non-self-discrimination and to propose a theoretical framework to view them in the context of pregnancy.

Breaking Free of Control: How Conventional T Cells Overcome Regulatory T Cell Suppression

Conventional T (Tcon) cells are crucial in shaping the immune response, whether it is protection against a pathogen, a cytotoxic attack on tumor cells, or an unwanted response to self-antigens in the context of autoimmunity. In each of these immune settings, regulatory T cells (Tregs) can potentially exert control over the Tcon cell response, resulting in either suppression or activation of the Tcon cells. Under physiological conditions, Tcon cells are able to transiently overcome Treg-imposed restraints to mount a protective response against an infectious threat, achieving clonal expansion, differentiation, and effector function. However, evidence has accumulated in recent years to suggest that Tcon cell resistance to Treg-mediated suppression centrally contributes to the pathogenesis of autoimmune disease. Tipping the balance too far in the other direction, cancerous tumors utilize Tregs to establish an overly suppressive microenvironment, preventing antitumor Tcon cell responses. Given the wide-ranging clinical importance of the Tcon/Treg interaction, this review aims to provide a better understanding of what determines whether a Tcon cell is susceptible to Treg-mediated suppression and how perturbations to this finely tuned balance play a role in pathological conditions. Here, we focus in detail on the complex array of factors that confer Tcon cells with resistance to Treg suppression, which we have divided into two categories: (1) extracellular factor-mediated signaling and (2) intracellular signaling molecules. Further, we explore the therapeutic implications of manipulating the phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway, which is proposed to be the convergence point of signaling pathways that mediate Tcon resistance to suppression. Finally, we address important unresolved questions on the timing and location of acquisition of resistance, and the stability of the “Treg-resistant” phenotype.

To drive or be driven: the path of a mouse model of recurrent pregnancy loss

This review is an example of the use of an animal model to try to understand the immune biology of pregnancy. A well-known model of recurrent spontaneous pregnancy loss is put in clinical, historical, and theoretical context, with emphasis on T cell biology.

Selective accumulation of pro-inflammatory T cells in the intestine contributes to the resistance to autoimmune demyelinating disease

Myelin-specific, pro-inflammatory T_H17 cells are widely regarded as the drivers of experimental autoimmune encephalomyelitis (EAE), an animal model for Multiple sclerosis (MS). The factors, responsible for the generation and maintenance of T_H17 cells as well as their participation in the pathogenic cascade leading to the demyelinating disease, have been studied extensively. However, how these harmful autoreactive cells are controlled in vivo remains unclear. By comparing TCR transgenic mice on a disease susceptible and a disease resistant genetic background, we show here that pathogenic T_H17 cells are sequestered within the intestine of spontaneous EAE resistant B10.S mice. Disease resistant B10.S mice harbored higher frequencies of T_H17 cells in the intestine compared to EAE susceptible SJL/J mice. Moreover, transferred T_H17 cells selectively migrated to intestinal lymphoid organs of B10.S mice. The sequestration of T_H17 cells in the gut was partially dependent on the gut homing receptor α4β7-mediated adhesion to the intestine. Administration of α4β7 blocking-antibodies increased the peripheral availability of T_H17 cells, resulting in increased EAE severity after immunization in B10.S mice. Together, these results support the concept that the intestine is a check-point for controlling pathogenic, organ-specific T cells.

Endocrine autoimmune diseases and female infertility

An increasing body of evidence suggests that immune-mediated processes affect female reproductive success at multiple levels. Crosstalk between endocrine and immune systems regulates a large number of biological processes that affect target tissues, and this crosstalk involves gene expression, cytokine and/or lymphokine release and hormone action. In addition, endocrine-immune interactions have a major role in the implantation process of the fetal (paternally derived) semi-allograft, which requires a reprogramming process of the maternal immune system from rejection to temporary tolerance for the length of gestation. Usually, the female immune system is supportive of all of these processes and, therefore, facilitates reproductive success. Abnormalities of the female immune system, including autoimmunity, potentially interfere at multiple levels. The relevance of the immune system to female infertility is increasingly recognized by investigators, but clinically is often not adequately considered and is, therefore, underestimated. This Review summarizes the effect of individual autoimmune endocrine diseases on female fertility, and points towards selected developments expected in the near future.

Genetics of experimental allergic encephalomyelitis supports the role of T helper cells in multiple sclerosis pathogenesis

OBJECTIVE

The major histocompatibility complex (MHC) is the primary genetic contributor to multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE), but multiple additional interacting loci are required for genetic susceptibility. The identity of most of these non-MHC genes is unknown. In this report, we identify genes within evolutionarily conserved genetic pathways leading to MS and EAE.

METHODS

To identify non-MHC binary and quantitative trait loci (BTL/QTL) important in the pathogenesis of EAE, we generated phenotype-selected congenic mice using EAE-resistant B10.S and EAE-susceptible SJL mice. We hypothesized that genes linked to EAE BTL/QTL and MS-GWAS can be identified if they belong to common evolutionarily conserved pathways, which can be identified with a bioinformatic approach using Ingenuity software.

RESULTS

Many known BTL/QTL were retained and linked to susceptibility during phenotype selection, the most significant being a region on chromosome 17 distal to H2 (Eae5). We show in pathway analysis that T helper (T(H))-cell differentiation genes are critical for both diseases. Bioinformatic analyses predicted that Eae5 is important in CD4 T-effector and/or Foxp3(+) T-regulatory cells (Tregs), and we found that B10.S-Eae5(SJL) congenic mice have significantly greater numbers of lymph node CD4 and Tregs than B10.S mice.

INTERPRETATION

These results support the polygenic model of MS/EAE, whereby MHC and multiple minor loci are required for full susceptibility, and confirm a critical genetic dependence on CD4 T(H)-cell differentiation and function in the pathogenesis of both diseases.

Histamine H4 receptor optimizes T regulatory cell frequency and facilitates anti-inflammatory responses within the central nervous system

Histamine is a biogenic amine that mediates multiple physiological processes, including immunomodulatory effects in allergic and inflammatory reactions, and also plays a key regulatory role in experimental allergic encephalomyelitis, the autoimmune model of multiple sclerosis. The pleiotropic effects of histamine are mediated by four G protein-coupled receptors, as follows: Hrh1/H(1)R, Hrh2/H(2)R, Hrh3/H(3)R, and Hrh4/H(4)R. H(4)R expression is primarily restricted to hematopoietic cells, and its role in autoimmune inflammatory demyelinating disease of the CNS has not been studied. In this study, we show that, compared with wild-type mice, animals with a disrupted Hrh4 (H(4)RKO) develop more severe myelin oligodendrocyte glycoprotein (MOG)(35\x{2013}55)-induced experimental allergic encephalomyelitis. Mechanistically, we also show that H(4)R plays a role in determining the frequency of T regulatory (T(R)) cells in secondary lymphoid tissues, and regulates T(R) cell chemotaxis and suppressor activity. Moreover, the lack of H(4)R leads to an impairment of an anti-inflammatory response due to fewer T(R) cells in the CNS during the acute phase of the disease and an increase in the proportion of Th17 cells.

Resolution of autoimmune oophoritis after thymectomy in a myasthenia gravis patient

Myasthenia gravis (MG) is an autoimmune disorder characterized by autoantibodies against acetylcholine receptors. MG is generally an isolated disorder but may occur concomitantly with other autoimmune diseases. We describe an eighteen-year-old girl with MG who was admitted to our clinic with secondary amenorrhea and diagnosed as autoimmune oophoritis. Since her myasthenic symptoms did not resolve with anticholinesterase therapy, thymectomy was performed. After thymectomy, her menses have been regular without any hormonal replacement therapy. To our knowledge, this is the first report on a patient with autoimmune ovarian insufficiency and MG in whom premature ovarian insufficiency resolved after thymectomy, without hormonal therapy.

Immunological variation between inbred laboratory mouse strains: points to consider in phenotyping genetically immunomodified mice

Inbred laboratory mouse strains are highly divergent in their immune response patterns as a result of genetic mutations and polymorphisms. The generation of genetically engineered mice (GEM) has, in the past, used embryonic stem (ES) cells for gene targeting from various 129 substrains followed by backcrossing into more fecund mouse strains. Although common inbred mice are considered "immune competent," many have variations in their immune system-some of which have been described-that may affect the phenotype. Recognition of these immune variations among commonly used inbred mouse strains is essential for the accurate interpretation of expected phenotypes or those that may arise unexpectedly. In GEM developed to study specific components of the immune system, accurate evaluation of immune responses must take into consideration not only the gene of interest but also how the background strain and microbial milieu contribute to the manifestation of findings in these mice. This article discusses points to consider regarding immunological differences between the common inbred laboratory mouse strains, particularly in their use as background strains in GEM.

Regulatory T cells control tolerogenic versus autoimmune response to sperm in vasectomy

Vasectomy is a well accepted global contraceptive approach frequently associated with epididymal granuloma and sperm autoantibody formation. To understand the long-term sequelae of vasectomy, we investigated the early immune response in vasectomized mice. Vasectomy leads to rapid epithelial cell apoptosis and necrosis, persistent inflammation, and sperm granuloma formation in the epididymis. Vasectomized B6AF1 mice did not mount autoimmune response but instead developed sperm antigen-specific tolerance, documented as resistance to immunization-induced experimental autoimmune orchitis (EAO) but not experimental autoimmune encephalomyelitis. Strikingly, tolerance switches over to pathologic autoimmune state following concomitant CD4(+)CD25(+)Foxp3(+) regulatory T cell (Treg) depletion: unilaterally vasectomized mice produce dominant autoantibodies to an orchitogenic antigen (zonadhesin), and develop CD4 T-cell- and antibody-dependent bilateral autoimmune orchitis. Therefore, (i) Treg normally prevents spontaneous organ-specific autoimmunity induction by persistent endogenous danger signal, and (ii) autoantigenic stimulation with sterile autoinflammation can lead to tolerance. Finally, postvasectomy tolerance occurs in B6AF1, C57BL/6, and A/J strains. However, C57BL/6 mice resisted EAO after 60% Treg depletion, but developed EAO after 97% Treg reduction. Therefore, variance in intrinsic Treg function--a possible genetic trait--can influence the divergent tolerogenic versus autoimmune response to vasectomy.

Dry olive leaf extract (DOLE) down-regulates the progression of experimental immune-mediated diabetes by modulation of cytokine profile in the draining lymph nodes

We have recently demonstrated the beneficial effects of dry olive leaf extract (DOLE) in two preclinical models of type 1 diabetes. Here we analyze the potential mechanisms underlying diabetes amelioration at the level of lymph node drainage. Treatment of C57BL/6 mice with DOLE during induction of diabetes with multiple low doses of streptozotocin (MLD-SZ) modulated cytokine expression and production in pancreatic lymph node cells, thereby changing the balance between potentially pathogenic and down-regulating cytokines. These results support the immunoregulatory potential of DOLE which takes place at the level of lymph node drainage and preserves the target tissue from autoimmune attack.