An aggressive form of polyarticular arthritis in a man with CD154 mutation (X-linked hyper-IgM syndrome)

Primary immunodeficiency and autoimmunity: A comprehensive review

The primary immunodeficiency diseases (PIDs) include many genetic disorders that affect different components of the innate and adaptive responses. The number of distinct genetic PIDs has increased exponentially with improved methods of detection and advanced laboratory methodology. Patients with PIDs have an increased susceptibility to infectious diseases and non-infectious complications including allergies, malignancies and autoimmune diseases (ADs), the latter being the first manifestation of PIDs in several cases. There are two types of PIDS. Monogenic immunodeficiencies due to mutations in genes involved in immunological tolerance that increase the predisposition to develop autoimmunity including polyautoimmunity, and polygenic immunodeficiencies characterized by a heterogeneous clinical presentation that can be explained by a complex pathophysiology and which may have a multifactorial etiology. The high prevalence of ADs in PIDs demonstrates the intricate relationships between the mechanisms of these two conditions. Defects in central and peripheral tolerance, including mutations in AIRE and T regulatory cells respectively, are thought to be crucial in the development of ADs in these patients. In fact, pathology that leads to PID often also impacts the Treg/Th17 balance that may ease the appearance of a proinflammatory environment, increasing the odds for the development of autoimmunity. Furthermore, the influence of chronic and recurrent infections through molecular mimicry, bystander activation and super antigens activation are supposed to be pivotal for the development of autoimmunity. These multiple mechanisms are associated with diverse clinical subphenotypes that hinders an accurate diagnosis in clinical settings, and in some cases, may delay the selection of suitable pharmacological therapies. Herein, a comprehensively appraisal of the common mechanisms among these conditions, together with clinical pearls for treatment and diagnosis is presented.

Immunoglobulin class switch recombination deficiency type 1 or CD40 ligand deficiency: from bedside to bench and back again

The immunoglobulin class switch recombination deficiency or hyper-IgM syndrome is characterized by normal or elevated serum IgM and low serum levels of other immunoglobulins. Since the first reported patient with hyper-IgM, more than 200 patients with this phenotype resulted from CD40 ligand deficiency have been reported. However, in addition to this common finding, they presented with different manifestations like opportunistic infections, autoimmunity and malignancies each of them are worth a detailed look. In this review, we will focus on different underlying mechanisms of these presentations to review what we have learned from our patients. In the end, we will discuss different treatment options available for these patients using this knowledge.

Autoimmunity in hyper-IgM syndrome

INTRODUCTION

Immunodeficiency with hyper-IgM (HIGM) results from genetic defects in the CD40-CD40 ligand (CD40L) pathway or in the enzymes required for immunoglobulin class switch recombination and somatic hypermutation. HIGM can thus be associated with an impairment of both B-cell and T-cell activation.

RESULTS AND DISCUSSIONS

There are seven main subtypes of HIGM and the most frequent is X-linked HIGM, resulting from CD40L mutations. In addition to the susceptibility to recurrent and opportunistic infections, these patients are prone to autoimmune manifestations, especially hematologic abnormalities, arthritis, and inflammatory bowel disease. Furthermore, organ-specific autoantibodies are commonly found in HIGM patients.

CONCLUSIONS

The mechanisms by which HIGM associates to autoimmunity are not completely elucidated but a defective development of regulatory T cells, the presence of IgM autoantibodies and an impaired peripheral B-cell tolerance checkpoint have been implicated. This article reviews the main subtypes of HIGM syndrome, the clinical autoimmune manifestations found in these patients, and the possible mechanisms that would explain this association.

Nodular regenerative hyperplasia: the main liver disease in patients with primary hypogammaglobulinemia and hepatic abnormalities

BACKGROUND/AIMS

Liver lesions associated with primary hypogammaglobulinemia have been poorly described. We aimed to assess the clinical, histological and immune features and outcome of hepatic injury in patients with primary hypogammaglobulinemia.

METHODS

The medical records of 51 patients (23 patients with liver biopsy) with primary hypogammaglobulinemia and liver abnormalities were retrospectively reviewed. Forty-three controls with primary hypogammaglobulinemia but with no hepatic manifestations were analyzed in parallel.

RESULTS

Cholestasis (65%), mainly anicteric, and portal hypertension (50%) were the main hepatic manifestations. Histological analysis revealed non-fibrosing architectural abnormalities consistent with nodular regenerative hyperplasia (NRH) in 84% of CVID patients and in all HIGM and XLA patients. Intrasinusoidal lymphocytic infiltration, abnormalities of portal vessels and epithelioid granulomas were observed in 90%, 43% and 44% of patients, respectively. NRH was associated with portal hypertension in 75% of the cases. These patients more often presented with autoimmune diseases and peripheral lymphocytic abnormalities than control patients (p < 0.05).

CONCLUSIONS

Liver involvement in primary hypogammaglobulinemia mainly consists of NRH leading to chronic cholestasis and portal hypertension. Association with intrasinusoidal T cell infiltration, portal vein endotheliitis, autoimmune diseases and peripheral lymphocytic abnormalities suggests an autoimmune mechanism.

Bone and joint disease associated with primary immune deficiencies

Primary immune deficiencies (PIDs) are characterized by functional and/or quantitative abnormalities of one or more immune system components. Several bone and joint abnormalities can occur in patients with PID, with arthritis being the most common. Joint manifestations, of which arthritis is the most common, occur chiefly in humoral PIDs (agammaglobulinemia, common variable immunodeficiency, hyper-IgM syndromes, and IgA deficiency) and occasionally in other PIDs (chronic granulomatous disease and Wiskott-Aldrich syndrome). Monoarthritis or oligoarthritis is the usual pattern, although polyarthritis may occur, occasionally with nodules suggesting rheumatoid arthritis. Arthritis in patients with PID is usually infectious in nature, the most common causative organism being Mycoplasma, followed by Staphylococcus, Streptococcus, and Haemophilus. These bacteria can induce not only synovial infections, but also aseptic arthritogenic inflammatory responses. Arthritis having no demonstrable relation to chronic infection has been reported also and ascribed to dysimmunity-driven mechanisms that exhibit a number of specific features. Bone lesions are far less common and usually due to infections complicating humoral PID. Distinctive bone manifestations occur in a number of rare PIDs (e.g., hyper-IgE syndrome and Di George syndrome) and in syndromes characterized by spondyloepiphyseal dysplasia. Familiarity with PID syndromes both enhances the diagnostic capabilities of physicians and provides insight into the pathophysiology of bone and joint abnormalities associated with immune dysfunction. In children and occasionally in adults, a combination of bone and/or joint manifestations and hypogammaglobulinemia may indicate PID. When there is no evidence of lymphoproliferative disease, infection, or iatrogenic complications, investigations for PID should be obtained. PID-related arthritis is a unique model for studying the pathogenesis of presumably postinfectious arthritis and of inflammatory joint diseases including rheumatoid arthritis.

TNF-alpha is crucial for the development of autoimmune arthritis in IL-1 receptor antagonist-deficient mice

IL-1 receptor antagonist-deficient (IL-1Ra(-/-)) mice spontaneously develop autoimmune arthritis. We demonstrate here that T cells are required for the induction of arthritis; T cell-deficient IL-1Ra(-/-) mice did not develop arthritis, and transfer of IL-1Ra(-/-) T cells induced arthritis in nu/nu mice. Development of arthritis was also markedly suppressed by TNF-alpha deficiency. We found that TNF-alpha induced OX40 expression on T cells and blocking the interaction between either CD40 and its ligand or OX40 and its ligand suppressed development of arthritis. These findings suggest that IL-1 receptor antagonist deficiency in T cells disrupts homeostasis of the immune system and that TNF-alpha plays an important role in activating T cells through induction of OX40.

IL-17 production from activated T cells is required for the spontaneous development of destructive arthritis in mice deficient in IL-1 receptor antagonist

IL-17 is a T cell-derived, proinflammatory cytokine that is suspected to be involved in the development of various inflammatory diseases. Although there are elevated levels of IL-17 in synovial fluid of patients with rheumatoid arthritis, the pathogenic role of IL-17 in the development of rheumatoid arthritis remains to be elucidated. In this report, the effects of IL-17 deficiency were examined in IL-1 receptor antagonist-deficient (IL-1Ra(-/-)) mice that spontaneously develop an inflammatory and destructive arthritis due to unopposed excess IL-1 signaling. IL-17 expression is greatly enhanced in IL-1Ra(-/-) mice, suggesting that IL-17 activity is involved in the pathogenesis of arthritis in these mice. Indeed, the spontaneous development of arthritis did not occur in IL-1Ra(-/-) mice also deficient in IL-17. The proliferative response of ovalbumin-specific T cells from DO11.10 mice against ovalbumin cocultured with antigen-presenting cells from either IL-1Ra(-/-) mice or wild-type mice was reduced by IL-17 deficiency, indicating insufficient T cell activation. Cross-linking OX40, a cosignaling molecule on CD4(+) T cells that plays an important role in T cell antigen-presenting cell interaction, with anti-OX40 Ab accelerated the production of IL-17 induced by CD3 stimulation. Because OX40 is induced by IL-1 signaling, IL-17 induction is likely to be downstream of IL-1 through activation of OX40. These observations suggest that IL-17 plays a crucial role in T cell activation, downstream of IL-1, causing the development of autoimmune arthritis.

The role of B cells in rheumatoid arthritis: mechanisms and therapeutic targets

Our understanding of the role of B cells as part of the immune system has been remarkably expanded in the past few years. Autoimmunity, the production of autoantibodies or the activation and expansion of autoimmune T cells, is relatively common, whereas the development of autoimmune diseases with destruction of tissue is much less frequent. In rheumatoid arthritis, the autoantigen(s) involved in tissue damage and their role in disease have not been fully elucidated. Recent data suggest that the impact of B cells in rheumatoid arthritis may be of significance; therefore, a depleting anti-B cell therapy appears to be another therapeutic strategy. This review will focus on recent findings of the role of B cells in rheumatoid arthritis and the implications to target B cells in this disease.