Defective maturation of dendritic cells in common variable immunodeficiency

Dendritic cells in inborn errors of immunity

Dendritic cells (DCs) are crucial cells for initiating and maintaining immune response. They play critical role in homeostasis, inflammation, and autoimmunity. A number of molecules regulate their functions including synapse formation, migration, immunity, and induction of tolerance. A number of IEI are characterized by mutations in genes encoding several of these molecules resulting in immunodeficiency, inflammation, and autoimmunity in IEI. Currently, there are 465 Inborn errors of immunity (IEI) that have been grouped in 10 different categories. However, comprehensive studies of DCs have been reported in only few IEI. Here we have reviewed biology of DCs in IEI classified according to recently published IUIS classification. We have reviewed DCs in selected IEI in each group category and discussed in depth changes in DCs where significant data are available regarding role of DCs in clinical and immunological manifestations. These include severe immunodeficiency diseases, antibody deficiencies, combined immunodeficiency with associated and syndromic features, especially disorders of synapse formation, and disorders of immune regulation.

Intravenous Immunoglobulins Promote an Expansion of Monocytic Myeloid-Derived Suppressor Cells (MDSC) in CVID Patients

Common variable immunodeficiency disorders (CVID), the most common primary immune deficiency, includes heterogeneous syndromes characterized by hypogammaglobulinemia and impaired antibody responses. CVID patients frequently suffer from recurrent infections and inflammatory conditions. Currently, immunoglobulin replacement therapy (IgRT) is the first-line treatment to prevent infections and aminorate immune alterations in CVID patients. Intravenous Immunoglobulin (IVIg), a preparation of highly purified poly-specific IgG, is used for treatment of immunodeficiencies as well as for autoimmune and inflammatory disorders, as IVIg exerts immunoregulatory and anti-inflammatory actions on innate and adaptive immune cells. To determine the mechanism of action of IVIg in CVID in vivo, we determined the effect of IVIg infusion on the transcriptome of peripheral blood mononuclear cells from CVID patients, and found that peripheral blood monocytes are primary targets of IVIg in vivo, and that IVIg triggers the acquisition of an anti-inflammatory gene profile in human monocytes. Moreover, IVIg altered the relative proportions of peripheral blood monocyte subsets and enhanced the proportion of CD14⁺ cells with a transcriptional, phenotypic, and functional profile that resembles that of monocytic myeloid-derived suppressor cells (MDSC). Therefore, our results indicate that CD14 + MDSC-like cells might contribute to the immunoregulatory effects of IVIg in CVID and other inflammatory disorders.

Common variable immune deficiency: Dissection of the variable

Starting about 60 years ago, a number of reports appeared that outlined the severe clinical course of a few adult subjects with profound hypogammaglobinemia. Puzzled by the lack of family history and adult onset of symptoms in most, the name "acquired" hypogammaglobinemia was given, but later altered to the current name common variable immune deficiency. Pathology reports remarked on the loss of lymph node architecture and paucity of plasma cells in lymphoid tissues in these subjects. While characterized by reduced serum IgG and IgA and often IgM, and thus classified among the B-cell defects, an increasing number of cellular defects in these patients have been recognized over time. In the early years, severe respiratory tract infections commonly led to a shortened life span, but the wide spread availability of immune globulin concentrates for the last 25 years has improved survival. However, chronic non-infectious inflammatory and autoimmune conditions have now emerged as challenging clinical problems; these require further immunologic understanding and additional therapeutic measures. Recent study of this phenotypic syndrome have provided an increasingly fertile ground for the identification of autosomal recessive and now more commonly, autosomal dominant gene defects which lead to the loss of B-cell development in this syndrome.

The role of toll-like receptors in B-cell development and immunopathogenesis of common variable immunodeficiency

Common variable immunodeficiency (CVID) is the most frequent symptomatic primary immune deficiency and is characterized by hypogammaglobulinemia, defect in specific antibody response and increased susceptibility to recurrent infections, malignancy and autoimmunity. Patients with CVID often have defects in post-antigenic B-cell differentiation, with fewer memory B cells and impaired isotype switching. Toll-like receptors (TLRs) are expressed on various immune cells as key elements of innate and adaptive immunity. TLR signaling in B cells plays multiple roles in cell differentiation and activation, class-switch recombination and cytokine and antibody production. Moreover, recent studies have shown functional alteration of TLRs responses in CVID patients including poor cell proliferation, impaired upregulation of co-stimulatory molecules and failure in cytokine and immunoglobulin production. The purpose of the present review is to discuss the role of TLRs in B-cell development and function as well as their role in the immunopathogenesis of CVID.

Multiple malignancies in a female patient with common variable immunodeficiency syndrome

We herein present the case of a 55-year-old woman with a previous history of malignancies--uterine adenocarcinoma, basal cell carcinoma (which occurred twice consecutively), recurrent respiratory infections due to common variable immunodeficiency (CVID), and systemic granulomatous disease diagnosed at a later age. The patient suffered from diffuse large B cell lymphoma (DLBCL), which was successfully treated with R-CHOP chemotherapy, and continued with immunoglobulin supplementation. The patient was free of lymphoma and infectious complications for over 20 months despite her persistent immunodeficiency, but eventually developed colorectal adenocarcinoma. To the best of our knowledge, this is the first reported case of CVID associated with multiple solid tumours and DLBCL.

Common variable immunodeficiency revisited: normal generation of naturally occurring dendritic cells that respond to Toll-like receptors 7 and 9

Patients with common variable immunodeficiency (CVID) have reduced numbers and frequencies of dendritic cells (DCs) in blood, and there is also evidence for defective activation through Toll-like receptors (TLRs). Collectively, these observations may point to a primary defect in the generation of functional DCs. Here, we measured frequencies of plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) in peripheral blood of 26 CVID patients and 16 healthy controls. The results show that the patients have reduced absolute counts of both subsets. However, the decreased numbers in peripheral blood were not reflected in reduced frequencies of CD34(+) pDC progenitors in the bone marrow. Moreover, studies at the single cell level showed that DCs from CVID patients and healthy controls produced similar amounts of interferon-α or interleukin-12 and expressed similar levels of activation markers in response to human cytomegalovirus and ligands for TLR-7 and TLR-9. The study represents the most thorough functional characterization to date, and the first to assess bone marrow progenitor output, of naturally occurring DCs in CVID. In conclusion, it seems unlikely that CVID is secondary to insufficient production of naturally occurring DCs or a defect in their signalling through TLR-7 or TLR-9.

T-cell activation discriminates subclasses of symptomatic primary humoral immunodeficiency diseases in adults

Background

Symptomatic Primary Humoral Immunodeficiency Diseases (PHID) constitute a highly heterogeneous group of diseases characterized by a shared hypogammaglobulinemia, resulting in increased risk of recurrent or severe infections. Associations have been described with a variety of immunological abnormalities involving B and T-cell differentiation, T-cell activation and innate immunity. However, PHID discrimination remains based on B-lymphocyte abnormalities and other components of the immune system have not been sufficiently taken into account. We carried out unsupervised and supervised methods for classification in a cohort of 81 symptomatic PHID patients to evaluate the relative importance of 23 immunological parameters and to select relevant markers that may be useful for diagnosis and prognosis.

Results

We identified five groups of patients, among which the percentage of PHID complications varied substantially. Combining the set of markers involved in PHID supported the existence of two distinct mechanisms associated with complications. Switched memory B-cell attrition and CD8+ HLA-DR + activated T-cell increase were the prominent abnormalities observed in PHID complications. Furthermore, in a subgroup of 57 patients with common variable immunodeficiency, the classification that added CD8+ HLA-DR + to the consensual EUROclass classification was better than the EUROclass model in predicting complications.

Conclusion

These results highlight the importance of T-cell activation that may improve discrimination of PHID patients in specific subgroups and help to identify patients with different clinical outcomes.

The Hedgehog inhibitor suppresses the function of monocyte-derived dendritic cells from patients with advanced cancer under hypoxia

Immunotherapy using monocyte derived dendritic cells (Mo-DCs) from cancer patients has been developed; however, the Mo-DCs regularly studied have been derived from non-cancer bearing donors or mice, and evaluated in normoxic conditions. In the present study, we investigated the effects of Hedgehog (Hh) inhibitors which are being developed as molecular target drugs for cancer on the functions of Mo-DCs derived from patients with advanced cancer when cultured in a tumor-like hypoxic environment. Mo-DC induction, migration, chemotaxis, phagocytosis, maturation, IL-12 p40 or p70 secretion and the allogeneic lymphocyte stimulation activity of Mo-DCs from patients with advanced cancer were all significantly inhibited by the Hh inhibitor, cyclopamine under hypoxic conditions. Our results suggest that Hh signaling plays an important role in the maintenance and function of Mo-DCs derived from patients with advanced cancer when cultured under hypoxic conditions.

Monocyte activation is a feature of common variable immunodeficiency irrespective of plasma lipopolysaccharide levels

Common variable immunodeficiency disorders (CVID), the most frequent cause of symptomatic primary immunodeficiency, are defined by impaired antibody production. Notwithstanding, T cell activation and granulomatous manifestations represent the main causes of CVID morbidity even in patients receiving immunoglobulin (Ig) G replacement therapy. Additionally, gut pathology is a frequent feature of CVID. In this study, we investigated monocyte imbalances and their possible relationship with increased microbial translocation in CVID patients. Monocyte subsets were defined according to CD14 and CD16 expression levels and evaluated in terms of human leucocyte antigen D-related (HLA-DR), CD86 and programmed death-1 molecule ligand 1 (PD-L1) expression by flow cytometry, in parallel with the quantification of plasma lipopolysaccharide (LPS) and serum levels of soluble CD14 (sCD14), LPS-binding protein (LBP) and anti-LPS antibodies. CVID patients (n=31) featured significantly increased levels of serum sCD14 and an expansion of CD14(bright) CD16(+) monocytes in direct correlation with T cell and B cell activation, the latter illustrated by the frequency of the CD21(low) CD38(low) subset. Such alterations were not observed in patients lacking B cells due to congenital agammaglobulinaemia (n=4). Moreover, we found no significant increase in circulating LPS or LBP levels in CVID patients, together with a relative preservation of serum anti-LPS antibodies, in agreement with their presence in commercial IgG preparations. In conclusion, CVID was associated with monocyte imbalances that correlated directly with T cell activation markers and with B cell imbalances, without an association with plasma LPS levels. The heightened monocyte activated state observed in CVID may represent an important target for complementary therapeutic strategies.

TLR-mediated B cell defects and IFN-α in common variable immunodeficiency

Common variable immune deficiency (CVID) B cells have impaired responses to TLR7 and TLR9 agonists including poor cell proliferation, loss of cytokine production, and failure to produce IgG or IgA. We show that TLR7- or 9-activated B cells from CVID subjects with >0.5% peripheral isotype-switched CD27(+) B cells (group 2) have increased mature Cγ1 and Cγ2 heavy-chain mRNA transcripts compared to subjects who have <0.5% isotype-switched cells (group 1). While TLR-stimulated CVID plasmacytoid dendritic cells for all subjects had impaired IFN-α production, TLR7 or TLR9 stimulation in the presence IFN-α normalized isotype-switched CD27(+) B cells, enhanced activation-induced cytidine deaminase mRNA, and significantly improved IgG production only for group 2 subjects. IFN-α also upregulated TLR7 and TLR9 mRNA expression comparable to normal levels in B cells of group 2 subjects, indicating that the loss of IFN-α could be a significant component of the B-cell defect for these subjects.

"A rose is a rose is a rose," but CVID is Not CVID common variable immune deficiency (CVID), what do we know in 2011?

Common variable immune deficiency (CVID) is the commonest symptomatic primary immunodeficiency and represents a heterogenous collection of disorders resulting mostly in antibody deficiency and recurrent infections. However, autoimmunity, granulomatous inflammation and malignancy frequently occur as part of the syndrome. The etiology of the condition has been poorly understood although in recent years, significant progress has been made in elucidating genetic mechanisms that can result in a CVID phenotype. In parallel to this, advances in treatment of the condition have also resulted in improved survival and quality of life for patients. There still remains significant work to be done in improving our understanding of the disease. In addition, recognition of the condition remains poor with significant diagnostic delays and avoidable morbidity. In this article, we review CVID with a particular focus on the areas of improving diagnosis and classification, recent developments in understanding the underlying etiology and genetics; and current treatment and monitoring recommendations for patients.

Curcumin for the prevention of progression in monoclonal gammopathy of undetermined significance: A word of caution

A recent pilot study found that curcumin, in certain patients with monoclonal gammopathy of undetermined significance (MGUS), decreases the paraprotein load and the urinary N-telopeptide of type 1 collagen bone turnover marker. While this result is encouraging, the easy availability of the food component turmeric, containing curcumin, may lead to intake by MGUS patients without medical supervision. Curcumin is generally considered safe. Nevertheless, it is known that curcumin inhibits interleukin-12 production in dendritic cells, thereby dampening the Th1 response. It is also well established that Th1 cells are protective against invading pathogens and tumors. The present study describes a case in which bronchitis developed upon turmeric intake for gastrointestinal complaints. While one case does not provide proof of curcumin toxicity, a thorough literature overview suggests that turmeric may have an immunosuppressive effect, notably in patients with a compromised immune system. A warning against the use of turmeric or curcumin without medical supervision in immunocompromised patients seems therefore very opportune. Patients with MGUS, in whom the levels of non-affected immunoglobulins are reduced, should be carefully monitored for toxicity when curcumin is administered.

Common variable immunodeficiency

Common variable immunodeficiency is the most prevalent clinically significant antibody deficiency at all ages. The disorder is defined principally by characteristic infection susceptibility with hypogammaglobulinemia and impaired-specific antibody response. Several recent large registry-based studies have defined distinct phenotypic subtypes. Several studies have also correlated specific immunologic markers with these phenotypes. The biochemical or genetic abnormality in the majority of patients remains unknown. Recently, several molecular genetic lesions have been defined. Among these, mutations of inducible costimulator, and CD19, appear to be disease causing by themselves. These account for about 1% of cases. Other mutations or polymorphisms, such as in the human homolog of Escherichia coli MutS 5 (MSH5), and transmembrane activator and calcium mobilizing ligand interactor, seem to be disease associated in 5-10% of patients, but may require additional immunologic abnormalities for full expression of the phenotype, as unaffected heterozygotes have also been described.