Genetic study confirms association of HLA-DPA101:03 subtype with ankylosing spondylitis in HLA-B27-positive populations

The association of human leukocyte antigen (HLA)-B27 with ankylosing spondylitis (AS) has been known for over 38 years. However, it is not the only gene associated with AS. The aim of this study was to confirm the association of HLA markers around HLA-DPA1/DPB1 region with AS in HLA-B27 positive populations. Five SNPs (rs422544, rs6914849, rs92777535, rs3128968 and rs2295119) from the HLA-DPA1/DPB1 region were genotyped in 340 individuals HLA-B27-positive from Portugal (137 AS patients and 203 healthy controls). Characterizations of HLA-DPA1/DPB1 alleles were also performed. rs422544 revealed a significant association with AS (P < 0.05) and sliding windows (SW) analysis showed association of some groups of adjacent SNPs within HLA-DPA1/DPB1 region with AS (P < 0.05). We also found association of the HLA-DPA1^∗01:03 allele with AS (P < 0.05). This is the first study that confirms the association of HLA markers and haplotypes around HLA-DPA1 and HLA-DPB1 with AS.     

Anti-HLA-E mAb 3D12 mimics MEM-E/02 in binding to HLA-B and HLA-C alleles: Web-tools validate the immunogenic epitopes of HLA-E recognized by the antibodies

HLA-E shares several peptide sequences with HLA-class Ia molecules. Therefore, anti-HLA-E antibodies that recognize the shared sequences may bind to HLA-class Ia alleles. This hypothesis was validated with a murine anti-HLA-E monoclonal antibody (mAb) MEM-E/02, which reacted with microbeads coated with several HLA-B and HLA-C antigens. In this report, the hypothesis was reexamined with another mAb 3D12, considered to be specific for HLA-E. The antibody binding is evaluated by measuring mean fluorescence index [MFI] with Luminex Multiplex Flow-Cytometric technology. The peptide-inhibition experiments are carried out with synthetic shared peptides, most prevalent to HLA-E and HLA-Ia alleles. The results showed that mAb 3D12 simulated MEM-E/02 in recognizing several HLA-B and HLA-C antigens. Both 3D12 and MEM-E/02 did not bind to HLA-A, HLA-F and HLA-G molecules. As observed with MEM-E/02, binding of 3D12 to HLA-E is inhibited by the peptides sequences ¹¹⁵QFAYDGKDY¹²³ and ¹³⁷DTAAQI¹⁴². Decrease in binding of mAb 3D12 to HLA class Ia, after heat treatment of antigen coated microbeads, supports the contention that the epitope may be located at the outside of the “thermodynamically stable” α-helix conformations of HLA-E. Several sequence and structure-based web-tools were employed to validate the discontinuous epitopes recognized by the mAbs. The scores obtained by these web-tools distinguished the shared peptide sequences that inhibited the mAb binding to HLA-E. Furthermore, ElliPro web tool points out that both mAbs recognize the conformational discontinuous epitopes (the shared inhibitory peptide sequences) in the secondary structure of the HLA-E molecule. The study favors the contention that the domain of the shared inhibitory peptide sequences may be the most immunogenic site of HLA-E molecule. It also postulates and clarifies that amino acid substitution on or near the binding domains may account for the lack of cross reactivity of 3D12 and MEM-E/02 with HLA-A, HLA-F and HLA-G molecules.     

KIR3DL1-HLA-Bw4 combination and IL28B polymorphism predict response to Peg-IFN and ribavirin with and without telaprevir in chronic hepatitis C

Natural killer cells play a key role in the immune control of viral infections. Killer immunoglobulin-like receptors (KIRs) regulate natural killer cell activation and inhibition through the recognition of their cognate HLA class I ligands. We assessed the predictive factors of a sustained virological response (SVR) in 200 Japanese patients with chronic genotype 1b hepatitis C who were treated with telaprevir (TVR), pegylated-interferon-α2b (PEG-IFN), and ribavirin (RBV) triple therapy (92 patients) or PEG-IFN/RBV therapy alone (108 patients). Sixteen KIR genotypes, HLA-A, -B and -C ligands, and an interleukin (IL) 28B polymorphism (rs8099917) were analyzed. We observed that triple therapy, white blood cell count, hemoglobin value, hepatitis C viral load, a rapid virological response (RVR), IL28B TT genotype, and KIR3DL1-HLA-Bw4 genotype were associated with an SVR. In multivariate regression analysis, we identified an RVR (P < 0.000001; odds ratio [OR] = 20.95), the IL28B TT genotype (P = 0.00014; OR = 5.53), and KIR3DL1-HLA-Bw4 (P = 0.004, OR = 3.42) as significant independent predictive factors of an SVR. In conclusion, IL28B and KIR3DL1/HLA-Bw4 are independent predictors of an SVR in Japanese patients infected with genotype 1b HCV receiving TVR/PEG-IFN/RBV or PEG-IFN/RBV therapy.     

Mechanisms of human smooth muscle cell proliferation and transplant vasculopathy induced by HLA class I antibodies: In vitro and in vivo studies

Vascular smooth muscle cells (SMC) play an important role in the pathophysiology of transplant vasculopathy (TV), a major cause of late death in patients receiving an organ transplant. In this review we describe the proliferative effect in vitro and in vivo of HLA class I antibodies on human SMC. We have developed an experimental model using segments of human mesenteric arteries transplanted in the position of the infrarenal aorta in immunodeficient mice (SCID/beige). Weekly injections of transplanted mice with a monoclonal antibody towards HLA class I provoked typical lesions of TV after 6 weeks in the human graft while transplanted mice receiving an irrelevant antibody did not develop any significant lesion. In vitro, the anti-HLA antibodies were mitogenic to SMC and we showed that they activate a stress-induced signaling pathway implicating matrix metalloproteinases (MMP) and neutral sphingomyelinase 2 (nSMase-2). The proliferative effect of anti-HLA antibodies could be blocked by pharmacological inhibitors or by siRNA. Administration of pharmacological inhibitors diminished the development of TV in grafted mice injected with anti-HLA antibodies demonstrating an important role of the MMP/nSMase-2 pathway in antibody-induced TV. This observation opens new perspectives for the management of TV in clinical settings.     

Assessing the potential of angiotensin II type 1 receptor and donor specific anti-endothelial cell antibodies to predict long-term kidney graft outcome

Endothelial cell antigens have been reported as potential targets for antibodies in the context of organ transplantation, leading to increased risk for graft failure. Serum samples from 142 consecutive living donor kidney recipients were tested for the presence of antibodies to angiotensin II – type 1 receptor (AT1R), donor endothelial cells, and donor HLA. Graft survival was monitored for five years post-transplant, and secondary outcomes, including biopsy-proven rejection, proteinuria, biopsy-proven vasculopathy, and renal function based on serum creatinine were also assessed for the first two to three years. AT1R antibody levels were positive (>17 U/mL) in 11.3%, 18.8% and 8.1% of patients pre-transplant, post-transplant and at time of indication biopsy, respectively. XM-ONE assay was positive in 17.6% of patients pre-transplant (7 IgG+; 15 IgM+; 3 IgG+/IgM+). Overall, 4 patients experienced antibody-mediated rejection (AMR), 31 borderline cellular rejection (BCR), 19 cellular rejection (CR) and 3 mixed AMR and CR within the first 24 months. While pre-existing and de novo donor-specific HLA antibodies were associated with graft failure and many secondary outcomes, no statistical association was found for either anti-endothelial or anti-AT1R antibodies, indicating that these tests may not be the best predictors of graft outcome in living donor renal transplantation.     

The role of the IL-33/IL-1RL1 axis in mast cell and basophil activation in allergic disorders

Interleukin-33 (IL-33) is a recently discovered cytokine that belongs to the IL-1 superfamily and acts as an important regulator in several allergic disorders. It is considered to function as an alarmin, or danger cytokine, that is released upon structural cell damage. IL-33 activates several immune cells, including Th2 cells, mast cells and basophils, following its interaction with a cell surface heterodimer consisting of an IL-1 receptor-related protein ST2 (IL-1RL1) and IL-1 receptor accessory protein (IL-1RAcP). This activation leads to the production of a variety of Th2-like cytokines that mediate allergic-type immune responses. Thus, IL-33 appears to be a double-edged sword because, in addition to its important contribution to host defence, it exacerbates allergic responses, such as allergic rhinitis and asthma. A major purported mechanism of IL-33 in allergy is the activation of mast cells to produce a variety of pro-inflammatory cytokines and chemokines. In this review, we summarize the current knowledge regarding the genetics and physiology of IL-33 and IL-1RL1 and its association with different allergic diseases by focusing on its effects on mast cells and basophils.     

Interplay between immune responses to HLA and non-HLA self-antigens in allograft rejection

Recent studies strongly suggest an increasing role for immune responses against self-antigens (Ags) which are not encoded by the major histocompatibility complex in the immunopathogenesis of allograft rejection. Although, improved surgical techniques coupled with improved methods to detect and avoid sensitization against donor human leukocyte antigen (HLA) have improved the immediate and short term function of transplanted organs. However, acute and chronic rejection still remains a vexing problem for the long term function of the transplanted organ. Immediately following organ transplantation, several factors both immune and non immune mechanisms lead to the development of local inflammatory milieu which sets the stage for allograft rejection. Traditionally, development of antibodies (Abs) against mismatched donor HLA have been implicated in the development of Ab mediated rejection. However, recent studies from our laboratory and others have demonstrated that development of humoral and cellular immune responses against non-HLA self-Ags may contribute in the pathogenesis of allograft rejection. There are reports demonstrating that immune responses to self-Ags especially Abs to the self-Ags as well as cellular immune responses especially through IL17 has significant pro-fibrotic properties leading to chronic allograft failure. This review summarizes recent studies demonstrating the role for immune responses to self-Ags in allograft immunity leading to rejection as well as present recent evidence suggesting there is interplay between allo- and autoimmunity leading to allograft dysfunction.     

Characterization and allelic variation of the transporters associated with antigen processing (TAP) genes in the domestic dog (Canis lupus familiaris)

The function of the transporters associated with antigen processing (TAP) complex is to shuttle antigenic peptides from the cytosol to the endoplasmic reticulum to load MHC class I molecules for CD8⁺ T-cell immunosurveillance. Here we report the promoter and coding regions of the canine TAP1 and TAP2 genes, which encode the homologous subunits forming the TAP heterodimer. By sampling genetically divergent breeds, polymorphisms in both genes were identified, although there were few amino acid differences between alleles. Splice variants were also found. When aligned to TAP genes of other species, functional regions appeared conserved, and upon phylogenetic analysis, canine sequences segregated appropriately with their orthologs. Transfer of the canine TAP2 gene into a murine TAP2-defective cell line rescued surface MHC class I expression, confirming exporter function. This data should prove useful in investigating the association of specific TAP defects or alleles with immunity to intracellular pathogens and cancer in dogs.     

Regions recognized on the light chain of botulinum neurotoxin type A by T lymphocytes of SJL and BALB/c mice primed with inactivated toxin

Lymph node cells (LNC) from SJL (H-2^s) and BALB/c (H-2^d) mice primed once with inactivated botulinum neurotoxin type A (BoNT/A) were examined for their T-cell responses to each of 32 synthetic overlapping peptides (19 residues each, L1–L32) that encompass the entire L chain (residues 1–448) of BoNT/A. LNC of SJL gave strong responses to 6 regions on, L2 (residues 15–23), L10/11/12 (127–173), L19 (253–271) and L21 (281–299), and moderate to weak responses to L9 (113–131), L14/15 (183–215) and L27 (365–383). In BALB/c, LNC gave a substantial T-cell response only against peptide L12 (residues 155–173), and responded very weakly to 9 other peptides. The results were compared with the recognition profiles determined previously in these two strains after multiple BoNT/A injections. Overall responses to the L-chain peptides of T cells in later profiles were found to be somewhat weakened in SJL and stayed essentially at a similar level in BALB/c, although responses to BoNT/A increased. In SJL, response to L10 (127–145) remained the highest in the later profile. Strong responses against L12 (155–173) observed in both strains at early stage were reduced to an insignificant level. Cross-reactivity to tetanus neurotoxin by BoNT/A-specific T cells was observed in SJL but not in BALB/c. Design of an effective synthetic peptide vaccine will require incorporation of both T cell- and Ab-recognition elements of the BoNT molecule. Significance and possible implications of these results on BoNT/A-specific T-cell responses of BoNT-treated patients are discussed.     

Protection against malaria is conferred by passive transferring rabbit F(ab)(2)' antibody fragments, induced by Plasmodium falciparum MSP-1 site-directed designed pseudopeptide-BSA conjugates assessed in a rodent model

F(ab)₂′-immunoglobulin (Ig) fragments induced by site-directed designed immunogens are emerging as novel tools of potential utility in the treatment of clinical episodes of transmissible diseases such as malaria. Immunogens based on reduced amide pseudopeptides based on site-directed molecular modifications represent structural probes that could be considered as novel vaccine candidates, as we have previously demonstrated.We have obtained F(ab)₂′-Ig rabbit antibodies induced against the N-terminal sequence of the native Merozoite Surface Protein-1 (MSP-1) of Plasmodium falciparum and a set of five MSP-1-derived reduced amide pseudopeptides. Pseudopeptides were designed for inducing functional neutralizing mono-specific polyclonal antibodies with potential applications in the control of malaria. Following a classical enzyme immunoglobulin fractionation, F(ab)₂′-Ig fragments were tested for their ability to suppress blood-stage parasitemia by passive immunization in malaria-infected mice. Some of these fragments proved totally effective in suppressing a lethal blood-stage challenge infection and others reduced malarial parasitemia.These data suggest that protection against Plasmodium yoelii malaria following passive transfer of structurally well-defined β-strand F(ab)₂′-Ig fragments can be associated with specific immunoglobulins induced by site-directed designed MSP-1 reduced amide pseudopeptides.     

The characteristics and pivotal roles of triggering receptor expressed on myeloid cells-1 in autoimmune diseases

Triggering receptor expressed on myeloid cells-1 (TREM-1) engagement can directly trigger inflammation or amplify an inflammatory response by synergizing with TLRs or NLRs. Autoimmune diseases are a family of chronic systemic inflammatory disorders. The pivotal role of TREM-1 in inflammation makes it important to explore its immunological effects in autoimmune diseases. In this review, we summarize the structural and functional characteristics of TREM-1. Particularly, we discuss recent findings on TREM-1 pathway regulation in various autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), type 1 diabetes (T1D), and psoriasis. This receptor may potentially be manipulated to alter the inflammatory response to chronic inflammation and possible therapies are explored in this review.     

Influence of ERAP1 and ERAP2 gene polymorphisms on disease susceptibility in different populations

The endoplasmic reticulum aminopeptidases (ERAPs), ERAP1 and ERAP2, makes a role in shaping the HLA class I peptidome by trimming peptides to the optimal size in MHC-class I-mediated antigen presentation and educating the immune system to differentiate between self-derived and foreign antigens. Association studies have shown that genetic variations in ERAP1 and ERAP2 genes increase susceptibility to autoimmune diseases, infectious diseases, and cancers. Both ERAP1 and ERAP2 genes exhibit diverse polymorphisms in different populations, which may influence their susceptibly to the aforementioned diseases. In this article, we review the distribution of ERAP1 and ERAP2 gene polymorphisms in various populations; discuss the risk or protective influence of these gene polymorphisms in autoimmune diseases, infectious diseases, and cancers; and highlight how ERAP genetic variations can influence disease associations.     

Skeletal muscle cells actively shape (auto)immune responses

Histopathological analyses of muscle specimens from myositis patients indicate that skeletal muscle cells play an active role in the interaction with immune cells. Research over the last few decades has shown that skeletal muscle cells exhibit immunobiological properties that perfectly define them as non-professional antigen presenting cells. They are able to present antigens via major histocompatibility complex molecules, exhibit costimulatory molecules and secrete soluble molecules that actively shape the immune response in an either pro- or anti-inflammatory manner. Skeletal muscle cells regulate both innate and adaptive immune responses and are essentially involved in the pathophysiological processes of idiopathic inflammatory myopathies. Understanding the role of skeletal muscle cells might help to identify new therapeutic targets for these devastating diseases. This review summarizes the immunobiological features of skeletal muscle cells, especially in the context of idiopathic inflammatory myopathies, and discusses shortcomings and limitations in skeletal muscle related research providing potential perspectives to overcome them in the future.     

The acidic tumour microenvironment: Manipulating the immune response to elicit escape

The success of cancer treatment relies on the composition of the tumour microenvironment which is comprised of tumour cells, blood vessels, stromal cells, immune cells, and extracellular matrix components. Barriers to effective cancer treatment need to be overcome, and the acidic microenvironment of the tumour provides a key target for treatment. This review intends to provide an overview of the effects that low extracellular pH has on components of the tumour microenvironment and how they contribute to immune escape. Further, potential therapeutic targets will be discussed.