Marcella Prete

β2-Microglobulin-Free HLA Class I Heavy Chain Epitope Mimicry by Monoclonal Antibody HC-10-Specific Peptide

mAb HC-10 loses its reactivity with HLA class I (HLA-I) H chain (HC) following its association with β2-microglobulin (β2m). Furthermore, the HC-10 defined epitope appears to be involved in the pathogenesis of spondyloarthropathies, because HC-10 reduced their incidence in HLA-B27+β2m°/MHC class II knockout mice. This study has characterized the determinant recognized by HC-10. Panning of a phage display peptide library with HC-10 resulted in isolation of the motif PxxWDR, which could be aligned with P57, W60, D61, and R62 of the first domain of the HLA-I HC allospecificities reactive with HC-10. The 55EGPEYWDR(N/E)T64 (p-1) is the shortest motif-bearing peptide that reacts with HC-10 and inhibits its binding to soluble HLA-B7 HC, irrespective of whether N (p-1a) or E (p-1b) is present at position 63. By contrast, HC-10 did not react with six additional peptides, each bearing motif amino acid substitutions present in HC-10-not-reactive HLA-I allospecificities. The p-1-derived Qp-1, synthesized with the additional conserved Q54, which displays the highest in vitro reactivity with HC-10, was the only one to induce in mice IgG resembling HC-10 in their fine specificity. Mapping of the HC-10-defined determinant suggests that the lack of mAb reactivity with β2m-associated HLA-I HC is caused by blocking by the peptide in the groove of β2m-associated HLA-I HC, though a role of HC conformational changes following its association with β2m cannot be excluded. This information contributes to our understanding of the molecular basis of the antigenic profiles of β2m-free and β2m-associated HLA-I HC and may serve to develop active specific immunotherapy of spondyloarthropathies.

Rheumatic disorders as paraneoplastic syndromes

The long-established observation that some rheumatologic disorders (RDs) are associated with--or precede--the clinical manifestations of a variety of solid and hematological tumors represents an important clue for the early diagnosis and effective treatment of the cancers. Inflammatory myopathies, seronegative rheumatoid arthritis and some atypical vasculitides are the most frequently reported paraneoplastic RDs, although paraneoplastic scleroderma- and lupus-like syndromes, erythema nodosum, and Raynauds syndrome have also been observed. Generally, the clinical course of a paraneoplastic RD parallels that of the cancer, and surgical removal of the tumor or its medical treatment usually results in a marked regression of the clinical manifestations of the RD. Most paraneoplastic RDs are difficultly distinguishable from idiopathic RDs. Even so, some atypical features of the clinical presentation raise the suspicion of an underlying tumor. This review summarizes current hypotheses for the pathogenesis that leads a tumor to present as an RD and discusses the clinical features that help distinguish paraneoplastic from idiopathic RDs.

Extra-articular manifestations of rheumatoid arthritis: An update.

Rheumatoid arthritis (RA) is an immune-mediated disease involving chronic low-grade inflammation that may progressively lead to joint destruction, deformity, disability and even death. Despite its predominant osteoarticular and periarticular manifestations, RA is a systemic disease often associated with cutaneous and organ-specific extra-articular manifestations (EAM). Despite the fact that EAM have been studied in numerous RA cohorts, there is no uniformity in their definition or classification. This paper reviews current knowledge about EAM in terms of frequency, clinical aspects and current therapeutic approaches. In an initial attempt at a classification, we separated EAM from RA co-morbidities and from general, constitutional manifestations of systemic inflammation. Moreover, we distinguished EAM into cutaneous and visceral forms, both severe and not severe. In aggregated data from 12 large RA cohorts, patients with EAM, especially the severe forms, were found to have greater co-morbidity and mortality than patients without EAM. Understanding the complexity of EAM and their management remains a challenge for clinicians, especially since the effectiveness of drug therapy on EAM has not been systematically evaluated in randomized clinical trials.

CD20-depleting therapy in autoimmune diseases: from basic research to the clinic

Abstract.  Perosa F, Prete M, Racanelli V, Dammacco F (University of Bari Medical School, Bari, Italy). CD20‐depleting therapy in autoimmune diseases: from basic research to the clinic (Review). J Intern Med 2010; 267: 260–277.

Autoantibodies to intracellular antigens: generation and pathogenetic role.

Autoantibodies to intracellular antigens form a large family of immunoglobulins directed to a variety of ubiquitously expressed intracellular molecules, including numerous enzymes, some ribonucleoproteins and double-stranded DNA. These anti-self antibodies have been found to be selectively expressed in sera of patients with several systemic (non-organ-specific) autoimmune diseases, such as systemic sclerosis (SSc), SLE, mixed connective tissue disease, Sjögrens syndrome and idiopathic myopathies. Despite their important diagnostic and prognostic value and their utility in assessing disease activity, little is known about the molecular mechanisms involved in their generation and role in autoimmune diseases nor is it known why particular autoantibodies are preferentially expressed in certain diseases. Here, we review the different lines of research which are presently being conducted to understand how these autoantibodies are generated (e.g. through apoptotic body formation, molecular mimicry and other mechanisms) and how they encounter antigen in order to cause an autoimmune disease. The recently reported mechanism of intracellular immunity mediated by Ro52 (or tripartite motif containing 21, TRIM21) in a cellular model of adenovirus infection is opening new perspectives for studying the effects of autoantibodies once they get inside cells.

International consensus: What else can we do to improve diagnosis and therapeutic strategies in patients affected by autoimmune rheumatic diseases (rheumatoid arthritis, spondyloarthritides, systemic sclerosis, systemic lupus erythematosus, antiphospholipid syndrome and Sjogren's syndrome)?: The unmet needs and the clinical grey zone in autoimmune disease management

Autoimmune diseases are a complex set of diseases characterized by immune system activation and, although many progresses have been done in the last 15years, several unmet needs in the management of these patients may be still identified. Recently, a panel of international Experts, divided in different working groups according to their clinical and scientific expertise, were asked to identify, debate and formulate a list of key unmet needs within the field of rheumatology, serving as a roadmap for research as well as support for clinicians. After a systematic review of the literature, the results and the discussions from each working group were summarised in different statements. Due to the differences among the diseases and their heterogeneity, a large number of statements was produced and voted by the Experts to reach a consensus in a plenary session. At all the steps of this process, including the initial discussions by the steering committee, the identification of the unmet needs, the expansion of the working group and finally the development of statements, a large agreement was attained. This work confirmed that several unmet needs may be identified and despite the development of new therapeutic strategies as well as a better understanding of the effects of existing therapies, many open questions still remain in this field, suggesting a research agenda for the future and specific clinical suggestions which may allow physicians to better manage those clinical conditions still lacking of scientific clarity.

Increased serum levels of β2m‐free HLA class I heavy chain in multiple myeloma

Serum levels of β2‐microglobulin (β2m)‐free HLA class I heavy chain (FHC) in 94 patients with multiple myeloma (MM) were higher than in 29 patients with monoclonal gammopathy of undetermined significance (MGUS) (P = 0.023) and in 97 sex‐ and age‐matched healthy controls (P < 0.0001). Spearman correlation analysis indicated that in MM, FHC correlated with β2m (r = 0.31, P = 0.003) and the percentage of bone marrow plasma cells (BMPC%) (r = 0.36, P = 0.002), whereas β2m, in addition to BMPC% (r = 0.43, P = 0.0003), also correlated with creatinine levels (r = 0.63, P < 0.0001), haemoglobin levels (r = −0.35, P = 0.0007) and patient age (r = 0.34, P < 0.0011). Furthermore, MM patients with poor prognosis (β2m  6 mg/l) displayed higher FHC levels than those with a better prognosis (β2m < 6mg/l) (P < 0.021). At variance from β2m, these levels were not influenced by renal failure, as indicated by the lack of Spearman correlation of FHC with creatinine concentration and of statistical significance between the median FHC concentration of MM patients with creatinine < 176.6 μmol/l and those with creatinine  176.6 μmol/l (P = 0.3). Stratification of patients according to disease activity and stage showed that FHC levels were only statistically different (P = 0.04) for disease activity, whereas β2m and C‐reactive protein were not. Taken together, our data indicate that serum FHC may be a useful disease marker in MM.

Biological therapy with monoclonal antibodies: a novel treatment approach to autoimmune disease

Most autoimmune diseases (ADs) are still associated with high morbidity and mortality despite the use of a wide range of drugs that can delay their progression, control their symptoms, but never bring about a complete cure. This failure has aroused interest in new forms of monoclonal antibody-based experimental immunotherapy (IT), aiming at targeting cellular antigens or cytokines involved in the pathogenesis of ADs. The first part of this review offers a general overview of the molecular mechanisms that mediate the immune response and the molecule regarded as potential IT targets. A critical evaluation will then be made of some forms of IT, with particular emphasis on TNF-α and CD20-blocking reagents. Lastly an account will be given of active IT whereby an endogenous response against antigens regarded as the target of passive IT can be induced by anti-idiotype or peptides.

Anti-centromere protein A antibodies in systemic sclerosis: Significance and origin

Systemic sclerosis (SSc) is systemic, autoimmune, connective tissue disorder characterized by vascular abnormalities, collagen deposition (fibrosis), and the production of autoantibodies to nuclear proteins. About 20%-40% of patients have antibodies to centromere protein (CENP)-A or -B. Despite the known association of anti-CENP antibodies with certain clinical features of SSc, the role of these antibodies in SSc physiopathology is still poorly understood. To better understand the clinical significance and origin of these antibodies, we and others have been studying the epitopic motifs (amino acid contact sites) on CENP-A with the aim of determining whether other proteins can prime or be targeted by them. Here, we review published and ongoing studies aimed at defining the fine specificity and origin of anti-CENP-A antibodies. We describe progress made in identifying the CENP-A epitopic motif amino acids, and the discovery of one of these motifs in forkhead box protein E3 (FOXE-3), a transcription factor previously studied only for its role in the development of lens fiber cells. Moreover, we discuss preliminary evidence for a possible role of FOXE-3 in SSc pathogenesis and for the association of different subsets of anti-CENP-A antibodies, heterogeneously expressed among SSc patients, with some clinical correlates.

Staging multiple myeloma patients with active disease using serum levels of β2m-free HLA class I heavy chain together with IgM or platelet count

PURPOSE In multiple myeloma (MM), serum beta-2-microglobulin (beta2m)-free heavy chains (FHC) of HLA class I has been shown to reflect disease activity. We investigated the possibility of stratifying patients with active disease according to FHC and other clinical parameters. EXPERIMENTAL DESIGN We studied 146 patients with MM, including 100 at diagnosis, 31 in relapse and 15 unresponsive to therapy. Univariate and multivariate analyses were used to assess the prognostic significance of FHC together with continuous variables (age, albumin, creatinine, hemoglobin, erythrocyte sedimentation rate, beta2m, calcium, IgM, platelet count) and categorical variables (Durie-Salmon disease stage, gender, bone lesion burden, heavy and light chain isotypes of M-component, clinical status). Survival tree analysis on significant variables was used to develop an MM staging system. RESULTS FHC, IgM, platelet count and hemoglobin were independent predictors of prognosis. Survival tree analysis of these variables defined 2 three-risk-group staging systems involving FHC and either IgM or platelet count. Median survival for FHC/IgM stages II and III was 41.5 and 27.8 months, whereas it was not reached for stage I patients (p<0.0001). In the FHC/platelets system, median survival was 93.2 (stage I), 44.1 (stage II) or 27.8 (stage III) months (p<0.0001). Similar results were obtained for the 117 MM patients without renal insufficiency (FHC/IgM p<0.0001; FHC/platelets p=0.001). For the 100 patients at diagnosis, FHC/IgM (p=0.001) was more effective than FHC/platelets (p=0.04). CONCLUSIONS The independent prognostic markers FHC, IgM and platelets provide two staging systems unaffected by renal insufficiency. Both are effective in evaluating MM patients with active disease.