Lack of association of angiotensin I-converting enzyme gene polymorphism and premature myocardial infarction in Mauritian Indians

Eighty-five young Mauritian Indians, male survivors of premature myocardial infarction (MI) and thus belonging to a high risk group, were compared with 108 stringently selected controls for a possible association between premature MI and an insertion/deletion (I/D) polymorphism in the gene encoding angiotensin I-converting enzyme (ACE). The frequency of the D allele was 0.42 in the MI group and 0.43 in the control group, and thus no association between I/D polymorphism of ACE with susceptibility to early-onset MI was found in this population group. Other gene components of the renin-angiotensin system and lipid metabolism need to be explored to understand the genetic factors involved in causing MI at an early age.     

T-cell receptor variable region of the β-chain gene use in peripheral blood and multiple synovial membranes during rheumatoid arthritis

In order to look for a site-specific T-cell response in RA SM, PCR analyses using oligonucleotide primers specific for 24 TCRBV (Vβ) families were performed to compare the respective usage of each TCRBV gene by T cells present in PB and SM of 13 patients with RA. In four patients, SM cells from two or three sites of inflammation were subjected to analysis. In one patient, synovial tissue was studied at two different phases of the disease, resulting in a total number of 19 samples of SM cells, which were compared with paired samples of PB cells. The results showed that whereas all 24 TCRBV gene families could be detected in both PB and SM cells, there was some skewing of increased or decreased usage frequencies of particular TCR Vβ genes among SM cells. Three TCRBV families were often overexpressed in SM: Vβ3, Vβl7, and Vβ22. Moreover, Vβ4 was often decreased in SM (7 out of 13). This decrease was statistically significant in the RA population studied. SM from different joints of a given patient showed similar variations of T-cell repertoire compared to PB, even 6 months later in the course of the disease. These results demonstrate a biased TCRBV gene utilization in RA SM. This bias appears to be similar in different joints and at different times in the course of the disease. No correlation was found between the bias of TCR repertoire in SM and the HLA typing of these patients.     

Identification of B- and T-Cell Epitopes of BB, a Carrier Protein Derived from the G Protein of Streptococcus Strain G148

Most conventional vaccines consist of killed organisms or purified antigenic proteins. Such molecules are generally poorly immunogenic and need to be coupled to carrier proteins. We have identified a new carrier molecule, BB, derived from the G protein of Streptococcus strain G148. We show that BB is able to induce strong antibody responses when conjugated to peptides or polysaccharides. In order to localize T and B cell epitopes in BB and match them with the albumin-binding region of the molecule, we immunized mice with BB, performed B and T pepscan analyses, and compared the results with pepscan done with sera and cells from humans. Our results indicate that BB has two distinct T helper epitopes, seven linear B-cell epitopes, and one conformational B-cell epitope in BALB/c mice. Four linear B-cell epitopes were identified from human sera, three of which overlapped mouse B-cell epitopes. Finally, three human T-cell epitopes were detected on the BB protein. One of these T-cell epitopes is common to BALB/c mice and humans and was localized in the region that contains the albumin-binding site. These data are of interest for the optimization of new carrier molecules derived from BB.     

Anti-HBs Cellular Immune Response in Kidney Recipients before and 4 Months after Transplantation

Patients with renal failure represent a population at risk for hepatitis B, since only 50 to 60% of them develop protective humoral responses after vaccination. As this could be due to an altered regulation of cellular immune responses, the objectives of the present study were to evaluate the proliferative abilities of lymphocytes from patients with chronic renal failure after stimulation in vitro with a mitogen (pokeweed mitogen [PWM]) or HBsAg. In order to differentiate between the immunodeficiency associated with renal failure and that due to immunosuppression posttransplantation, the same subjects were tested before and 4 months after kidney transplantation. The lymphoproliferation assay used was performed by flow cytometry, which is based on sequential analysis of the cell cycle and which allows analysis of cytokine production. Serologically, the group of 36 patients tested comprised 22% nonresponders, 30% poor responders, and 48% responders. Lymphocyte growth was observed for all patients after stimulation with PWM, indicating that these cells had the capacity to proliferate in vitro. The level of lymphoproliferation in response to PWM was significantly reduced after transplantation, yet both before and after transplantation, all serologic nonresponders developed cellular responses to at least two vaccines. No correlation between humoral and cellular responses was shown. Proliferating cells were lymphocytes, which mostly secreted interleukin 4 (IL-4) and IL-10 for the three serologic groups. This study suggests that even when repeated vaccination fails to induce significant antibody levels in patients with renal failure, specific HBs cellular responses develop, and these may prove to be efficient in protecting these patients against hepatitis B.     

Threshold effect of urinary glycosaminoglycans and the walk test as indicators of disease progression in a survey of subjects with Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome)

A cross-sectional survey in individuals affected with the lysosomal storage disease Mucopolysaccharidosis VI (MPS VI) was conducted to establish demographics, urinary glycosaminoglycan (GAG) levels, and clinical progression of the disease. The survey evaluated 121 bona fide MPS VI-affected individuals over the age of 4 years from 15 countries across the Americas, Europe, and Australasia representing greater than 10% of the estimated world prevalence of the disease. A medical history, complete physical exam, urinary GAG determination, and assessment of several clinical measures related to physical endurance, pulmonary function, joint range of motion, strength, and quality of life were completed for each participant. Although a wide variation in clinical presentation was observed, several general findings were obtained reflecting progression of the disease. Impaired physical endurance, as measured by the distance achieved in a 6-min walk, could be demonstrated across all age groups of MPS VI-affected individuals. High urinary GAG values (>200 mug/mg creatinine) were associated with an accelerated clinical course comprised of age-adjusted short stature and low body weight, impaired endurance, compromised pulmonary function, and reduced joint range of motion. An unexpected result was the predominance of urinary GAG values <100 mug/mg creatinine for those participants over the age of 20 years. Pending the collection of longitudinal data, these results suggest that urinary GAG levels predict clinical morbidity, and longer-term survival is associated with urinary GAG levels below a threshold of 100 mug/mg creatinine.     

A novel de novo PDGFRB variant in a child with severe cerebral malformations,intracerebral calcifications,and infantile myofibromatosis

The spectrum of clinical consequences of variants in the Platelet derived growth factor receptor beta (PDGFRB) gene is wide. Missense variants leading to variable loss of signal transduction in vitro have been reported in the idiopathic basal ganglia calcification (IBGC) syndrome Type 4. In contrast, gain‐of‐function variants have been reported in infantile myofibromatosis, Penttinen syndrome, and Kosaki overgrowth syndrome. Here, we report a patient harboring a novel postzygotic variant in PDGFRB (c.1682_1684del, p.[Arg561_Tyr562delinsHis]) and presenting severe cerebral malformations, intracerebral calcifications, and infantile myofibromatosis. This observation expands the phenotype associated with PDGFRB variants and illustrates the wide clinical spectrum linked to dysregulation of PDGFRB.     

Circulating CD26 is negatively associated with inflammation in human and experimental arthritis

Dipeptidyl peptidase IV (DPPIV, CD26), a protease-cleaving N-terminal X-Pro dipeptide from selected proteins including some chemokines, is expressed both as a soluble form in plasma and on the cell surface of various immune and nonimmune cell types. To gain insights into the pathophysiological role of CD26 in arthritis, we explored DPPIV/CD26 expression during murine antigen-induced arthritis (AIA), an experimental model of arthritis. AIA induction led to reduced plasma DPPIV activity. In CD26-deficient mice, the severity of AIA was increased as assessed by enhanced technetium uptake and by increased histological parameters of inflammation (synovial thickness and exudate). We demonstrated that CD26 controls the in vivo half-life of the intact active form of the proinflammatory chemokine stromal cell-derived factor-1 (SDF-1). CD26-deficient mice exhibited increased levels of circulating active SDF-1, associated with increased numbers of SDF-1 receptor (CXCR4)-positive cells infiltrating arthritic joints. In a clinical study, plasma levels of DPPIV/CD26 from rheumatoid arthritis patients were significantly decreased when compared to those from osteoarthritis patients and inversely correlate with C-reactive protein levels. In conclusion, decreased circulating CD26 levels in arthritis may influence CD26-mediated regulation of the chemotactic SDF-1/CXCR4 axis.