The Prevalence Of Osteoporosis Is Low in Adult Cutaneous Mastocytosis Patients.

BACKGROUND: Systemic mastocytosis (SM) is a clonal disorder of mast cells (MCs) frequently associated with vertebral osteoporosis (OP) and subsequent vertebral fractures (VFs). The natural history of this OP remains unclear. Importantly, we do not know whether OP represents an early event triggered alongside MC abnormalities, and whether MC clonality is sufficient to trigger osteoporosis. OBJECTIVE: To describe OP in patients with medullar clonality in cutaneous mastocytosis (CM) and monoclonal mast cell activation syndrome (MMAS) and to compare their osteoporosis characteristics with those of nonadvanced SM patients (bone marrow mastocytosis and indolent systemic mastocytosis). METHODS: We retrospectively analyzed clinical, biological, and densitometric data of 27 CM, 13 MMAS, and 135 SM patients from the Mastocytosis Expert Center (CEREMAST) in Toulouse, France. RESULTS: The OP (respectively 3.7, 30.8, and 34.1%) and VFs (0.0%, 15.4%, and 20%) were less frequent in CM than in MMAS and SM, despite the presence of clonal MCs in the bone marrow. Most patients with OP and VFs in the non-SM groups had the usual risk factors for OP. Interestingly, the only non-SM patient with a typical SM-like OP had high bone marrow tryptase, developed bone marrow KIT mutation during follow-up, and had a family history of SM. Our data show that OP is not a common clinical finding in CM but is frequent in MMAS. When OP and VFs occur in CM and MMAS patients, they differ from the usual phenotype of SM bone fragility. CONCLUSIONS: Our findings suggest that, in most CM patients, the meaning and management of OP differs from that of OP in MMAS and nonadvanced SM. Prospective longitudinal studies and the validation of predictors are needed to identify CM and MMAS patients developing SM-related OP.

Hydroxychloroquine as a novel therapeutic approach in mast cell activation diseases.

There is no therapeutic agent approved in cutaneous mastocytosis and mast cell activation syndrome. We report the efficacy of hydroxychloroquine in four patients with cutaneous mastocytosis (n = 2) and mast cell activation syndrome (n = 2). We show that this molecule reduces the long-term survival of primary human mast cells, interferes with lysosome function and leads to the accumulation of non-functional tryptase in the mast cell granules. Furthermore, hydroxychloroquine decreases the production of pro-inflammatory mediators.

Prevalence and risk factors for fragility fracture in systemic mastocytosis.

OBJECTIVES: Systemic mastocytosis (SM) is characterized by the accumulation of mast cells in tissues other than the skin. Bone involvement although frequent has not been thoroughly evaluated. Primary objective was to determine risk factors associated with fragility fractures (FF) in SM. Secondary objectives were to evaluate the ability of bone marrow tryptase (BMT) level to identify patients with FF, and to describe bone involvement in SM. METHODS: We analyzed retrospectively all consecutive patients seen in our expert center, with a diagnosis of SM according to the 2001 WHO criteria, and with complete bone assessment. We collected data about lifetime fractures, types of cutaneous manifestations, degranulation symptoms, blood and BMT levels, bone mineral density assessed by densitometry and KIT mutation. We performed a univariate analysis investigating the factors associated with FF and then a logistic multivariable regression analysis. We assessed the ability of bone marrow tryptase to identify patients with FF. RESULTS: Eighty-nine patients with SM were included. Thirty-six patients (40.4%) suffered from osteoporosis and twenty-five (28.1%) experienced lifetime FF. Univariate analysis identified age at diagnosis and disease onset, presence of telangiectasia macularis eruptiva perstans, digestive symptoms, mast cells activation symptoms, elevated BMT, low femoral and lumbar BMD, as associated with FF. Multivariate analysis identified elevated BMT, low femoral T score and older age at diagnosis as independently associated with FF. CONCLUSIONS: Low femoral T-score, BMT level, and older age at diagnosis are markers associated with FF in SM. BMT may represent an important biomarker to predict FF in SM patients.

Photo-induced graft-versus-host disease.

Overlap chronic graft-versus-host disease (GVHD) associates both features of acute and chronic GVHD. Trigger factors for chronic GVHD are unclear. We describe two patients who received allogenic haematopoietic stem-cell transplantation, and who later developed overlap chronic GVHD after sun exposure. Available data from in vivo investigations suggest ultraviolet B radiation (UVB) has a beneficial effect on acute and chronic GVHD. The role of sun irradiation as a trigger for isomorphic cutaneous GVHD has been rarely reported in the literature. Herein, we demonstrate for the first time, using repetitive broadband phototesting, that UVB triggers chronic GVHD.

Telangiectasia macularis eruptiva perstans (TMEP): A form of cutaneous mastocytosis with potential systemic involvement.

BACKGROUND: Telangiectasia macularis eruptiva perstans (TMEP) has not been fully characterized. OBJECTIVE: We sought to estimate the frequency and clinical characteristics of TMEP in a cohort of adult patients with cutaneous mastocytosis, and to assess the presence of systemic involvement. METHODS: We included all consecutive patients evaluated for cutaneous mastocytosis in 2 centers: the Mastocytosis Competence Center of the Midi-Pyrénées from May 2006 to December 2013, and the French Reference Center for Mastocytosis from January 2008 to September 2013. Skin phenotype, histopathology, presence of KIT mutation in the skin, and assessment of systemic involvement according to World Health Organization (WHO) criteria were prospectively investigated. RESULTS: Of 243 patients with cutaneous mastocytosis, 34 (14%) were given a diagnosis of TMEP. The diagnosis of systemic mastocytosis was established in 16 patients (47%) with TMEP. Three patients (9%) had aggressive systemic mastocytosis (C-findings according to WHO). In all, 32 patients (94%) exhibited at least 1 mast cell activation-related symptom. LIMITATIONS: Patient recruitment was undertaken at 2 referral centers with expertise in the diagnosis and treatment of mastocytosis so that the clinical findings and incidence of systemic involvement may be overestimated in comparison with the overall population of patients with TMEP. CONCLUSION: TMEP accounts for about 14% of patients with cutaneous mastocytosis. The disease manifests as mast cell activation symptoms in almost all patients and can be associated with systemic involvement in about 50% of cases.

Modulation of gene expression in CD4+ T lymphocytes following in vitro HIV infection: a comparison between human and chimpanzee.

Chimpanzees are susceptible to experimental infection by human deficiency virus (HIV)-1, but unlike humans, they exceptionally develop an immunodeficiency syndrome after HIV-1 inoculation. To explore the difference between human and chimpanzee, we analyzed the expression of 1547 genes of various functions in human or chimpanzee CD4+ lymphoblasts inoculated in vitro with HIV-1. We observed that, 1 day after HIV inoculation, fifty-eight genes were up-regulated in lymphoblasts of the three humans while their expression remained unchanged in lymphoblasts of the three chimpanzees. One gene is involved in adhesion of HIV (catenin-alpha), three in the immune response (semaphorin 4D, placental growth factor, IL-6), three in apoptosis (deleted in colorectal carcinoma, caspase 9 and FOXO1A). No difference between species was revealed for the expression of 373 genes related to glycosylation pathways. The in vitro human/chimpanzee comparison reveals new candidate genes up-regulated after inoculation with HIV-1 only in human lymphoblasts and which could be related to the higher sensitivity of human to HIV-induced AIDS.

Characterization of MHC class I transcripts of a Malaysian cynomolgus macaque by high-throughput pyrosequencing and EST libraries.

We characterized the repertoire of MHC class I transcripts of a Malaysian cynomolgus macaque by the study of EST libraries derived from the mRNA extracted from six tissues (thymus, spleen, bone marrow, liver, heart and pancreas). The MHC class I transcripts present in a lymph node of the same animal were characterized by pyrosequencing of amplified cDNA fragments (515 bp from exon 2 to the beginning of exon 4). All pyrosequence consensus sequences, but three corresponding to rare transcripts, were identical to those obtained from EST libraries. In total, we characterized 19 classical class I transcripts in the Malaysian macaque studied here. By means of high-throughput sequencing of exon 2 amplified from the genomic DNA (190 bp), we characterized 38 classical class I genes in the genome of this animal. By comparison, using the same method, we found 23 classical class I genes in the genome of a MHC homozygous Mauritian animal (H2/H2). All these results suggested that the Malaysian animal was most probably heterozygous. This study reveals that the high-throughput pyrosequencing allows not only to characterize the MHC class I transcripts but also to estimate the number of MHC class I genes in the genome of cynomolgus macaque.

Human fibroblasts share immunosuppressive properties with bone marrow mesenchymal stem cells.

INTRODUCTION: Bone marrow mesenchymal stem cells (BM-MSCs) and adipose tissue-derived stem cells share immunosuppressive capacities, suggesting that the latter could be a general property of stromal cells. METHODS: To check this hypothesis, we compared human BM-MSC and fibroblasts for their in vitro multi-potentiality, expandability and their immunomodulatory properties under normalized optimized culture conditions. RESULTS: We report that, unlike BM-MSCs, fibroblasts cannot differentiate in vitro into adipocytes and osteoblasts and differ from BM-MSCs by the expression of membrane CD106, CD10 and CD26 and by the expression of collagen VII mRNA. Like BM-MSCs, fibroblasts are unable to provoke in vitro allogeneic reactions, but strongly suppress lymphocyte proliferation induced by allogeneic mixed lymphocyte culture (MLC) or mitogens. We show that fibroblasts' immunosuppressive capacity is independent from prostaglandin E2, IL-10 and the tryptophan catabolising enzyme indoleamine 2,3-dioxygenase and is not abrogated after the depletion of CD8+ T lymphocytes, NK cells and monocytes. CONCLUSION: Finally, fibroblasts and BM-MSCs act at an early stage through blockage of lymphocyte activation, as demonstrated by down-regulation of GZMB (granzyme B) and IL2RA (CD25) expression.

Study of Cynomolgus monkey (Macaca fascicularis) MhcDRB (Mafa-DRB) polymorphism in two populations.

Cynomolgus monkey is one of the macaque species currently used as an animal model for experimental surgery and medicine, in particular, to experiment new drugs or therapy protocols designed for the prevention of allograft rejection. In this field, it is of utmost importance to select histoincompatible recipient-donor pairs. One way to ensure incompatibility between donor and recipient is to check their major histocompatibility complex (MHC) genotypes at the loci playing a determinant role in histocompatibility. We report in this paper on the cynomolgus monkey DRB polymorphism evidenced by sequencing of amplified exon 2 separated either by denaturing gradient gel electrophoresis (DGGE), or by cloning. By the study of 253 unrelated animals from two populations (Mauritius and The Philippines), we characterized 50 exon 2 sequences among which 28 were identical to sequences already reported in Macaca fascicularis or other macaque species (Macaca mulatta, Macaca nemestrina). By cloning and sequencing DRB cDNA, we revealed two additional DRB alleles. Out of the 20 haplotypes that we defined here, only two were found in both populations. The functional impact of DR incompatibility was studied in vitro by mixed lymphocyte culture.

Sequence, evolution and ligand binding properties of mammalian Duffy antigen/receptor for chemokines.

The Duffy antigen/ receptor for chemokine, DARC, acts as a widely expressed promiscuous chemokine receptor and as the erythrocyte receptor for Plasmodium vivax. To gain insight into the evolution and structure/function relations of DARC, we analyzed the binding of anti-human Fy monoclonal antibodies (mAbs) and human chemokines to red blood cells (RBCs) from 11 nonhuman primates and two nonprimate mammals, and we elucidated the structures of the DARC genes from gorilla, gibbon, baboon, marmoset, tamarin, night monkey and cattle. CXCL-8 and CCL-5 chemokine binding analysis indicated that the promiscuous binding profile characteristic of DARC is conserved across species. Among three mAbs that detected the Fy6 epitope by flow cytometric analysis of human and chimpanzee RBCs, only one reacted with night monkey and squirrel monkey. Only chimpanzee RBCs bound a significant amount of the anti-Fy3 mAb. Fy3 was also poorly detected on RBCs from gorilla, baboon and rhesus monkey, but not from new world monkeys. Alignment of DARC homologous sequences allowed us to construct a phylogenetic tree in which all branchings were in accordance with current knowledge of primate phylogeny. Although DARC was expected to be under strong internal and external selection pressure, in order to maintain chemokine binding and avoid Plasmodium vivax binding, respectively, our present study did not provide arguments in favor of a selection pressure on the extracellular domains involved in ligand specificity. The amino acid variability of DARC-like polypeptides was found to be well correlated with the hydrophilicity indexes, with the highest divergence on the amino-terminal extracellular domain. Analysis of the deduced amino acid sequences highlighted the conservation of some amino acid residues, which should prove to be critical for the structural and functional properties of DARC.