Characterization of CD34+ hematopoietic cells in systemic mastocytosis: Potential role in disease dissemination.

BACKGROUND: Recent studies show that most systemic mastocytosis (SM) patients, including indolent SM (ISM) with (ISMs+) and without skin lesions (ISMs-), carry the KIT D816V mutation in PB leukocytes. We investigated the potential association between the degree of involvement of BM hematopoiesis by the KIT D816V mutation and the distribution of different maturation-associated compartments of bone marrow (BM) and peripheral blood (PB) CD34+ hematopoietic precursors (HPC) in ISM and identified the specific PB cell compartments that carry this mutation. METHODS: The distribution of different maturation-associated subsets of BM and PB CD34+ HPC from 64 newly diagnosed (KIT-mutated) ISM patients and 14 healthy controls was analyzed by flow cytometry. In 18 patients, distinct FACS-purified PB cell compartments were also investigated for the KIT mutation. RESULTS: ISM patients showed higher percentages of both BM and PB MC-committed CD34+ HPC vs controls, particularly among ISM cases with MC-restricted KIT mutation (ISMMC ); this was associated with progressive blockade of maturation of CD34+ HPC to the neutrophil lineage from ISMMC to multilineage KIT-mutated cases (ISMML ). Regarding the frequency of KIT-mutated cases and cell populations in PB, variable patterns were observed, the percentage of KIT-mutated PB CD34+ HPC, eosinophils, neutrophils, monocytes and T cells increasing from ISMs-MC and ISMs+MC to ISMML patients. CONCLUSION: The presence of the KIT D816V mutation in PB of ISM patients is associated with (early) involvement of circulating CD34+ HPC and multiple myeloid cell subpopulations, KIT-mutated PB CD34+ HPC potentially contributing to early dissemination of the disease.

Increased IL6 plasma levels in indolent systemic mastocytosis patients are associated with high risk of disease progression.

Systemic mastocytosis (SM) is a heterogeneous disease with altered interleukin (IL)-6 and IL13 plasma levels. However, no study has simultaneously investigated the plasma levels of IL1ß, IL6, IL13, CCL23 and clusterin in SM at diagnosis and correlated them with disease outcome. Here we investigated IL1ß, IL6, IL13, CCL23 and clusterin plasma levels in 75 SM patients--66 indolent SM (ISM) and 9 aggressive SM--and analyzed their prognostic impact among ISM cases grouped according to the extent of hematopoietic involvement of the bone marrow cells by the KIT D816V mutation. Although increased IL1ß, IL6 and CCL23 levels were detected in SM patients versus healthy controls, only IL6 and CCL23 levels gradually increased with disease severity. Moreover, increased IL6 plasma levels were associated with ISM progression to more aggressive disease, in particular among ISM patients with multilineal KIT mutation (ISM-ML), these patients also showing a higher frequency of organomegalies, versus other ISM-ML patients. Of note, all ISM patients who progressed had increased IL6 plasma levels already at diagnosis. Our results indicate that SM patients display an altered plasma cytokine profile already at diagnosis, increased IL6 plasma levels emerging as an early marker for disease progression among ISM cases, in particular among high-risk ISM patients who carry multilineage KIT mutation.

Dopamine transporter down-regulation following repeated cocaine: implications for 3,4-methylenedioxymethamphetamine-induced acute effects and long-term neurotoxicity in mice.

BACKGROUND AND PURPOSE: 3,4-Methylenedioxymethamphetamine (MDMA) and cocaine are two widely abused psychostimulant drugs targeting the dopamine transporter (DAT). DAT availability regulates dopamine neurotransmission and uptake of MDMA-derived neurotoxic metabolites. We aimed to determine the effect of cocaine pre-exposure on the acute and long-term effects of MDMA in mice. EXPERIMENTAL APPROACH: Mice received a course of cocaine (20 mg*kg(-1), x2 for 3 days) followed by MDMA (20 mg*kg(-1), x2, 3 h apart). Locomotor activity, extracellular dopamine levels and dopaminergic neurotoxicity were determined. Furthermore, following the course of cocaine, DAT density in striatal plasma membrane and endosome fractions was measured. KEY RESULTS: Four days after the course of cocaine, challenge with MDMA attenuated the MDMA-induced striatal dopaminergic neurotoxicity. Co-administration of the protein kinase C (PKC) inhibitor NPC 15437 prevented cocaine protection. At the same time, after the course of cocaine, DAT density was reduced in the plasma membrane and increased in the endosome fraction, and this effect was prevented by NPC 15437. The course of cocaine potentiated the MDMA-induced increase in extracellular dopamine and locomotor activity, following challenge 4 days later, compared with those pretreated with saline. CONCLUSIONS AND IMPLICATIONS: Repeated cocaine treatment followed by withdrawal protected against MDMA-induced dopaminergic neurotoxicity by internalizing DAT via a mechanism which may involve PKC. Furthermore, repeated cocaine followed by withdrawal induced behavioural and neurochemical sensitization to MDMA, measures which could be indicative of increased rewarding effects of MDMA.