Oncogenic D816V-KIT signaling in mast cells causes persistent IL-6 production.

Persistent dysregulation of IL-6 production and signaling have been implicated in the pathology of various cancers. In systemic mastocytosis, increased serum levels of IL-6 associate with disease severity and progression, although the mechanisms involved are not well understood. Since systemic mastocytosis often associates with the presence in hematopoietic cells of a somatic gain-of-function variant in KIT, D816V-KIT, we examined its potential role in IL-6 upregulation. Bone marrow mononuclear cultures from patients with greater D816V allelic burden released increased amounts of IL-6 which correlated with the percentage of mast cells in the cultures. Intracellular IL-6 staining by flow cytometry and immunofluorescence was primarily associated with mast cells and suggested a higher percentage of IL-6 positive mast cells in patients with higher D816V allelic burden. Furthermore, mast cell lines expressing D816V-KIT, but not those expressing normal KIT or other KIT variants, produced constitutively high IL-6 amounts at the message and protein levels. We further demonstrate that aberrant KIT activity and signaling are critical for the induction of IL-6 and involve STAT5 and PI3K pathways but not STAT3 or STAT4. Activation of STAT5A and STAT5B downstream of D816V-KIT was mediated by JAK2 but also by MEK/ERK1/2, which not only promoted STAT5 phosphorylation but also its long-term transcription. Our study thus supports a role for mast cells and D816V-KIT activity in IL-6 dysregulation in mastocytosis and provides insights into the intracellular mechanisms. The findings contribute to a better understanding of the physiopathology of mastocytosis and suggest the importance of therapeutic targeting of these pathways.

Stigma and illness uncertainty: adding to the burden of sickle cell disease.

BACKGROUND: Persons with sickle cell disease (SCD) experience multiple medical and physical complications; the disease also has numerous effects on their social and emotional well-being. We hypothesized that adults with SCD in Jamaica experience moderate levels of stigma and illness uncertainty and that these experiences may be associated with socio-demographic factors, such as gender, educational status and economic status. METHODS: We surveyed 101 adults with SCD (54.5% female; mean age 31.6 ± 10.4 years; 72.2% homozygous SCD) using the Stigma in Sickle Cell Disease Scale (Adult), Mishel Uncertainty in Illness Scale (Adult) and a Socio-Demographic questionnaire. RESULTS: The mean stigma score was 33.6 ± 21.6 (range: 2-91) with no significant difference between males and females (32.3 ± 21.3 vs. 34.7 ± 21.9; p-value = 0.58). Illness uncertainty was greater in females than in males, though not statistically significant, (88.7 ± 13.5 vs. 82.6 ± 19.2; p-value: 0.07). Stigma and uncertainty had a significant positive correlation (r: 0.31; p-value: 0.01). In an age and sex controlled model, stigma scores were lower with higher numbers of household items (coef: -2.26; p-value: 0.001) and higher in those living in greater crowding (coef: 7.89; p-value: 0.002). Illness uncertainty was higher in females (coef: 6.94; p-value: 0.02) and lower with tertiary as compared with primary education (coef: -16.68; p-value: 0.03). CONCLUSION: The study highlights socioeconomic factors to be significant to the stigma and illness uncertainty experiences in SCD. Efforts by healthcare workers to reduce patient illness uncertainty may have additional impact, reducing their stigma.