Recombinant Human Tryptase beta-2 Protein (a.a. 31-275) [His]

Background: Telangiectasia macularis eruptiva perstans (TMEP) is a rare form of cutaneous mastocytosis (CM). Although TMEP has been traditionally thought to be restricted to the skin, a recent retrospective multicentric study established a diagnosis with systemic involvement of mastocytosis in 47% patients affected by TMEP and aggressive systemic mastocytosis in 9%. Objectives: To evaluate systemic involvement in patients affected by TMEP. Materials and Methods: We conducted a retrospective monocentric study among patients affected by TMEP visited in our dermatology clinic. Data regarding gender, age at diagnosis, duration of the disease before diagnosis, topography, clinical features, presence of extra-cutaneous symptoms, serum tryptase levels, and histopathological and bone marrow biopsy features were analysed. Results: Among 119 patients classified with mastocytosis, eight patients (six males, two females) with TMEP and one female patient affected by mastocytosis in the skin, a TMEP variant, were retrospectively studied. The mean diagnostic delay was two years (range: 8-26 months). In two patients (25%), bone marrow involvement was identified and osteoporosis and hepatosplenomegaly were also found. The two patients with systemic involvement exhibited a statistically significant increase in serum tryptase levels (p < 0.05). The detection of KIT gene mutation in skin specimens revealed a somatic mutation, KITD816 V, only in these two patients. Conclusion: TMEP is a rare form of CM, often neglected. A correct and early diagnosis of TMEP is important to rule out systemic involvement of the disease. Detection of serum tryptase levels may be a useful, rapid, and non-invasive marker of systemic involvement.

Mast cells (MCs) are granular cells of the innate immune system which develop from CD34(+)/CD117(+) progenitors and play a role in orchestrating adaptive immune responses. They have a well-known role in allergic reactions following immunoglobulin (Ig)E-mediated activation of the cell-surface expressed IgE high-affinity receptor (Fc epsilon RI). MCs can also respond to various other stimuli due to the expression of a variety of receptors including toll-like receptors (TLRs), immunoglobulin (IgG) receptors (Fc gamma R), complement receptors such as C5a (CD88) expressed by skin MCs, neuropeptides receptors including nerve growth factor receptor, (NGFR), cytokines receptors such as (IL)-1R and IL-3R, and chemokines receptors including CCR-1 and CCR-3. MCs release three groups of mediators upon degranulation differentiated according to their chemical composition, storage, and time to release. These include preformed mediators (mainly histamine, tryptase, and chymase), de novo synthesized mediators such as prostaglandin (PG)D2, leukotriene (LT)B4 and LTD4, and cytokines including IL-1 beta, IL-3, tumor necrosis factor (TNF)alpha, and transforming growth factor(TGF)-beta. Emerging evidence indicates a role for IgE-independent MC activation in the late-stage asthmatic response as well as in non-allergic airway diseases including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and lung cancer. MC infiltration/activation has been reported in some, but not all, studies of lung cancer. MC-derived TNF-alpha possesses tumor-suppressive activity while IL-1 beta supports tumor progression and metastasis. In IPF lungs, an increase in density of tryptase- and chymase-positive MCs (MCTC) and overexpression of TGF-beta support the fibrosis progression. MC-derived chymase activates latent TGF-beta that induces the differentiation of fibroblasts to matrix-producing myofibroblasts. In summary, increasing evidence highlights a critical role of MCs in non-allergic diseases that may indicate new approaches for therapy.