Transglutaminase 2 expressed in mast cells recruited into skin or bone marrow induces the development of pediatric mastocytosis

The Role of Mast Cells in the Induction and Maintenance of Inflammation in Selected Skin Diseases

Under physiological conditions, skin mast cells play an important role as guardians that quickly react to stimuli that disturb homeostasis. These cells efficiently support, fight infection, and heal the injured tissue. The substances secreted by mast cells allow for communication inside the body, including the immune, nervous, and blood systems. Pathologically non-cancerous mast cells participate in allergic processes but also may promote the development of autoinflammatory or neoplastic disease. In this article, we review the current literature regarding the role of mast cells in autoinflammatory, allergic, neoplastic skin disease, as well as the importance of these cells in systemic diseases with a pronounced course with skin symptoms.

Molecular Background, Clinical Features and Management of Pediatric Mastocytosis: Status 2021

Pediatric mastocytosis is a heterogeneous disease characterized by accumulation of mast cells in the skin and less frequently in other organs. Somatic or germline mutations in the KIT proto-oncogene are detected in most patients. Cutaneous mastocytosis is the most common form of the disease in children. In the majority of cases, skin lesions regress spontaneously around puberty. However, in few patients, mastocytosis is not a self-limiting disease, but persists into adulthood and can show signs of systemic involvement, especially when skin lesions are small-sized and monomorphic. Children with mastocytosis often suffer from mast cell mediator-related symptoms. Severe hypersensitivity reactions can also occur, mostly in patients with extensive skin lesions and blistering. In a substantial number of these cases, the triggering factor of anaphylaxis remains unidentified. Management of pediatric mastocytosis is mainly based on strict avoidance of triggers, treatment with H1 and H2 histamine receptor blockers, and equipment of patients and their families with epinephrine auto-injectors for use in severe anaphylactic reactions. Advanced systemic mastocytosis occurs occasionally. All children with mastocytosis require follow-up examinations. A bone marrow investigation is performed when advanced systemic mastocytosis is suspected and has an impact on therapy or when cutaneous disease persists into adulthood.

Inhibition of Osteoarthritis-Related Molecules by Isomucronulatol 7-O-β-d-glucoside and Ecliptasaponin A in IL-1β-Stimulated Chondrosarcoma Cell Model

Osteoarthritis (OA) is the common form of arthritis and is characterized by disability and cartilage degradation. Although natural product extracts have been reported to have anti-osteoarthritic effects, the potential bioactivity of Ryupunghwan (RPH), a traditional Korean medicinal botanical formula that contains Astragalus membranaceus, Turnera diffusa, Achyranthes bidentata, Angelica gigas, Eclipta prostrata, Eucommia ulmoides, and Ilex paraguariensis, is not known well. Therefore, the inhibitory effects of single compounds isolated from RPH on the OA-related molecules were investigated using IL-1β-stimulated chondrosarcoma SW1353 (SW1353) cell model. Two bioactive compounds, isomucronulatol 7-O-β-d-glucoside (IMG) and ecliptasaponin A (ES) were isolated and purified from RPH using column chromatography, and then the structures were analyzed using ESI-MS, ¹H-NMR, and ¹³C-NMR spectrum. The expression or amount of matrix metalloproteinase 13 (MMP13), COX1/2, TNF-α, IL-1β or p65 was determined by RT-PCR, Western blot, and enzyme-linked immunosorbent assay (ELISA). RPH pretreatment reduced the expression and amounts of MMP13, and the expression of collagen II, COX1/2, TNF-α, IL-1β or p65, which were increased in IL-1β-stimulated SW1353 cells. IMG reduced the expression of all OA-related molecules, but the observed inhibitory effect was less than that of RPH extract. The other single compound ES showed the reduced expression of all OA-related molecules, and the effect was stronger than that in IMG (approximately 100 fold). Combination pretreatment of both single components remarkably reduced the expression of MMP13, compared to each single component. These synergic effects may provide potential molecular modes of action for the anti-osteoarthritic effects of RPH observed in clinical and animal studies.

Association of TG2 from mast cells and chronic spontaneous urticaria pathogenesis

BACKGROUND

Mast cells and their mediators play important roles in chronic spontaneous urticaria (CSU) pathogenesis. Transglutaminase 2 (TG2) is expressed in activated mast cells and contributes to airway inflammation in allergic asthma.

OBJECTIVE

To investigate the role of TG2 in CSU.

METHODS

Patients with CSU (n = 72) and healthy controls (n = 51) were evaluated. Skin biopsy specimens were obtained from 5 patients with CSU and 2 healthy controls. Cord blood-derived human mast cells and peripheral blood-derived human mast cells were activated with IgE. TG2 activity and inflammatory mediators, such as histamine, leukotriene C4, and cytokines, were measured in serum or supernatant from cultured mast cells by enzyme-linked immunosorbent assay. Colocalization of mast cells and TG2 was determined in skin tissues by immunofluorescence.

RESULTS

TG2 activity was significantly higher in serum samples from patients with CSU than in serum samples from healthy controls (P < .001). Colocalization of mast cell surface marker c-kit and TG2 was significantly increased in the lesional skin of patients with CSU compared with that in healthy controls. The levels of histamine, leukotriene C4, tumor necrosis factor α, transforming growth factor β, and interleukins 4, 5, and 6 were significantly higher in patients with CSU than in healthy controls (P < .001). Serum TG2 levels had positive correlations with each inflammatory mediator (P < .001). TG2 activity was increased in cord blood-derived human mast cells (CBMCs) and peripheral blood-derived human mast cells activated with IgE compared with those without activation (P < .05).

CONCLUSION

Our findings suggest that TG2 expressed in and released from mast cells plays an important role in CSU pathogenesis.