Cytokine secretion by human mast cells

The Alleviating Effect of Lagerstroemia indica Flower Extract on Stretch Marks through Regulation of Mast Cells

Striae distensae (SD) or stretch marks are common linear scars of atrophic skin with disintegrating extracellular matrix (ECM) structures. Although fibroblasts contribute to the construction of ECM structure in SD, some studies have reported that mast cell degranulation causes the disruption of ECM in early SD lesions. Lagerstroemia indica flower (LIF) has traditionally been used in India as a diuretic. However, little is known about the effect and molecular action of Lagerstroemia indica flower extract (LIFE) on alleviating SD. This study evaluated the effects of LIFE on mast cell degranulation and the synthesis of ECM components in fibroblasts. LIFE inhibits the adhesion of rat basophilic leukemia (RBL) cells, RBL-2H3 on fibronectin (FN) and the expression of integrin, a receptor for FN, thereby reducing focal adhesion kinase (FAK) phosphorylation. In addition, LIFE attenuated the allergen-induced granules and cytokine interleukin 3 (IL-3) through the adhesion with FN. Moreover, the conditioned medium (CM) of activated mast cells decreases the synthesis of ECM components, and LIFE restores the abnormal expressions induced by activated mast cells. These results demonstrate that LIFE suppresses FN-induced mast cell activation and promotes the synthesis of ECM components in fibroblast, which indicates that LIFE may be a useful cosmetic agent for SD treatment.

Mast cells and the liver aging process

It has now ascertained that the clinical manifestations of liver disease in the elderly population reflect both the cumulative effects of longevity on the liver and the generalized senescence of the organism ability to adjust to metabolic, infectious, and immunologic insults. Although liver tests are not significantly affected by age, the presentation of liver diseases such as viral hepatitis may be subtler in the elderly population than that of younger patients.

Human immunosenescence is a situation in which the immune system, particularly T lymphocyte function, deteriorates with age, while innate immunity is negligibly affected and in some cases almost up-regulated.

We here briefly review the relationships between the liver aging process and mast cells, the key effectors in a more complex range of innate immune responses than originally though.

The complex functions of mast cells in chronic human liver diseases

Mast cells (MCs) are multifunctional effector cells of the immune system. MCs were originally thought to be involved in IgE-associated immediate hypersensitivity and allergic disorders, but it is now known that they contain or elaborate an array of mediators with a multitude of effects on many other cells. A number of studies have found that MCs are involved in various liver diseases. Although still controversial, they seem to be involved in the liver's fibrotic response to chronic inflammation and parasitic infection. Hepatic fibrosis is the most frequent liver response to toxic, infectious, or metabolic agents. During the establishment of this pathological condition, there is an increase in the components of the basement membrane that leads to continuous basement membrane-like structures being raised within Disse's space and a decrease in the number of sinusoid endothelial fenestrae. This leads to a complex process called "sinusoidal capillarization." At the cellular level, liver fibrogenesis is initiated by hepatocyte necrosis, which induces the recruitment of a large number of inflammatory cells, including MCs, which can be considered the primary effectors of the process changing sinusoidal endothelial cells into capillary-type endothelial cells. We review the roles played by MCs in hepatic chronic diseases and describe a biopsy section of hepatic tissue taken from a patient with chronic C virus-related hepatitis showing diffuse sinusoidal capillarization and a high density of MCs. This observation has led us to hypothesize a relationship between these highly specialized cells and sinusoidal capillarization.

Mast cells regulate IFN-gamma expression in the skin and circulating IgE levels in allergen-induced skin inflammation

BACKGROUND

Mast cells are important effector cells in IgE-mediated allergic reactions. They are present in normal skin and increased in skin lesions of patients with atopic dermatitis (AD).

OBJECTIVE

We used mice deficient in mast cells (W/W(v)) to assess the role of these cells in a murine model of allergen-induced skin inflammation induced by repeated epicutaneous sensitization with ovalbumin (OVA); the model exhibits many of the characteristics of AD.

METHODS

Mice deficient in mast cells were sensitized with OVA. Histologic and immunohistochemical examinations, as well as measurements of IL-4 and IFN-gamma mRNA, were performed on OVA-sensitized skin. Total and antigen-specific serum IgE levels were determined.

RESULTS

Infiltration in W/W(v) mice by mononuclear cells, T cells, and eosinophils in OVA-sensitized skin was comparable to that in wild-type (WT) controls. Expression of IL-4 mRNA in sensitized skin sites was similarly increased in WT and W/W(v) mice. However, IFN-gamma mRNA expression was significantly increased in sensitized skin of W/W(v) mice but not in that of WT controls. IL-4 mRNA was readily detectable in unsensitized skin of WT controls but not in that of W/W,(v) mice, whereas expression of IL-12 p40 mRNA was significantly increased in unsensitized skin of W/W(v) mice in comparison with WT controls. Total serum IgE levels were significantly increased after epicutaneous sensitization in W/W(v) mice in comparison with WT controls.

CONCLUSION

These results suggest that mast cells regulate IFN-gamma expression in the skin and IgE levels in the circulation in a model of allergen-induced skin inflammation with similarities to AD. This is important, given the role of IFN-gamma in keratinocyte injury in AD and the role of IgE-mediated reactions in exacerbating AD.

Degranulation influences heparin-associated inhibition of RT-PCR in human lung mast cells

BACKGROUND

The study of gene expression from human lung mast cells (HLMC) has been limited by the ability to reliably detect mRNA transcripts from scant quantities of mast cell RNA contaminated with heparin.

OBJECTIVE

As heparin is granule-associated within the mast cell, we examined the role of degranulation in altering the intrinsic ability of this proteoglycan to inhibit reverse transcription polymerase chain reaction (RT-PCR) from HLMC RNA. We also explored alternative means of RNA isolation to eliminate primary heparin contamination.

METHODS

Purified HLMC (> 90% pure) were challenged for 2 h with buffer, anti-IgE (3 microg/mL) and/or ionophore A23187 (100 ng/mL) or phorbol 12-myristate 13-acetate (50 ng/mL). Histamine release was measured using a spectroflourometric assay. Following challenge, RNA was isolated by either phenol-chloroform extraction or by nitrocellulose spin column. Parallel samples were either treated with heparinase or placed on ice for 2 h prior to reverse transcription. PCR was performed using primers specific for the housekeeping gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

RESULTS

In each of five studies, GAPDH bands were detected at greater intensity in total cellular RNA (tcRNA) derived from degranulated than from non-degranulated mast cells. However, when examining heparinase-treated tcRNA from the same mast cell samples, the intensity of GAPDH bands normalized between degranulated and non-degranulated cells. When comparing parallel samples of column-purified tcRNA, subsequent treatment of samples with heparinase had no effect on the detection of GAPDH, indicating that endogenous heparin was effectively removed by the technique. Moreover, no variability was noted in GAPDH signal detected from resting vs. degranulated mast cells (n = 3).

CONCLUSIONS

Degranulation influences the degree of heparin-associated inhibition of RT-PCR in HLMC, and that spin column purification of tcRNA is a time-saving, effective alternative to heparinase pre-treatment.

Roles of mitogen-activated protein kinase pathways for mediator release from human cultured mast cells

Human cultured mast cells (HCMC) secrete histamine, sulfidoleukotrienes (LTs), and prostaglandin D(2) (PGD(2)), and produce a variety of cytokines after aggregation of high-affinity receptors for IgE (FcepsilonRI). With respect to the mitogen-activated protein kinase (MAPK) family, extracellular signal-regulated kinases (ERKs), c-Jun NH(2)-terminal kinases (JNKs), and p38 mitogen-activated protein kinase (p38 MAPK) are known. To investigate the roles of these kinase pathways for mediator release from human mast cells, we examined the participation of the activation of these kinases in mediator release, using 1,4-diamino-2, 3-dicyano-1,4-bis(2-aminophenylthio)butadiene (U0126), an ERK pathway inhibitor, and 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imid azo le (SB203580), a p38 MAPK pathway inhibitor. U0126 inhibited ERK activation, LT and PGD(2) release, and granulocyte macrophage-colony stimulating factor (GM-CSF) production after stimulation of HCMC. SB203580, on the other hand, potentiated JNK activation and GM-CSF production. The findings of the present study demonstrated that: (i) the release of arachidonic acid metabolites is mediated by the ERK pathway; (ii) GM-CSF production may be driven by both the ERK and JNK pathways; and (iii) the p38 MAPK pathway negatively regulates the JNK pathway. This suggests that MAPK pathways play important roles in mediator release from human mast cells.

In activated mast cells, IL-1 up-regulates the production of several Th2-related cytokines including IL-9

Mast cells can play detrimental roles in the pathophysiology and mortality observed in anaphylaxis and other Th2-dominated allergic diseases. In contrast, these cells contribute to protective host defense mechanisms against parasitic worm infections. After IgE/Ag activation, mast cells can produce multiple cytokines that may enhance allergic inflammations, while a similar panel of Th2-related cytokines may support immunological strategies against parasites. Here we report that in primary mouse bone marrow-derived mast cells activated by ionomycin or IgE/Ag, the proinflammatory mediator IL-1 (alpha or beta) up-regulated production of IL-3, IL-5, IL-6, and IL-9 as well as TNF, i.e., cytokines implicated in many inflammatory processes including those associated with allergies and helminthic infections. IL-1 did not induce significant cytokine release in the absence of ionomycin or IgE/Ag, suggesting that Ca-dependent signaling was required. IL-1-mediated enhancement of cytokine expression was confirmed at the mRNA level by Northern blot and/or RT-PCR analysis. Our study reveals a role for IL-1 in the up-regulation of multiple mast cell-derived cytokines. Moreover, we identify mast cells as a novel source of IL-9. These results are of particular importance in the light of recent reports that strongly support a central role of IL-9 in allergic lung inflammation and in host defense against worm infections.

Adhesion of human mast cells to extracellular matrix provides a co-stimulatory signal for cytokine production

Engagement of integrin receptors during cell adhesion leads to changes in the morphology and the state of activation of cells. We therefore examined whether mast cell adhesion to extracellular matrix proteins affects the synthesis and release of various proinflammatory cytokines. Cells of the human mast cell line HMC-1 were added to fibronectin (FN)-, vitronectin (VN)- or, as a control, bovine serum albumin (BSA)-coated wells and were stimulated with phorbol 12-myristate 13-acetate (PMA) and/or calcium ionophore A23187 (ionophore). Cytokine production was evaluated using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis of cell extracts and enzyme-linked immunosorbent assay (ELISA) analysis of cell supernatants. After a 4-hr incubation, mRNA expression of interleukin (IL)-8 (and weakly of IL-6) was up-regulated in matrix-adherent cells, with further increase in the presence of PMA and/or ionophore, compared with unstimulated cells. High-level de novo expression of IL-3 and of granulocyte-macrophage colony-stimulating factor (GM-CSF) was observed mainly in matrix-adherent cells. These changes were paralleled by the secretory pattern of HMC-1 cells after a 24-hr stimulation. Unstimulated cells adherent to FN or VN had already released small amounts of IL-8, and both VN- and FN-adherent cells produced, almost invariably, a higher level of cytokines than BSA-exposed cells after additional stimulation. These results show that mast cell adhesion to matrix proteins by itself has only selected and minor effects, but additional activation of mast cells by secretory stimuli causes significantly enhanced cytokine gene expression and secretion, suggesting that mast cells are far more active in their natural tissue environment than hitherto suggested from data in suspension cultures.

Mast cells in the cytokine network: the what, where from and what for

The basic understanding of mast cell ontogeny and function has been fundamentally changed in recent years with observations that the cells produce and respond to a broad range of cytokines. These rapidly accruing data and their potential significance were discussed at the recent symposium "Mast Cells in the Cytokine Network", and the overview lectures of most speakers are summarized in this special journal issue. In the present introductory manuscript, the organizers of the meeting discuss data fundamental to an understanding of the topic and highlight aspects of special interest. They consider mast cells to be defined most reliably by their unique ultrastructure since the cells are highly heterogeneous in dependence of the species studied, their tissue location, their stage of development and probably also in relation to cytokines. Most other characteristics of mast cells are shared with diverse other cell types. Murine mast cell development is induced by several cytokines. These factors are mostly ineffective in human cells except for stem cell factor which causes mast cell development from CD34+/c-kit+ progenitors. There is however recent evidence that fibroblasts and keratinocytes produce additional growth factors for human mast cells. Regarding cytokine secretion, most molecules known so far are produced by both murine and human mast cells. The cells furthermore bear receptors for several cytokines, enabling them to respond in an autocrine and paracrine fashion. Mast cells may thus function within a complex cytokine network, affecting physiological as well as immunological and inflammatory processes.