The role of histamine in wound healing I. The effect of high doses of histamine on collagen and glycosoaminoglycan content in wounds

Increased tissue survival in experimental skin flaps in mast cell-deficient rats

AIM

The role of mast cells and their principal mediator, histamine, in surgical skin flap survival was investigated using mast cell-deficient (Ws/Ws); their congenic littermates wild-type (+/+), and Wistar rats.

METHODS

A standardized dorsal skin flap was raised and sutured back into position, and 6 days later the percentage of flap survival was assessed. Moreover, endogenous histamine concentration in the dorsal skin during the surgical preparation was determined using in vivo microdialysis technique together with high performance liquid chromatography-fluorometry. Accumulation of skin flap myeloperoxidase (MPO) (reflecting leucocyte recruitment) was determined spectrophotometrically.

RESULTS

The experimental skin flaps in genetically mast cell-deficient rats exhibited increased tissue survival and showed little accumulation of MPO and rather low and stable level of histamine output in comparison with skin flaps in the wild-type (+/+) littermates or normal Wistar rats. Antihistamine treatment inhibited but did not prevent leucocyte recruitment in the skin flaps post-surgery in +/+ and Wistar rats.

CONCLUSION

It is suggested that mast cell derived histamine plays an important role in leucocyte recruitment in skin flaps. However, mast cell-independent factors should be taken into consideration and needs further investigation as even in mast cell-deficient animals there was some accumulation of leucocytes and tissue necrosis in the skin flaps post-surgery.

Temporary augmentation of glycosaminoglycans content in the heart after left coronary artery ligation

Introduction: Augmentation of glycosaminoglycans (GAG) in various tissues after injury is well known, however, there is no information about the metabolism of GAG during the heart remodeling after infarction. The study is focused on the changes of total GAG concentrations in the viable myocardium and scar after experimental left coronary artery occlusion. To shed some light on the possible mechanism of the changes, GAG were also evaluated in the skin. Methods: Male Wistar rats were subjected to left coronary artery ligation or to sham operation. After 3, 6 or 12 weeks of follow up the rats were sacrificed and the heart and skin were collected. The heart was cut into parts: right ventricle, septum, viable region of left ventricle and scar. The Farndale method was used for the estimation of GAG in the samples. Results: High level of GAG in the myocardial scar tissue was seen in the 3 weeks of follow up and reached maximum in the 6 weeks and then decreased in week 12. Similar pattern of GAG changes was found in the contractile part of the heart. In both viable part of the left ventricle and septum the peak level of GAG was found in rats 6 weeks after the onset of infarction. Than the content of GAG decreased towards the control level. There was no alteration in the GAG content in the skin and a wall of the right ventricle. Conclusion: Temporary augmentation of GAG content is present not only in myocardium directly injured by ischaemia but also in the viable part of the heart subjected mainly to increased haemodynamic stresses. The local nature of mechanisms responsible for the GAG changes has been postulated.

The mast cell in wound healing

This review describes the role of the mast cell in the pathobiology of skin healing. After illustrating its main morphofunctional characteristics, with special reference to the dog and cat, we consider the involvement of the mast cell in the various phases of skin repair. With the aid of a wide array of newly formed or preformed mediators released by degranulation, the activated mast cell controls the key events of the healing phases: triggering and modulation of the inflammatory stage, proliferation of connective cellular elements and final remodelling of the newly formed connective tissue matrix. The importance of the mast cell in regulating healing processes is also demonstrated by the fact that a surplus or deficit of degranulated biological mediators causes impaired repair, with the formation of exuberant granulation tissue (e.g. keloids and hypertrophic scars), delayed closure (dehiscence) and chronicity of the inflammatory stage.

Effect of mast cell-derived mediators and mast cell-related neutral proteases on human dermal fibroblast proliferation and type I collagen production

BACKGROUND

Possible involvement of mast cells in various fibrotic conditions has been suggested, but the relative contribution of each mast cell mediator and neutral protease to fibroproliferative activity remains to be elucidated.

OBJECTIVE

We investigated the effect of mast cell-derived mediators and mast cell-related neutral proteases on type I collagen production and proliferation by human dermal fibroblasts.

METHODS

Mast cell-derived mediators or neutral proteases were added to cultured fibroblasts from normal dermis, and cell proliferation and type I collagen synthesis were assayed.

RESULTS

Fibroblast proliferation was increased by 2.8 x 10(-9) mol/L prostaglandin D(2) and 10 microgram/mL carboxypeptidase A, but not by leukotriene D(4) or cathepsin G at the concentrations studied. Proliferation was increased by tryptase in a concentration-dependent manner, and a significant increase was observed at concentrations of 1 and 10 microgram/mL. Production of type I collagen by fibroblasts was increased in the presence of 2.0 x 10(-9) mol/L leukotriene D(4) and 10 microgram/mL tryptase.

CONCLUSION

Mast cell-derived mediators prostaglandin D(2) and leukotriene D(4) and mast cell-related neutral proteases carboxypeptidase A and tryptase increase the proliferation and type I collagen production of human dermal fibroblasts in various manners.

The role of mast cell-derived histamine in the closure of an in vitro wound

We have previously reported that mast cells (MC) stimulate 3T3 fibroblast migration and proliferation into an in vitro model of wound obtained by producing in a confluent 3T3 monolayer, a midline cut and by scraping the cells from half of the monolayer. The purpose of the present study was to determine the contribution of mast cell-derived histamine to this MC increasing effect. Histamine levels in supernatants of MC/ 3T3 cultures unactivated or activated with either compound 48/80 or anti-IgE antibodies (10 min) did not correlate to the degree of fibroblast migration and proliferation into the wound space (42 h). Various concentrations of histamine were added to 3T3 fibroblast monolayers in the absence of cocultured MC, and fibroblasts beyond the wound line were counted (42 h). Addition of 100 ng/ml histamine had the highest stimulating effect on fibroblast numbers. This effect was abrogated by the addition of cimetidine (an H-2 antagonist). Addition of cimetidine to unactivated MC/ 3T3 cultures did not affect the increasing activity of MC presence on the wounded monolayer, although it diminished the enhancing effect obtained after MC activation with compound 48/80. These results indicate that histamine is partially responsible for the mast cell enhancing effect on fibroblast migration and proliferation in an in vitro model of wound.

Characterization and functional studies of rheumatoid synovial mast cells. Activation by secretagogues, anti-IgE, and a histamine-releasing lymphokine

Microscopic analysis of synovial specimens from 35 patients with rheumatoid arthritis (RA) and 7 patients with osteoarthritis revealed mast cell hyperplasia in perivascular regions, in fibrous interstitial areas, and clustered around the periphery of lymphoid aggregates. Metachromatic staining, immunofluorescence studies, and ultrastructural analysis revealed a single population of connective tissue-type mast cells with surface IgE receptors. Total extractable histamine of synovial tissue was 4.15 +/- 2.30 micrograms/gm (n = 8) for RA synovium and 0.53 +/- 0.23 microgram/gm (n = 7) for OA synovium. Mast cell secretion was assessed and specific release of histamine from RA synovial mast cells was observed following stimulation with anti-IgE (32.3%), compound 48/80 (40.1%), calcium ionophore A23187 (25.2%), and a partially purified lymphokine with histamine-releasing activity (23.9%).

Alterations in histamine and collagen induced in chick embryos by aminoguanidine and 48/80

The effects of aminoguanidine (a histamine inhibitor) and 48/80 (a histamine liberator) on the levels of histamine, soluble collagen fraction and total collagen in the chick embryos were studied. Histamine content in bones (tibia and femur) and skin markedly increased in the embryos treated with aminoguanidine. Aminoguanidine treatment was followed by a decrease of total collagen and an increase of soluble collagen fraction both in bones and skin. 48/80 did not change the histamine level in the bones but decreased that in the skin. 48/80 administration resulted in an augmentation of the total collagen content in the skin. Both in the skin and bones soluble collagen fraction was found to be lower in 48/80 treated embryos.

The role of histamine in wound healing. II. The effect of antagonists and agonists of histamine receptors (H1 and H2) on collagen levels in granulation tissue

The effects of mepyramine (H1-receptor antagonist), cimetidine (H2-receptor antagonist), IEM-813 (H1-receptor agonist) abd 4-Met-Hi (H2-receptor agonist) on collagenogenesis processes in subcutaneous implanted sponges of rats were studied. Administration into sponges of cimetidine 30 min before histamine injection blocked both the stimulatory effect of low histamine doses and the inhibitory effect of high histamine doses of collagen formation. Low doses of 4-Met-Hi increased collagen levels but reduced the levels at high doses. Mepyramine and IEM-813 did not influence collagen biosynthesis.