Leukocytes as secretory organs of inflammation

Aedes albopictus D7 Salivary Protein Prevents Host Hemostasis and Inflammation

Mosquitoes inject saliva into the host skin to facilitate blood meal acquisition through active compounds that prevent hemostasis. D7 proteins are among the most abundant components of the mosquito saliva and act as scavengers of biogenic amines and eicosanoids. Several members of the D7 family have been characterized at the biochemical level; however, none have been studied thus far in Aedes albopictus, a permissive vector for several arboviruses that causes extensive human morbidity and mortality. Here, we report the binding capabilities of a D7 long form protein from Ae. albopictus (AlboD7L1) by isothermal titration calorimetry and compared its model structure with previously solved D7 structures. The physiological function of AlboD7L1 was demonstrated by ex vivo platelet aggregation and in vivo leukocyte recruitment experiments. AlboD7L1 binds host hemostasis agonists, including biogenic amines, leukotrienes, and the thromboxane A2 analog U-46619. AlboD7L1 protein model predicts binding of biolipids through its N-terminal domain, while the C-terminal domain binds biogenic amines. We demonstrated the biological function of AlboD7L1 as an inhibitor of both platelet aggregation and cell recruitment of neutrophils and eosinophils. Altogether, this study reinforces the physiological relevance of the D7 salivary proteins as anti-hemostatic and anti-inflammatory molecules that help blood feeding in mosquitoes.

The novel 13S,14S-epoxy-maresin is converted by human macrophages to maresin 1 (MaR1), inhibits leukotriene A4 hydrolase (LTA4H), and shifts macrophage phenotype

Maresins are produced by macrophages from docosahexaenoic acid (DHA) and exert potent proresolving and tissue homeostatic actions. Maresin 1 (MaR1; 7R,14S-dihydroxy-docosa-4Z,8E,10E,12Z,16Z,19Z-hexaenoic acid) is the first identified maresin. Here, we investigate formation, stereochemistry, and precursor role of 13,14-epoxy-docosahexaenoic acid, an intermediate in MaR1 biosynthesis. The 14-lipoxygenation of DHA by human macrophage 12-lipoxygenase (hm12-LOX) gave 14-hydro(peroxy)-docosahexaenoic acid (14-HpDHA), as well as several dihydroxy-docosahexaenoic acids, implicating an epoxide intermediate formation by this enzyme. Using a stereo-controlled synthesis, enantiomerically pure 13S,14S-epoxy-docosa-4Z,7Z,9E,11E,16Z,19Z-hexaenoic acid (13S,14S-epoxy-DHA) was prepared, and its stereochemistry was confirmed by NMR spectroscopy. When this 13S,14S-epoxide was incubated with human macrophages, it was converted to MaR1. The synthetic 13S,14S-epoxide inhibited leukotriene B4 (LTB4) formation by human leukotriene A4 hydrolase (LTA4H) ∼40% (P<0.05) to a similar extent as LTA4 (∼50%, P<0.05) but was not converted to MaR1 by this enzyme. 13S,14S-epoxy-DHA also reduced (∼60%; P<0.05) arachidonic acid conversion by hm12-LOX and promoted conversion of M1 macrophages to M2 phenotype, which produced more MaR1 from the epoxide than M1. Together, these findings establish the biosynthesis of the 13S,14S-epoxide, its absolute stereochemistry, its precursor role in MaR1 biosynthesis, and its own intrinsic bioactivity. Given its actions and role in MaR1 biosynthesis, this epoxide is now termed 13,14-epoxy-maresin (13,14-eMaR) and exhibits new mechanisms in resolution of inflammation in its ability to inhibit proinflammatory mediator production by LTA4 hydrolase and to block arachidonate conversion by human 12-LOX rather than merely terminating phagocyte involvement.

Host mediators in gingival crevicular fluid: implications for the pathogenesis of periodontal disease

During the past few years, a considerable number of studies have examined different aspects of the host response in gingival crevicular fluid (GCF), including the relationship of specific markers to the active phases of periodontal disease. Various indicators of the acute inflammatory response (the lysosomal enzymes beta-glucuronidase and collagenase, the cytoplasmic enzyme aspartate aminotransferase, and the arachidonic acid metabolite PGE2) have been shown to be associated with clinical attachment loss in chronic adult periodontitis in man and experimental periodontitis in animal models. In contrast, the relationship of indicators of the humoral immune response in GCF to active periodontal disease is equivocal. Furthermore, a number of indicators of the cellular immune response have been identified recently in GCF (i.e., Interleukin-1 alpha, IL-1 beta, tumor necrosis factor-alpha), but their relationship to active phases of periodontal disease have not been studied. The polymorphonuclear leukocyte (PMN) is the cellular hallmark of acute inflammation. Evidence from the GCF studies suggests that hyperreactivity of these cells plays a critical role in the active phases of some forms of periodontal disease. Metabolic activation of PMN can be associated with a number of potentially destructive reactions. The major effector mechanism for tissue destruction that can be specifically identified with the PMN is the synergistic effect of the release of PMN proteases and the generation of reactive oxygen metabolites by these cells. Priming of the PMN, where the PMN response is enhanced by agents that do not initiate the response, may be an important mechanism for PMN activation in the crevicular environment; for example, cytokines such as IL-1 beta and TNF-alpha, and lipopolysaccharides released from subgingival Gram-negative bacteria, can serve this function. The hypothesis proposed here argues that in addition to the severe forms of periodontal disease that have been associated with qualitative or quantitative PMN defects, tissue destruction in the periodontum can be observed with hyperreactivity of these cells. These differing conclusions do not create a dilemma, but may represent opposite ends of a balance that is no longer in equilibrium.

Tumor-elicited polymorphonuclear cells, in contrast to "normal" circulating polymorphonuclear cells, stimulate invasive and metastatic potentials of rat mammary adenocarcinoma cells

Circulating polymorphonuclear cell (PMN) levels rise in proportion to the metastatic potential of the tumor in 13762NF mammary adenocarcinoma tumor-bearing rats. These tumor-elicited PMNs (tcPMNs) secrete high levels of the basement-membrane-degrading enzymes, type IV collagenase and heparanase, suggesting that metastatic tumor cells stimulate neutrophilia so that the tcPMNs might assist tumor cell extravasation during metastasis. To test this hypothesis, purified proteose peptone-elicited PMNs from peritoneal exudate, circulating normal PMNs, and tcPMNs were evaluated for their effects on in vitro invasive and in vivo metastatic potentials of syngeneic 13762NF mammary adenocarcinoma tumor cells. tcPMNs caused a dose-dependent increase in invasion through a reconstituted basement membrane barrier in an in vitro invasion assay. At PMN:tumor cell ratios of 30:1, invasion potential significantly (P less than 0.05) rose to 26-fold, 40-fold, and 37-fold for poorly metastatic MTLn2 cells, highly metastatic MTLn3 cells, and moderately metastatic MTF7 cells, respectively. In contrast, purified proteose peptone-elicited PMNs and circulating normal PMNs did not significantly alter invasive potential. Intravenous coinjections of purified proteose peptone-elicited PMNs did not change the number of experimental lung metastases, but tcPMNs at ratios to 50:1 significantly raised the mean number of metastases 23-fold for MTLn2, 3- to 4-fold for MTLn3, and 1.6- to 1.8-fold for MTF7. These results demonstrate that tcPMNs contribute to the metastatic propensity of mammary adenocarcinoma clones by increasing efficiency of invasion through basement membrane.

Effects of levamisole on experimental periodontitis

Although the chemotaxis and efflux of functionally normal polymorphonuclear leukocytes (PMN) into the periodontal sulcus may have a protective role in periodontitis, these cells are also associated with periodontal tissue destruction. The immunomodulating agent, levamisole hydrochloride, is known to enhance PMN chemotaxis. The present study was designed to evaluate the effects of enhanced PMN chemotaxis on the tissue destruction associated with an experimental periodontitis. Levamisole was administered by oro-gastric intubation to 4 squirrel monkeys (experimental) at 3 mg/kg/bw every 2 days for 18 days. After 2 doses of levamisole, marginal periodontitis was induced around maxillary and mandibular bicuspids and the maxillary first molars by tying plaque-retentive ligatures at the gingival margins. Periodontitis was induced around corresponding teeth in 4 animals (control) which had not received levamisole. All animals were killed 2 weeks after induction of periodontitis. Clinically, gingival inflammation was more pronounced in experimental animals at both 7 and 14 days after periodontitis induction. The progression of periodontitis was evaluated histometrically and alterations in the cell populations characterized using step serial sections. The results were analyzed statistically. No significant differences were observed between the groups with respect to areas of infiltrated supracrestal connective tissue and total numbers of cells present, loss of connective tissue attachment and loss of coronal alveolar bone. However, in experimental specimens, a much denser band of inflammatory cells was evident between the apical extent of the bacterial plaque and the gingival sulcular tissues the connective tissue of which contained significantly fewer inflammatory cells and demonstrated more pronounced fibrogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of polymorphonuclear leukocytes (PMN) on the growth and metastatic potential of 13762NF mammary adenocarcinoma cells

Circulating neutrophil (PMN) levels can increase in rats bearing subcutaneously growing clones of the 13762NF mammary adenocarcinoma and the level of increase correlates with the metastatic potential of the clone. In rats with poorly metastatic MTC tumors, numbers of circulating PMN did not rise, whereas PMN levels rose 50-fold in rats bearing highly metastatic MTLn3, 12-fold in rats with weakly metastatic MTLn2, and 14-fold in those with moderately metastatic MTF7 tumors. Neutrophilia was caused partly by tumor size, but metastatic potential was a stronger determinant, suggesting that PMNs may play a role in the metastatic process. To determine whether circulating PMNs indeed contribute to cellular metastatic potential, we examined effects of PMN on various aspects of the metastatic process. Experimental metastasis assays involving i.v. co-injections of PMNs yielded a dose-dependent increase in extrapulmonary metastases for MTLn3, but no change in lung colonization potential for any of the clones examined. The change in the metastatic profile was not due to any modification in in vivo distribution of i.v. injected tumor cells or in adhesion to endothelial monolayers in vitro. PMNs also had no effect on in vitro DNA, RNA or protein synthesis and were not cytolytic (E:T 100:1). However, PMNs collected from high-passage MTLn3 tumor-bearing rats had a 50% increase in heparanase and type-IV collagenolytic activity as compared to unstimulated PMNs isolated from normal rats. These results indicate that polymorphonuclear cells may contribute to the metastatic potential of highly metastatic clones from the 13762NF mammary adenocarcinoma cells by assisting in the degradation of basement membrane during extravasation.

Auranofin modulates mast cell histamine and polymorphonuclear leukocyte collagenase release

Auranofin, an orally gold preparation, effective in the treatment of rheumatoid arthritis, was found to be a potent noncytotoxic inhibitor of histamine and collagenase release from mast cells and polymorphonuclear (PMN) leukocytes respectively. Histamine release has been inhibited by auranofin in dose-dependent fashion. Auranofin at concentration of 10(-5) M inhibited 100% of the release, lower concentration 10(-6) M and 10(-7) M produced 80 and 40% decrease. The exposure of PMN-leukocytes to auranofin caused also dose-dependent inhibition of collagenase release. Auranofin at a concentration of 10(-4) M produced a marked reduction (75-100%) of enzyme release from human and rat blood PMN-leukocytes. The modest inhibition 40 and 15-20% at a concentration of 10(-5) M and 10(-6) M respectively was obtained. Auranofin more significantly suppressed collagenase release from leukocytes isolated from inflammatory exudate. Decrease of 100, 80 and 60% were observed upon addition of 10(-4) M, 10(-5) M and 10(-6) M of auranofin. These results suggest that therapeutic action of auranofin may be caused, at least in part, by the inhibition of cellular release of histamine and collagenase in the course of inflammation.

Surgery of the immunodeficient child

A great deal has been learned about the surgery of immunodeficient patients. If one assesses the problem and follows the surgical principles described, in most instances one can solve the problem and be a great help to the oncologist and immunotherapist. A team approach is most important.

The reactivity of neutrophils at the site of an acute inflammatory reaction as measured by chemiluminescence

In this study the technique of luminol-enhanced chemiluminescence (LECL), which was shown to be dependent on the generation of superoxide anion, has been employed to investigate the reactivity of polymorphonuclear leukocytes found at the site of inflammation. Cells derived from the pleural cavity of rats undergoing an acute inflammatory reaction initiated by an intrapleural injection of calcium pyrophosphate or normal serum demonstrated a significantly higher chemiluminescent response compared to cells derived from animals injected with plasma, saline or phosphate-buffered saline. In addition in vitro studies showed that calcium pyrophosphate crystals could stimulate the cells per se and could increase their reactivity.

Effects of gold salts on experimental periodontitis. II. Cell population characteristics

A previous study showed that the systemic administration of soluble gold salts (gold sodium thiomalate) resulted in significantly less periodontal destruction after 2 weeks of experimentally induced periodontitis. In order to provide information on the possible mechanisms of action of gold salts in the experimental periodontitis situation, the present study analyzed and compared the characteristics of the inflammatory cell populations in animals receiving gold salts with those present in animals which had not received gold salts. Maxillary gingival biopsy specimens were obtained from the buccal aspect of ligatured teeth after 2 weeks of experimental periodontitis. Cell populations were characterized and enumerated, on 1-micron sections, in an epithelial and superficial connective tissue zone, and a deep connective tissue zone. Significantly fewer inflammatory cells were present in experimental (gold receiving) specimens, and this reduction was due primarily to fewer polymorphonuclear leucocytes (PMNs). No significant reduction occurred in any other inflammatory cell-type. The reduction in number of PMNs in experimental specimens was associated with a decreased number of morphologically altered, degenerating fibroblasts in the connective tissue compared to the PMN-dominated lesion of control specimens. Mechanisms whereby gold salts can reduce chemotaxis and functional capabilities of inflammatory cells are discussed.

Cutaneous infections and disorders of inflammation

In 1908, the Nobel Prize in Physiology and Medicine was shared by Elie Metchnikoff and Paul Ehrlich. Their joint commendation acknowledged the vigorous debate which then existed and, in a sense, paved the way for our modern recognition that both cellular and humoral mechanisms might participate in immunity. Of Ehrlich's and Metchnikoff's many accomplishments, those concerning the basic nature of the inflammatory reaction suggested a clinical potential that has been realized only in the last decade. Central to their theories was the implication that normal inflammatory processes were of benefit to the host and that disordered inflammation was likely to lead to disease. Over the past decade or so, we have recognized an extensive set of diseases associated with primary or acquired deficiencies of inflammation, thus beginning to catch up to the genius of Ehrlich and Metchnikoff. Most, if not all, of these disorders demonstrate major cutaneous involvement in their clinical and biologic presentations. It is thus of essential importance that the dermatologist be familiar with this fascinating spectrum of disease, and it is to this end that this review is directed.

Malacoplakia of the bladder: efficacy of bethanechol chloride therapy

Present evidence suggests that malacoplakia is the result of a functional defect in the mononuclear cells of the lesion caused by a deficiency of cyclic 3',5' guanosine monophosphate. This defect results in the impaired ability of the macrophage to release lysosomal enzymes necessary for the digestion of phagocytized bacteria. The persistent inflammatory reaction produces the characteristic granuloma of malacoplakia. Previous laboratory studies indicate that the phagocytic defect is reversible by cholinergic agonists, which led to the use of bethanechol chloride in the treatment of patients with malacoplakia. We report on 3 patients with vesical malacoplakia who were treated successfully with bethanechol chloride.