Prostaglandins and inflammation: Enhancement of monocyte chemotactic responsiveness by prostaglandin E2

The effects of prostaglandins on human monocyte chemotaxis were studied $\text{in vitro}$. None of the prostaglandins tested, including members of the A, B, E or F series, were chemotactic for monocytes. Prostaglandin E₂ however, enhanced the chemotactic responsiveness of monocytes to complement - activated human serum by almost 200%. The enhancement of chemotaxis was not directly related to the ability of PGE₂ to raise intracellular cyclic AMP levels. These studies support a role for prostaglandins as modulators of the inflammatory response.     

Coexistence of a chemotactic factor and a retroviral P15E-related chemotaxis inhibitor in human tumor cell culture supernatants

Two sets of seemingly contradictory evidence have been reported concerning the effects of tumor cell products on the regulation of monocyte migration in vitro and presumably the extravasation of macrophages into tumors in vivo. The present study was designed to explore the relationship between chemotactic and anti-chemotactic products related to tumor cells: a tumor-derived chemotactic factor (TDCF) and retroviral P15E-related inhibitor(s) of chemotaxis. Culture supernatants of the human 8387 sarcoma and SW626 ovarian carcinoma were depleted of P15E-related antigens with immobilized anti-P15E monoclonal antibodies. This treatment produced a significant and consistent increase of the polarizing and chemotactic activity in the tumor cell supernatants. The material eluted from Sepharose-bound anti-P15E antibodies was devoid of chemotactic and polarizing activity and suppressed the polarization and migration of monocytes in response to chemoattractants. These results demonstrate the coexistence in culture supernatants of two human tumor cell lines of factors with opposite influences on monocyte chemotaxis. The data suggest that the entry of monocytes into neoplastic tissue may be regulated by the interplay of chemotactic and anti-chemotactic principals produced by tumor cells.     

Recruitment of osteoclast precursors by purified bone matrix constituents

The osteoclast, the multinucleated giant cell of bone, is derived from circulating blood cells, most likely monocytes. Evidence has accrued that is consistent with the hypothesis that the recruitment of monocytes for osteoclast development occurs by chemotaxis. In the present study, we have examined the chemotactic response of human peripheral blood monocytes and related polymorphonuclear leucocytes to three constituents of bone matrix: peptides from Type I collagen, alpha 2-HS glycoprotein, and osteocalcin (bone gla protein). The latter two substances are among the major noncollagenous proteins of bone and are uniquely associated with calcified connective tissue. In chemotaxis assays using modified Boyden chambers, Type I collagen peptides, alpha 2HS glycoprotein, and osteocalcin evoke a dose-dependent chemotactic response in human monocytes. No chemotaxis is observed on PMNs despite their ontogenetic relationship to monocytes and their documented sensitivity to a broad range of other chemical substances. Our observations are consistent with the view that osteoclast precursors (monocytes) are mobilized by chemotaxis, and suggest that the chemoattractants responsible for this activity are derived from the bone matrix or, in the case of collagen and osteocalcin; directly from the osteoblasts which produce them.     

Differential role of neurokinin receptors in human lymphocyte and monocyte chemotaxis

The precise nature of neurokin receptor involvement in human immune cell chemotaxis is unclear. This study therefore sought to directly compare the chemotactic effects of neurokinins on human T lymphocytes and monocytes. Substance P was found to have a similar dose-dependent chemotactic action on T lymphocyte and monocyte populations. In contrast, T lymphocytes were found to be more responsive than monocytes both to the highly selective NK-1 agonist, [Sar(9)Met O(2)(11)]-substance P, and also to the NK-2 selective agonist, beta-alanine neurokinin A((4-10)). Consistent with these findings, substance P-induced chemotaxis of both T lymphocyte and monocytes was attenuated by the selective NK-1 antagonist LY303870. However, the selective NK-2 antagonist MEN 10,376 was only effective in inhibiting the T lymphocyte response. The study confirms that neurokinins have chemotactic actions on immune cells and indicates important functional differences between human T lymphocyte and monocyte responses. This provides a potential mechanism by which the nervous system can selectively influence cellular recruitment in inflammatory disease.     

A quantitative and qualitative study of blood monocytes in patients with bronchogenic carcinoma

Summary Absolute circulating number and functions of blood monocytes (i.e., pinocytosis, phagocytosis, and chemotaxis) were studied in 25 patients with untreated bronchogenic carcinoma and in 28 control subjects. The absolute circulating monocyte count was increased in 20 (80%) of the patients. There was no difference in the pinocytic and phagocytic activity of patient and control monocytes. In contrast, patient monocytes showed depressed chemotactic responsiveness. This defect was more severe in small cell anaplastic carcinoma than in the other histologic types of bronchogenic carcinoma (P=0.001), and may explain the difference in macrophage infiltration seen in solid tumours of the lung. There was no correlation between chemotaxis and clinical stage. Depressed chemotaxis may be related to a plasma factor, since patient plasma inhibited the chemotaxis of control monocytes as well as the activity of chemotactic agents. The defective chemotaxis and the presence of plasma inhibitory activity may interfere with the ability of blood monocytes to accumulate as macrophages in tumour sites. Abbreviations used in this paper are: MCR, monocyte chemotactic response; SAC, small cell anaplastic bronchogenic carcinoma; OBC, non-small cell bronchogenic carcinoma MEM, Eagle's minimal essential medium; CFI, chemotactic factor inhibitor(s); HSA, human serum albumin     

Decreased chemotaxis of human peripheral phagocytes exposed to a strong static magnetic field

The chemotaxis of human peripheral phagocytes, neutrophils and monocytes was examined in a strong static magnetic field (0.317+/-0.012 Tesla). The chemotaxis of the suspension of purified neutrophils and monocytes was tested in the Boyden chamber using C5a as a chemotactic signal. The chambers were placed into a temperature regulated (36.6 degrees C) equipment producing a strong static magnetic field (0.317 Tesla) for 60 minutes. The movement of cells proceeded into a nitrocellulose membrane toward the north-pole of the magnet, i.e. in the direction of the Earth's gravitational pull. The C5a induced chemotaxis of human neutrophils decreased significantly in the strong static magnetic field. Monocytes were not significantly effected. The strong static magnetic field decreased the chemotactic movement of neutrophils and this phenomenon may have implications when humans are exposed to magnetic resonance imaging for extended periods of time.     

The role of cyclic AMP in the chemotactic responsiveness and spontaneous motility of rabbit peritoneal neutrophils. The inhibition of neutrophil movement and the elevation of cyclic AMP levels by catecholamines, prostaglandins, theophylline and cholera toxin.

Agents known to affect intracellular levels of cyclic AMP in many diverse systems have been tested for their effect on the chemotaxis induced by Escherichia coli culture filtrates, spontaneous motility and cyclic AMP levels of rabbit peritoneal neutrophils. Prostaglandin E1 and A1 but not prostaglandin F2alpha increased neutrophil cyclic AMP levels and, correspondingly, only the former two prostaglandins inhibited chemotaxis. Nevertheless, a quantitative relationship between prostaglandin stimulation of cyclic AMP and inhibition of chemotaxis could not be found. Epinephrine, isoproterenol, and, to a much lesser extent, norepinephrine increased neutrophil cyclic AMP through beta adrenergic stimulation. Only epinephrine and isoproterenol inhibited chemotaxis, but the inhibition was variable and not related to the ability of these catecholamines to increase intracellular cyclic AMP. Cholera toxin increased neutrophil cyclic AMP after a 30-min lag period which paralled its inhibitory effect on chemotaxis and spontaneous motility. However, the effect on chemotaxis require 50 ng/ml of toxin whereas the effect on cyclic AMP was manifested at 2 ng/ml of toxin. Prior to 30-min preincubation there was no effect of even 1250 ng/ml of toxin on either cyclic AMP or chemotaxis. Choleragenoid prevented the effects of toxin on both cyclic AMP and chemotaxis. The bacterial chemotactic factor obtained from E. coli culture filtrates did not effect a measurable change in levels of neutrophil cyclic AMP. The data indicate that even though cyclic AMP is not, in the main sequence of events, triggering the chemotactic response, increases in neutrophil cyclic AMP may modulate the movement and thus the chemotactic responsiveness of the neutrophil.     

Effects of serotonin, carbamylcholine, and ascorbic acid on leukocyte cyclic GMP and chemotaxis

Serotonin, ascorbic acid, and carbamylcholine enhanced the chemotactic responsiveness of human monocytes to endotoxin-treated serum. These agents caused significant accumulation of cyclic GMP in monocytes. PMN leukocyte chemotaxis was also enhanced by these agents although significant increases in cyclic GMP were not demonstrated.     

Human granulocytes and granulocytes from other species demonstrate differences in chemotactic responsiveness to oxidized N-formyl-methionyl-leucyl-phenylalanine

1. Oxidation of the methionine of N-formyl-methionyl-leucyl-phenylalanine to the sulfoxide or sulfone derivative results in the loss of the peptide's chemotactic activity for human granulocytes. 2. The oxidized peptides are chemotactic for human monocytes; however, 10- to 100-fold higher concentrations are required for optimal monocyte chemotaxis. 3. Mouse, guinea pig and rabbit granulocytes, and the WBC264-9 human-mouse hybrid cell line migrated to the oxidized peptides and required 10- to 1000-fold higher concentrations of the oxidized peptides to elicit optimal chemotactic responses. 4. Human granulocytes appear to be unique in their lack of responsiveness to oxidized derivatives.     

Chemotactic factor and P15E-related chemotaxis inhibitor in human melanoma cell lines with different macrophage content and tumorigenicity in nude mice

The present study was designed to characterize the production of chemoattractants by human melanoma lines with high (M4Be, M3Da, NTerDa) or low tumorigenic (Doc8, M1Do) potential when heterotransplanted in nude mice. Supernatants from the Doc8 and M1Do cell lines were strongly chemotactic in vitro for mononuclear phagocytes. Chemotactic activity was destroyed by proteolytic enzymes, and upon gel filtration on Sephadex G75, it eluted in the cytochrome c region corresponding to an apparent m.w. of 12,000. Upon chromatofocusing, the Sephadex-separated tumor-derived chemotactic factor (TDCF) showed an isoelectric point of 5.5 to 6. Cell lines with high tumorigenic potential contained low or no detectable chemotactic activity. When culture supernatants of cell lines with modest (M3Da) or no (M4Be) chemotactic activity were exposed to immobilized monoclonal antibodies directed against the retroviral transmembrane protein P15E, appreciable chemotactic activity was detectable (M4Be) or preexisting levels increased (M3Da). The material eluted from Sepharose-bound anti-P15E antibodies inhibited the migration of monocytes in response to chemoattractants. These findings demonstrate the coexistence in some human melanoma cell line supernatants of factors (TDCF and P15E-related inhibitor) with opposite influence on monocyte chemotaxis. That tumor cell products play a pivotal role in regulating the extravasation of monocytes into neoplastic tissues is suggested by the close correlation observed between macrophage levels in melanomas grown in nude mice and levels of chemotactic activity detectable in culture supernatants.     

Monocyte chemotaxis in patients with nonseminomatous testicular carcinoma

Summary The chemotactic responsiveness of blood monocytes was tested in 16 patients with nonseminomatous testicular carcinoma before, during, and after chemotherapy. All the patients initially had monocyte chemotaxis within the normal range. No correlation with the histology of the tumor, the clinical stage, or the presence in serum of -fetoprotein and human chorionic gonadotropin was observed. Plasma from the patients did not inhibit the chemotaxis of normal monocytes, and serum from the patients contained no chemotactic factor inhibitor. During intensive chemotherapy with cis-platinum, bleomycin, and vinblastine a reversible defect in chemotaxis occurred without correlation to the development of fever. Two months after the completion of chemotherapy the chemotactic responsiveness was unchanged compared with pretreatment values. In conclusion, this study shows normal monocyte chemotaxis in patients with testicular carcinoma, which is in contrast to reports on a variety of other solid tumors.     

Stimulation of Locomotion of Peripheral Blood Monocytes by Human Plasma Fibronectin

The motility of human peripheral blood granulocytes and monocytes in response to human plasma fibronectin was quantified by an in vitro assay using blind-well chemotaxis chambers. Purified fibronectin under nondenaturing conditions produced increased migration of granulocytes only at concentrations higher than 100 nm, and induced increased chemotactic and random locomotion of monocytes at concentrations higher than 0.1 nm. The monocyte migration-inducing activity of fibronectin was concentration dependent, and was strongly inhibited by low concentrations of colchicine (100 nm–100 μm). These findings suggest the possibility that plasma fibronectin serves as a chemotactic stimulus for monocytes in vivo and attracts these cells to sites of microscopic tissue injury where plasma fibronectin is deposited.     

Selective inhibition of human neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine by sulfones

The therapeutic efficacy of the sulfones, dapsone, and sulfoxone in neutrophilic dermatoses may be related to the effects of these drugs on neutrophil function. Therefore we determined whether neutrophil chemotactic migration to various chemoattractants could be inhibited by sulfones in vitro. The chemotactic responses of human neutrophils from healthy donors were tested by using N-formyl-methionyl-leucyl-phenylalanine (F-met-leu-phe), purified human C5a, and leukocyte-derived chemotactic factor (LDCF). Therapeutic concentrations of sulfones selectively inhibited neutrophil chemotaxis to F-met-leu-phe, but did not affect neutrophil chemotaxis to LDCF or C5a. Inhibition of neutrophil chemotaxis to F-met-leu-phe was induced by both dapsone and sulfoxone at a concentration of 10 micrograms/ml without affecting random migration, and the inhibition was reversed by washing the neutrophils. When dapsone- and sulfoxone-treated neutrophils (100 micrograms/ml) were stimulated with F-met-leu-phe, neutrophil superoxide generation was not inhibited. Sulfapyridine (10 micrograms/ml) also selectively inhibited neutrophil chemotaxis to F-met-leu-phe; however, sulfamethoxazole and sulfisoxazole did not affect chemotaxis. The inhibitory effects of dapsone, sulfoxone, and sulfapyridine could not be demonstrated with granulocytes from rabbits or guinea pigs nor with human monocytes. Experiments with radiolabeled dapsone showed rapid, nonspecific, and reversible binding of dapsone to human neutrophils. These data suggest that a mechanism of action of sulfones in neutrophilic dermatoses may be a selective inhibition of neutrophil migration to as yet undefined chemoattractants in the skin.     

A complex of Wiskott-Aldrich syndrome protein with mammalian verprolins plays an important role in monocyte chemotaxis

The Wiskott-Aldrich syndrome protein (WASP) is a product of the gene defective in an Xid disorder, Wiskott-Aldrich syndrome. WASP expression is limited to hemopoietic cells, and WASP regulates the actin cytoskeleton. It has been reported that monocytes/macrophages from WASP-deficient Wiskott-Aldrich syndrome patients are severely defective in chemotaxis, resulting in recurrent infection. However, the molecular basis of such chemotactic defects is not understood. Recently, the WASP N-terminal region was found to bind to the three mammalian verprolin homologs: WASP interacting protein (WIP); WIP and CR16 homologous protein (WICH)/WIP-related protein (WIRE); and CR16. Verprolin was originally found to play an important role in the regulation of actin cytoskeleton in yeast. We have shown that WASP, WIP, and WICH/WIRE are expressed predominantly in the human monocyte cell line THP-1 and that WIP and WICH/WIRE are involved in monocyte chemotaxis. When WASP binding to verprolins was blocked, chemotactic migration of monocytes was impaired in both THP-1 cells and primary human monocytes. Increased expression of WASP and WIP enhanced monocyte chemotaxis. Blocking WASP binding to verprolins impaired cell polarization but not actin polymerization. These results indicate that a complex of WASP with mammalian verprolins plays an important role in chemotaxis of monocytes. Our results suggest that WASP and mammalian verprolins function as a unit in monocyte chemotaxis and that the activity of this unit is critical to establish cell polarization. In addition, our results also indicate that the WASP-verprolin complex is involved in other functions such as podosome formation and phagocytosis.     

Production of a retroviral P15E-related chemotaxis inhibitor by IL-1-treated endothelial cells. A possible negative feedback in the regulation of the vascular response to monokines

The effects of IL-1 on vascular endothelium result in a complex set of alterations which are potentially disruptive of vessel wall and underlying tissue integrity. The present study was aimed at investigating possible regulation of such potentially destructive responses elicited by IL-1 on endothelial cells. Culture supernatants of IL-1-treated human umbilical vein endothelial cells (HEC) were depleted of retroviral p15E-related Ag with immobilized anti-p15E mAb. The monocyte chemotactic and polarizing activity of supernatants of IL-1-treated HEC (presumably related to colony-stimulating factors being released by HEC) was markedly augmented by absorption on immobilized anti-p15E antibodies. Irrelevant IgG had no effect and anti-p15E antibodies did not affect the chemotactic activity of supernatants from unstimulated HEC. The material eluted from Sepharose-bound anti-p15E antibodies was devoid of chemotactic and polarizing activity and suppressed the polarization and migration of monocytes in response to chemoattractants. The alpha and beta molecular species of IL-1 were equally effective in inducing the production of p15E-related inhibitor. The production of a p15E-related inhibitor of chemotaxis induced by IL-1 in HEC may represent a negative signal in the regulation of the potentially destructive responses to pro-inflammatory cytokines.     

HIV-1 and its envelope glycoprotein down-regulate chemotactic ligand receptors and chemotactic function of peripheral blood monocytes

Peripheral blood monocytes from AIDS patients exhibit defective migratory responses to chemotactic stimuli in vitro and to inflammatory sites in vivo. In studies presented here, normal monocytes were infected with the HIV-1/HTLV-IIIBa-L isolate in vitro and evaluated for chemotactic responsiveness. Within 2 days after viral exposure, but before evidence of virus production in the monocytes, chemotactic activity was significantly impaired. Decreased chemotactic activity was associated with modulation of receptors for the chemotactic ligands, C5a and FMLP, on the monocyte cell surface. In addition to HIV-1, monocytes treated with purified HIV-1 envelope glycoprotein gp120 demonstrated a comparable modulation of chemotactic ligand receptors and migratory function. In addition, the HIV-1 or HIV-1 gp120-treated monocytes were induced to undergo differentiation as monitored by HLA-DR expression. Immunoprecipitation of the gp120 with a specific antibody reversed its effects on monocyte chemotaxis and HLA-DR expression. Taken together, these data indicate that the initial interaction of HIV-1 with the monocyte is not passive, but that the binding of HIV-1 and/or HIV-1 gp120 to the CD4R on monocytes transduces a signal leading to transient monocyte activation.     

Val-Gly-Val-Ala-Pro-Gly, a repeating peptide in elastin, is chemotactic for fibroblasts and monocytes

Recent studies have demonstrated that tropoelastin and elastin-derived peptides are chemotactic for fibroblasts and monocytes. To identify the chemotactic sites on elastin, we examined the chemotactic activity of Val-Gly-Val-Ala-Pro-Gly (VGVAPG), a repeating peptide in tropoelastin. We observed that VGVAPG was chemotactic for fibroblasts and monocytes, with optimal activity at approximately 10(-8) M, and that the chemotactic activity of VGVAPG was substantial (half or greater) relative to the maximum responses to other chemotactic factors such as platelet-derived growth factor for fibroblasts and formyl-methionyl-leucyl-phenylalanine for monocytes. The possibility that at least part of the chemotactic activity in tropoelastin and elastin peptides is contained in VGVAPG sequences was supported by the following: (a) polyclonal antibody to bovine elastin selectively blocked the fibroblast and monocyte chemotactic activity of both elastin-derived peptides and VGVAPG; (b) monocyte chemotaxis to VGVAPG was selectively blocked by preexposing the cells to elastin peptides; and (c) undifferentiated (nonelastin producing) bovine ligament fibroblasts, capable of chemotaxis to platelet-derived growth factor, did not show chemotactic responsiveness to either VGVAPG or elastin peptides until after matrix-induced differentiation and the onset of elastin synthesis. These studies suggest that small synthetic peptides may be able to reproduce the chemotactic activity associated with elastin-derived peptides and tropoelastin.     

Effect of prostaglandins E1, E2 and F2alpha on neutrophil aggregation.

Recently we have found that chemotactic factors stimulate neutrophils in suspension to aggregate. Because of an obvious analogy to platelet aggregation, we examined the influence of three prostaglandins on this process. Prostaglandins E1, E2 and F2alpha alone did not cause aggregation of the neutrophils but were able to partially inhibit the aggregation response induced by the synthetic chemotactic tripeptide, formyl-methionyl-leucyl-phenylalanine. The minimal inhibitory concentrations for prostaglandins E1, E2 and F2alpha were 10(-7), 10(-6) and 10(-5)M, respectively. These results are similar to those found for the prostaglandin-induced inhibition of platelet aggregation. It may be, therefore, that neutrophil aggregation, like platelet aggregation, is modulated by intracellular prostaglandins and other products of arachidonic acid metabolism.     

Chemotactic response of monocytes to thrombin

Human alpha-thrombin, the procoagulant activation product of prothrombin, elicits chemotaxis in human peripheral blood monocytes and several macrophagelike continuous cell lines, most notably J-774.2, but not in human peripheral blood granulocytes. alpha-Thrombin is effective in stimulating cell movement at concentrations ranging from 10(-10) to 10(-6) M but is optimally active at 10(-8) M. At the latter concentration, the degree of response is equivalent, on a molar basis, to that observed with the peptide formylmethionylleucylphenylalanine, (FMP). In contrast to thrombin, prothrombin produces a minimal chemotactic response in monocytes and J-774.2. Blockade of alpha- thrombin's active center with diisopropylfluorophosphate (DIP-F) or tryptic proteolysis of the procoagulant exosite (i.e., gamma-thrombin) fails to alter chemotactic activity. On the other hand, addition of equimolar amounts of antithrombin III (AT3) to alpha-thrombin reduces thrombin-mediated chemotaxis by 60%, and increased ratios of AT3 to enzyme completely suppress chemotaxis. We conclude that thrombin is a potent monocyte chemotaxin and that the domains in thrombin involved in stimulating cell movement are distinct from the catalytic site and the fibrin recognition exosite. These chemotactic domains appear to be sequestered in prothrombin and in the thrombin-AT3 complex and, as such, are unavailable to the chemotactic receptor on the monocyte cell membrane.