Biomedical subjects

R M Strieter

Publications and source records attributed to R M Strieter.

At least 199 records · Page 11Linked to original sources

PubMed1996

Th1 and Th2 responses regulate experimental lung granuloma development.

The pathogenesis of chronic interstitial lung disease is often characterized as an intense inflammatory response with accompanying fibroproliferation and deposition of extracellular matrix. Certain of these lung disorders share common characteristics, including an unknown etiology, ill defined mechanisms of initiation and maintenance, and end-stage fibrosis. Progressive pulmonary inflammation, as can occur in diseases such as idiopathic pulmonary fibrosis and end-stage sarcoidosis, is associated with substantial morbidity and mortality. Unfortunately, efficacious therapeutic options are not available for the treatment of these diseases, reflecting the limited scientific understanding of these disorders. However, it is likely that cytokine networks are operative in dictating the progression of these diseases. Recent studies show that various cytokines affect fibroblast activation, proliferation, and collagen deposition during the evolution of chronic fibrotic lung disease. In particular, gamma interferon suppresses such fibroblast activities as proliferation and collagen production, while interleukin-4 augments fibroblast growth and collagen production. Interestingly, these two mediators are the prototypic cytokines which functionally define either a Th1 or a Th2 response. Thus, experimental models of granulomatous lung inflammation, which are characterized by either a Th1 or a Th2 response, will be useful in delineating the mechanisms which maintain and resolve chronic granulomatous lung inflammation. These experimental systems will prove to be especially important as the degree of inflammation and fibroblast activation/proliferation during the pathogenesis of chronic pulmonary inflammation may be dependent upon a balance of Th1- and Th2-like cytokines which are expressed during the evolution of the disease.

Animals↗

PubMed1995

The role of monocyte chemotactic protein-1 (MCP-1) in the recruitment of monocytes and CD4+ T cells during a pulmonary Cryptococcus neoformans infection.

Cryptococcus neoformans is acquired via the respiratory tract and is the leading cause of fatal mycosis in AIDS. Development of a T cell-mediated pulmonary inflammatory response is critical for clearance of this pathogen; however, the chemotactic factors that mediate inflammatory cell recruitment into the lungs have not been identified. In the present study, the bronchoalveolar lavage (BAL) fluid levels of the C-C chemokine monocyte chemotactic protein-1 (MCP-1) and the recruitment of inflammatory cells both increased following pulmonary infection with C. neoformans. The kinetics of MCP-1 production in the lungs correlated most closely with the recruitment of CD4+ T cells and monocytes/macrophages. Administration of neutralizing anti-MCP-1 Abs in vivo reduced the BAL fluid levels of MCP-1, decreased the recruitment of both macrophages (> 95%) and CD4+ T cells (76 +/- 9%), and inhibited cryptococcal clearance. Although no in vitro neutrophil or B cell chemotactic activity has been reported for MCP-1, recruitment of these leukocytes was also decreased in anti-MCP-1-treated mice (most likely an indirect effect of reducing the number of CD4+ T cells and macrophages). Neutralization of MCP-1 also resulted in decreased BAL fluid levels of TNF-alpha and IL-6. This is the first demonstration of a role for MCP-1 in clearance of an infection, and provides direct evidence that MCP-1 plays a critical role in the T cell-dependent immune response to C. neoformans.

Animals↗

PubMed1995

An important role for the chemokine macrophage inflammatory protein-1 alpha in the pathogenesis of the T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is a CD4+ T cell-mediated, inflammatory demyelinating disease of the central nervous system (CNS) that serves as a model for the human demyelinating disease, multiple sclerosis. A critical event in the pathogenesis of EAE is the entry of both Ag-specific T lymphocytes and Ag-nonspecific mononuclear cells into the CNS. In the present report we investigated the role of two C-C chemokines (macrophage inflammatory protein-1 alpha (MIP-1 alpha) and monocyte chemotactic protein-1) and a C-x-C chemokine (MIP-2) in the pathogenesis of EAE. Production in the CNS of MIP-1 alpha, but not that of MIP-2, a rodent homologue of IL-8, or monocyte chemotactic protein-1, correlated with development of severe clinical disease. Administration of anti-MIP-1 alpha, but not that of anti-monocyte chemotactic protein-1, prevented the development of both acute and relapsing paralytic disease as well as infiltration of mononuclear cells into the CNS initiated by the transfer of neuroantigen peptide-activated T cells. Ab therapy could also be used to ameliorate the severity of ongoing clinical disease. Anti-MIP-1 alpha did not affect the activation of encepahlitogenic T cells as measured by cytokine secretion, surface marker expression, and ability to adoptively transfer EAE. These results demonstrate that MIP-1 alpha plays an important role in directing the chemoattraction of mononuclear inflammatory cells in the T cell-mediated autoimmune disease, EAE.

Animals↗

PubMed1995

The functional role of the ELR motif in CXC chemokine-mediated angiogenesis.

In this study, we demonstrate that the CXC family of chemokines displays disparate angiogenic activity depending upon the presence or absence of the ELR motif. CXC chemokines containing the ELR motif (ELR-CXC chemokines) were found to be potent angiogenic factors, inducing both in vitro endothelial chemotaxis and in vivo corneal neovascularization. In contrast, the CXC chemokines lacking the ELR motif, platelet factor 4, interferon gamma-inducible protein 10, and monokine induced by gamma-interferon, not only failed to induce significant in vitro endothelial cell chemotaxis or in vivo corneal neovascularization but were found to be potent angiostatic factors in the presence of either ELR-CXC chemokines or the unrelated angiogenic factor, basic fibroblast growth factor. Additionally, mutant interleukin-8 proteins lacking the ELR motif demonstrated potent angiostatic effects in the presence of either ELR-CXC chemokines or basic fibroblast growth factor. In contrast, a mutant of monokine induced by gamma-interferon containing the ELR motif was found to induce in vivo angiogenic activity. These findings suggest a functional role of the ELR motif in determining the angiogenic or angiostatic potential of CXC chemokines, supporting the hypothesis that the net biological balance between angiogenic and angiostatic CXC chemokines may play an important role in regulating overall angiogenesis.

Amino Acid Sequence↗

PubMed1995

Experimental Listeria meningoencephalitis. Macrophage inflammatory protein-1 alpha and -2 are produced intrathecally and mediate chemotactic activity in cerebrospinal fluid of infected mice.

In bacterial meningitis, the recruitment of leukocytes across the blood-brain barrier into the central nervous system may be crucial for both elimination of pathogens and tissue injury. In addition to bacterial cell wall products, host factors including chemokines may lead to accumulation of phagocytes within the central nervous system. As shown by Northern analysis, brains of mice infected intracerebrally with Listeria monocytogenes (LM) express mRNA for three chemokines, the macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, and MIP-2. The cellular sources of these chemokines comprise both the blood-derived polymorphonuclear leukocytes (PMNs) and monocytes infiltrating the meninges, the ventricular system and the periventricular area. In the course of meningitis a time-dependent increase of MIP-1 alpha and MIP-2 was found in the cerebrospinal fluid (CSF) by ELISA. CSF taken 24 h after infection (CSF-LM24) induced migration of human leukocytes when treated in chemotactic chambers in vitro. Neutralizing Abs to chemokines identified MIP-1 alpha and MIP-2 to be responsible for CSF-LM24 mediated chemotaxis of monocytes and PMNs, respectively. CSF obtained from mock-infected animals contained no MIP-1 alpha or MIP-2 and did not lead to migration of leukocytes. When testing CSF-LM24 on mouse spleen cells, the chemotactic activity detected for mononuclear cells was only partly inhibited by Abs to MIP-1 alpha and -1 beta. Thus, in addition to MIP-1 and -2 other not yet defined chemotactic factors are of importance for recruitment of leukocytes in bacterial meningitis.

Animals↗

PubMed1995

Production of chemokines, interleukin-8 and monocyte chemoattractant protein-1, during monocyte: endothelial cell interactions.

The extravasation of leukocytes from the lumen of the vessel to a site of inflammation requires specific binding events. The interaction of leukocytes with endothelium, via specific receptors, may provide intracellular signals that activate extravasating cells. In the present study, we have investigated the production of chemokines, interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) during monocyte: endothelial cell interactions. Both unstimulated and interferon-gamma (IFN-gamma)-prestimulated human umbilical vein endothelial cells (HUVEC) produced low constitutive levels of IL-8 and MCP-1. The addition of enriched monocytes with unstimulated HUVEC resulted in synergistic increases in production of both IL-8 and MCP-1. Monocytes cultured with IFN-gamma-preactivated HUVECs demonstrated little additional increase in IL-8 and MCP-1 production in coculture assays compared with unstimulated HUVEC. Northern blot analysis paralleled the protein data, demonstrating upregulated expression of IL-8 and MCP-1 mRNA in stimulated and unstimulated coculture assays. Culture of enriched monocytes and endothelial cells in transwells demonstrated no increases in IL-8 or MCP-1, indicating the necessity for cellular contact for chemokine production. In previous investigations, we have demonstrated that increased monocyte-derived MIP-1 alpha production was induced by intracellular adhesion molecule-1 (ICAM-1) interactions on activated HUVECs. In contrast, addition of anti-ICAM-1 monoclonal antibodies (MoAbs) did not diminish the production of IL-8 and MCP-1 in the present study. Furthermore, neither antibodies to IL-1 nor tumor necrosis factor (TNF) diminished the production of either IL-8 or MCP-1. However, when soluble matrix proteins were added to the coculture to block cellular interactions, the chemokine protein and mRNA levels were significantly decreased. IL-8 production was decreased by both soluble collagen and fibronectin, whereas MCP-1 was decreased by only soluble collagen, suggesting differential activation pathways. These results indicate that IL-8 and MCP-1 production are increased during monocyte and endothelial cell interactions in part due to matrix protein binding mechanisms. This mechanism may serve a role in cell activation, production of chemokines, as well as extravasation and recruitment of additional leukocytes during inflammatory responses.

Antibodies, Monoclonal↗

PubMed1995

Down-regulation of the afferent phase of T cell-mediated pulmonary inflammation and immunity by a high melanin-producing strain of Cryptococcus neoformans.

The interaction(s) between cryptococcal virulence factors and leukocytes involved in generating protective cell-mediated immunity is not well defined. Intratracheal inoculation of Cryptococcus neoformans strain 52 induced a vigorous T cell-mediated pulmonary inflammatory response that controlled the growth of the organism. In contrast, strain 145 induced a pulmonary inflammatory response that was delayed in onset, slower to develop, and ineffective in controlling the infection. In addition, the expansion of cryptococcus-specific lymphocytes in the pulmonary lymph nodes and titer of specific Abs in the serum of strain 145-infected mice were both diminished markedly. Of the known cryptococcal virulence factors, these two strains differed only in melanin production (52-low and 145-high). Heat-killed strain 145 cryptococci (HKC-145) that had been rendered melanin-negative induced TNF-alpha production by alveolar macrophages in vitro and stimulated vigorous cryptococcus-specific lymphoproliferation. In contrast, high melanin-containing HKC-145 inhibited TNF-alpha production and lymphoproliferation. In vivo, mice infected with melanin low strain 52, but not melanin high strain 145, had elevated levels of TNF-alpha in the bronchoalveolar lavage fluid. Mice co-infected with strains 145 and 52 generated a pulmonary inflammatory response resulting in increased long-term survival. Taken together, these studies demonstrate that melanin does not protect cryptococci from being eliminated in vivo by recruited, activated effector cells; but melanin can inhibit the recognition of the organism by host defenses, thereby down-regulating the afferent phase of T cell-mediated immunity, e.g., TNF-alpha production and lymphoproliferation.

Animals↗

PubMed1995

Growth-related gene product alpha. A chemotactic cytokine for neutrophils in rheumatoid arthritis.

Leukocyte recruitment is critical in the inflammation seen in rheumatoid arthritis (RA). To determine whether the chemokine growth-related gene product alpha (gro alpha) plays a role in this process, we examined synovial tissue (ST), synovial fluid (SF), and plasma samples from 102 patients with arthritis. RA SF contained more antigenic gro alpha (mean 5.3 +/- 1.9 ng/ml) than did SFs from either osteoarthritis (OA) or other forms of arthritis (mean 0.1 ng/ml) (p < 0.05). RA plasma contained more gro alpha (mean 4.3 +/- 1.8 ng/ml) than normal plasma (mean 0.1 ng/ml) (p < 0.05). RA ST fibroblasts (1.2 x 10(5)/cells/mI RPMI 1640/24 h) produced antigenic gro alpha (mean 0.2 +/- 0.1 ng/ml), and this production was increased significantly upon incubation with TNF-alpha (mean 1.3 +/- 0.3 ng/ml) or IL-1 beta (mean 2.3 +/- 0.6 ng/ml) (p < 0.05). Cells from RA SF also produced gro alpha: neutrophils (PMNs) (10(7) cells/mI/24 h) produced 3.7 +/- 0.7 ng/ml. RA SF mononuclear cells produced gro alpha, particularly upon incubation with LPS or PHA. Immunoreactive ST gro alpha was found in greater numbers of RA compared with either OA or normal lining cells, as well as in RA compared with OA subsynovial macrophages (p < 0.05). IL-8 accounted for a mean of 36% of the RA SF chemotactic activity for PMNs, while epithelial neutrophil-activating peptide-78 accounted for 34%, and gro alpha for 28%, of this activity. Combined neutralization of all three chemokines in RA SFs resulted in a mean decrease of 50% of the chemotactic activity for PMNs present in the RA SFs. These results indicate that gro alpha plays an important role in the ingress of PMNs into the RA joint.

Arthritis, Rheumatoid↗

PubMed1995

Neutralization of IL-10 increases lethality in endotoxemia. Cooperative effects of macrophage inflammatory protein-2 and tumor necrosis factor.

The overzealous production of pro-inflammatory cytokines during endotoxemia can result in shock, multiorgan dysfunction, and even death. The extent of tissue injury that occurs in endotoxemia is determined not only by the release of pro-inflammatory cytokines, but also by the expression of endogenous counter-regulatory cytokines, such as IL-10. In this study, we defined the role of endogenously-produced IL-10 in a murine model of endotoxemia. Initial studies indicated that LPS administration to mice i.p. induces a significant time-dependent increase in plasma IL-10. Passive immunization with anti-IL-10 serum before LPS administration resulted in substantial increases in endotoxin-induced lethality. Furthermore, the inhibition of IL-10 bioactivity in vivo resulted in a greater and more sustained increase in plasma TNF and macrophage inflammatory protein-2 (MIP-2) levels, as compared with control animals, which was accompanied by early increases in lung polymorphonuclear leukocyte influx and lung capillary leak. Finally, anti-IL-10-mediated lethality was significantly abrogated by concomitant treatment with anti-MIP-2 serum and/or sTNFR:Fc alone or in combination. These observations indicate that TNF and MIP-2 are important cytokine mediators during endotoxemia, and endogenously produced IL-10 is instrumental in down-regulating the overzealous production of both TNF and MIP-2 that occurs in response to systemic endotoxin exposure.

Animals↗

PubMed1995

Macrophage inflammatory protein-1 alpha mediates lung leukocyte recruitment, lung capillary leak, and early mortality in murine endotoxemia.

Systemic exposure to LPS initiates a complex sequence of events resulting in organ-specific leukocyte recruitment and end-organ injury. We hypothesized that macrophage inflammatory protein-1 alpha (MIP-1 alpha), a C-C chemokine with leukocyte chemotactic and activating properties, may play an important role in lung inflammatory cell recruitment, subsequent lung injury, and mortality in endotoxemia. CD-1 mice were challenged with LPS (200 micrograms), resulting in a maximal 3.5-fold increase in neutrophils (polymorphonuclear leukocytes (PMNs)) at 6 h post-LPS, and a 2.6-fold increase in numbers of macrophages (M phi) within lung minces at 24 h. A time-dependent increase in MIP-1 alpha mRNA and protein was detected in lung after LPS treatment, with immunolocalization of MIP-1 alpha to blood and lung M phi, and the subendothelium. The pretreatment of mice with rabbit anti-MIP-1 alpha Ab resulted in a decrease in the influx of PMNs at 6 h, and influx of M phi at 24 h post-LPS challenge, an approximately 65% reduction in LPS-induced lung permeability to Evans blue, and a modest decrease in mortality at 24, but not 48 h post-LPS. Furthermore, passive immunization of mice with anti-MIP-1 alpha serum resulted in a 35% reduction in ICAM-1 mRNA levels within lung homogenates post-LPS. Finally, the pretreatment of animals with sTNFR:Fc (soluble TNF receptor:Ig construct) resulted in a 60% reduction in LPS-induced MIP-1 alpha mRNA expression within lung homogenates at 4 h post-LPS. Our studies indicate that MIP-1 alpha plays an integral role as a mediator of both PMN and M phi recruitment in murine endotoxemia.

Animals↗

PubMed1995

Neutralization of IL-10 increases survival in a murine model of Klebsiella pneumonia.

Effective host defense against bacterial infection is dependent upon the vigorous recruitment and activation of neutrophils and macrophages. We hypothesized that IL-10 is produced in the setting of bacterial pneumonia, and this cytokine may attenuate host defense by inhibiting the expression of important activating and chemotactic cytokines. CD-1 mice were challenged with either 30 microliters of saline or saline containing 10(3) CFUs of Klebsiella pneumoniae intratracheally (i.t.) and lungs were harvested at 8, 24, and 48 h. The i.t. inoculation with K. pneumoniae resulted in a 13-, 14-, and 8-fold increase in lung homogenate TNF, macrophage inflammatory protein-2 (MIP-2), and macrophage inflammatory protein-1 alpha (MIP-1 alpha) levels, respectively, as compared with control animals. In addition, we observed an increase in IL-10 mRNA and protein levels in lung homogenates, maximal at 48 h postinoculation. To establish the biologic relevance of IL-10 in Klebsiella pneumonia, we passively immunized CD-1 mice with 0.5 ml of rabbit anti-murine IL-10 serum or preimmune serum i.p. 2 h before i.t. administration of K. pneumoniae. Treatment of animals with anti-IL-10 serum resulted in increased levels of TNF, MIP-2, and MIP-1 alpha, respectively, within lung homogenates at 24 and 48 h, as compared with preimmune-treated animals. Furthermore, neutralization of IL-10 resulted in a significant decrease in K. pneumoniae CFU in both lung homogenates and plasma harvested at 48 h, as well as a significant increase in survival in these animals. Our studies indicate that 1) IL-10 is produced during Klebsiella pneumonia; and 2) inhibition of IL-10 bioactivity in vivo results in enhanced bacterial clearance, increased expression of proinflammatory cytokines, and prolonged survival.

Animals↗

PubMed1995

TNF-alpha mediates recruitment of neutrophils and eosinophils during airway inflammation.

Airway inflammation is characterized by leukocyte extravasation around the peribronchial mucosa and into the airway of the lung. In the present study we utilized a model of airway inflammation induced by intratracheal challenge with soluble parasite (Schistosoma mansoni) egg Ag (SEA) in presensitized mice. The subsequent inflammatory response and leukocyte recruitment consists of early neutrophil (8 to 24 h) and later eosinophil (48 to 72 h) infiltration into the interstitium and airway. Little neutrophil and no eosinophil recruitment was observed in presensitized control mice challenged with vehicle. Multiple studies have demonstrated a crucial role for TNF-alpha during inflammatory responses. In these experiments we investigated the role of TNF-alpha in Ag-specific eosinophilic airway inflammation. Measurement of TNF-alpha expression by reverse transcriptase-PCR and ELISA in whole lung homogenates of SEA-challenged mice demonstrated an early increase in TNF-alpha levels (1 to 8 h). To determine the specific role of TNF-alpha in leukocyte recruitment during airway inflammation, mice were treated with soluble TNF-alpha receptor linked to an Fc Ab molecule (sTNFr-:Fc). This treatment has previously been used to effectively neutralize TNF in vivo. Intratracheal SEA-challenged mice treated with sTNFr-FC demonstrated significantly decreased leukocyte recruitment into the lung and airway. The inflammatory response in the lungs in sTNFr-Fc-treated mice was significantly decreased throughout the study period, as compared with control mice. An approximate decrease in early neutrophil infiltration into the airway was observed when sTNFr-Fc was administered 2 h before the Ag challenge. Eosinophil infiltration was also diminished when sTNFr-Fc was administered before Ag challenge. Interestingly, when sTNFr-Fc was administered therapeutically 24 h after Ag challenge, the eosinophil response was nearly abrogated at 48 h after challenge. These studies indicate that TNF-alpha acts as an initial inflammatory cytokine that subsequently regulates both early neutrophil infiltration and eosinophil recruitment into the lung and airspace.

Animals↗

PubMed1995

Interferon gamma-inducible protein 10 (IP-10), a member of the C-X-C chemokine family, is an inhibitor of angiogenesis.

Angiogenesis is fundamental to a variety of physiological and pathological processes. While a number of factors have been identified that induce neovascularization, it is becoming increasingly apparent that endogenous angiostatic factors may play an important role in the regulation of angiogenesis during wound repair, chronic inflammation, and growth of solid tumors. In this study, we demonstrate the novel finding that IP-10, a member of the C-X-C chemokine family, is a potent inhibitor of both IL-8 and bFGF-induced angiogenic activity using in vitro and in vivo assays of angiogenesis. These findings support the contention that IP-10 may be a pivotal cytokine in the regulation of neovascularization.

Amino Acid Sequence↗

PubMed1995

Compartmentalized expression of RANTES in a murine model of endotoxemia.

Systemic exposure to LPS initiates a complex sequence of events culminating in organ-specific leukocyte recruitment and end organ injury. We hypothesized that RANTES, a C-C chemokine with potent M phi (mononuclear phagocyte) chemotactic activity, is expressed in vivo in response to endotoxemia, and that this protein may play an important role in the recruitment of M phi to the lung. CD-1 mice were challenged with LPS (200 micrograms), resulting in a maximal fourfold increase in polymorphonuclear leukocyte (neutrophils) at 6 h post LPS, and a 2.4-fold increase in numbers of M phi within lung minces at 24 h. A time-dependent increase in RANTES mRNA was detected in lung after LPS treatment, whereas minimal quantities of RANTES mRNA were detected in blood buffy coats and liver. Furthermore, treatment with LPS resulted in time-dependent increase in RANTES protein within lung homogenates, with immunolocalization to alveolar epithelial cells. The pretreatment of mice with goat anti-RANTES Ab significantly inhibited the influx of lung M phi, but not polymorphonuclear leukocyte and lymphocytes, at 24 h post-LPS challenge. Lastly, the pretreatment of animals with soluble TNF receptor: Ig construct 2 h before LPS resulted in a 60% reduction in steady state levels of RANTES mRNA within lung homogenates at 4 h post-LPS. Our observations suggest that RANTES represents an important mediator of lung M phi recruitment in the setting of endotoxemia, and that the expression of RANTES in vivo is dependent upon the endogenous production of TNF.

Animals↗

PubMed1995

Macrophage inflammatory protein-1 alpha influences eosinophil recruitment in antigen-specific airway inflammation.

Allergic airway inflammation is characterized by peribronchial eosinophil accumulation within the submucosa of the airway of the lung. In the present study we have utilized a model of airway inflammation induced by intratracheal challenge with parasite (Schistosoma mansoni) egg antigen (SEA) in presensitized mice. The recruitment of neutrophils and eosinophils into the airway was found to be maximal at 8 and 48 h post challenge, respectively. Since macrophage inflammatory protein-1 alpha (MIP-1 alpha) has previously been found to be chemotactic for eosinophils, in vitro, we postulated that MIP-1 alpha was involved in the airway inflammation and more specifically in eosinophil recruitment into the airway. Initial studies demonstrated an increase in MIP-1 alpha mRNA expression at 8 h post-SEA challenge, as compared to vehicle-treated control mice. We next demonstrated a significant increase in MIP-1 alpha protein in the lungs of SEA-challenged mice at 8 h compared to control challenged mice, correlating to the mRNA data. Immunohistochemical staining of lungs from SEA-challenged mice demonstrated MIP-1 alpha protein expression in airway epithelial cells, alveolar macrophages and in recruited mononuclear cell populations. Immunolocalization of MIP-1 alpha to cells within the bronchoalveolar lavage fluid demonstrated that macrophages and eosinophils stained positive for the protein. To determine the contribution of MIP-1 alpha expression to eosinophil accumulation, SEA-challenged mice were passively immunized with either neutralizing MIP-1 alpha antibodies or normal rabbit IgG, 3-4 h prior to the intratracheal SEA challenge. These studies demonstrated a > 50% decrease in eosinophil recruitment to the lungs and airway in animals receiving neutralizing MIP-1 alpha antibodies with no effect on early neutrophil recruitment. These results suggest that the production of MIP-1 alpha, induced by an antigen-specific response, plays an important role in recruitment of eosinophils in this airway model of inflammation.

Animals↗

PubMed1995

Role of C-X-C chemokines as regulators of angiogenesis in lung cancer.

Lung cancer is the leading cause of malignancy-related mortality in the U.S. and is predicted to increase over the remainder of this decade. Despite attempts to advance early diagnosis and use combination therapies, the clinical response of this cancer yields an overall 5-year survival rate of less than 15%. Clearly, new strategies for therapy are indicated. Although carcinogenesis is complex, tumor growth beyond 1-2 mm3 is dependent on angiogenesis. One of the potential mechanisms that allows for tumorigenesis is dysregulation of the balance of angiogenic and angiostatic factors that favors net neovascularization within the primary tumor. Numerous studies have investigated the role of a variety of molecules in the regulation of angiogenesis. Recently, interleukin-8 (IL-8), a member of the C-X-C chemokine family, has been found to be an angiogenic factor. In contrast, platelet factor 4 (PF4), another C-X-C chemokine, has been shown to have angiostatic properties. It is interesting that the major structural difference between IL-8 and PF4 is the presence of the NH2-terminal ELR (Glu-Leu-Arg) motif that precedes the first cysteine amino acid residue of IL-8 and is important in ligand/receptor interactions. We hypothesize that angiogenesis associated with tumorigenesis is dependent on members of the C-X-C chemokine family acting as either angiogenic or angiostatic factors. This paradigm predicts that the biological balance in the expression of these C-X-C chemokines dictates whether the neoplasm grows and develops metastatic potential or regresses. In this review we discuss our recent laboratory findings that support this contention and suggest that further elucidation of the biology of C-X-C chemokines in the context of neovascularization of nonsmall cell lung cancer will permit novel targeted therapy aimed specifically at attenuating tumor growth and metastasis.

Amino Acid Sequence↗

PubMed1995

A role for C-C chemokines in fibrotic lung disease.

Pulmonary fibrosis is the end point of a chronic inflammatory process characterized by leukocyte recruitment and activation, fibroblast proliferation, and increased extracellular matrix production. Previous studies of models of pulmonary fibrosis have investigated the role of cytokines in the evolution of the fibrotic response. The involvement of tumor necrosis factor and interleukin-1 in bleomycin-induced lung injury, a model of idiopathic pulmonary fibrosis, has been well established, suggesting that cytokines mediate the initiation and maintenance of chronic inflammatory lesions. However, the aforementioned cytokines alone cannot account for the recruitment and activation of specific leukocyte populations found in the bleomycin model. Recently, a family of novel proinflammatory cytokines (chemokines) was cloned and characterized, yielding many putative mediators of leukocyte functions. Macrophage inflammatory protein-1 alpha (MIP-1 alpha) and monocyte chemoattractant protein-1 (MCP-1) belong to the C-C chemotactic cytokine family, a group of low-molecular-weight peptides. These molecules modulate chemotaxis, proliferation, and cytokine expression in leukocyte subsets. Our group has investigated the roles of MCP-1 and MIP-1 alpha in the bleomycin model. Both MCP-1 and MIP-1 alpha are expressed in a time-dependent manner after bleomycin challenge, and passive immunization of these animals with either anti-MIP-1 alpha or anti-MCP-1 antibodies attenuated leukocyte accumulation. In addition, we have identified specific cell types expressing MCP-1 or MIP-1 alpha by in situ hybridization and immunohistochemical localization, respectively. Furthermore, our results indicate that MIP-1 alpha expression is mediated by alveolar macrophage-derived tumor necrosis factor, identifying an important cytokine pathway in the initiation of pulmonary fibrosis. Finally, anti-MIP-1 alpha therapy attenuated fibrosis, providing direct evidence for its involvement in fibrotic pathology. Our work has clearly established that the C-C chemokines MCP-1 and MIP-1 alpha are expressed and contribute to the initiation and maintenance of the bleomycin-induced pulmonary lesion.

Bleomycin↗

PubMed1995

Interferon-alpha and interferon-gamma down-regulate the production of interleukin-8 and ENA-78 in human monocytes.

The two chemotactic cytokines interleukin-8 (IL-8) and epithelial neutrophil activating protein 78 (ENA-78) were recently shown to be potent chemoattractants and activators of neutrophil function and to be present in certain inflammatory diseases. We have studied the effects of recombinant and natural interferon-alpha (IFN-alpha) and of recombinant interferon gamma (rIFN-gamma) on the production of IL-8 and ENA-78 in lipopolysaccharide- and interleukin-1-stimulated human monocytes. Both types of interferons showed a strong, concentration-dependent inhibition of neutrophil-stimulating bioactivity. Similarly, the secretion of IL-8 and ENA-78 was also inhibited by up to 73%. Northern blot experiments demonstrated that IFN-alpha decreases the steady-state levels of IL-8 and ENA-78 mRNA in monocytes, suggesting that IFN-alpha as well as IFN-gamma may control the expression of neutrophil chemotactic cytokines at the mRNA level.

Base Sequence↗