IFN-gamma and IL-12 differentially regulate CC-chemokine secretion and CCR5 expression in human T lymphocytes

Interleukin (IL)-12, especially in the presence of neutralizing anti-IL-4 monoclonal antibodies, primed CD45RO(-) T clones for high CCL3/macrophage-inflammatory protein-1alpha (MIP-1alpha) and CCL4/MIP-1beta levels. In CD4(+) and CD8(+) clones from two patients deficient for IL-12Rbeta1 (IL-12Rbeta1(-/-)), production of CCL3/MIP-1alpha and CCL4/MIP-1beta was defective. CD4(+) clones from two patients deficient for interferon-gamma (IFN-gamma) R1 (IFN-gammaR1(-/-)) produced somewhat decreased CCL4/MIP-1beta levels. IL-12 failed to prime CD4(+) or CD8(+) healthy clones for high CCL5/regulated on activation, normal T expressed and secreted (RANTES) production, although its secretion was impaired in CD4(+) clones from IL-12Rbeta1(-/-) and IFN-gammaR1(-/-) patients. CCR5 surface expression was up-regulated in resting peripheral blood mononuclear cells and CD4(+) clones from both kinds of patients, rendering them more susceptible to CCR5-dependent (R5) HIV-1 infection. Neutralization of IFN-gamma increased CCR5 expression and decreased CC-chemokine secretion by CD4(+) clones from healthy and IL-12Rbeta1(-/-) individuals, suggesting an IFN-gamma-dependent control of CCR5 expression. These data provide the first documented analysis of chemokine secretion and chemokine receptor expression on T cells from IL-12 and IFN-gamma receptor-deficient patients and dissect the role of IL-12 and IFN-gamma on inducing inflammatory chemokine secretion and down-regulating CCR5 expression in human T cells.     

Down-regulation of CXCR-4 and CCR-5 expression by interferon-gamma is associated with inhibition of chemotaxis and human immunodeficiency virus (HIV) replication but not HIV entry into human monocytes

Alterations in the expression of CXCR4 and CCR5, the co-receptors for HIV entry, may be associated with susceptibility of monocytic cells to HIV infection. Interferon (IFN)-gamma has been shown to inhibit HIV replication in monocytic cells, but the molecular mechanism involved is not well understood. To determine if IFN-gamma regulates HIV replication by altering CXCR-4/CCR-5 expression and hence virus entry into monocytic cells, we investigated the effects of IFN-gamma on CXCR-4 and CCR-5 expression and its biological implications with respect to HIV entry, replication and chemotaxis towards the CXCR-4 and CCR-5 ligands SDF-1 and MIP-1alpha, respectively. IFN-gamma decreased CXCR-4 and CCR-5 expression on monocytes derived from HIV-negative adults, HIV-positive adults and HIV-negative cord blood. This down-regulation of chemokine receptor expression did not result in a corresponding change in mRNA expression but was associated with elevated levels of the endogenously produced chemokines SDF-1 and RANTES. Furthermore, IFN-gamma inhibited chemotaxis in response to SDF-1 and MIP-1alpha, inhibited HIV replication, but failed to inhibit virus entry in monocytic cells. These results suggest that although IFN-gamma-induced down-regulation of CXCR-4 and CCR-5 expression is associated with an inhibition of SDF-1-/MIP-1alpha-mediated chemotaxis, IFN-gamma-induced inhibition of HIV replication may be mediated at levels subsequent to the virus entry.     

Recall antigen activation induces prompt release of CCR5 ligands from PBMC: implication in memory responses and immunization

CCR5 ligands RANTES, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta are potent and specific inhibitors of strains of human immunodeficiency virus (HIV) that use CCR5 as a receptor, which are the strains most involved in primary infection. Recently, we observed that release of CCR5 ligands is a consistent and reproducible parameter of response to antigen activation in studies using PBMC. In this study, we show that CCR5 ligands are released upon antigen [Fragment C of tetanus toxin (TTC)] stimulation in 81% (n = 16) of subjects tested, as detected by a standard ELISA in tissue culture supernatants of antigen-activated cells. In contrast, ELISA for other cytokines from the same supernatants revealed that IFN-gamma release could be detected only in 31% of subjects, IL-2 could be detected only in 12% of the subjects and IL-4 was not detectable in any of the subjects tested. Similarly, proliferative responses to TTC, as measured by a standard tritiated thymidine incorporation assay, were detectable in only 56% of the subjects. Similar observations have been reported in flow cytometric studies, and resonate with previous findings emphasizing the role of CCR5 in T cell responses. In addition, the levels of CCR5 ligands in supernatants from antigen-activated cells were sufficient to inhibit infection of R5 HIV. Thus, CCR5 ligands might play a role in controlling HIV in vivo. Taken together, these observations suggest that CCR5 ligands, and in particular MIP-1alpha and MIP-1beta, released in the course of memory responses may play a role in protecting CD4(+) memory T cells from infection.     

Genetics of resistance to HIV infection: Role of co-receptors and co-receptor ligands

Susceptibility to HIV infection and AIDS progression is variable among individuals and populations, and in part genetically determined. Genetic variants of genes encoding HIV co-receptors and their chemokine ligands have been described, and some of these variants were associated with resistance to HIV infection and/or disease progression. We review here the reported data regarding the variants of the CCR5, CCR2, CX3CR1, MIP-1alpha/CCL3, MIP-1beta/CCL4, RANTES/CCL5 and SDF-1/CXCL12 genes. The Delta32 deletion mutant of CCR5, resulting in a non-functional receptor not reaching the cell surface, is unambiguously associated with strong, although incomplete, resistance to HIV infection for homozygotes, and retarded progression for heterozygotes. Specific haplotypes encompassing the CCR5 and CCR2 loci, and the copy number of the CCL3L1 gene, have also been convincingly correlated with delayed progression. For other gene variants, involving CXCL12/SDF-1 and CX3CR1, conclusive evidence for their relevance in the frame of HIV susceptibility is still lacking.     

Human peripheral blood T cells, monocytes, and macrophages secrete macrophage inflammatory proteins 1alpha and 1beta following stimulation with heat-inactivated Brucella abortus

Heat-killed Brucella abortus (HBa) has been proposed as a carrier for therapeutic vaccines for individuals with immunodeficiency, due to its abilities to induce interleukin-2 (IL-2) and gamma interferon (IFN-gamma) in both CD4(+) and CD8(+) T cells and to upregulate antigen-presenting cell functions (including IL-12 production). In the current study, we investigated the ability of HBa or lipopolysaccharide isolated from HBa (LPS-Ba) to elicit beta-chemokines, known to bind to the human immunodeficiency virus type 1 (HIV-1) coreceptor CCR5 and to block viral cell entry. It was found that human peripheral blood mononuclear cells secreted beta-chemokines following stimulation with HBa, and this effect could not be blocked by anti-IFN-gamma neutralizing antibodies. Among purified T cells, macrophage inflammatory protein 1alpha and 1beta (MIP-1alpha and MIP-1beta, respectively) secretion was observed primarily in human CD8(+) T cells. The kinetics of beta-chemokine induction in T cells were slow (3 to 4 days). The majority of beta-chemokine-producing CD8(+) T cells also produced IFN-gamma following HBa stimulation, as determined by triple-color intracellular staining. A significant number of CD8(+) T cells contained stored MIP-1beta that was released after HBa stimulation. Both HBa and LPS-Ba stimulated high levels of MIP-1alpha and MIP-1beta production in elutriated monocytes and even higher levels in macrophages. In these cells, beta-chemokine mRNA was upregulated within 30 min and proteins were secreted within 4 h of stimulation. The monocyte- and macrophage-derived beta-chemokines were sufficient to block CCR5-dependent HIV-1 envelope-mediated cell fusion. These data suggest that, in addition to the ability of HBa to elicit antigen-specific humoral and cellular immune responses, HBa-conjugated HIV-1 proteins or peptides would also generate innate chemokines with antiviral activity that could limit local viral spread during vaccination in vivo.     

CCL3/MIP-1alpha is pro-inflammatory in murine T cell-mediated hepatitis by recruiting CCR1-expressing CD4(+) T cells to the liver

T cell-mediated hepatitis is associated with significant morbidity and mortality worldwide. Levels of C-C chemokine ligand 3/macrophage inflammatory protein-1alpha (CCL3/MIP-1alpha) are elevated in the serum of patients with T cell-mediated liver diseases, but its role is not fully understood. Con A-induced hepatitis is a murine liver-specific inflammation mediated by activated T cells and is driven by an up-regulation of the hepatic expression of IFN-gamma. In this study, we have used CCL3/MIP-1alpha gene-deficient mice to examine the role of CCL3/MIP-1alpha in the pathogenesis of Con A-induced hepatitis. We demonstrate a novel pro-inflammatory role for CCL3/MIP-1alpha since CCL3/MIP-1alpha deficiency significantly attenuated hepatic injury, both biochemically and histologically. Moreover, the recruitment of CCR1-expressing CD4(+) T cells to the liver after Con A treatment was strikingly attenuated by CCL3/MIP-1alpha deficiency. Correspondingly, hepatic IFN-gamma produced by the recruited CD4(+) T cells was significantly reduced by CCL3/MIP-1alpha deficiency during Con A-induced hepatitis. Furthermore, treatment of mice with a dual CCR1/CCR5 peptide antagonist, methionylated RANTES, also markedly reduced hepatic injury and decreased the numbers of CD4(+) T cells within the liver producing IFN-gamma during Con A-induced hepatitis. These findings demonstrate that blockade of the CCL3/MIP-1alpha-CCR1 pathway may represent a novel therapeutic target for treating T cell-mediated liver diseases.     

Chemokine receptor expression and chemotactic responsiveness of human monocytes after influenza A virus infection

Chemokines and their receptors play an important role in site-directed migration and activation of leukocytes. To understand how viral infections may impair this function, we analyzed chemokine receptor expression and responsiveness of human monocytes after infection with influenza A virus. Whereas treatment with infectious virus induced a rapid down-regulation of the CCL2/monocyte chemoattractant protein-1 (MCP-1)-specific receptor CCR2, inactivated virus did not significantly alter CCR2 surface expression. In parallel, the response to CCL2/MCP-1 was lost after infection with active virus: Neither a CCL2/MCP-1-induced shift of intracellular calcium concentrations nor the chemotactic response to CCL2/MCP-1 was detectable. In striking contrast, the presence of CCR1 and CCR5 on the cell surface remained unchanged or was even slightly up-regulated after viral infection. However, the remaining expression of CCR1 and CCR5 correlated reciprocally with an ongoing unresponsiveness to the CCR1 and CCR5 agonists CCL3/macrophage-inflammatory protein-1alpha (MIP-1alpha), CCL4/MIP-1beta, and CCL5/regulated on activation, normal T expressed and secreted (RANTES), all chemokines binding to these two receptors. The CCL3/MIP-1alpha-induced shifts of intracellular calcium concentrations declined gradually to almost undetectable levels, and most conspiciuously, the chemotactic response to CCL3/MIP-1alpha, CCL4/MIP-1beta, and CCL5/RANTES was lost after infection with active influenza virus. Inactivated virus particles did not significantly alter the responsiveness induced by CCR1 and CCR5 agonists. Despite the inability of chemokine receptors to elicit migration, phosphorylation of protein kinase B was not altered in virus-infected monocytes. Thus, influenza A virus infection rapidly abolishes the functional responsiveness of monocytes and prevents an adequate response of the infected cells to chemokine stimulation.     

Polyfunctional T cell responses are a hallmark of HIV-2 infection

HIV-2 is distinguished clinically and immunologically from HIV-1 infection by delayed disease progression and maintenance of HIV-specific CD4(+) T cell help in most infected subjects. Thus, HIV-2 provides a unique natural human model in which to investigate correlates of immune protection against HIV disease progression. Here, we report a detailed assessment of the HIV-2-specific CD4(+) and CD8(+) T cell response compared to HIV-1, using polychromatic flow cytometry to assess the quality of the HIV-specific T cell response by measuring IFN-gamma, IL-2, TNF-alpha, MIP-1beta, and CD107a mobilization (degranulation) simultaneously following Gag peptide stimulation. We find that HIV-2-specific CD4(+) and CD8(+) T cells are more polyfunctional that those specific for HIV-1 and that polyfunctional HIV-2-specific T cells produce more IFN-gamma and TNF-alpha on a per-cell basis than monofunctional T cells. Polyfunctional HIV-2-specific CD4(+) T cells were generally more differentiated and expressed CD57, while there was no association between function and phenotype in the CD8(+) T cell fraction. Polyfunctional HIV-specific T cell responses are a hallmark of non-progressive HIV-2 infection and may be related to good clinical outcome in this setting.     

Inhibition of respiratory syncytial virus infection with the CC chemokine RANTES (CCL5)

Respiratory syncytial virus (RSV) is a major cause of respiratory tract disease in infants, aged adults, and immunosuppressed patients. The only approved medicines for RSV disease are administration of prophylatic antibodies or treatment with a synthetic nucleoside. Both approaches are expensive and the latter is not without risk and of controversial benefit. The present investigation studied whether pharmaceutical or biologic compounds based upon chemokines might be useful in preventing RSV disease. Of interest was RANTES/CCL5, which inhibits infection by HIV strains that use chemokine receptor (CCR)-5 as co-receptor. Herein, we report that prior or simultaneous treatment of HEp-2 cells with recombinant human CCL5 provides dose-dependent inhibition of infection with RSV. Other recombinant chemokines (MIP-1alpha/CCL3, MIP-1beta/CCL4, MCP-2/CCL8, eotaxin/CCL11, MIP-1delta/CCL15, stromal cell derived factor (SDF)-1alpha/CXCL12) were not inhibitory. The data suggested that CCL5 might inhibit infection by blocking fusion (F) protein-epithelial cell interactions. Infections by mutant RSV strains deleted of small hydrophobic and/or attachment proteins and only expressing F protein in the envelope were inhibited by prior treatment with CCL5 or a biologically inactive N-terminally modified met-CCL5. Inhibition was also observed when virus adsorption and treatment with CCL5 were performed at 4 degrees C. Flow cytometry further revealed that epithelial cells were positive for CCR3, but not CCR1 or CCR5. Thus, novel mimetics of CCL5 may be useful prophylatic agents to prevent respiratory tract disease caused by RSV.     

Chemotaxis of human tonsil B lymphocytes to CC chemokine receptor (CCR) 1, CCR2 and CCR4 ligands is restricted to non-germinal center cells

We have investigated the effects of nine CC chemokines, i.e. macrophage inflammatory protein (MIP)-1alpha/CCL3, MIP-1beta/CCL4, MIP-3alpha/CCL20, MIP-5/CCL15, monocyte chemotactic protein (MCP)-1/CCL2, MCP-2/CCL8, MCP-3/CCL7, eotaxin/CCL11 and macrophage-derived chemokine (MDC)/CCL22 on the locomotion of human tonsil B lymphocytes and their subsets. Upon isolation, B cells were poorly responsive, but, following short-term culture, they displayed statistically significant chemotactic responses (P < 0.001) to MIP-1alpha, MIP-5, MCP-1, MCP-2, MCP-3 and MDC. CC chemokine receptor (CCR) 1 to CCR6 were up-regulated after culture. MIP-1beta, MIP-3alpha and eotaxin did not stimulate B cell migration. Scattered information is available on B cell subset responses to chemokines. Therefore, we investigated the effects of MIP-1alpha, MIP-5, MCP-1, MCP-2, MCP-3 and MDC on the in vitro locomotion of non-germinal center (GC) (CD38(-)) and GC (CD38(+)) B cells. All chemokines enhanced significantly (P < 0.001) the migration of the former, but not of the latter, cells. CCR1, CCR2 and CCR4 were detected by flow cytometry on non-GC (i.e. naive and memory) B cells, whereas they were absent (CCR1 and CCR2) or poorly expressed (CCR4) on GC B cells.     

Downregulation of CCR5 on activated CD4 T cells in HIV-infected Indians

BACKGROUND: HIV infection in India is unique as it occurs predominantly by CCR5-utilizing isolates that exhibit no co-receptor switch. OBJECTIVES: To study HIV-1 co-receptor dynamics on T cells and monocytes following viral infection. STUDY DESIGN: HIV co-receptor expression was evaluated by flow cytometry on various cell subsets in HIV-infected Indians and in vitro in human peripheral blood mononuclear cells infected with CCR5- or CXCR4-utilizing HIV-1. Transfection of the T cell line CEM-CCR5 (which expresses CD4, CCR5 and CXCR4) with HIV-1 Nef or Vpu expression vectors, or treatment with recombinant soluble gp120 from CCR5- and CXCR4-tropic HIV-1, was carried out to determine their effects on co-receptor expression. RESULTS: Indian HIV patients had fewer CD4(+)CCR5(+) T cells and CCR5-expressing activated CD4(+) T cells, but higher CXCR4-expressing activated CD4(+) T cells compared with controls. Expression of CCR5 was not different on monocytes in HIV patients as compared to controls. The CCR5 downregulation on T cells was HIV infection specific and was governed by the co-receptor-utilization phenotype of the virus. The Nef and soluble gp120 proteins induced CCR5 downregulation, the latter in a co-receptor-utilization phenotype specific manner. CONCLUSIONS: The HIV-1 co-receptor dynamics in Indian patients is distinct from western patients and depends upon the virus surface protein. We propose this to be a viral survival strategy.     

CCL2: a potential prognostic marker and target of anti-inflammatory strategy in HIV/AIDS pathogenesis

Chemokines are critical components of the immune system that participate in immune homeostasis and alterations in chemokine balance can result in severe inflammatory and autoimmune diseases. The role of chemokines and their receptors in viral infections including HIV-1 was predicted from the early studies of HIV-1 co-receptor CCR5 and its ligands and a divergent role of C-C chemokines in HIV-1 pathogenesis has been established. For example, CCL3 (MIP-1α), CCL4 (MIP-1β) and CCL5 (RANTES) have been shown to possess antiviral effects by binding to the HIV-1 co-receptor CCR5, whereas CCL2, a pro-inflammatory chemokine, supports HIV-1 replication despite being a member of same chemokine family. Furthermore, the well-established role of CCL2 in driving the Th2 immune response supports its potential role in HIV-1/AIDS. Recent reports suggest multiple pathways of CCL2 affect HIV-1 infection. In this review, we provide a comprehensive overview of the role and potential mechanisms of the HIV-1-CCL2 interplay in driving virus-induced immuno-pathology, suggesting that CCL2 could be an anti-inflammatory target in the treatment of HIV-1 infection.     

In vitro effect of anti-human immunodeficiency virus CCR5 antagonist maraviroc on chemotactic activity of monocytes, macrophages and dendritic cells

Compounds targeting the chemokine receptor CCR5 have recently been approved for treatment of human immunodeficiency virus (HIV) infection. Given the central role of CCR5 in inflammation and recruitment of antigen-presenting cells (APC), it is important to investigate the immunological consequences of pharmacological inhibition of CCR5. We evaluated the in vitro effect of different concentrations of CCR5 antagonist maraviroc (MVC) on cell migration of monocytes, macrophages (MO) and monocyte-derived dendritic cells (MDC) towards peptide formyl-methionyl-leucyl-phenylalanine (fMLP) and chemokines regulated upon activation normal T cell expressed and secreted (RANTES) and CCL4/macrophage inflammatory protein-1 (MIP-1β) and CCL2/monocyte chemotactic protein-1 (MCP-1). Results of flow cytometric analysis showed that monocytes treated in vitro with MVC exhibited a significant dose-dependent reduction of chemotaxis towards MIP-1β and MCP-1. fMLP-induced chemotactic activity decreased only at higher concentration (1 μM and 10 μM of MVC). In addition, all concentrations of MVC (0·1, 1 and 10 μM) induced in vitro a significant inhibition of chemotaxis of MO and MDC in response to all tested chemoattractants. No change in phenotype (CD1a and CD14) and CCR1, CCR4, CCR5 and formyl peptide receptor (FPR) expression was seen after in vitro treatment with MVC. These findings suggest that CCR5 antagonist MVC may have the in vitro ability of inhibiting the migration of innate immune cells by mechanism which could be independent from the pure anti-HIV effect. The drug might have a potential role in the down-regulation of HIV-associated chronic inflammation by blocking the recirculation and trafficking of MO and MDC.     

PDL-1 upregulation on monocytes and T cells by HIV via type I interferon: restricted expression of type I interferon receptor by CCR5-expressing leukocytes

The programmed death (PD)-1 interacts with its ligand (PDL-1) delivering a negative signal to T cells. During human immunodeficiency virus (HIV)-1 infection PD-1 and PDL-1 expressions are increased. Here we show that monocytes and CCR5(+) T cells of HIV-uninfected donors upregulated PDL-1 upon in vitro exposure to HIV. HIV-induced PDL-1 required interferon (IFN)-alpha, but not IFN-gamma, production. Inhibition of endocytosis, required for HIV-induced IFN-alpha production, prevented PDL-1 upregulation. IFN-alpha-inducing Toll-like receptor (TLR) agonists increased PDL-1 on monocytes and CCR5(+) T cells. CD80 and CD86 were also increased on monocytes and CCR5(+) T cells after HIV exposure, but only CD80 was IFN-alpha-dependent. IFN-alpha-receptor subunit 2 (IFNAR2), was expressed only by CCR5(+) T cells and monocytes, explaining why these leukocytes responded to HIV-induced IFN-alpha. Finally, T cell proliferation was improved by PDL-1 blockade in HIV-treated PBMC. In the setting of HIV infection, IFN-alpha may negatively affect T cell responses by inducing PDL-1.     

Infiltrating CD8+ T cells in oral lichen planus predominantly express CCR5 and CXCR3 and carry respective chemokine ligands RANTES/CCL5 and IP-10/CXCL10 in their cytolytic granules: a potential self-recruiting mechanism

Lichen planus is a chronic inflammatory disease of the skin and oral mucosa in which the cell-mediated cytotoxicity is regarded as a major mechanism of pathogenesis. To understand its pathophysiology further, the present study examined the in situ expression of chemokines and chemokine receptors in oral lichen planus. Immunohistochemical analysis of 15 cases has consistently revealed that infiltrating CD4(+) and CD8(+) T cells in the submucosa predominantly expressed CCR5 and CXCR3. Furthermore, infiltrating T cells, particularly CD8(+) T cells, were positive for RANTES/CCL5 and IP-10/CXCL10, the ligands of CCR5 and CXCR3, respectively. By immunoelectron microscopy, these chemokines were localized in the cytolytic granules of CD8(+) T cells. Lesional keratinocytes also overexpressed the ligands of CXCR3, namely, MIG/CXCL9, CXCL10, and I-TAC/CXCL11. Our data suggest that the chemokines signaling via CCR5 and CXCR3, which are known to be selectively expressed by type 1 T cells, are predominantly involved in T-cell infiltration of oral lichen planus. Furthermore, the presence of CCL5 and CXCL10 in the cytolytic granules of tissue-infiltrating CD8(+) T cells expressing CCR5 and CXCR3 reveals a potential self-recruiting mechanism involving activated effector cytotoxic T cells.     

Infiltration of CD8+ T cells containing RANTES/CCL5+ cytoplasmic granules in actively inflammatory lesions of human chronic gastritis

Chronic gastritis is frequently associated with infection of Helicobacter pylori and characterized by tissue infiltration of neutrophils, lymphocytes, and plasma cells. To address the mechanism of lymphocyte infiltration in chronic gastritis, we examined the expression of chemokines and their receptors using frozen sections of chronic gastritis, obtained from 23 patients who underwent gastrectomy for gastric cancer. By immunohistochemistry, lymphocytes in inflamed gastric mucosa expressed CCR5 abundantly, CXCR3 less frequently, and CCR4 sparsely. The numbers of CCR5(+) cells, which were composed of mainly CD8(+) and partly CD4(+) T cells, were positively correlated with the degree of neutrophil infiltration, and decreased in areas with intestinal metaplasia or mucosal atrophy. RANTES/CCL5, one of the ligands of CCR5, was localized mainly in CD8(+) and partly CD4(+) T cells with a characteristic dotted pattern, and such lymphocytes were most densely distributed around the neck region of gastric glands. In situ hybridization confirmed the expression of CCL5 mRNA in these cells, and immunoelectron microscopy revealed localization of CCL5 in the membrane-bound granules, which most probably corresponded to the cytolytic granules of cytotoxic T cells. The numbers of CCL5(+) lymphocytes showed a close correlation with the degree of neutrophil infiltration and markedly decreased in intestinal metaplasia. In conclusion, our data suggest that, together with neutrophils, CCL5(+) T cells, presumably activated cytotoxic T cells, would play important roles in the active inflammatory process of chronic gastritis. Our data also suggest a self-recruiting mechanism involving CCR5 and CCL5 for tissue accumulation of such T cells.     

Crucial role of CCL3/MIP-1alpha in the recurrence of autoimmune anterior uveitis induced with myelin basic protein in Lewis rats

In this study, we examined the role of CCL2/MCP-1, CCL3/MIP-1alpha, CCL4/MIP-1beta, and CCL5/RANTES during recurrent anterior uveitis (RAU). LEW rats injected with myelin basic protein (MBP) developed experimental autoimmune encephalomyelitis (EAE) and associated anterior uveitis (AU), which was mediated by CD4(+) T cells. After recovery, rats become resistant to EAE but developed RAU. Rats reinjected with MBP developed RAU without EAE. The chemokines tested were detected in the eye at RAU accelerated onset, increased as the disease progressed, and fell as clinical signs improved. At the same time, in the spinal cords of rats, these chemokines were still detected but at reduced levels. Administration of anti-MIP-1alpha neutralizing antibodies resulted in almost complete suppression of clinical RAU and significant reduction of inflammatory cell recruitment into the iris. Anti-MIP-1beta and anti-MCP-1 antibodies were effective in suppression of RAU but to lesser degree. Treatment with anti-RANTES antibodies was not effective in protecting against the recurrent development of the disease. In the eyes, the message for CCR1 and CCR5 was considerably elevated prior to the onset of AU and decreased after treatment with anti-chemokine antibodies. Our results suggest a crucial role of CCL3/MIP-1alpha in the development of RAU in Lewis rats. In addition, CCL2/MCP-1 and CCL4/MIP-1beta may also play a role in immunopathogenesis of RAU.     

Gene expression contributing to recruitment of circulating cells in response to vesicular stomatitis virus infection of the CNS

During acute Vesicular Stomatitis Virus (VSV) infection of the mouse central nervous system, neutrophils, natural killer (NK) cells, macrophages, and CD4+ and CD8+ T cells are recruited from the circulation in response to chemokines and cytokines. This study elucidated the production of these factors and infiltration of these peripheral cells. Chemokines that were observed included CCL1, CXCL10 (IP-10), CCL5 (RANTES), CCL3 (MIP-1alpha), CCL4 (MIP-1beta), CXCL1 (MIP-2), CCL2 (MCP-1), and CCL11 (eotaxin). Cytokines produced in response to the infection include IL-1 and interferon-gamma, but not type I interferons. Neutrophils are the first recruited cell type, appearing as early as 24 h after intranasal application of the virus. NK cells follow, but T cells are not detected until 6 days postinfection.     

A novel role for tumor necrosis factor-alpha in regulating susceptibility of activated CD4+ T cells from human and nonhuman primates for distinct coreceptor using lentiviruses

Although CD4+ T-cell activation has long been shown to promote infection and replication of simian immunodeficiency virus (SIV) and HIV, recent studies have documented that not all activated CD4+ T cells from human and nonhuman primates are susceptible to infection with HIV/SIV, respectively. Activation of CD4+ T cells with anti-CD3 + anti-CD28 conjugated beads led to induction of a state of anti-viral resistance to infection with strains of viruses that primarily use CCR5 as a coreceptor. The studies reported herein were designed to address the mechanism by which anti-CD3 + anti-CD28-induced stimulation in turn induced antiviral resistance. Results of these studies show that the anti-viral resistance induced by activation of CD4+ T cells with anti-CD3 + anti-CD28 is primarily conferred by the synthesis of tumor necrosis factor-alpha (TNF-alpha), and highlight a unique regulatory role for TNF-alpha in regulating synthesis of MIP-1alpha, MIP-1beta, and regulated-on-activation normal T-expressed and secreted cells, which contributes to this state of antiviral resistance to R5-tropic strains of HIV/SIV. However, while TNF-alpha has a protective role in antiviral resistance of activated CD4+ T cells to R5-tropic viruses, it enhances CXCR4 expression of CD4+ T cells and mediates increased susceptibility to infection with X4-tropic strains of HIV and recombinant SIVs. The results of the studies reported herein also suggest that it is not the Th1 v/s Th2 cytokine profile but the mode of CD4+ T-cell activation that dictates the synthesis of distinct cytokines which regulate the expression of chemokines and chemokine receptors which in turn regulate and confer susceptibility/resistance to R5 v/s X4-tropic HIV and SIV.