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Antigen-induced differential gene expression in lymphocytes and gene expression profile in synovium prior to the onset of arthritis.

To explore early signature genes playing critical roles in the initial steps in an autoimmune murine model of rheumatoid arthritis (RA) (proteoglycan (PG)-induced arthritis; PGIA), we performed gene expression profiling of "arthritogenic" spleen cells stimulated with cartilage PG, and compared them to differentially expressed genes, identified in joints prior to the onset of arthritis, and then in the acute and chronic phases of the disease. A total of 280 genes were up-regulated and 226 genes were suppressed in in vitro PG-stimulated lymphocytes at a minimum of 2-fold expression change. Functional gene classification identified several major clusters of biological activity. Expression of immunoglobulin genes (66 transcripts) was downregulated by approximately 3.7-fold, whereas most of the other genes with immune/inflammation-associated functions such as interleukins (IL-1, -2, -4, -6, -10, -12, -16, -17), chemokine receptors and their ligands (Cxcl1, Ccl2, 7, 8, 9, 10, 22, Ccr2, Ccr5), and major components of the complement cascade were upregulated. Using adoptive disease transfer with stimulated lymphocytes into SCID mice, followed by gene expression profiling of SCID paws, indicated that 37 genes were differentially expressed in yet non-inflamed (pre-arthritic) paws; these genes were related mostly to chemokine, IFN-gamma and TNF-alpha signaling. However, the majority of differentially expressed immune response-related genes were silent in pre-arthritic joints, and only 12 genes were found differentially expressed both in antigen (PG)-stimulated lymphocytes and in the synovium prior to the onset of arthritis. Most of these "arthritis-initiation" genes belonged to chemokine mediated cell motility. Transcripts of chemokine receptor 5 (Ccr5), chemokine ligand 7 (Ccl7) and IFN-gamma-inducible proteins (Ifi47) and GTP-ase 1 were expressed at the highest levels in both antigen-stimulated lymphocytes and pre-inflamed synovium, which suggests a key role of these genes in both lymphocyte maturation and arthritis initiation.

Adoptive Transfer↗

Dynamic expression of chemokines and the infiltration of inflammatory cells in the HSV-infected cornea and its associated tissues.

BACKGROUND: The chemotactic signals regulating cell trafficking in the herpes simplex virus type 1 (HSV-1) infected cornea are well documented, however, those in the cornea-associated tissues, such as the trigeminal ganglion (TG) and draining lymph nodes (LNs), are largely unknown. OBJECTIVES: To examine chemokine expression and subsequent cell infiltration in the HSV-1 infected cornea and its associated tissues. STUDY DESIGN: Eight-week-old female BALB/c mice were infected with 10 mu l HSV-1 (CHR3 strain: 5 x 106 PFU/ml) by corneal scarification. Total RNAs were extracted from the corneas, TGs, and LNs at pre-inoculation, 3 days post-inoculation (P.I.) and 7 days P.I. The mRNA for 28 different chemokines in the extracts was amplified by RT-PCR. Infiltrating cells were identified by immunohistochemistry. RESULT: After the HSV-1 infection, the corneal stroma became edematous by infiltrated cells under the eroded epithelium. The TG and LNs were markedly swollen. The cornea was infiltrated with granulocytes and CD11b+ cells at 3 days P.I., followed by CD4+ and CD8+ T cells at 12 days P.I. In the TG, CD11b+ cells, but no granulocytes, infiltrated throughout the observation period. T cells migrated into the TG earlier than into the cornea. Gene expressions of neutrophil-attracting chemokines (CXCL1, 2, 3, and 5) increased in the cornea, but they did not enhance in the TG or LNs. On the other hand, gene expressions of chemokines which attract CD11b+ cells such as CCL2, 8, 7, 12, CCL3, 4, and CCL5, increased in the cornea and TG with its peak at 3 days P.I. Gene expressions of chemokines those work on T cells and B cells, such as CCL19, CCL21, CXCL9, CXCL13, CXCL10, XCL1, and CXCL16, were up-regulated and peaked at 3 days P.I. in the cornea and in the TG. Thus, pattern of chemokine gene expression was similar in the cornea and in the TG. On the contrary, gene expressions of chemokines in the draining LNs affecting CD11b+ cells and T cells were temporarily down-regulated. CONCLUSION: Upon HSV-1 infection, dynamic gene expression of chemokines was observed not only in the inoculated cornea but also in its associated tissues.

Animals↗

Intracerebral infection with murine cytomegalovirus induces CXCL10 and is restricted by adoptive transfer of splenocytes.

The brain's intrinsic immune system consists of glial cells that produce cytokines and chemokines in response to stimulation with cytomegalovirus (CMV). The present experiments were undertaken to determine whether this intrinsic glial cell response alone is sufficient to control CMV infection of the central nervous system (CNS) or whether effector cells from the somatic immune system are also required. Following stereotactic, intracerebroventricular (icv), injection of murine cytomegalovirus (MCMV) into immunocompetent (C.B-17) mice, viral spread in the brain was limited to the cells of the ventricular walls and the infection was resolved by 10 days post infection (p.i.). In contrast, icv infection of immunodeficient (C.B-17 SCID/bg) mice resulted in viral spread from the ventricles throughout the brain parenchyma and these mice succumbed to lethal disease. Adoptive transfer of total splenocytes from major histocompatibility complex (MHC)-matched, MCMV-primed animals restricted intracerebral viral infection to the periventricular cells and reduced levels of reporter gene expression from the viral genome. Peripheral immune cell transfer also protected immunodeficient animals from lethal disease. Depletion of Thy 1.2(+) cells from MCMV-primed splenocytes abolished the protective effect of adoptive transfer. Viral expression was found to be fourfold greater in the brains of animals given Thy 1.2-depleted splenocytes than from those receiving total undepleted cells. As MCMV infection proceeded in the brains of immunodeficient mice, levels of the T-cell chemoattractants CXCL10 and CCL2 remained elevated, whereas CXCL10 levels waned in the brains of animals receiving transferred splenocytes. Taken together, these results demonstrate the ability of T lymphocytes to restrict intracerebral viral spread and indicate that intrinsic glial cell responses alone are insufficient to control MCMV brain infection.

Animals↗

Differential responses of human brain cells to West Nile virus infection.

In recent years, West Nile virus (WNV) has emerged as a major cause of encephalitis in the United States. However, the neuropathogenesis of this flavivirus is poorly understood. In the present study, the authors used primary human brain cell cultures to investigate two neuropathogenic features: viral replication and induction of cytokines. Although neurons and astrocytes were found to support productive WNV infection, viral growth was poorly permissive in microglial cells. Compared to neuronal cultures that sustained viral growth for at least 2 weeks, replication peaked in astrocytes by 72 h post infection. In response to viral infection, astrocytes produced chemokines (CXCL10 and CCL5), but none of the cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, interferon alpha or gamma) tested could be detected. Although microglial cells failed to support viral replication, WNV induced production of the proinflammatory cytokines IL-6 and TNF-alpha. Microglial cells also released robust amounts of the chemokines CXCL10 and CCL2, as well as lower levels of CCL5, in response to WNV infection. WNV-induced chemokine and cytokine production by microglia was coupled with activation of mitogen-activated protein kinase (MAPK) intracellular signaling pathways. Inhibition of p38 MAPK decreased chemokine production in response to WNV. Taken together, these findings suggest that microglial cell responses may influence the neuropathogenesis of WNV infection.

Animals↗

Cytokines in host defense against Aspergillus: recent advances.

Many aspects of antimicrobial host responses are orchestrated by a complex network of cytokines and their receptors. This review focuses on recent progress in our understanding of the function of cytokines in innate immune responses to Aspergillus. TNF, a recognition cytokine, has been shown to be required for initiation of the innate response in the mouse model of invasive aspergillosis. Several recruitment cytokines play critical roles in mediating influx of specific leukocytes to the site of infection in invasive aspergillosis. Among these, the ELR + subset of CXC chemokines and their receptor CXCR2 are critical to neutrophil recruitment, while CCL3/macrophage inflammatory protein (MIP)-1alpha and CCL2/ monocyte chemoattractant protein (MCP)-1 are critical to recruitment of monocyte-lineage leukocytes and NK cells, respectively. Of the activation cytokines, those associated with the Th-1 phenotype, including interleukin (IL)-12, IL-18, and interferon-gamma (IFN-gamma), are critical to protective responses to the infection. Conversely, the Th2-phenotype cytokines IL-4 and IL-10 contribute to progression of infection. Modulation of the immune response to Aspergillus by manipulating these mediators remains intriguing as a potential adjunctive treatment in patients with invasive aspergillosis.

Animals↗

Secondary lymphoid-tissue chemokine induced modulation of T cells.

In this study we were interested in investigating the extent to which stimulation through a chemokine receptor could modulate TCR function. We report that splenic T cells exposed to secondary lymphoid-tissue chemokine (SLC, CCL21) for 72, but not 2 or 24 hours, exhibited a decreased ability to produce IFN-gamma following CD3 crosslinking. Similar findings were observed with CCL2 and CCL5. The decrease in IFN-gamma production was not attributed to a decrease in T cell viability, was not accompanied with an increase in IL-4 production, and could be induced using a G protein coupled receptor agonist indicating involvement of chemokine receptors. One explanation for these findings was that following chemokine exposure the T cells were less efficient at TCR capping and exhibited a decrease in ZAP-70 protein expression. Consequently, these data indicate that CCL21 could modulate the function and expression of proteins necessary for T cell activation.

Animals↗

Fractalkine preferentially mediates arrest and migration of CD16+ monocytes.

CD16+ monocytes represent 5-10% of peripheral blood monocytes in normal individuals and are dramatically expanded in several pathological conditions including sepsis, human immunodeficiency virus 1 infection, and cancer. CD16+ monocytes produce high levels of proinflammatory cytokines and may represent dendritic cell precursors in vivo. The mechanisms that mediate the recruitment of CD16+ monocytes into tissues remain unknown. Here we investigate molecular mechanisms of CD16+ monocyte trafficking and show that migration of CD16+ and CD16- monocytes is mediated by distinct combinations of adhesion molecules and chemokine receptors. In contrast to CD16- monocytes, CD16+ monocytes expressed high CX3CR1 and CXCR4 but low CCR2 and CD62L levels and underwent efficient transendothelial migration in response to fractalkine (FKN; FKN/CX3CL1) and stromal-derived factor 1 alpha (CXCL12) but not monocyte chemoattractant protein 1 (CCL2). CD16+ monocytes arrested on cell surface-expressed FKN under flow with higher frequency compared with CD16- monocytes. These results demonstrate that FKN preferentially mediates arrest and migration of CD16+ monocytes and suggest that recruitment of this proinflammatory monocyte subset to vessel walls via the CX3CR1-FKN pathway may contribute to vascular and tissue injury during pathological conditions.

Antibodies, Monoclonal↗

Inhibition of astroglial nuclear factor kappaB reduces inflammation and improves functional recovery after spinal cord injury.

In the central nervous system (CNS), the transcription factor nuclear factor (NF)-kappaB is a key regulator of inflammation and secondary injury processes. After trauma or disease, the expression of NF-kappaB-dependent genes is highly activated, leading to both protective and detrimental effects on CNS recovery. We demonstrate that selective inactivation of astroglial NF-kappaB in transgenic mice expressing a dominant negative (dn) form of the inhibitor of kappaB alpha under the control of an astrocyte-specific promoter (glial fibrillary acidic protein [GFAP]-dn mice) leads to a dramatic improvement in functional recovery 8 wk after contusive spinal cord injury (SCI). Histologically, GFAP mice exhibit reduced lesion volume and substantially increased white matter preservation. In parallel, they show reduced expression of proinflammatory chemokines and cytokines, such as CXCL10, CCL2, and transforming growth factor-beta2, and of chondroitin sulfate proteoglycans participating in the formation of the glial scar. We conclude that selective inhibition of NF-kappaB signaling in astrocytes results in protective effects after SCI and propose the NF-kappaB pathway as a possible new target for the development of therapeutic strategies for the treatment of SCI.

Animals↗

Respiratory syncytial virus-induced chemokine production: linking viral replication to chemokine production in vitro and in vivo.

Respiratory syncytial virus (RSV) is a negative-sense, single-strand RNA virus that can initiate severe bronchiolitis in infants, as well as in elderly adults. Although RSV preferentially infects and replicates in the airway epithelium, studies have shown that RSV has the ability to infect and, to a limited extent, replicate in alveolar macrophages. In the present study, we sought to characterize the RSV-induced chemokine production in vitro and in vivo, because chemokines have been shown to contribute to both the inflammation and pathophysiology of disease. Our results show that RSV-infected airway epithelial cells and alveolar macrophages display differential profiles of chemokine production: airway epithelial cells produce CCL2/monocyte chemoattractant protein-1, CCL5/RANTES, CXCL10/gamma interferon inducible protein-10, and kerotinocyte cytokine (KC); and alveolar macrophages up-regulate CCL5 and macrophage inflammatory protein (MIP)-2 after RSV infection. In vivo, we observed the induction of CCL2, CCL3/MIP-1 alpha, CCL5, CXCL10, and KC after RSV infection. In the present study, we also addressed the necessity for viral infection and/or replication in chemokine induction by use of ultraviolet (UV)-inactivated RSV, as well as RSV inhibitors of binding/infection and replication, that is, NMSO3, a sulfated sialyl lipid compound, and ribavirin, respectively. Our results suggest that viral replication is necessary for optimal chemokine production.

Animals↗

Chemokine CC receptor 2 is important for acute control of cardiac parasitism but does not contribute to cardiac inflammation after infection with Trypanosoma cruzi.

The CC chemokine ligand 2 (CCL2) and CC chemokine receptor 2 (CCR2) are expressed in the heart after infection with Trypanosoma cruzi, suggesting that they play an important role in host defense. Infection of CCR2-deficient (CCR2(-/-)) mice with T. cruzi resulted in increased cardiac parasitism, yet the severity of cardiac inflammation was not affected. In addition, expression of interferon- gamma and inducible NO synthase in the heart, which are associated with effective killing of trypomastigotes, was not affected in CCR2(-/-) mice. These observations reveal that CCR2 signaling plays a distinct role that is separate from that of influencing either chemotaxis or previously defined anti-trypomastigote mechanisms for the control of T. cruzi's replication in the heart.

Animals↗

Differential expression of chemokines and their receptors in adult and neonatal macrophages infected with human or avian influenza viruses.

In 1997, avian influenza virus H5N1 was transmitted directly from chicken to human and resulted in a severe disease that had a higher mortality rate in adults than in children. The characteristic mononuclear leukocyte infiltration in the lung and the high inflammatory response in H5N1 infection prompted us to compare the chemokine responses between influenza virus-infected adult and neonatal monocyte-derived macrophages (MDMs). The effects of avian influenza virus A/Hong Kong/483/97 (H5N1) (H5N1/97), its precursor A/Quail/Hong Kong/G1/97 (H9N2) (H9N2/G1), and human influenza virus A/Hong Kong/54/98 (H1N1) (H1N1/98) were compared. Significantly higher expression of CCL2, CCL3, CCL5, and CXCL10 was induced by avian influenza viruses than by human influenza virus. Moreover, the increase in CCL3 expression in H5N1/97-infected adult MDMs was significantly higher than that in neonatal MDMs. Enhanced expression of CCR1 and CCR5 was found in avian virus-infected adult MDMs. The strong induction of chemokines and their receptors by avian influenza viruses, particularly in adult MDMs, may account for the severity of H5N1 disease.

Adult↗

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.

Animals↗

Herpes simplex virus type 1 induction of chemokine production is unrelated to viral load in the cornea but not in the nervous system.

Herpes simplex virus type 1 elicits a strong host inflammatory response after corneal infection. The purpose of the current study was to compare the production of chemokines induced by viral infection at sites known to harbor virus after ocular inoculation in order to determine the relationship between viral load and chemokine expression. Using highly resistant IFN-alpha1 transgenic mice whose transgene is under the control of the glial fibrillary acidic protein promoter in comparison with the more sensitive wild-type counterparts, we compared the expression of chemokines versus the amount of infectious virus recovered from the anterior segment of the eye and nervous system. Consistent with our predicted outcome, the level of infectious virus recovered in the iris, trigeminal ganglia, and brainstem of resistant versus sensitive mice correlated with chemokine production; that is, the less virus recovered the less chemokine (CCL2, CCL3, CCL5, CXCL9, and CXCL10) produced. In contrast to the nervous system and iris, there was no correlation between chemokine expression and level of infectious virus recovered in the cornea. We interpret these results as suggesting chemokine expression within the cornea in response to herpes simplex virus type 1 infection is driven by factors other than antigenic stimulation.

Animals↗

Detecting protein dissimilarities in multiple alignments using Bayesian variable selection.

MOTIVATION: We present an application of Bayesian variable selection to the novel detection of sequence elements that confer negative design to protein structure and function. As an illustration, we analyze the different dimer interfaces between the CXCL8 chemokine family with the CCL4 and CCL2 chemokine families to discover the changes that disfavor CXCL8 of quaternary structure. RESULTS: In comparison with known experimental results, our method identifies evolutionarily conserved sequence changes in the CC families that inhibit CXCL8 quaternary structure. Therefore, we find positive selection of negative design elements. Furthermore, our approach predicts that a two-residue deletion conserved in the CCL4 chemokine family disfavors CXCL8 dimerization. AVAILABILITY: The Matlab code for the Bayesian variable selection is freely available at http://stat.tamu.edu/~mvannucci/webpages/codes.html

Algorithms↗

Detection of differentially expressed genes in synovial fibroblasts by restriction fragment differential display.

OBJECTIVE: To identify differentially expressed genes in synovial fibroblasts and examine the effect on gene expression of exposure to TNF-alpha and IL-1beta. METHODS: Restriction fragment differential display was used to isolate genes using degenerate primers complementary to the lysophosphatidic acid acyl transferase gene family. Differential gene expression was confirmed by reverse transcription-polymerase chain reaction and immunohistochemistry using a variety of synovial fibroblasts, including cells from patients with osteoarthritis and self-limiting parvovirus arthritis. RESULTS: Irrespective of disease process, synovial fibroblasts constitutively produced higher levels of IL-6 and monocyte chemoattractant protein 1 (MCP-1) (CCL2) than skin fibroblasts. Seven genes were differentially expressed in synovial fibroblasts compared with skin fibroblasts. Of these genes, four [tissue factor pathway inhibitor 2 (TFPI2), growth regulatory oncogene beta (GRObeta), manganese superoxide dismutase (MnSOD) and granulocyte chemotactic protein 2 (GCP-2)] were all found to be constitutively overexpressed in synoviocytes derived from patients with osteoarthritis. These four genes were only weakly expressed in other synovial fibroblasts (rheumatoid and self-limiting parvovirus infection). However, expression in all types of fibroblasts was increased after stimulation with TNF-alpha and IL-1beta. Three other genes (aggrecan, biglycan and caldesmon) were expressed at higher levels in all types of synovial fibroblasts compared with skin fibroblasts even after stimulation with TNF-alpha and IL-1. CONCLUSIONS: Seven genes have been identified with differential expression patterns in terms of disease process (osteoarthritis vs rheumatoid arthritis), state of activation (resting vs cytokine activation) and anatomical location (synovium vs skin). Four of these genes, TFPI2, GRObeta (CXCL2), MnSOD and GCP-2 (CXCL6), were selectively overexpressed in osteoarthritis fibroblasts rather than rheumatoid fibroblasts. While these differences may represent differential behaviour of synovial fibroblasts in in vitro culture, these observations suggest that TFPI2, GRObeta (CXCL2), MnSOD and GCP-2 (CXCL6) may represent new targets for treatments specifically tailored to osteoarthritis.

Adult↗

The gammaherpesvirus chemokine binding protein can inhibit the interaction of chemokines with glycosaminoglycans.

Chemokines are small glycosaminoglycan (GAG) binding proteins that direct the migration of leukocytes by signaling through G protein coupled receptors (GPCR). Many viruses encode proteins that disrupt chemokine responses. The murine gammaherpesvirus-68 gene M3 encodes a chemokine binding protein (vCKBP-3), which has no sequence similarity to chemokine receptors. Initial characterization of vCKBP-3 showed that it inhibits receptor binding and chemokine-induced calcium influx. The structural requirements for the chemokines CXCL8 and CCL2 to bind to vCKBP-3 have been determined. Both chemokines bind to vCKBP-3 via their N-loop, a site that can participate in GAG binding for some chemokines. We have investigated the effect of vCKBP-3 on the interaction of chemokines with GAGs. We found that vCKBP-3 can prevent a range of chemokines from binding to GAGs. Moreover, we also found that vCKBP-3 can displace chemokines from a heparin-coated surface. Together, these data imply that vCKBP-3 can inhibit chemokine activity at two distinct levels. First, it inhibits chemokines from binding to their GPCR. Second, it inhibits their GAG binding and disrupts pre-formed chemokine gradients. This dual ability of vCKBP-3 makes it a more effective inhibitor of chemokine activity.

Animals↗

LPS regulates proinflammatory gene expression in macrophages by altering histone deacetylase expression.

Bacterial LPS triggers dramatic changes in gene expression in macrophages. We show here that LPS regulated several members of the histone deacetylase (HDAC) family at the mRNA level in murine bone marrow-derived macrophages (BMM). LPS transiently repressed, then induced a number of HDACs (Hdac-4, 5, 7) in BMM, whereas Hdac-1 mRNA was induced more rapidly. Treatment of BMM with trichostatin A (TSA), an inhibitor of HDACs, enhanced LPS-induced expression of the Cox-2, Cxcl2, and Ifit2 genes. In the case of Cox-2, this effect was also apparent at the promoter level. Overexpression of Hdac-8 in RAW264 murine macrophages blocked the ability of LPS to induce Cox-2 mRNA. Another class of LPS-inducible genes, which included Ccl2, Ccl7, and Edn1, was suppressed by TSA, an effect most likely mediated by PU.1 degradation. Hence, HDACs act as potent and selective negative regulators of proinflammatory gene expression and act to prevent excessive inflammatory responses in macrophages.

Animals↗

Cytokine and chemokine gene polymorphisms among ethnically diverse North Americans with HIV-1 infection.

Twenty-four common single nucleotide polymorphisms (SNPs) in 10 cytokine and chemokine genes were defined in 579 North Americans at high risk of HIV-1 infection due to sexual behavior and injection drug use. Among the 3 major ethnic (African-American, Hispanic/Latino, and other) groups involved, HIV-1-seropositive individuals differed significantly from ethnically matched HIV-1-seronegative individuals (odds ratios = 2.13-4.82; P = 0.003-0.05) for several SNPs and haplotypes defined at the IL4, IL4R, IL6, IL10, CCL5 (RANTES), and CXCL12 (SDF1) loci. In addition, the homozygous IL4-590T/T genotype was associated with higher (+87-131 cells/microL) CD4 T-cell counts in HIV-1-infected and AIDS-free adolescents not receiving antiretroviral therapy (adjusted P = 0.004). No SNPs at IFNG, IL2, IL12B, TNF, or CCL2 (MCP1) showed any association with HIV-related outcomes. Additional typing for IL1A, IL1B, IL1R1, IL1RN, and TGFB1 SNPs also failed to demonstrate any influence on HIV-1 infection or virologic/immunologic control in more selected patient groups. Coupled with previous findings, our data suggest that heritable IL4 and IL10 variations may contribute to the acquisition or progression of HIV infection and that the effects of other targeted loci in the cytokine and chemokine system cannot be established unequivocally in the study populations.

Adolescent↗