The relative activity of CXCR3 and CCR5 ligands in T lymphocyte migration: concordant and disparate activities in vitro and in vivo

Heterodimers Are an Integral Component of Chemokine Signaling Repertoire

Chemokines are a family of signaling proteins that play a crucial role in cell-cell communication, cell migration, and cell trafficking, particularly leukocytes, under both normal and pathological conditions. The oligomerization state of chemokines influences their biological activity. The heterooligomerization occurs when multiple chemokines spatially and temporally co-localize, and it can significantly affect cellular responses. Recently, obligate heterodimers have emerged as tools to investigate the activities and molecular mechanisms of chemokine heterodimers, providing valuable insights into their functional roles. This review focuses on the latest progress in understanding the roles of chemokine heterodimers and their contribution to the functioning of the chemokine network.

Interleukin-6 trans-signaling induced laminin switch contributes to reduced trans-endothelial migration of granulocytic cells

BACKGROUND AND AIMS

Laminins are essential components of the endothelial basement membrane, which predominantly contains LN421 and LN521 isoforms. Regulation of laminin expression under pathophysiological conditions is largely unknown. In this study, we aimed to investigate the role of IL-6 in regulating endothelial laminin profile and characterize the impact of altered laminin composition on the phenotype, inflammatory response, and function of endothelial cells (ECs).

METHODS

HUVECs and HAECs were used for in vitro experiments. Trans-well migration experiments were performed using leukocytes isolated from peripheral blood of healthy donors. The BiKE cohort was used to assess expression of laminins in atherosclerotic plaques and healthy vessels. Gene and protein expression was analyzed using Microarray/qPCR and proximity extension assay, ELISA, immunostaining or immunoblotting techniques, respectively.

RESULTS

Stimulation of ECs with IL-6+sIL-6R, but not IL-6 alone, reduces expression of laminin α4 (LAMA4) and increases laminin α5 (LAMA5) expression at the mRNA and protein levels. In addition, IL-6+sIL-6R stimulation of ECs differentially regulates the release of several proteins including CXCL8 and CXCL10, which collectively were predicted to inhibit granulocyte transmigration. Experimentally, we demonstrated that granulocyte migration is inhibited across ECs pre-treated with IL-6+sIL-6R. In addition, granulocyte migration across ECs cultured on LN521 was significantly lower compared to LN421. In human atherosclerotic plaques, expression of endothelial LAMA4 and LAMA5 is significantly lower compared to control vessels. Moreover, LAMA5-to-LAMA4 expression ratio was negatively correlated with granulocytic cell markers (CD177 and myeloperoxidase (MPO)) and positively correlated with T-lymphocyte marker CD3.

CONCLUSIONS

We showed that expression of endothelial laminin alpha chains is regulated by IL-6 trans-signaling and contributes to inhibition of trans-endothelial migration of granulocytic cells. Further, expression of laminin alpha chains is altered in human atherosclerotic plaques and is related to intra-plaque abundance of leukocyte subpopulations.

Chemokine Receptor Expression on T Cells Is Modulated by CAFs and Chemokines Affect the Spatial Distribution of T Cells in Pancreatic Tumors

Simple Summary

The infiltration of T cells in pancreatic tumors has been correlated with better overall survival. However, the dense desmoplastic stroma, mainly composed by cancer-associated fibroblasts (CAFs), can sequester the T cells in the stroma preventing them from reaching the tumor nests. Chemokines are small molecules capable of directing T cell migration. Here, we explored whether CAFs could modulate the expression of chemokine receptors on T cells and examined if the spatial distribution of T cells within tumors was correlated to chemokine secretion patterns. Overall, we found that CXCR3 ligands was associated with an increased number of T cells in tumor rich areas and that CAFs downregulated the expression of CXCR3 on T cells. Understanding the mechanisms by which T cells are prevented from reaching the tumor nests is of great importance for the development of novel targeting therapies.

Abstract

The accumulation of T cells is associated with a better prognosis in pancreatic cancer. However, the immunosuppressive tumor microenvironment, largely composed by cancer-associated fibroblasts (CAFs), can prevent T cells from reaching the tumor nests. We examined how human CAFs modulated chemokine receptors known to be associated with T cell trafficking, CXCR3 and CCR5, and T cell exclusion, CXCR4. CAFs decreased the expression of CXCR3 and CCR5 but increased CXCR4 expression in both 2D and 3D cultures, affecting the migratory capacity of T cells towards CXCL10. An immunohistochemistry analysis showed that very few T cells were found in the tumor nests. Within the stroma, CD8⁺ T cells were localized more distantly from the malignant cells whereas CD4⁺ T cells were more equally distributed. Tumor tissues with a high production of chemokines were associated with less T cell infiltration when the whole tissue was analyzed. However, when the spatial localization of CD8⁺ T cells within the tissue was taken into account, levels of CXCR3 ligands and the CCR5 ligand CCL8 showed a positive association with a high relative T cell infiltration in tumor-rich areas. Thus, CXCR3 ligands could mediate T cell trafficking but CAFs could prevent T cells from reaching the malignant cells.

Inflammatory cytokine profile and T cell responses in African tick bite fever patients

African tick bite fever, an acute febrile illness, is caused by the obligate intracellular bacterium Rickettsia africae. Immune responses to rickettsial infections have so far mainly been investigated in vitro with infected endothelial cells as the main target cells, and in mouse models. Patient studies are rare and little is known about the immunology of human infections. In this study, inflammatory mediators and T cell responses were examined in samples from 13 patients with polymerase chain reaction-confirmed R. africae infections at different time points of illness. The Th1-associated cytokines IFNγ and IL-12 were increased in the acute phase of illness, as were levels of the T cell chemoattractant cytokine CXCL-10. In addition, the anti-inflammatory cytokine IL-10 and also IL-22 were elevated. IL-22 but not IFNγ was increasingly produced by CD4⁺ and CD8⁺ T cells during illness. Besides IFNγ, IL-22 appears to play a protective role in rickettsial infections.

Semen: A modulator of female genital tract inflammation and a vector for HIV-1 transmission

In order to establish productive infection in women, HIV must transverse the vaginal epithelium and gain access to local target cells. Genital inflammation contributes to the availability of HIV susceptible cells at the female genital mucosa and is associated with higher HIV transmission rates in women. Factors that contribute to genital inflammation may subsequently increase the risk of HIV infection in women. Semen is a highly immunomodulatory fluid containing several bioactive molecules with the potential to influence inflammation and immune activation at the female genital tract. In addition to its role as a vector for HIV transmission, semen induces profound mucosal changes to prime the female reproductive tract for conception. Still, most studies of mucosal immunity are conducted in the absence of semen or without considering its immune impact on the female genital tract. This review discusses the various mechanisms by which semen exposure may influence female genital inflammation and highlights the importance of routine screening for semen biomarkers in vaginal specimens to account for its impact on genital inflammation.

Targeting regulator of G protein signaling 1 in tumor-specific T cells enhances their trafficking to breast cancer

Reduced infiltration of anti-tumor lymphocytes remains a major cause of tumor immune evasion and is correlated with poor cancer survival. Here, we found that upregulation of regulator of G protein signaling (RGS)1 in helper TH1 cells and cytotoxic T lymphocytes (CTLs) reduced their trafficking to and survival in tumors and was associated with shorter survival of patients with breast and lung cancer. RGS1 was upregulated by type II interferon (IFN)-signal transducer and activator of transcription (STAT)1 signaling and impaired trafficking of circulating T cells to tumors by inhibiting calcium influx and suppressing activation of the kinases ERK and AKT. RGS1 knockdown in adoptively transferred tumor-specific CTLs significantly increased their infiltration and survival in breast and lung tumor grafts and effectively inhibited tumor growth in vivo, which was further improved when combined with programmed death ligand (PD-L)1 checkpoint inhibition. Our findings reveal RGS1 is important for tumor immune evasion and suggest that targeting RGS1 may provide a new strategy for tumor immunotherapy.

Microbial mismanagement: how inadequate treatments for vaginal dysbiosis drive the HIV epidemic in women

Women and girls represent a key population driving new HIV infections and persistence of the HIV pandemic. A key determinant of HIV susceptibility is the composition of the vaginal microbiome, which can influence the local immune cell population, inflammation status, and HIV prevention drug levels. While a low-diversity composition dominated by Lactobacillus crispatus is associated with a decreased risk of HIV acquisition, high diversity environments associated with bacterial vaginosis increase risk of HIV. Given the important role of the vaginal microbiome in determining HIV susceptibility, altering the microbiome towards a Lactobacillus-dominated state is an attractive complementary strategy to reduce HIV incidence rates. Here, we provide an overview of the mechanisms by which the vaginal microbiome may contribute to HIV acquisition risk. Furthermore, we address the advantages and limitations of historical treatments and emerging technologies under investigation to modify the vaginal microbiome, including: antibiotics, bacteriophages, probiotics, topicals, and engineered bacteria. By addressing the current state of vaginal microbiome knowledge and strategies for manipulation, we hope to amplify the growing calls for increased resources and research into vaginal microbial health, which will be essential to accelerating preventative efforts amongst the world's most vulnerable populations.

Transient association between semen exposure and biomarkers of genital inflammation in South African women at risk of HIV infection

INTRODUCTION

Semen induces mucosal changes in the female reproductive tract to improve pregnancy outcomes. Since semen-induced alterations are likely short-lived and genital inflammation is linked to HIV acquisition in women, we investigated the contribution of recent semen exposure on biomarkers of genital inflammation in women at high HIV risk and the persistence of these associations.

METHODS

We assessed stored genital specimens from 152 HIV-negative KwaZulu-Natal women who participated in the CAPRISA 008 trial between November 2012 and October 2014. During the two-year study period, 651 vaginal specimens were collected biannually (mean five samples per woman). Cervicovaginal lavage (CVL) was screened for prostate-specific antigen (PSA) by ELISA, whereas Y-chromosome DNA (YcDNA) detection and quantification were conducted by RT-PCR, representing semen exposure within 48 hours (PSA+YcDNA+) and semen exposure within three to fifteen days (PSA-YcDNA+). Soluble protein concentrations were measured in CVLs by multiplexed ELISA. T-cell frequencies were assessed in cytobrushes by flow-cytometry, and vulvovaginal swabs were used to detect common vaginal microbes by PCR. Linear mixed models adjusting for factors associated with genital inflammation and HIV risk were used to assess the impact of semen exposure on biomarkers of inflammation over multiple visits.

RESULTS

Here, 19% (125/651) of CVLs were PSA+YcDNA+, 14% (93/651) were PSA-YcDNA+ and 67% (433/651) were PSA-YcDNA-. Semen exposure was associated with how often women saw their partners, the frequency of vaginal sex in the past month, HSV-2 antibody detection, current gonorrhoea infection and Nugent Score. Both PSA detection (PSA+YcDNA+) and higher cervicovaginal YcDNA concentrations predicted increases in several cytokines, barrier-related proteins (MMP-2, TIMP-1 and TIMP-4) and activated CD4+CCR5+HLA-DR+ T cells (β = 0.050; CI 0.001 to 0.098; p = 0.046) and CD4+HLA-DR+ T cells (β = 0.177; CI 0.016 to 0.339; p = 0.032) respectively. PSA detection was specifically associated with raised pro-inflammatory cytokines (including IL-6, TNF-α, IP-10 and RANTES), and with the detection of BVAB2 (OR = 1.755; CI 1.116 to 2.760; p = 0.015), P. bivia (OR = 1.886; CI 1.102 to 3.228; p = 0.021) and Gardnerella vaginalis (OR = 1.815; CI 1.093 to 3.015; p = 0.021).

CONCLUSIONS

More recent semen exposure was associated with raised levels of inflammatory biomarkers and the detection of BV-associated microbes, which declined by three to fifteen days of post-exposure. Although transient, semen-induced alterations may have implications for HIV susceptibility in women.

Germinated black soybean fermented with Lactobacillus pentosus SC65 alleviates DNFB-induced delayed-type hypersensitivity in C57BL/6N mice

ETHNOPHARMACOLOGICAL RELEVANCE

Rhynchosia nulubilis (black soybean) has many applications in oriental medicine. It is traditionally used to treat disease related with high blood pressure, diabetes, inflammation, and osteoporosis. Furthermore, fermented soybean foods have traditionally been used for immunity enhancement in East Asia. However, the anti-inflammatory effects of germinated R. nulubilis (GR) against delayed-type hypersensitivity (DTH) are not fully understood.

AIM OF STUDY

This study aimed to investigate the anti-inflammatory effects of germinated Rhynchosia nulubilis (GR) fermented with the lactic acid bacterium Lactobacillus pentosus SC65 (GR-SC65) isolated from pickled burdock.

MATERIALS AND METHODS

We investigated the effects of GR-SC65 (300 mg/kg/day) on ear thickness and immune cell infiltration in DNFB-induced DTH in mice. We used dexamethasone (3 mg/kg) as a reference drug. Changes in infiltration of CD4+ and CD8+ T cells and NK cells were examined by immunohistochemistry. In addition, we investigated cytokine and chemokine production related to DTH using reverse transcription-polymerase chain reaction. We also investigated DTH-related cytokine production using lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells.

RESULTS

Two lactic acid bacterial strains (Lactobacillus pentosus SC65 and Pediococcus pentosaceus ON81A) were selected for fermenting GR due to their high 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity. The total polyphenol contents (TPCs) in GR-SC65 and GR-ON81A were higher than that in unfermented GR (∗∗∗P < 0.001 vs. GR). Content of daidzein, glycitein, and genistein, the deglycosylated form of isoflavonoids, was higher in GR-SC65 than in unfermented GR. The ethanol extracts of GR-SC65 exerted a stronger anti-inflammatory activity than GR by inhibiting pro-inflammatory cytokines, such as tumor necrosis factor (TNF), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in LPS-induced RAW264.7 macrophages. GR-SC65 reduced 1-fluoro-2,4-dinitrofluorobenzene (DNFB)-induced ear swelling and hyperplasia as well as vascular permeability. Fewer infiltrated CD4+ and CD8+ T cells were observed in the ear tissue of the GR-SC65-treated mice than those of the unfermented GR-treated mice. Furthermore, fewer infiltrated NK cells were observed in the GR-SC65 treated mice, than in the GR-treated mice. GR-SC65 significantly diminished the levels of CCL5 and COX-2 mRNAs and increased the level of IL-10 mRNA.

CONCLUSIONS

These data suggest that GR-SC65 can be used as a health supplement or a prophylactic against delayed-type hypersensitive inflammatory disease.

Identification of New Soluble Factors Correlated With the Development of Graft Failure After Haploidentical Hematopoietic Stem Cell Transplantation

Graft failure is a severe complication of allogeneic hematopoietic stem cell transplantation (HSCT). The mechanisms involved in this phenomenon are still not completely understood; data available suggest that recipient T lymphocytes surviving the conditioning regimen are the main mediators of immune-mediated graft failure. So far, no predictive marker or early detection method is available. In order to identify a non-invasive and efficient strategy to diagnose this complication, as well as to find possible targets to prevent/treat it, we performed a detailed analysis of serum of eight patients experiencing graft failure after T-cell depleted HLA-haploidentical HSCT. In this study, we confirm data describing graft failure to be a complex phenomenon involving different components of the immune system, mainly driven by the IFNγ pathway. We observed a significant modulation of IL7, IL8, IL18, IL27, CCL2, CCL5 (Rantes), CCL7, CCL20 (MIP3a), CCL24 (Eotaxin2), and CXCL11 in patients experiencing graft failure, as compared to matched patients not developing this complication. For some of these factors, the difference was already present at the time of infusion of the graft, thus allowing early risk stratification. Moreover, these cytokines/chemokines could represent possible targets, providing the rationale for exploring new therapeutic/preventive strategies.

Inflammation, HIV, and Immune Quiescence: Leveraging on Immunomodulatory Products to Reduce HIV Susceptibility

The relationship between inflammation and HIV has been a focus of research over the last decade. In HIV-infected individuals, increased HIV-associated immune activation significantly correlated to disease progression. While genital inflammation (GI) has been shown to significantly increase the risk of HIV acquisition and transmission, immune correlates for reduced risk remain limited. In certain HIV-exposed seronegative individuals, an immune quiescent phenotype characterized reduced risk. Immune quiescence is defined by specific, targeted, highly regulated immune responses that hinder overt inflammation or immune activation. Targeted management of inflammation, therefore, is a plausible strategy to mitigate HIV risk and slow disease progression. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as hydroxychloroquine and aspirin have shown encouraging preliminary results in low-risk women by reducing systemic and genital immune activation. A topical NSAID, containing ibuprofen, is effective in treating vulvovaginal inflammation. Additionally, the glucocorticoids (GCs), prednisolone, and dexamethasone are used to treat HIV-associated immune activation. Collectively, these data inform on immune-modulating drugs to reduce HIV risk. However, the prolonged use of these pharmaceutical drugs is associated with adverse effects, both systemically and to a lesser extent topically. Natural products with their reduced side effects coupled with anti-inflammatory properties render them viable options. Lactic acid (LA) has immunomodulatory properties. LA regulates the genital microbiome by facilitating the growth of Lactobacillus species, while simultaneously limiting bacterial species that cause microbial dysbiosis and GI. Glycerol monolaurate, besides being anti-inflammatory, also inhibited SIV infections in rhesus macaques. The proposed pharmaceutical and natural products could be used in combination with either antiretrovirals for treatment or preexposure prophylaxis for HIV prevention. This review provides a summary on the associations between inflammation, HIV risk, and disease progression. Furthermore, we use the knowledge from immune quiescence to exploit the use of pharmaceutical and natural products as strategic interventions to manage inflammation, toward mitigating HIV infections.

CXCL14 Preferentially Synergizes With Homeostatic Chemokine Receptor Systems

Reflecting their importance in immunity, the activity of chemokines is regulated on several levels, including tissue and context-specific expression and availability of their cognate receptor on target cells. Chemokine synergism, affecting both chemokine and chemokine receptor function, has emerged as an additional control mechanism. We previously demonstrated that CXCL14 is a positive allosteric modulator of CXCR4 in its ability to synergize with CXCL12 in diverse cellular responses. Here, we have extended our study to additional homeostatic, as well as a selection of inflammatory chemokine systems. We report that CXCL14 strongly synergizes with low (sub-active) concentrations of CXCL13 and CCL19/CCL21 in in vitro chemotaxis with immune cells expressing the corresponding receptors CXCR5 and CCR7, respectively. CXCL14 by itself was inactive, not only on cells expressing CXCR5 or CCR7 but also on cells expressing any other known conventional or atypical chemokine receptor, as assessed by chemotaxis and/or β-arrestin recruitment assays. Furthermore, synergistic migration responses between CXCL14 and inflammatory chemokines CXCL10/CXCL11 and CCL5, targeting CXCR3 and CCR5, respectively, were marginal and occasional synergistic Ca²⁺ flux responses were observed. CXCL14 bound to 300-19 cells and interfered with CCL19 binding to CCR7-expressing cells, suggesting that these cellular interactions contributed to the reported CXCL14-mediated synergistic activities. We propose a model whereby tissue-expressed CXCL14 contributes to cell localization under steady-state conditions at sites with prominent expression of homeostatic chemokines.

Concepts of GPCR-controlled navigation in the immune system

G‐protein–coupled receptor (GPCR) signaling is essential for the spatiotemporal control of leukocyte dynamics during immune responses. For efficient navigation through mammalian tissues, most leukocyte types express more than one GPCR on their surface and sense a wide range of chemokines and chemoattractants, leading to basic forms of leukocyte movement (chemokinesis, haptokinesis, chemotaxis, haptotaxis, and chemorepulsion). How leukocytes integrate multiple GPCR signals and make directional decisions in lymphoid and inflamed tissues is still subject of intense research. Many of our concepts on GPCR‐controlled leukocyte navigation in the presence of multiple GPCR signals derive from in vitro chemotaxis studies and lower vertebrates. In this review, we refer to these concepts and critically contemplate their relevance for the directional movement of several leukocyte subsets (neutrophils, T cells, and dendritic cells) in the complexity of mouse tissues. We discuss how leukocyte navigation can be regulated at the level of only a single GPCR (surface expression, competitive antagonism, oligomerization, homologous desensitization, and receptor internalization) or multiple GPCRs (synergy, hierarchical and non‐hierarchical competition, sequential signaling, heterologous desensitization, and agonist scavenging). In particular, we will highlight recent advances in understanding GPCR‐controlled leukocyte navigation by intravital microscopy of immune cells in mice.

The role of miR-146a in viral infection

Cellular microRNAs (miRNAs) were identified as a key player in the posttranscriptional regulation of cellular-genes regulatory pathways. They also emerged as a significant regulator of the immune response. In particular, miR-146a acts as an importance modulator of function and differentiation cells of the innate and adaptive immunity. It has been associated with disorder including cancer and viral infections. Given its significance in the regulation of key cellular processes, it is not surprising which virus infection have found ways to dysregulation of miRNAs. miR-146a has been identified in exosomes (exosomal miR-146a). After the exosomes release from donor cells, they are taken up by the recipient cell and probably the exosomal miR-146a is able to modulate the antiviral response in the recipient cell and result in making them more susceptible to virus infection. In this review, we discuss recent reports regarding miR-146a expression levels, target genes, function, and contributing role in the pathogenesis of the viral infection and provide a clue to develop the new therapeutic and preventive strategies for viral disease in the future.

The emerging role of epigenetic therapeutics in immuno-oncology

The past decade has seen the emergence of immunotherapy as a prime approach to cancer treatment, revolutionizing the management of many types of cancer. Despite the promise of immunotherapy, most patients do not have a response or become resistant to treatment. Thus, identifying combinations that potentiate current immunotherapeutic approaches will be crucial. The combination of immune-checkpoint inhibition with epigenetic therapy is one such strategy that is being tested in clinical trials, encompassing a variety of cancer types. Studies have revealed key roles of epigenetic processes in regulating immune cell function and mediating antitumour immunity. These interactions make combined epigenetic therapy and immunotherapy an attractive approach to circumvent the limitations of immunotherapy alone. In this Review, we highlight the basic dynamic mechanisms underlying the synergy between immunotherapy and epigenetic therapies and detail current efforts to translate this knowledge into clinical benefit for patients.

Interleukin-1β induces CXCR3-mediated chemotaxis to promote umbilical cord mesenchymal stem cell transendothelial migration

BACKGROUND

Mesenchymal stem cells (MSCs) are known to home to injured and inflamed regions via the bloodstream to assist in tissue regeneration in response to signals of cellular damage. However, the factors and mechanisms that affect their transendothelial migration are still unclear. In this study, the mechanisms involved in interleukin-1β (IL-1β) enhancing the transendothelial migration of MSCs were investigated.

METHODS

Immunofluorescence staining and Western blotting were used to observe IL-1β-induced CXC chemokine receptor 3 (CXCR3) expression on MSCs. Quantitative real-time PCR and ELISA were used to demonstrate IL-1β upregulated both chemokine (C-X-C motif) ligand 9 (CXCL9) mRNA and CXCL9 ligand secretion in human umbilical vein endothelial cells (HUVECs). Monolayer co-cultivation, agarose drop chemotaxis, and transwell assay were conducted to investigate the chemotaxis invasion and transendothelial migration ability of IL-1β-induced MSCs in response to CXCL9.

RESULTS

In this study, our immunofluorescence staining showed that IL-1β induces CXCR3 expression on MSCs. This result was confirmed by Western blotting. Following pretreatment with protein synthesis inhibitor cycloheximide, we found that IL-1β induced CXCR3 on the surface of MSCs via protein synthesis pathway. Quantitative real-time PCR and ELISA validated that IL-1β upregulated both CXCL9 mRNA and CXCL9 ligand secretion in HUVECs. In response to CXCL9, chemotaxis invasion and transendothelial migration ability were increased in IL-1β-stimulated MSCs. In addition, we pretreated MSCs with CXCR3 antagonist AMG-487 and p38 MAPK inhibitor SB203580 to confirm CXCR3-CXCL9 interaction and the role of CXCR3 in IL-1β-induced chemotaxis invasion and transendothelial migration.

CONCLUSION

We found that IL-1β induces the expression of CXCR3 through p38 MAPK signaling and that IL-1β also enhances CXCL9 ligand secretion in HUVECs. These results indicated that IL-1β promotes the transendothelial migration of MSCs through CXCR3-CXCL9 axis. The implication of the finding could enhance the efficacy of MSCs homing to target sites.

HIV-1-Induced miR-146a Attenuates Monocyte Migration by Targeting CCL5 in Human Primary Macrophages

MicroRNAs (miRNAs) are widely involved in immune regulation during virus infection. Several studies showed that the expression of miR-146a was increased in human immunodeficiency virus type I (HIV-1)-infected cells, but the definitive function of miR-146a in HIV-1 infection remains obscure. The production of chemokine (C-C motif) ligand 5 (CCL5) in macrophages has been reported to play an important role in HIV/AIDS-associated pathogenesis. In this study, we examined the effects of miR-146a on CCL5 regulation in HIV-1-infected macrophages. Gain and loss of function studies showed that CCL5 might be one of the miR-146a targets, as miR-146a mimic reduced, while miR-146a inhibitor increased CCL5 production in HIV-1-infected macrophages. In addition, we demonstrated that miR-146a reduced CCL5-induced monocyte migration. Our study provided evidence that miR-146a targets CCL5 3' untranslated regions, downregulates its release from macrophages, and affects monocyte migration consequently. These findings drew a novel layer of posttranscriptional control of the chemokine CCL5 by miR-146a during HIV infection, which might contribute to HIV pathogenesis.

Interferon α2 and interferon γ induce the degranulation independent production of VEGF-A and IL-1 receptor antagonist and other mediators from human mast cells

Background

Mast cells are resident immune effector cells, often studied in the context of allergic disease. Found in substantial numbers at sites of potential infection they are increased at sites of angiogenesis and can be pivotal for the sensing and clearance of a variety of pathogens. Interferons (IFNs) are cytokines that are critical for host defence against intracellular pathogens. Increased levels of IFNs are observed during viral infection and in autoimmune diseases. IFNs are also widely used therapeutically and have been examined in the therapy of severe asthma.

Objective

To define the selective human mast cell cytokine and chemokine response following activation with type I or type II IFN's.

Methods

The ability of both IFNα2 and IFNγ to induce cytokine production by human cord blood‐derived mast cells was examined in vitro. Cytokine and chemokine production at 6 and 24 h was assessed by multiplex protein analysis. Degranulation was assessed by β‐hexosaminidase release. Mast cells were also treated with reovirus or respiratory syncytial virus and their production of CXCL10, IL‐1 receptor antagonist (IL‐1Ra), and vascular endothelial growth factor (VEGF) examined after 24 h.

Results

In addition to increased expression of classical IFN response genes, such as CXCL10, small but significant increases in CCL5 and IL‐17 production were observed following IFN activation. Notably, human mast cells produced both VEGF and IL‐1Ra in a dose dependent manner. These responses occurred in the absence of mast cell degranulation by a mechanism consistent with classical IFN signaling. Both reovirus and respiratory syncytial virus infection of mast cells, were also associated with IFN‐dependent IL‐1Ra expression.

Conclusion and Clinical Relevance

Our findings demonstrate that IFNs have profound impact on cytokine and chemokine expression by human mast cells, alone or in the context of viral infection. Mast cell VEGF and IL‐1Ra responses to IFNs could impact the regulation of local inflammatory responses and subsequent tissue remodeling.

Epithelial chemokine CXCL14 synergizes with CXCL12 via allosteric modulation of CXCR4

The chemokine receptor, CXC chemokine receptor 4 (CXCR4), is selective for CXC chemokine ligand 12 (CXCL12), is broadly expressed in blood and tissue cells, and is essential during embryogenesis and hematopoiesis. CXCL14 is a homeostatic chemokine with unknown receptor selectivity and preferential expression in peripheral tissues. Here, we demonstrate that CXCL14 synergized with CXCL12 in the induction of chemokine responses in primary human lymphoid cells and cell lines that express CXCR4. Combining subactive concentrations of CXCL12 with 100–300 nM CXCL14 resulted in chemotaxis responses that exceeded maximal responses that were obtained with CXCL12 alone. CXCL14 did not activate CXCR4-expressing cells (i.e., failed to trigger chemotaxis and Ca²⁺ mobilization, as well as signaling via ERK1/2 and the small GTPase Rac1); however, CXCL14 bound to CXCR4 with high affinity, induced redistribution of cell-surface CXCR4, and enhanced HIV-1 infection by >3-fold. We postulate that CXCL14 is a positive allosteric modulator of CXCR4 that enhances the potency of CXCR4 ligands. Our findings provide new insights that will inform the development of novel therapeutics that target CXCR4 in a range of diseases, including cancer, autoimmunity, and HIV.—Collins, P. J., McCully, M. L., Martínez-Muñoz, L., Santiago, C., Wheeldon, J., Caucheteux, S., Thelen, S., Cecchinato, V., Laufer, J. M., Purvanov, V., Monneau, Y. R., Lortat-Jacob, H., Legler, D. F., Uguccioni, M., Thelen, M., Piguet, V., Mellado, M., Moser, B. Epithelial chemokine CXCL14 synergizes with CXCL12 via allosteric modulation of CXCR4.

Infiltrating T cells promote renal cell carcinoma (RCC) progression via altering the estrogen receptor β-DAB2IP signals

Previous studies indicated the T cells, one of the most common types of immune cells existing in the microenvironment of renal cell carcinoma (RCC), may influence the progression of RCC. The potential linkage of T cells and the estrogen receptor beta (ERβ), a key player to impact RCC progression, however, remains unclear. Our results demonstrate that RCC cells can recruit more T cells than non-malignant kidney cells. Using an in vitro matrigel invasion system, we found infiltrating T cells could promote RCC cells invasion via increasing ERβ expression and transcriptional activity. Mechanism dissection suggested that co-culturing T cells with RCC cells released more T cell attraction factors, including IFN-γ, CCL3 and CCL5, suggesting a positive regulatory feed-back mechanism. Meanwhile, infiltrating T cells may also promote RCC cell invasion via increased ERβ and decreased DAB2IP expressions, and knocking down DAB2IP can then reverse the T cells-promoted RCC cell invasion. Together, our results suggest that infiltrating T cells may promote RCC cell invasion via increasing the RCC cell ERβ expression to inhibit the tumor suppressor DAB2IP signals. Further mechanism dissection showed that co-culturing T cells with RCC cells could produce more IGF-1 and FGF-7, which may enhance the ERβ transcriptional activity. The newly identified relationship between infiltrating T cells/ERβ/DAB2IP signals may provide a novel therapeutic target in the development of agents against RCC.

Genital inflammation, immune activation and risk of sexual HIV acquisition

PURPOSE OF REVIEW

Women who have genital inflammation are at increased risk of sexual HIV infection. The purpose of this review is to evaluate the mechanisms for this relationship, causes of genital inflammation, and strategies to manage this condition.

RECENT FINDINGS

We have recently shown in a cohort of South African women that HIV seroconversion was associated with persistently raised genital inflammatory cytokines (including MIP-1α, MIP-1β, and IP-10). Elevated inflammatory cytokine concentrations may facilitate HIV infection by recruiting and activating HIV target cells and disrupting the mucosal epithelial barrier. Bacterial vaginosis and sexually transmitted infections (STIs), which are predominantly asymptomatic in women, cause lower genital tract inflammation and increased HIV acquisition risk. In Africa, where syndromic management of STIs and bacterial vaginosis is standard-of-care, the substantial burden of asymptomatic infections has likely contributed to high-HIV incidence rates.

SUMMARY

A genital inflammatory profile contributes to the high risk of HIV acquisition in African women. STIs and bacterial vaginosis are poorly managed in Africa and other developing nations and as such remain major drivers of persistent genital inflammation and HIV acquisition among these women.

Cervicovaginal Inflammation Facilitates Acquisition of Less Infectious HIV Variants

We evaluated whether genital inflammation affects the selection of the transmitted virus. Among South African women, we found that preinfection genital inflammation facilitates transmission of less infectious human immunodeficiency virus, but highly infectious viruses are able to establish infection regardless of inflammation status. This suggests that viral phenotype can influence transmission risk.

Self-adjuvanted mRNA vaccines induce local innate immune responses that lead to a potent and boostable adaptive immunity

mRNA represents a new platform for the development of therapeutic and prophylactic vaccines with high flexibility with respect to production and application. We have previously shown that our two component self-adjuvanted mRNA-based vaccines (termed RNActive® vaccines) induce balanced immune responses comprising both humoral and cellular effector as well as memory responses. Here, we evaluated the early events upon intradermal application to gain more detailed insights into the underlying mode of action of our mRNA-based vaccine. We showed that the vaccine is taken up in the skin by both non-leukocytic and leukocytic cells, the latter being mostly represented by antigen presenting cells (APCs). mRNA was then transported to the draining lymph nodes (dLNs) by migratory dendritic cells. Moreover, the encoded protein was expressed and efficiently presented by APCs within the dLNs as shown by T cell proliferation and immune cell activation, followed by the induction of the adaptive immunity. Importantly, the immunostimulation was limited to the injection site and lymphoid organs as no proinflammatory cytokines were detected in the sera of the immunized mice indicating a favorable safety profile of the mRNA-based vaccines. Notably, a substantial boostability of the immune responses was observed, indicating that mRNA can be used effectively in repetitive immunization schedules. The evaluation of the immunostimulation following prime and boost vaccination revealed no signs of exhaustion as demonstrated by comparable levels of cytokine production at the injection site and immune cell activation within dLNs. In summary, our data provide mechanistic insight into the mode of action and a rational for the use of mRNA-based vaccines as a promising immunization platform.

Injectable Progestin-Only Contraception is Associated With Increased Levels of Pro-Inflammatory Cytokines in the Female Genital Tract

PROBLEM

Genital inflammatory changes may be a mechanism of increased HIV risk among injectable progestin-only contraception (IPC) users.

METHOD OF STUDY

We conducted a cross-sectional analysis of 376 Kenyan and South African women. Genital cytokines and secretory leukocyte peptidase inhibitor concentrations in a reference population were compared to IPC users and women with reproductive tract infections.

RESULTS

No significant variability in marker concentrations was observed by age or site. Depot medroxyprogesterone acetate (DMPA) users had significantly higher MIP-1α, MIP-1β, IL-6, IL-8, IP-10, and RANTES concentrations. Norethisterone oenanthate users had significantly higher IL-6, IL-8, and RANTES concentrations. Women with sexually transmitted infections had variable inflammation, and women with bacterial vaginosis exhibited a mixed profile of up and downregulation.

CONCLUSION

The finding of substantial mucosal inflammation among DMPA users provides evidence which, combined with the results of prior studies, suggests that DMPA may create an immune environment conducive to HIV target cell recruitment and inhibitory for antiviral activity.

Genital inflammation and the risk of HIV acquisition in women

BACKGROUND

Women in Africa, especially young women, have very high human immunodeficiency virus (HIV) incidence rates that cannot be fully explained by behavioral risks. We investigated whether genital inflammation influenced HIV acquisition in this group.

METHODS

Twelve selected cytokines, including 9 inflammatory cytokines and chemokines (interleukin [IL]-1α, IL-1β, IL-6, tumor necrosis factor-α, IL-8, interferon-γ inducible protein-10 [IP-10], monocyte chemoattractant protein-1, macrophage inflammatory protein [MIP]-1α, MIP-1β), hematopoietic IL-7, and granulocyte macrophage colony-stimulating factor, and regulatory IL-10 were measured prior to HIV infection in cervicovaginal lavages from 58 HIV seroconverters and 58 matched uninfected controls and in plasma from a subset of 107 of these women from the Centre for the AIDS Programme of Research in South Africa 004 tenofovir gel trial.

RESULTS

HIV seroconversion was associated with raised genital inflammatory cytokines (including chemokines MIP-1α, MIP-1β, and IP-10). The risk of HIV acquisition was significantly higher in women with evidence of genital inflammation, defined by at least 5 of 9 inflammatory cytokines being raised (odds ratio, 3.2; 95% confidence interval, 1.3-7.9; P = .014). Genital cytokine concentrations were persistently raised (for about 1 year before infection), with no readily identifiable cause despite extensive investigation of several potential factors, including sexually transmitted infections and systemic cytokines.

CONCLUSIONS

Elevated genital concentrations of HIV target cell-recruiting chemokines and a genital inflammatory profile contributes to the high risk of HIV acquisition in these African women.

Gene-expression profiling of calves 6 and 9 months after inoculation with Mycobacterium avium subspecies paratuberculosis

Early detection of Johne’s disease (JD) caused by Mycobacterium avium subspecies paratuberculosis (MAP) is essential to reduce transmission; consequently, new diagnostic techniques and approaches to detect MAP or markers of early MAP infection are being explored. The objective was to identify biomarkers associated with MAP infection at 6 and 9 months after oral inoculation. Therefore, gene expression analysis was done using whole blood cells obtained from MAP-infected calves. All MAP-inoculated calves had a cell-mediated immune response (IFN-γ) to Johnin PPD specific antigens, and 60% had an antibody response to MAP antigens. Gene expression analysis at 6 months after inoculation revealed downregulation of chemoattractants, namely neutrophil beta-defensin-9 like peptide (BNBD9-Like), S100 calcium binding protein A9 (s100A9) and G protein coupled receptor 77 (GPR77) or C5a anaphylatoxin chemotactic receptor (C5a2). Furthermore, BOLA/MHC-1 intracellular antigen presentation gene was downregulated 9 months after inoculation. In parallel, qPCR experiments to evaluate the robustness of some differentially expressed genes revealed consistent downregulation of BOLA/MHC-I, BNBD9-Like and upregulation of CD46 at 3, 6, 9, 12, and 15 months after inoculation. In conclusion, measuring the expression of these genes has potential for implementation in a diagnostic tool for the early detection of MAP infection.

'Neuroinflammation' differs categorically from inflammation: transcriptomes of Alzheimer's disease, Parkinson's disease, schizophrenia and inflammatory diseases compared

'Neuroinflammation' has become a widely applied term in the basic and clinical neurosciences but there is no generally accepted neuropathological tissue correlate. Inflammation, which is characterized by the presence of perivascular infiltrates of cells of the adaptive immune system, is indeed seen in the central nervous system (CNS) under certain conditions. Authors who refer to microglial activation as neuroinflammation confuse this issue because autoimmune neuroinflammation serves as a synonym for multiple sclerosis, the prototypical inflammatory disease of the CNS. We have asked the question whether a data-driven, unbiased in silico approach may help to clarify the nomenclatorial confusion. Specifically, we have examined whether unsupervised analysis of microarray data obtained from human cerebral cortex of Alzheimer's, Parkinson's and schizophrenia patients would reveal a degree of relatedness between these diseases and recognized inflammatory conditions including multiple sclerosis. Our results using two different data analysis methods provide strong evidence against this hypothesis demonstrating that very different sets of genes are involved. Consequently, the designations inflammation and neuroinflammation are not interchangeable. They represent different categories not only at the histophenotypic but also at the transcriptomic level. Therefore, non-autoimmune neuroinflammation remains a term in need of definition.

RGS16 attenuates pulmonary Th2/Th17 inflammatory responses

The regulators of G protein signaling (RGS) protein superfamily negatively controls G protein-coupled receptor signal transduction pathways. RGS16 is enriched in activated/effector T lymphocytes. In this paper, we show that RGS16 constrains pulmonary inflammation by regulating chemokine-induced T cell trafficking in response to challenge with Schistosoma mansoni. Naive Rgs16(-/-) mice were "primed" for inflammation by accumulation of CCR10(+) T cells in the lung. Upon pathogen exposure, these mice developed more robust granulomatous lung fibrosis than wild-type counterparts. Distinct Th2 or putative Th17 subsets expressing CCR4 or CCR10 accumulated more rapidly in Rgs16(-/-) lungs following challenge and produced proinflammatory cytokines IL-13 and IL-17B. CCR4(+)Rgs16(-/-) Th2 cells migrated excessively to CCL17 and localized aberrantly in challenged lungs. T lymphocytes were partially excluded from lung granulomas in Rgs16(-/-) mice, instead forming peribronchial/perivascular aggregates. Thus, RGS16-mediated confinement of T cells to Schistosome granulomas mitigates widespread cytokine-mediated pulmonary inflammation.

Cytokine-like factor 1 gene expression is enriched in idiopathic pulmonary fibrosis and drives the accumulation of CD4+ T cells in murine lungs: evidence for an antifibrotic role in bleomycin injury

Idiopathic pulmonary fibrosis (IPF) is a progressive and typically fatal lung disease. To gain insight into the pathogenesis of IPF, we reanalyzed our previously published gene expression data profiling IPF lungs. Cytokine receptor-like factor 1 (CRLF1) was among the most highly up-regulated genes in IPF lungs, compared with normal controls. The protein product (CLF-1) and its partner, cardiotrophin-like cytokine (CLC), function as members of the interleukin 6 (IL-6) family of cytokines. Because of earlier work implicating IL-6 family members in IPF pathogenesis, we tested whether CLF-1 expression contributes to inflammation in experimental pulmonary fibrosis. In IPF, we detected CLF-1 expression in both type II alveolar epithelial cells and macrophages. We found that the receptor for CLF-1/CLC signaling, ciliary neurotrophic factor receptor (CNTFR), was expressed only in type II alveolar epithelial cells. Administration of CLF-1/CLC to both uninjured and bleomycin-injured mice led to the pulmonary accumulation of CD4(+) T cells. We also found that CLF-1/CLC administration increased inflammation but decreased pulmonary fibrosis. CLF-1/CLC leads to significantly enriched expression of T-cell-derived chemokines and cytokines, including the antifibrotic cytokine interferon-γ. We propose that, in IPF, CLF-1 is a selective stimulus of type II alveolar epithelial cells and may potentially drive an antifibrotic response by augmenting both T-helper-1-driven and T-regulatory-cell-driven inflammatory responses in the lung.

CCL5: a double-edged sword in host defense against the hepatitis C virus

C-C motif ligand 5 (CCL5) facilitates induction of chemotaxis in immune cells and activation of hepatic stellate cells (HSC) at sites of liver inflammation during chronic hepatitis C virus (HCV) infection. Importantly, CCL5 participates in the establishment of T-helper 1 responses crucial in controlling liver disease and HCV infection outcome and demonstrates distinct gene expression patterns between the blood and the liver, stressing the importance of immunoregulatory networks differentially functioning between these compartments. This review illustrates the significance of CCL5-dependent pathways in HCV-related immunopathogenesis by elaborating on biological mechanisms interconnecting peripheral and tissue immunology, liver pathology, HSC activation, and interferon-α immunotherapy.

CCR5 blockade is well tolerated and induces changes in the tissue distribution of CCR5+ and CD25+ T cells in healthy, SIV-uninfected rhesus macaques

BACKGROUND

CCR5 is a main co-receptor for HIV, but also homes lymphocytes to sites of inflammation. We hypothesized that inhibition of CCR5 signaling would reduce HIV-associated chronic immune activation.

METHODS

To test this hypothesis, we administered an antagonistic anti-CCR5 monoclonal antibody (HGS101) to five uninfected rhesus macaques (RMs) and monitored lymphocyte dynamics in blood and tissue.

RESULTS

CCR5 blockade resulted in decreased levels of CCR5+ T cells in blood and, at later timepoints, in lymph nodes. Additionally, the levels of CD25+ T cells increased in lymph nodes, but decreased in blood, bone marrow, and rectal mucosa. Finally, a profile of gene expression from HGS101-treated RMs revealed a subtle, but consistent, in vivo signature of CCR5 blockade that suggests a mild immune-modulatory effect.

CONCLUSIONS

Treatment with anti-CCR5 antibody induces changes in the tissue distribution of CCR5+ and CD25+ T cells that may impact on the overall levels of immune activation during HIV and SIV infection.

Cyclophilin A cooperates with MIP-2 to augment neutrophil migration

Background

Chemokines contribute to inflammatory responses by inducing leukocyte migration and extravasation. In addition, chemoattractants other than classical chemokines can also be present. Many chemokines have been demonstrated to cooperate, leading to an augmentation in leukocyte recruitment and providing a potential role for the presence of multiple chemoattractants. Extracellular cyclophilins are a group of alternative chemotactic factors, which can be highly elevated during various inflammatory responses and, as we have previously shown, can contribute significantly to neutrophil recruitment in an animal model of acute lung inflammation. In the current studies we investigated whether the most abundant extracellular cyclophilin, CypA, has the capacity to function in partnership with 2 classical chemokines known to be secreted in the same model, macrophage inflammatory protein (MIP)-2/CXCL2 and keratinocyte chemoattractant (KC)/CXCL1.

Methods

Neutrophil migration in response to combinations of CypA and MIP-2 or CypA and KC was measured by in vitro chemotaxis assays. Biochemical responses of neutrophils incubated with the combinations of chemoattractants were determined by changes in chemokine receptor internalization and actin polymerization measured by flow cytometry, and changes in intracellular calcium mobilization measured with a calcium sensitive fluorochrome.

Results

A combination of CypA and MIP-2, but not KC, augmented neutrophil migration. Based on the level of augmentation, the cooperation between CypA and MIP-2 appeared to be synergistic. Evidence that CypA and MIP-2 cooperate at the biochemical level was demonstrated by increases in receptor internalization, calcium mobilization, and actin polymerization.

Conclusion

These findings provide evidence for the capacity of extracellular cyclophilins to interact with classical chemokines, resulting in greater and more efficient leukocyte recruitment.

CXCR3 blockade inhibits T-cell migration into the CNS during EAE and prevents development of adoptively transferred, but not actively induced, disease

Autoreactive T-cell infiltration into the CNS is critical in MS and EAE. The chemokine receptor CXCR3 and its ligands are implicated in MS and mouse EAE, but the contribution of CXCR3 to T-cell migration into the inflamed CNS remains controversial. During active disease in a rat EAE model, blood T-cell, spleen T-cell and T lymphoblast migration into the CNS was inhibited by a CXCR3 blocking mAb by, 30-70%, ∼75% and 50-80%, respectively. However, CXCR3 blockade after active immunization did not inhibit EAE, did not alter total T-cell accumulation in the CNS and did not affect Treg accumulation or the presence of cells producing IFN-γ or IL-17. Conversely, CXCR3 blockade during EAE induced by adoptive transfer of myelin basic protein-activated T cells delayed disease onset, shortened its duration and reduced disease severity. Moreover, CXCR3 blockade inhibited leukocyte infiltration of the CNS>95%, virtually abolishing infiltration of transferred T cells. Thus, CXCR3 plays a major role in T-cell migration to the CNS and can be critical for encephalitogenic T-cell migration into the CNS to induce disease, but CXCR3-independent recruitment can also produce EAE.

[Enhancement of antibody-dependent cellular cytotoxicity by tandem Fc multimerization]

Monoclonal antibodies are being used as therapeutics for a number of cancers, such as leukemia, breast and colon cancers, and a lot of monoclonal antibodies specific for tumor-related antigens have been on clinical trials. Antibody-dependent cellular cytotoxicity (ADCC) is one of the major mechanisms by which antibodies exert anti-tumor effects. ADCC occurs through interaction between the Fc domains of IgG antibodies bound to target cells and Fcgamma receptors on the surface of effector cells. In our study, a chimeric antibody, designated M-Ab, was constructed with the V regions from mouse anti-CD20 mAb 1F5 and the C regions from human IgG1 and kappa chain. Two or three Fc domains were tandemly repeated downstream of the C-terminus of the M-Ab to give D0-Ab (Fc dimer Ab without a linker), T0-Ab (Fc trimer Ab without a linker), and T3-Ab (Fc trimer Ab with a (GGGGS)(3) linker in front of the second and third hinge regions). Here, we show that Fc tandem repeat antibodies bind to all the low-affinity Fcgamma receptors with very potent avidities and have greatly enhanced ADCC activity. T3-Ab is about 100 times more potent than the parental 1F5 chimeric antibody in terms of both Fcgamma receptor binding and exerted ADCC activity at a 50-100 times less concentration as compared with the parental antibody. Thus, Fc tandem repeat antibodies are anticipated to be candidates for anti-tumor therapeutics and useful tools to elucidate the biological roles of Fcgamma receptors.

Lymphocyte recruitment and homing to the liver in primary biliary cirrhosis and primary sclerosing cholangitis

The mechanisms operating in lymphocyte recruitment and homing to liver are reviewed. A literature review was performed on primary biliary cirrhosis (PBC), progressive sclerosing cholangitis (PSC), and homing mechanisms; a total of 130 papers were selected for discussion. Available data suggest that in addition to a specific role for CCL25 in PSC, the CC chemokines CCL21 and CCL28 and the CXC chemokines CXCL9 and CXCL10 are involved in the recruitment of T lymphocytes into the portal tract in PBC and PSC. Once entering the liver, lymphocytes localize to bile duct and retain by the combinatorial or sequential action of CXCL12, CXCL16, CX3CL1, and CCL28 and possibly CXCL9 and CXCL10. The relative importance of these chemokines in the recruitment or the retention of lymphocytes around the bile ducts remains unclear. The available data remain limited but underscore the importance of recruitment and homing.

Selective accumulation of virus-specific CD8+ T cells with unique homing phenotype within the human bone marrow

The bone marrow plays a unique role within the immune system. We compared the phenotype and function of virus-specific CD8(+) T cells from matched samples of human peripheral blood and bone marrow. Analysis of virus-specific memory CD8(+) T cells showed widely divergent partition of antigen-specific populations between blood and bone marrow. T cells specific for Epstein-Barr virus (EBV) lytic antigens were enriched 3-fold in marrow compared with blood, whereas the response to EBV latent epitopes was equivalent between the 2 compartments. No difference in EBV viral load or expression of the EBV lytic protein was observed between blood and bone marrow. In direct contrast, although cytomegalo-virus (CMV)-specific T cells were the largest virus-specific population within peripheral blood, they were reduced by 60% within marrow. Bone marrow T cells were found to exhibit a unique CCR5(+)CXCR6(+)CXCR3(-) homing phenotype which has not been observed on T cells from other secondary lymphoid organs or peripheral organs. Expression of CCR5 and CXCR6 was higher on EBV-specific T cells within peripheral blood compared with CMV-specific populations. These observations identify a novel bone marrow homing phenotype for CD8(+) memory T cells, which necessitates a reevaluation of the magnitude of antigen-specific populations within the lymphoid system.

CXCR3 and CCR5 chemokines in induced sputum from patients with COPD

BACKGROUND

COPD is associated with increased numbers of CD4(+) and CD8(+) lymphocytes and macrophages in the small airways and lung parenchyma. The chemokines regulating T-cell recruitment into the lung are unknown but may involve CXCR3 and CCR5 chemoattractants. The aims of this study were to determine the concentrations of CXCR3 chemokines CXCL9, CXCL10, CXCL11, and the CCR5 chemokine CCL5 in induced sputum from patients with COPD, smokers, and nonsmokers, and to examine the relationship between chemokine expression, inflammatory cells, and airway obstruction.

METHODS

Differential cell counts were performed and concentrations of CXCL9, CXCL10, CXCL11, and CCL5 were measured in induced sputum from nonsmokers (n = 18), smokers (n = 20), and COPD patients (n = 35) using an enzyme-linked immunosorbent assay.

RESULTS

Concentrations of CXCL9, CXCL10, CXCL11, and CCL5 were significantly increased in the sputum of patients with COPD when compared with nonsmokers but not smokers without obstruction: CXCL9 (median, 14.3 pg/mL; interquartile range [IQR], 6.5 to 99.3; vs median, 1.4 pg/mL; IQR, 0 to 10.4 [p < 0.001]; vs 8.5 pg/mL; IQR, 0 to 16.0, respectively); CXCL10 (16.9 pg/mL; IQR, 6.2 to 148.8; vs 3.7 pg/mL; IQR, 0 to 18.8 [p < 0.05]; vs 11.3 pg/mL; IQR, 3.7 to 46.7); CXCL11 (58.1 pg/mL; IQR, 34.5 to 85.3; vs 33.5 pg/mL; IQR, 23.2 to 49.7 [p < 0.05]; vs 49.8 pg/mL; IQR, 32.6 to 105.6); and CCL5 (59.9 pg/mL; IQR, 57.1 to 67.8; vs 33.5 pg/mL; IQR, 31.6 to 36.9 [p < 0.001]). CCL5 in sputum from smokers was also significantly increased compared with that from nonsmokers (median, 63.0 pg/mL; IQR, 60.8 to70.2; p < 0.001). There was a negative correlation between FEV(1) percentage of predicted, FEV(1)/FVC ratio, and percentage of macrophages, and all the chemokines analyzed. Neutrophil numbers correlated positively with the concentrations of chemokines.

CONCLUSIONS

CXCR3 chemokines and CCL5 are increased in sputum from COPD patients compared with nonsmokers, and may be important in COPD pathogenesis.

Cell surface CCR5 density determines the intensity of T cell migration towards rheumatoid arthritis synoviocytes

As we have recently shown that the number of CCR5 molecules at the cell surface determines the efficiency of its function as a chemokine receptor, we tested the hypothesis that cell surface CCR5 density could influence the intensity of T lymphocyte recruitment into the rheumatoid joint. For this purpose, we established two Jurkat cell line-derived clones that differed only by their cell surface CCR5 densities. We studied their chemotaxis towards TNF-alpha-transduced rheumatoid synoviocytes supernatant. The Jurkat cell subline that expressed the higher cell surface CCR5 density migrated more intensively towards the supernatant of TNF-alpha-transduced synoviocytes than the Jurkat cell subline that expressed a lower surface CCR5 density. Moreover, this migration was blocked by an anti-CCR5 mAb. The CCR5 density on T cell surface, which is constant over time for a given individual, but varies drastically from one individual to another, might thus be a factor determining the intensity of joint inflammation in the course of RA.

Interferon-γ Axis in Graft Arteriosclerosis

Cardiac transplantation is the most effective treatment for advanced heart failure. Despite improvements in immunosuppression therapy that prevent acute rejection, cardiac allografts fail at rates of 3% to 5% per posttransplant year. The hallmark morphological lesion of chronically failing cardiac allografts, also seen in chronic renal and liver graft failure, is luminal stenosis of blood vessels, especially of conduit arteries. Late graft failure results from widespread secondary ischemic injury to the graft parenchyma rather than direct immune-mediated damage. Although this process affects the entire graft vasculature, graft arteriosclerosis is a suitable term to describe the problem because it applies to different types of failing organs and because it emphasizes the central feature, namely an accelerated form of arterial injury and remodeling. The precise pathogenesis of graft arteriosclerosis is unknown. In this review, we make the case that the signature T-helper type 1 cytokine, interferon (IFN)-γ, is a key effector in graft arteriosclerosis, which, together with the IFN-γ–inducing cytokine interleukin-12 and IFN-γ–inducible chemokines such as CXCR3 ligands, constitute a positive feedback loop for T-cell activation, differentiation, and recruitment that we refer to as the IFN-γ axis. We evaluate the evidence to support this hypothesis in clinical observational and experimental animal studies. Additionally, we examine the regulation of IFN-γ production within the artery wall, the effects of IFN-γ on vessel wall cells, and the outcome of therapeutic agents on IFN-γ production and signaling. These observations lead us to suggest that new therapies for graft arteriosclerosis should be optimized which focus on reducing IFN-γ synthesis or actions.

Colon carcinoma cells induce CXCL11-dependent migration of CXCR3-expressing cytotoxic T lymphocytes in organotypic culture

Adoptive immunotherapy of cancer patients with cytolytic T lymphocytes (CTL) has been hampered by the inability of the CTL to home into tumors in vivo. Chemokines can attract T lymphocytes to the tumor site, as demonstrated in animal models, but the role of chemokines in T-lymphocyte trafficking toward human tumor cells is relatively unexplored. In the present study, the role of chemokines and their receptors in the migration of a colon carcinoma (CC) patient's CTL toward autologous tumor cells has been studied in a novel three-dimensional organotypic CC culture. CTL migration was mediated by chemokine receptor CXCR3 expressed by the CTL and CXCL11 chemokine secreted by the tumor cells. Excess CXCL11 or antibodies to CXCL11 or CXCR3 inhibited migration of CTL to tumor cells. T cell and tumor cell analyses for CXCR3 and CXCL11 expression, respectively, in ten additional CC samples, may suggest their involvement in other CC patients. Our studies, together with previous studies indicating angiostatic activity of CXCL11, suggest that CXCL11 may be useful as an immunotherapeutic agent for cancer patients when transduced into tumor cells or fused to tumor antigen-specific Ab.

CXCL10 is the key ligand for CXCR3 on CD8+ effector T cells involved in immune surveillance of the lymphocytic choriomeningitis virus-infected central nervous system

IFN-gamma-inducible protein 10/CXCL10 is a chemokine associated with type 1 T cell responses, regulating the migration of activated T cells through binding to the CXCR3 receptor. Expression of both CXCL10 and CXCR3 are observed during immunopathological diseases of the CNS, and this receptor/ligand pair is thought to play a central role in regulating T cell-mediated inflammation in this organ site. In this report, we investigated the role of CXCL10 in regulating CD8(+) T cell-mediated inflammation in the virus-infected brain. This was done through analysis of CXCL10-deficient mice infected intracerebrally with lymphocytic choriomeningitis virus, which in normal immunocompetent mice induces a fatal CD8(+) T cell-mediated meningoencephalitis. We found that a normal antiviral CD8(+) T cell response was generated in CXCL10-deficient mice, and that lack of CXCL10 had no influence on the accumulation of mononuclear cells in the cerebrospinal fluid. However, analysis of the susceptibility of CXCL10-deficient mice to lymphocytic choriomeningitis virus-induced meningitis revealed that these mice just like CXCR3-deficient mice were partially resistant to this disease, whereas wild-type mice invariably died. Furthermore, despite marked up-regulation of the two remaining CXCR3 ligands: CXCL9 and 11, we found a reduced accumulation of CD8(+) T cells in the brain parenchyma around the time point when wild-type mice succumb as a result of CD8(+) T cell-mediated inflammation. Thus, taken together these results indicate a central role for CXCL10 in regulating the accumulation of effector T cells at sites of CNS inflammation, with no apparent compensatory effect of other CXCR3 ligands.

Involvement of CCR5 in the passage of Th1-type cells across the blood-retina barrier in experimental autoimmune uveitis

Although the recruitment of T helper cell type 1 (Th1)/Th2 cells into peripheral tissues is essential for inflammation and the host response to infection, the traffic signals that enable the distinct positioning of Th1/Th2 cells are unclear. We have determined the role of CC chemokine receptor 5 (CCR5) in this using experimental autoimmune uveitis (EAU) as a model system. In EAU, Th1-like cells are preferentially recruited into the retina across the blood-retina barrier, partly as a result of expression of the adhesion molecules P-selectin glycoprotein ligand 1 and lymphocyte function-associated antigen-1 on these cells. CD3+ T cells, infiltrating the retina, also expressed the chemokine receptor CCR5, and CCR5 ligands, macrophage-inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and regulated on activation, normal T expressed and secreted (RANTES), were strongly expressed in the retina at peak EAU. Th1-like cells, polarized in vitro, expressed high levels of CCR5. The trafficking of these CCR5+ cells was examined by tracking them after adoptive transfer in real time in vivo at an early disease stage using scanning laser ophthalmoscopy. Treatment of the cells with antibody against CCR5 prior to transfer resulted in a reduction in their infiltration into the retina. However, rolling velocity, rolling efficiency, and adherence of the cells to retinal endothelium were not reduced. CCR5 is clearly important for Th1 cell recruitment, and this study demonstrates for the first time in vivo that CCR5 may act at the level of transendothelial migration rather than at the earlier stage of rolling on the endothelium.

Synergy in cytokine and chemokine networks amplifies the inflammatory response

The inflammatory response is a highly co-ordinated process involving multiple factors acting in a complex network as stimulators or inhibitors. Upon infection, the sequential release of exogenous agents (e.g. bacterial and viral products) and induction of endogenous mediators (e.g. cytokines and chemokines) contribute to the recruitment of circulating leukocytes to the inflamed tissue. Microbial products trigger multiple cell types to release cytokines, which in turn are potent inducers of chemokines. Primary cytokines act as endogenous activators of the immune response, whereas inducible chemokines act as secondary mediators to attract leukocytes. Interaction between exogenous and endogenous mediators thus enhances the inflammatory response. In this review, the synergistic interaction between cytokines to induce chemokine production and the molecular mechanisms of the cooperation amongst co-induced chemokines to further increase leukocyte recruitment to the site of inflammation are discussed.

Absence of CD26 expression on skin-homing CLA+ CD4+ T lymphocytes in peripheral blood is a highly sensitive marker for early diagnosis and therapeutic monitoring of patients with Sezary syndrome

Patients with Sézary syndrome (SS) show clonal expansion in the peripheral blood of skin-homing CD4+ T-helper cells expressing cutaneous lymphocyte antigen (CLA). However, an increase of CLA+ CD4+ T cells can also be observed in various inflammatory dermatoses. To facilitate early diagnosis and therapeutic monitoring of SS using flow cytometry, we evaluated the expression of CD7 and CD26 on the CLA+ CD4+ lymphocyte subset. Peripheral lymphocytes from 7 patients with SS, 16 patients with mycosis fungoides (MF) and 11 healthy controls were analysed by flow cytometry for the expression of CD4, CD7, CD26, CLA and CCR4. In addition, a longitudinal study was performed over 16 months in two patients with SS. Absence of CD7 and CD26 on CLA+ CD4+ T cells was highly specific for SS. Importantly, the absence of CD26 on CLA+ CD4+ T cells was very sensitive for SS, at 100% in our patient cohort. The number of CD26- CLA+ CD4+ T cells closely correlated with therapeutic interventions in the longitudinal analysis of two patients over more than 1 year. We conclude that the absence of CD26 expression on skin-homing CLA+ CD4+ T-helper cells is a very sensitive and highly specific parameter for early diagnosis and therapeutic monitoring of patients with SS.

Intracellular signal cascade in CD4+ T-lymphocyte migration stimulated by interferon-gamma-inducible protein-10

The intracellular signal cascades involved in chemokine-stimulated migration of in vitro activated human peripheral blood CD4+ T-lymphocytes were investigated. IP-10-mediated chemotactic response of lymphocytes was decreased in the presence of selective inhibitors of Src-kinases (by 40-45%), PI3-kinases (35-40%), and MAP-kinases ERK1/2 (35-40%) and p38 (20%). Combined addition of specific inhibitors of Src-kinases and PI3-kinases and inhibitors of Src-kinases and ERK1/2 MAP-kinases did not result in the further increase of the inhibitory effect, while the combined addition of specific inhibitors of PI3-kinases and ERK1/2 MAP-kinases decreased migration of CD4+ T-lymphocytes more effectively (by 55-60%) than any individual inhibitor. Immunoblotting analysis of activation of MAP-kinases ERK1/2 and p38 revealed increased level of phosphorylation of ERK1/2 and p38 MAP-kinases in the presence IP-10. Selective inhibitors of Src-kinases and PI3-kinases significantly inhibited phosphorylation of p38 but did not influence phosphorylation of ERK1/2 MAP-kinases. Our results suggest that Src-kinases, PI3-kinases, and ERK1/2 MAP-kinases are involved in intracellular signal cascade activated during IP-10-stimulated migration of T-lymphocytes, whereas p38 MAP-kinases do not participate in the migration process, although its activation induced by IP-10 depends on Src-kinases and PI3-kinases.