Chemokine expression dynamics in mycobacterial (type-1) and schistosomal (type-2) antigen-elicited pulmonary granuloma formation

CD193 ( CCR3 ) expression by B cells correlates with reduced IgE production in paediatric schistosomiasis

We demonstrate that CD193, the eotaxin receptor, is highly expressed on circulating B cells in paediatric schistosomiasis mansoni. CD193 plays a role in directing granulocytes into sites of allergic-like inflammation in the mucosa, but little is known about its functional significance on human B cells. We sought to characterize CD193 expression and its relationship with S. mansoni infection. We found that CD193+ B cells increased with the intensity of schistosome infection. In addition, a significant negative association was observed between CD193 expression by B cells and IgE production. Decreased IgE levels are generally associated with susceptibility to re-infection. B cell stimulation with eotaxin-1 increased CD193 levels whereas IL-4 led to a reduction. This was supported by plasma levels of eotaxin-1 correlating with CD193 levels on B cells and other cells. In contrast, CD193 expression was induced on naive B cells with a combination of IL-10 and schistosome antigens. Whereas T cells had a modest increase in CD193 expression, only B cell CD193 appeared functionally chemotactic to eotaxin-1. Thus, CD193+ B cells, which co-express CXCR5, may be enroute to sites with allergic-like inflammation, such as gastrointestinal follicles, or even to Th2 granulomas, which develop around parasite eggs. Overall, our results suggest that schistosome infection may promote CD193 expression and suppress IgE via IL-10 and other undefined mechanisms related to B cell trafficking. This study adds to our understanding of why young children may have poor immunity. Nonetheless, praziquantel treatment was shown to reduce percentages of circulating CD193+ B cells lending hope for future vaccine efforts.

Transcription factor MAFB controls type I and II interferon response-mediated host immunity in Mycobacterium tuberculosis-infected macrophages

MAFB, v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog B, has been identified as a candidate gene for early tuberculosis (TB) onset in Thai and Japanese populations. Here, we investigated the genome-wide transcriptional profiles of MAFB-knockdown (KD) macrophages infected with Mycobacterium tuberculosis (Mtb) to highlight the potential role of MAFB in host immunity against TB. Gene expression analysis revealed impaired type I and type II interferon (IFN) responses and enhanced oxidative phosphorylation in MAFB-KD macrophages infected with Mtb. The expression of inflammatory chemokines, including IFN-γ-inducible genes, was confirmed to be significantly reduced by knockdown of MAFB during Mtb infection. A similar effect of MAFB knockdown on type I and type II IFN responses and oxidative phosphorylation was also observed when Mtb-infected macrophages were activated by IFN-γ. Taken together, our results demonstrate that MAFB is involved in the immune response and metabolism in Mtb-infected macrophages, providing new insight into MAFB as a candidate gene to guide further study to control TB.

The Role of CD4+CD8+ T Cells in HIV Infection With Tuberculosis

Background

Tuberculosis (TB) is an important opportunistic infection in acquired immunodeficiency diseases (AIDS). Although the frequency of CD4⁺CD8⁺ double-positive (DP) T cells has been observed to increase in pathological conditions, their role (phenotypic and functional) is poorly described, especially in human immunodeficiency virus (HIV) infection with TB (HIV/TB (HT) coinfection).

Methods

The percentage and phenotypic and functional properties of peripheral blood DP T cells in patients with HT coinfection in comparison to uninfected controls and to patients with HIV or TB mono-infection were analyzed by direct intracellular cytokine staining (ICS).

Results

Total and CD4^lowCD8^high DP T cells were significantly increased in patients with both HIV and TB mono-infection, especially in patients with HT coinfection. Compared with healthy controls (HCs), the percentage of DP T cells expressing chemokine receptor 5 (CCR5) in patients with HT coinfection was significantly higher. Compared with HCs and patients with TB, a lower percentage of tumor necrosis factor α (TNF-α) secreting DP T cells and a higher percentage of granzyme A-secreting DP T cells were observed in patients with HIV mono-infection and HT coinfection, respectively. In addition, DP T cells expressed more cytolytic markers (granzyme A and perforin) than CD4⁺ T cells, but similarly to CD8⁺ T cells in patients with HT coinfection.

Conclusions

Our data suggested that HT coinfection resulted in a marked increase in DP T cells, especially the CD4^lowCD8^high subpopulation. DP T cells may be susceptible to HT coinfection, and have the same cytotoxic function as CD8⁺ T cells.

Cell Biology of Intracellular Adaptation of Mycobacterium leprae in the Peripheral Nervous System

The mammalian nervous system is invaded by a number of intracellular bacterial pathogens which can establish and progress infection in susceptible individuals. Subsequent clinical manifestation is apparent with the impairment of the functional units of the nervous system, i.e., the neurons and the supporting glial cells that produce myelin sheaths around axons and provide trophic support to axons and neurons. Most of these neurotrophic bacteria display unique features, have coevolved with the functional sophistication of the nervous system cells, and have adapted remarkably to manipulate neural cell functions for their own advantage. Understanding how these bacterial pathogens establish intracellular adaptation by hijacking endogenous pathways in the nervous system, initiating myelin damage and axonal degeneration, and interfering with myelin maintenance provides new knowledge not only for developing strategies to combat neurodegenerative conditions induced by these pathogens but also for gaining novel insights into cellular and molecular pathways that regulate nervous system functions. Since the pathways hijacked by bacterial pathogens may also be associated with other neurodegenerative diseases, it is anticipated that detailing the mechanisms of bacterial manipulation of neural systems may shed light on common mechanisms, particularly of early disease events. This chapter details a classic example of neurodegeneration, that caused by Mycobacterium leprae, which primarily infects glial cells of the peripheral nervous system (Schwann cells), and how it targets and adapts intracellularly by reprogramming Schwann cells to stem cells/progenitor cells. We also discuss implications of this host cell reprogramming by leprosy bacilli as a model in a wider context.

Incorporation of a Ligand Peptide for Immune Inhibitory Receptor LAIR-1 on Biomaterial Surfaces Inhibits Macrophage Inflammatory Responses

Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is an inhibitory receptor broadly expressed on immune cells, with its ligands residing within the extracellular matrix protein collagen. In this study, surfaces are modified with a LAIR-1 ligand peptide (LP), and it is observed that macrophages cultured on LAIR-1 LP-conjugated surfaces exhibit significantly reduced secretion of inflammatory cytokines in response to proinflammatory stimuli that reflect an injured environment. These downregulated mediators include TNF-α, MIP-1α, MIP-1β, MIP-2, RANTES, and MIG. Knockdown of LAIR-1 using siRNA abrogates this inhibition of cytokine secretion, supporting the specificity of the inhibitory effect to this receptor. These results are the first to demonstrate that integration of LAIR-1 ligands with biomaterials could suppress inflammatory responses.

Canine influenza virus coinfection with Staphylococcus pseudintermedius enhances bacterial colonization, virus load and clinical presentation in mice

Background

Canine influenza virus (CIV) and Staphylococcus pseudintermedius (Sp) are pathogens that cause respiratory disease in dogs. Considering bacterial infections following influenza are a leading cause of illness and death, it is of particular meaning to investigate the interaction between these two pathogens. In this study, BALB/c mice were used as a mouse model to assess whether inoculation with CIV H3N2 followed by S. pseudintermedius 72 h later resulted in exacerbation of disease. Disease was characterized by assessment of body weight loss, titration of virus and bacteria, histopathology, and cytokine production.

Results

There was a significantly greater decrease in body weight in the co-infected group compared with the CIV-only and SP-only groups. CIV inoculation increased bacterial colonization, whereas secondary infection with S. pseudintermedius elevated the viral RNA load of CIV in tissues. The histological lesions in the brain, spleen and lung were more severe in the CIV/Sp group than in the singly treated groups. Infection with CIV alone, Sp alone or coinfection stimulated a significantly higher release of cytokines, such as interferon-gamma (IFN)-γ, interleukin 6 (IL)-6, tumor necrosis factor (TNF-α) and lymphotactin (Lptn), than was observed in the mock-infected group (PBS). Moreover, the levels of IFN-γ in the spleen and lung were higher in the CIV/Sp group compared with the CIV-only and Sp-only groups.

Conclusion

Our findings provide the first demonstration that the secondary infection of mice with Sp leads to increased clinical signs and lesions during canine influenza.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0708-6) contains supplementary material, which is available to authorized users.

Ingested (oral) anti-IL-12/23 inhibits EAE

BACKGROUND

Blocking the activity of IL-12/23 can inhibit autoimmune diseases such as psoriasis.

OBJECTIVE

We examined whether an antibody against IL-12/23, ustekinumab (UTZ) (Stelera®), used clinically in psoriasis would have similar anti-inflammatory effects in EAE after oral administration.

DESIGN/METHODS

B6 mice were immunized with MOG peptide 35-55 and gavaged with isotype IgG control or UTZ during ongoing disease. Splenocytes, CD4(+) T cells or macrophages/monocyte lineage cells (CD11b(+)) from control fed or UTZ fed mice were adoptively transferred into active MOG peptide 35-55 immunized recipient mice during ongoing disease. Actively fed and recipient mice were examined for disease inhibition, inflammation, and cytokine responses.

RESULTS

Ingested (oral) UTZ inhibited ongoing disease and decreased inflammation. Adoptively transferred cells from UTZ fed donors protected against actively induced disease and decreased inflammation. Oral UTZ decreased pro-inflammatory cytokines Th1-like cytokines IL-2, IL-12, IFN-γ, IL-17 (Teff) and TNF-α in UTZ fed mice and increased counter-regulatory cytokines IL-4, IL-10 and IL-13 in recipients of donor cells from UTZ fed mice.

CONCLUSIONS

Ingested (orally administered) UTZ can inhibit disease, CNS inflammation, decrease pro-inflammatory Th1-like and Th17 cytokines and increase Th2-like anti-inflammatory cytokines.

Cx3cr1 deficiency in mice attenuates hepatic granuloma formation during acute schistosomiasis by enhancing the M2-type polarization of macrophages

Acute schistosomiasis is characterized by pro-inflammatory responses against tissue- or organ-trapped parasite eggs along with granuloma formation. Here, we describe studies in Cx3cr1^−/− mice and demonstrate the role of Cx3cr1 in the pathoetiology of granuloma formation during acute schistosomiasis. Mice deficient in Cx3cr1 were protected from granuloma formation and hepatic injury induced by Schistosoma japonicum eggs, as manifested by reduced body weight loss and attenuated hepatomegaly along with preserved liver function. Notably, S. japonicum infection induced high levels of hepatic Cx3cr1 expression, which was predominantly expressed by infiltrating macrophages. Loss of Cx3cr1 rendered macrophages preferentially towards M2 polarization, which then led to a characteristic switch of the host immune defense from a conventional Th1 to a typical Th2 response during acute schistosomiasis. This immune switch caused by Cx3cr1 deficiency was probably associated with enhanced STAT6/PPAR-γ signaling and increased expression of indoleamine 2,3-dioxygenase (IDO), an enzyme that promotes M2 polarization of macrophages. Taken together, our data provide evidence suggesting that CX3CR1 could be a viable therapeutic target for treatment of acute schistosomiasis.

Highlighted Article: A reduction in CX3CR1 signaling provides protection for mice against pro-inflammatory responses and hepatic granuloma formation during acute schistosomiasis.

Bacterial-induced cell reprogramming to stem cell-like cells: new premise in host-pathogen interactions

Bacterial pathogens employ a myriad of strategies to alter host tissue cell functions for bacterial advantage during infection. Recent advances revealed a fusion of infection biology with stem cell biology by demonstrating developmental reprogramming of lineage committed host glial cells to progenitor/stem cell-like cells by an intracellular bacterial pathogen Mycobacterium leprae. Acquisition of migratory and immunomodulatory properties of such reprogrammed cells provides an added advantage for promoting bacterial spread. This presents a previously unseen sophistication of cell manipulation by hijacking the genomic plasticity of host cells by a human bacterial pathogen. The rationale for such extreme fate conversion of host cells may be directly linked to the exceedingly passive obligate life style of M. leprae with a degraded genome and host cell dependence for both bacterial survival and dissemination, particularly the use of host-derived stem cell-like cells as a vehicle for spreading infection without being detected by immune cells. Thus, this unexpected link between cell reprogramming and infection opens up a new premise in host-pathogen interactions. Furthermore, such bacterial ingenuity could also be harnessed for developing natural ways of reprogramming host cells for repairing damaged tissues from infection, injury and diseases.

Ingested (oral) tocilizumab inhibits EAE

BACKGROUND

Blocking the activity of IL-6 can inhibit autoimmune diseases such as rheumatoid arthritis and Crohn's disease.

OBJECTIVE

We examined whether an antibody against IL-6, tocilizumab (TCZ) (Actemra®), used clinically in rheumatoid arthritis (RA) would have similar anti-inflammatory effects in EAE after oral administration.

DESIGN/METHOD

B6 mice were immunized with MOG peptide 35-55 and gavaged with control saline or TCZ during ongoing disease. Splenocytes, CD4(+) T cells or macrophages/monocyte lineage cells (CD11b(+)) from control fed or TCZ fed mice were adoptively transferred into active MOG peptide 35-55 immunized recipient mice during ongoing disease. Actively fed and recipient mice were examined for disease inhibition, inflammation, and cytokine responses.

RESULTS

Ingested (oral) TCZ inhibited ongoing disease and decreased inflammation. Adoptively transferred cells from TCZ fed donors protected against actively induced disease and decreased inflammation. There was a decrease in IL-6 in actively treated spleen, decrease in TNF-α, Th1-like cytokine IL-12 and increase in Th2-like cytokine IL-10 in active fed and adoptively treated recipients.

CONCLUSIONS

Ingested (orally administered) TCZ can inhibit disease, CNS inflammation, decrease pro-inflammatory Th1-like cytokines and increase Th2-like anti-inflammatory cytokines.

Physiological and pathological angiogenesis in the adult pulmonary circulation

Angiogenesis occurs during growth and physiological adaptation in many systemic organs, for example, exercise-induced skeletal and cardiac muscle hypertrophy, ovulation, and tissue repair. Disordered angiogenesis contributes to chronic inflammatory disease processes and to tumor growth and metastasis. Although it was previously thought that the adult pulmonary circulation was incapable of supporting new vessel growth, over that past 10 years new data have shown that angiogenesis within this circulation occurs both during physiological adaptive processes and as part of the pathogenic mechanisms of lung diseases. Here we review the expression of vascular growth factors in the adult lung, their essential role in pulmonary vascular homeostasis and the changes in their expression that occur in response to physiological challenges and in disease. We consider the evidence for adaptive neovascularization in the pulmonary circulation in response to alveolar hypoxia and during lung growth following pneumonectomy in the adult lung. In addition, we review the role of disordered angiogenesis in specific lung diseases including idiopathic pulmonary fibrosis, acute adult distress syndrome and both primary and metastatic tumors of the lung. Finally, we examine recent experimental data showing that therapeutic enhancement of pulmonary angiogenesis has the potential to treat lung diseases characterized by vessel loss.

Heterogeneity of lung mononuclear phagocytes during pneumonia: contribution of chemokine receptors

Bacterial pneumonia is a common and dangerous illness. Mononuclear phagocytes, which comprise monocyte, resident and recruited macrophage, and dendritic cell subsets, are critical to antimicrobial defenses, but the dynamics of their recruitment to the lungs in pneumonia is not established. We hypothesized that chemokine-mediated traffic of mononuclear phagocytes is important in defense against bacterial pneumonia. In a mouse model of Klebsiella pneumonia, circulating Ly6C(hi) and, to a lesser extent, Ly6C(lo) monocytes expanded in parallel with accumulation of inflammatory macrophages and CD11b(hi) dendritic cells and plasmacytoid dendritic cells in the lungs, whereas numbers of alveolar macrophages remained constant. CCR2 was expressed by Ly6C(hi) monocytes, recruited macrophages, and airway dendritic cells; CCR6 was prominently expressed by airway dendritic cells; and CX3CR1 was ubiquitously expressed by blood monocytes and lung CD11b(hi) dendritic cells during infection. CCR2-deficient, but not CCL2-, CX3CR1-, or CCR6-deficient animals exhibited worse outcomes of infection. The absence of CCR2 had no detectable effect on neutrophils but resulted in reduction of all subsets of lung mononuclear phagocytes in the lungs, including alveolar macrophages and airway and plasmacytoid dendritic cells. In addition, absence of CCR2 skewed the phenotype of lung mononuclear phagocytes, abrogating the appearance of M1 macrophages and TNF-producing dendritic cells in the lungs. Taken together, these data define the dynamics of mononuclear phagocytes during pneumonia.

Serum CCL11 (eotaxin-1) and CCL17 (TARC) are serological indicators of multiple helminth infections and are driven by Schistosoma mansoni infection in humans

OBJECTIVES

To evaluate systemic serum cytokine and chemokine markers for inflammation and Th1/Th2 responses in relation to multiple helminth infections, parasite burden and/or nutritional status of individuals.

METHODS

In a longitudinal study, stool samples from 210 individuals from an area highly endemic for Ascaris lumbricoides, Necator americanus and Schistosoma mansoni were examined before and 12 months after clearance of parasites by chemotherapy. On both occasions, the presence of mono- or multiple infections and intensities of infection were compared with nutritional parameters and with serum cytokines or chemokines as markers for inflammatory, regulatory or Th1- or Th2-type immune responses.

RESULTS

Before treatment, we were not able to associate any altered nutritional parameters with increased inflammatory responses, and highest intensities of infection were found in eutrophic participants with multiple infections. In contrast, major changes in serum Th2-type chemokine levels were measured in individuals infected with intestinal helminths and/or S. mansoni, and resulted in significantly higher CCL11 and CCL17 concentrations, both before treatment and after reinfection.

CONCLUSIONS

The driving force for these elevated type 2 serum chemokine concentrations was an S. mansoni infection and faecal egg counts significantly correlated with serum IL-10 concentrations.

Chemokines in innate and adaptive granuloma formation

Granulomas are cellular inflammations that vary widely in histologic appearance depending upon the inciting agent and immunologic status of the responding host. Despite their heterogeneity, granulomas are at their core an ancient innate sequestration response characterized by the accumulation of mononuclear phagocytes. In fact, this innate cellular response was first observed by Metchnikov in simple invertebrates. Among higher vertebrates, environmental pressures have resulted in the evolution of more sophisticated adaptive immune responses which can be superimposed upon and modify the character of granulomatous inflammation. Compared to immune responses that rapidly neutralize and eliminate infectious agents, the granuloma represents a less desirable "fall back" response which still has value to the host but can be co-opted by certain infectious agents and contribute to bystander organ damage. Understanding granulomas requires an analysis of the complex interplay of innate and adaptive molecular signals that govern the focal accumulation and activity of their cellular components. Among these signals, small molecular weight chemoattractant proteins known as chemokines are potentially important contributors as they participate in both directing leukocyte migration and function. This tract will discuss the contribution of chemokines to the development of innate and adaptive granuloma formation, as well as describe their relationship to more recently evolved cytokines generated during adaptive immune responses.

Reprogramming adult Schwann cells to stem cell-like cells by leprosy bacilli promotes dissemination of infection

Differentiated cells possess a remarkable genomic plasticity that can be manipulated to reverse or change developmental commitments. Here, we show that the leprosy bacterium hijacks this property to reprogram adult Schwann cells, its preferred host niche, to a stage of progenitor/stem-like cells (pSLC) of mesenchymal trait by downregulating Schwann cell lineage/differentiation-associated genes and upregulating genes mostly of mesoderm development. Reprogramming accompanies epigenetic changes and renders infected cells highly plastic, migratory, and immunomodulatory. We provide evidence that acquisition of these properties by pSLC promotes bacterial spread by two distinct mechanisms: direct differentiation to mesenchymal tissues, including skeletal and smooth muscles, and formation of granuloma-like structures and subsequent release of bacteria-laden macrophages. These findings support a model of host cell reprogramming in which a bacterial pathogen uses the plasticity of its cellular niche for promoting dissemination of infection and provide an unexpected link between cellular reprogramming and host-pathogen interaction.

Correlation between lymph node pathology and chemokine expression during bovine tuberculosis

Bovine tuberculosis is a disease of worldwide importance yet comparatively little is known about chemokine responses to infection. We report on the levels of chemokine expression within lymph nodes of cattle infected with Mycobacterium bovis when infection would be well established. Expression levels of a number of chemokines were increased in infected cattle and could be correlated to levels of respective chemokine receptors. Several chemokines were significantly correlated to pathology within the lymph node, indicating a direct relationship between chemokine expression and disease. Vaccinated animals challenged with M. bovis had lower levels of chemokine expression than unvaccinated, challenged animals, correlating with lower levels of disease in vaccinated animals. The chemokine expression profile correlated with previous evidence for a pro-inflammatory bias within the lymph node. At this stage of infection we suggest there is on-going chemokine expression by cells associated with the granuloma and continual recruitment of cells to control infection.

Phthalate-Induced Liver Protection against Deleterious Effects of the Th1 Response: A Potentially Serious Health Hazard

Infection with Mycobacterium tuberculosis (TB) induces pulmonary immunopathology mediated by classical Th1 type of acquired immunity with hepatic involvement in up to 80% of disseminated cases. Since PPAR agonists cause immune responses characterized by a decrease in the secretion of Th1 cytokines, we investigated the impact of activating these receptors on hepatic pathology associated with a well-characterized model of Th1-type pulmonary response. Male Fischer 344 rats were either maintained on a drug-free diet (groups I and II), or a diet containing diethylhexylphthalate (DEHP), a compound transformed in vivo to metabolites known to activate PPARs, for 21 days (groups III and IV). Subsequently, animals were primed with Mycobacterium bovis purified protein derivative (PPD) in a Complete Freund's Adjuvant. Fifteen days later, animals in groups II and IV were challenged with Sepharose 4B beads covalently coupled with PPD, while animals in groups I and III received blank Sepharose beads. Animals with Th1 response (group II) showed a marked structural disruption in the hepatic lobule. Remarkably, these alterations were conspicuously absent in animals which received DEHP (group IV), despite noticeable accumulation of T cells in the periportal triads. Immunostaining and confocal microscopy revealed hepatic accumulation of IFNgamma+ Th1 and IL-4+ Th2 cells in animals from groups II and IV, respectively. Our data suggest a PPARalpha-mediated suppression of the development of a Th1 immune response in the liver, resulting in hepatoprotective effect. However, potentially negative consequences of PPAR activation, such as decreased ability of the immune system to fight infection and interference with the efficacy of vaccines designed to evoke Th1 immune responses, remain to be investigated.

Seric chemokines and chemokine receptors in eosinophils during acute human schistosomiasis mansoni

The recruitment of circulating eosinophils by chemokines and chemokine receptors plays an important role in the inflammation process in acute human schistosomiasis. Our main focus has been on the plasma chemokines (CXCL8/CCL2/CCL3/CCL24) and chemokine receptors (CCR2/CCR3/CCR5/CXCR1/CXCR2/CXCR3/CXCR4) expressed by circulating eosinophils from acute Schistosoma mansoni infected patients (ACT). Our studies compared ACT patients and healthy individuals as a control group. Our major findings demonstrated a plethora of chemokine secretion with significantly increased secretion of all chemokines analysed in the ACT group. Although no differences were detected for beta-chemokine receptors (CCR2, CCR3 and CCR5) or alpha-chemokine receptors (CXCR3 and CXCR4), a significantly lower frequency of CXCR1+ and CXCR2+ eosinophils in the ACT group was observed. The association between chemokines and their chemokine receptors revealed that acutely infected schistosome patients displaying decreased plasma levels of CCL24 are the same patients who presented enhanced secretion of CCL3, as well as increased expression of both the CCR5 and CXCR3 chemokine receptors. These findings suggest that CCL24 may influence the kinetics of chemokines and their receptors and eosinophils recruitment during human acute schistosomiasis mansoni.

Elevated serum levels of CCL17 correlate with increased peripheral blood platelet count in patients with active tuberculosis in China

The serum levels of Th2 markers, including CCL17 (thymus and activation-regulated chemokine [TARC]), CCL22 (macrophage-derived chemokine [MDC]), and soluble CD30, were measured in 101 HIV-negative tuberculosis patients, 103 healthy community controls, and 18 tuberculosis patients in recovery. The levels of CCL17/TARC (249.8 ± 19.91 versus 143.9 ± 10.54, P < 0.0001) and sCD30 (7.78 ± 0.44 versus 4.93 ± 0.23, P < 0.0001) were significantly higher in patients with active tuberculosis than in controls; however, the CCL22/MDC serum level had no statistical difference between the groups (579.9 ± 16.42 versus 556.5 ± 15.29, P = 0.298). The counts of platelet and eosinophil in the peripheral blood of patients with active tuberculosis are significantly increased as well (289.4 ± 8.14 versus 248.3 ± 5.34 [P < 0.0001] and 165.1 ± 14.33 versus 102.5 ± 10.72 [P = 0.0005], respectively), and the platelet counts were positively correlated with serum TARC levels (Pearson r = 0.456, P < 0.0001), which indicates a new source of Th2 bias showing in active TB patients.

CC chemokine receptor 4 contributes to innate NK and chronic stage T helper cell recall responses during Mycobacterium bovis infection

Cysteine-cysteinyl chemokine receptor 4 (CCR4) is expressed by a variety of T-cell subsets and leukocytes. This study examined the participation of CCR4 in response to pulmonary infection with Mycobacterium bovis Bacille-Calmette-Guerin (BCG). Constitutive and induced CCR4 agonist expression was detected among large mononuclear cells. The course of infection and mobilization of effector cell populations were then analyzed in CCR4 knockout (CCR4(-/-)) mice. Compared with controls, CCR4(-/-) mice displayed delayed innate stage (<2 weeks) bacterial clearance and reduced late stage inflammation. Innate impairment was associated with reduced natural killer cell activation. In the adaptive phase, CCR4(-/-) mice generated effector T cells in draining lymph nodes and accumulated effector T cells in lungs, which resulted in normal adaptive stage bacterial elimination at 2 to 4 weeks. However, during the late stage, CCR4(-/-) mice had reduced interferonγ+CD4(+)α/β+ (Th1) and interleukin (IL)-17+CD4(+)α/β+ (Th17) T helper cells in lungs. In contrast, IL-17+ γ/δ T cells in lungs were unaffected. When challenged with mycobacterial antigen- (Ag-) Ag-coated beads to elicit a recall granulomatous response, CCR4(-/-) mice displayed abrogated recall granuloma formation and reduced interferon γ+ Th1 cells. These findings indicate that CCR4 supports innate natural killer cell activation and sustains later CD4(+) Th effector/memory antimycobacterial responses in the lung but is redundant in the early adaptive elimination phase.

Cysteine-cysteinyl chemokine receptor 6 mediates invariant natural killer T cell airway recruitment and innate stage resistance during mycobacterial infection

This study examined the contribution of cysteine-cysteinyl chemokine receptor 6 (CCR6) to the innate pulmonary antimycobacterial immune response. Using a mouse model of Mycobacterium bovis BCG airway infection, we detected maximal induction of the CCR6 agonist CCL20 in lungs at 1 week after infection. Infected CCR6 knockout (CCR6-/-) mice displayed an early impairment of bacterial clearance, but ultimately eliminated the attenuated organisms with the onset of adaptive immunity. Flow-cytometric analyses of bronchoalveolar lavages and dispersed lungs revealed a 60% reduction in TCR-α/β+ T cells in airways but no compromise of TCR-γ/δ+ T cells. The subset of CD1d-restricted, CD8-TCR-α/β+ natural killer cells, which mediate innate mycobacterial resistance, was profoundly reduced (90%). Analysis of the adaptive response using ovalbumin-specific transgenic TCR T cell (OT-II) transfer combined with infection with recombinant M. bovis BCG producing ovalbumin peptide indicated no impairment of adaptive T cell activation in CCR6-/- mice. There was also no impairment of the induction of cytokine-producing cells in draining lymphoid tissue of CCR6-/- mice. Taken together, our findings indicate that CCR6 is not required for induction of the adaptive antimycobacterial response, but is likely critical to airway compartment mobilization of TCR-α/β+CCR6+ innate and adaptive effector T cells.

High gene expression of inflammatory markers and IL-17A correlates with severity of injection site reactions of Atlantic salmon vaccinated with oil-adjuvanted vaccines

Background

Two decades after the introduction of oil-based vaccines in the control of bacterial and viral diseases in farmed salmonids, the mechanisms of induced side effects manifested as intra-abdominal granulomas remain unresolved. Side effects have been associated with generation of auto-antibodies and autoimmunity but the underlying profile of inflammatory and immune response has not been characterized. This study was undertaken with the aim to elucidate the inflammatory and immune mechanisms of granuloma formation at gene expression level associated with high and low side effect (granuloma) indices.

Groups of Atlantic salmon parr were injected intraperitoneally with oil-adjuvanted vaccines containing either high or low concentrations of Aeromonas salmonicida or Moritella viscosa antigens in order to induce polarized (severe and mild) granulomatous reactions. The established granulomatous reactions were confirmed by gross and histological methods at 3 months post vaccination when responses were known to have matured. The corresponding gene expression patterns in the head kidneys were profiled using salmonid cDNA microarrays followed by validation by real-time quantitative PCR (qPCR). qPCR was also used to examine the expression of additional genes known to be important in the adaptive immune response.

Results

Granulomatous lesions were observed in all vaccinated fish. The presence of severe granulomas was associated with a profile of up-regulation of innate immunity-related genes such as complement factors C1q and C6, mannose binding protein, lysozyme C, C-type lectin receptor, CD209, Cathepsin D, CD63, LECT-2, CC chemokine and metallothionein. In addition, TGF-β (p = 0.001), IL-17A (p = 0.007) and its receptor (IL-17AR) (p = 0.009) representing T_H17 were significantly up-regulated in the group with severe granulomas as were arginase and IgM. None of the genes directly reflective of T_H1 T cell lineage (IFN-γ, CD4) or T_H2 (GATA-3) responses were differentially expressed.

Conclusions

Granulomatous reactions following vaccination with oil-based vaccines in Atlantic salmon have the profile of strong expression of genes related to innate immune responses. The expression of TGF-β, IL-17A and its receptor suggests an involvement of T_H17 T cell lineage and is in conformity with strong infiltration of neutrophils and macrophages into inflamed areas. Arginase upregulation shows that macrophages in these reactions are alternatively activated, indicating also a T_H2-profile. To what extent the expression of IL-17A and its receptor reflects an autoimmune vaccine-based reaction remains elusive but would be in conformity with previous observations of autoimmune reactions in salmon when vaccinated with oil-based vaccines.

Identification of key processes that control tumor necrosis factor availability in a tuberculosis granuloma

Tuberculosis (TB) granulomas are organized collections of immune cells comprised of macrophages, lymphocytes and other cells that form in the lung as a result of immune response to Mycobacterium tuberculosis (Mtb) infection. Formation and maintenance of granulomas are essential for control of Mtb infection and are regulated in part by a pro-inflammatory cytokine, tumor necrosis factor-α (TNF). To characterize mechanisms that control TNF availability within a TB granuloma, we developed a multi-scale two compartment partial differential equation model that describes a granuloma as a collection of immune cells forming concentric layers and includes TNF/TNF receptor binding and trafficking processes. We used the results of sensitivity analysis as a tool to identify experiments to measure critical model parameters in an artificial experimental model of a TB granuloma induced in the lungs of mice following injection of mycobacterial antigen-coated beads. Using our model, we then demonstrated that the organization of immune cells within a TB granuloma as well as TNF/TNF receptor binding and intracellular trafficking are two important factors that control TNF availability and may spatially coordinate TNF-induced immunological functions within a granuloma. Further, we showed that the neutralization power of TNF-neutralizing drugs depends on their TNF binding characteristics, including TNF binding kinetics, ability to bind to membrane-bound TNF and TNF binding stoichiometry. To further elucidate the role of TNF in the process of granuloma development, our modeling and experimental findings on TNF-associated molecular scale aspects of the granuloma can be incorporated into larger scale models describing the immune response to TB infection. Ultimately, these modeling and experimental results can help identify new strategies for TB disease control/therapy.

Tuberculosis is a common and deadly infectious disease caused by a highly successful bacterium, Mycobacterium tuberculosis (Mtb). Multiple host immune factors control the formation of a self-organizing aggregate of immune cells termed a granuloma in the lungs after inhalation of Mtb. One such factor, tumor necrosis factor-α (TNF), is a protein that regulates inflammatory immune responses. Availability of TNF within a TB granuloma has been proposed to have a critical role in the protective immunity against TB. However, direct measurement of the level of TNF in a granuloma is not experimentally feasible. Therefore, we develop a mathematical model based on an experimental model of granuloma developed in mice to predict TNF availability in a granuloma. We measure values of critical model parameters and explore mechanisms that influence TNF availability in the granuloma. We find that cellular organization in a granuloma and intracellular trafficking of TNF control TNF availability in a granuloma. Further, our model analysis also highlights anti-TNF drug properties that determine their TNF neutralization power. Our findings complement and extend those of recent studies on the role of TNF in the immune response against TB.

Temporal expression of chemokines dictates the hepatic inflammatory infiltrate in a murine model of schistosomiasis

Schistosomiasis continues to be an important cause of parasitic morbidity and mortality world-wide. Determining the molecular mechanisms regulating the development of granulomas and fibrosis will be essential for understanding how schistosome antigens interact with the host environment. We report here the first whole genome microarray analysis of the murine liver during the progression of Schistosoma japonicum egg-induced granuloma formation and hepatic fibrosis. Our results reveal a distinct temporal relationship between the expression of chemokine subsets and the recruitment of cells to the infected liver. Genes up-regulated earlier in the response included T- and B-cell chemoattractants, reflecting the early recruitment of these cells illustrated by flow cytometry. The later phases of the response corresponded with peak recruitment of eosinophils, neutrophils, macrophages and myofibroblasts/hepatic stellate cells (HSCs) and the expression of chemokines with activity for these cells including CCL11 (eotaxin 1), members of the Monocyte-chemoattractant protein family (CCL7, CCL8, CCL12) and the Hepatic Stellate Cell/Fibrocyte chemoattractant CXCL1. Peak expression of macrophage chemoattractants (CCL6, CXCL14) and markers of alternatively activated macrophages (e.g. Retnla) during this later phase provides further evidence of a role for these cells in schistosome-induced pathology. Additionally, we demonstrate that CCL7 immunolocalises to the fibrotic zone of granulomas. Furthermore, striking up-regulation of neutrophil markers and the localisation of neutrophils and the neutrophil chemokine S100A8 to fibrotic areas suggest the involvement of neutrophils in S. japonicum-induced hepatic fibrosis. These results further our understanding of the immunopathogenic and, especially, chemokine signalling pathways that regulate the development of S. japonicum-induced granulomas and fibrosis and may provide correlative insight into the pathogenesis of other chronic inflammatory diseases of the liver where fibrosis is a common feature.

Schistosomiasis, a disease caused by parasitic worms, is a significant cause of illness and death in the developing world. Furthermore, recent reports suggest that the global burden of disease due to schistosomiasis has been significantly underestimated. Schistosomiasis of the liver arises due to inflammation and the deposition of scar tissue around parasite eggs trapped in this organ. In the current study we analysed the gene-expression profile of the mouse liver at several time points following infection with a virulent strain of Schistosoma japonicum to better understand the mechanisms that regulate this process. Progression of disease was associated with increased expression of different groups of genes with distinct biological functions. Specifically, we identified several genes encoding chemical signalling molecules that contribute to different phases of the response by recruiting key cell types to the site of inflammation. This study represents the most comprehensive report to date of the gene expression profile in the liver during schistosomiasis. These results provide further insight into the mechanisms that regulate the development of schistosome-induced inflammation and scarring and will aid in the development of novel treatments to alleviate the burden of disease caused by this parasite.

Toll-like receptor 9 activation is a key mechanism for the maintenance of chronic lung inflammation

RATIONALE

Accumulating evidence supports the hypothesis that the continuous host response to a persistent challenge can polarize the cytokine environment toward a Th2 cytokine phenotype, but the mechanisms responsible for this skewing are not clear.

OBJECTIVES

We investigated the role of Toll-like receptor 9 (TLR9) in a Th2-driven pulmonary granulomatous response initiated via the embolization of Schistosoma mansoni eggs to the lungs of mice.

METHODS

Mice were intravenously injected with S. mansoni eggs. Histological and flow cytometric analysis, cytokine measurement, adoptive transfer of bone marrow (BM)-derived dendritic cells (DCs), and in vitro T-cell treatments with antigen-presenting cells were examined.

MEASUREMENTS AND MAIN RESULTS

In comparison to wild-type mice, TLR9(-/-) mice showed increased pulmonary granuloma size, augmented collagen deposition, increased Th2 cytokine phenotype, and impaired accumulation of DCs. BM-derived DCs, but not macrophages, recovered from animals with developed Th2-type lung granulomas promoted the production of type 2 cytokines from CD4(+) T cells. BM-derived DCs from TLR9(-/-) mice induced impaired Th1 cytokine and enhanced Th2 cytokine production by T cells, compared with DCs from WT mice. Macrophages from TLR9(-/-) mice expressed a significantly higher alternatively activated (M2) phenotype characterized by increased "found in inflammatory zone-1" (FIZZ1) and arginase-1 expression. The adoptive transfer of BM-derived DCs from syngeneic WT mice into TLR9(-/-) mice restored the granuloma phenotype seen in WT mice.

CONCLUSIONS

These studies suggest that TLR9 plays an important mechanistic role in the maintenance of the pulmonary granulomatous response.

Genetic association between a chemokine gene CXCL-10 (IP-10, interferon gamma inducible protein 10) and susceptibility to tuberculosis

Background

Previous studies showed that activation of CXCL-10 and other chemokines were prominent in many infectious diseases. These chemokines are components of innate immune response to respiratory tract pathogens. We examined the promoter variants of CXCL-10 and their role in predisposition to tuberculosis (TB).

Methods

The promoter 1.8 kb of CXCL-10 was sequenced in 24 healthy Chinese individuals to identify genetic polymorphisms. Three tagging SNPs in CXCL-10 promoter (− 1447A > G, − 872G > A, − 135G > A) were selected, and genotyping were performed in 240 TB patients and 176 healthy Chinese subjects. Disease associations were examined by χ² and Fisher exact test.

Results

A promoter SNP (− 135G > A) with minor allele frequency of 0.1 showed a moderate association with TB both in genotype analysis (p = 0.01) and allelic analysis (p = 0.03); other tagging SNPs (− 1447A > G, − 872G > A) were not associated with TB. The odd ratio of the protective allele − 135G > A was 0.51(C.I 0.29 − 0.91) for homozygotes and heterozygotes carriers of the A allele.

Conclusion

A new potential protective SNP (− 135G > A) for TB is identified in the promoter of chemokine gene, CXCL-10. Interestingly, the exact same allele has been shown to enhance IP-10 transactivation and susceptibility to Hepatitis B virus infection in a recent publication. This SNP, located at 14 bp upstream of a NF-kB binding site, might also account for the susceptibility to TB. Our results expanded the clinical significance of this SNP in CXCL-10 promoter.

Immunopathogenesis of human schistosomiasis

Schistosomiasis continues to be a significant cause of parasitic morbidity and mortality worldwide. This review considers the basic features of the pathology and clinical outcomes of hepatointestinal and genitourinary schistosomiasis, presents an overview of the numerous studies on animal models that have clarified many of the immunopathological features, and provides insight into our current understanding of the immunopathogenesis and genetic control of human schistosomiasis. In murine schistosomiasis, pathology is induced by a CD4(+) Th2 driven granulomatous response directed against schistosome eggs lodged in the host liver. The Th2 cytokines IL-4 and IL-13 drive this response, whereas IL-10, IL13Ralpha2, IFN-gamma and a subset of regulatory T-cells act to limit schistosome induced pathology. A variety of cell types including hepatic stellate cells, alternatively activated macrophages and regulatory T-cells have also been implicated in the pathogenesis of schistosomiasis. Current knowledge suggests the immunopathogenic mechanisms underlying human schistosomiasis are likely to be similar. The review also considers the future development of anti-pathology schistosome vaccines. As fibrosis is an important feature of many other diseases such as Crohn's disease and sarcoidosis, a comprehensive understanding of the cellular and molecular mechanisms involved in schistosomiasis may also ultimately contribute to the development an effective disease intervention strategy for other granulofibrotic diseases.

Early pulmonary cytokine and chemokine responses in mice immunized with three different vaccines against Mycobacterium tuberculosis determined by PCR array

In this study, the early pulmonary cytokine and chemokine responses in mice immunized with either BCG vaccine, a DeltasecA2 mutant of Mycobacterium tuberculosis, or a DNA vaccine expressing an ESAT6-antigen 85B fusion protein and then aerogenically challenged with a low dose of M. tuberculosis were evaluated by PCR array. The cellular immune responses at day 10 postchallenge were essentially equivalent in the lungs of mice immunized with either the highly immunogenic BCG vaccine or the DeltasecA2 M. tuberculosis mutant strain. Specifically, 12 immune biomolecules (including gamma interferon [IFN-gamma], interleukin-21 [IL-21], IL-27, IL-17f, CXCL9, CXCL10, and CXCL11) were differentially regulated, relative to the levels for naïve controls, in the lungs of vaccinated mice at this time point. Although the vaccine-related immune responses evoked in mice immunized with the DNA vaccine were relatively limited at 10 days postinfection, upregulation of IFN-gamma RNA synthesis as well as increased expression levels of CXCL9, CXCL10, and CXCL11 chemokines were detected.

The role of chemokines in controlling granulomatous inflammation in Schistosoma mansoni infection

Chemokines are a superfamily of low-molecular-weight cytokines that were initially described for their chemoattractant activity. It is now clear chemokines have several other activities that modulate immune processes. Chemokines appear to play a role in the pathogenesis of several inflammatory diseases. The role of chemokines and their receptors in mediating granulomatous inflammation induced by Schistosoma mansoni egg antigens presented in particulate manner have been studied in detail. Much less is known of the role of chemokines in mediating inflammation during the course of S. mansoni infection. Our studies in mice suggest a relevant role for the chemokine CCL3 and the receptor CCR5 in the pathogenesis of experimental S. mansoni infection. Absence of CCL3 is associated with decrease in granuloma size, fibrosis and parasite load. In humans, levels of CCL3 in plasma associate with disease severity and may be useful for diagnostic purposes. In contrast, absence of CCR5 is associated with enhanced lethality, granuloma size and fibrosis. It is suggested that the balance of chemokine production and chemokine receptor activation are important determinants of the fate of infection in experimental animals and humans.

Characterization of T-cell immunogenicity of two PE/PPE proteins of Mycobacterium tuberculosis

The PE and PPE proteins of Mycobacterium tuberculosis form a source of antigenic variation among different strains of this bacterium. Two of the PE_PGRS protein-encoding genes, rv3812 and rv3018c, are expressed in pathogenic mycobacteria and are implicated, respectively, in the persistence of the organism in macrophages and in virulence. Peptides derived from these proteins have been predicted to bind major histocompatibility complex (MHC) class I with high affinity on the basis of immunoinformatics analysis, suggesting a possible role for these proteins in antimycobacterial immunity. In the present work, using DNA constructs containing the rv3812 and rv3018c genes of M. tuberculosis, the immunogenicity of these proteins was demonstrated in BALB/c mice. Immunization with either DNA construct induced a significant number of CD8+-type T cells and a strong Th1-type response, with high gamma interferon (IFN-gamma) and low interleukin-4 responses. Three nonameric peptides of Rv3812 and two of Rv3018c elicited a strong T-cell response in an MHC-restricted manner. An epitope-specific response was demonstrated by the lysis of peptide-pulsed antigen-presenting cells, release of perforin and IFN-gamma production. Experimentally, these peptides bound with high affinity to MHC H-2Kd and showed low dissociation rates of peptide-MHC complexes. This study suggests that the identified T-cell epitopes may contribute to immunity against tuberculosis if included in a vaccine.

Live Mycobacterium avium subsp. paratuberculosis and a killed-bacterium vaccine induce distinct subcutaneous granulomas, with unique cellular and cytokine profiles

Type II (lepromatous) granulomas are characterized by a lack of organization, with large numbers of macrophages heavily burdened with bacilli and disorganized lymphocyte infiltrations. Type II granulomas are a characteristic feature of the enteric lesions that develop during clinical Mycobacterium avium subsp. paratuberculosis infection in the bovine. Considering the poor organization and function of these granulomas, it is our hypothesis that dendritic cell (DC) function within the granuloma is impaired during initial infection. In order to test our hypothesis, we used a subcutaneous M. avium subsp. paratuberculosis infection model to examine early DC function within M. avium subsp. paratuberculosis-induced granulomas. In this model, we first characterized the morphology, cellular composition, and cytokine profiles of subcutaneous granulomas that develop 7 days after subcutaneous inoculation with either vaccine or live M. avium subsp. paratuberculosis. Second, we isolated CD11c(+) cells from within granulomas and measured their maturation status and ability to induce T-cell responses. Our results demonstrate that M. avium subsp. paratuberculosis or vaccine administration resulted in the formation of distinct granulomas with unique cellular and cytokine profiles. These distinct profiles corresponded to significant differences in the phenotypes and functional responses of DCs from within the granulomas. Specifically, the DCs from the M. avium subsp. paratuberculosis-induced granulomas had lower levels of expression of costimulatory and chemokine receptors, suggesting limited maturation. This DC phenotype was associated with weaker induction of T-cell proliferation. Taken together, these findings suggest that M. avium subsp. paratuberculosis infection in vivo influences DC function, which may shape the developing granuloma and initial local protection.

The role of chemokines in Schistosoma mansoni infection: insights from human disease and murine models

Chemokines are a superfamily of low-molecular-weight cytokines that were initially described for their chemoattractant activity. It is now clear chemokines have several other activities that modulate immune processes. More than 50 chemokines ligands and at least 19 receptors have been described to date. Depending on the number of N-terminal cysteine residues, chemokines are grouped in the subfamilies CXC, CC, C or CX3C. A growing body of evidence suggests a role for chemokines in the pathogenesis of several inflammatory diseases. Our studies involving mice and humans infected with Schistosoma mansoni suggest an important role of the chemokine CCL3 and its receptors (CCR1 and CCR5) in the pathogenesis of severe schistosomiasis. We suggest that the differential activation of CCR1 or CCR5 during the course of schistosomiasis may dictate the outcome of the disease.

TLR9 activation is a key event for the maintenance of a mycobacterial antigen-elicited pulmonary granulomatous response

Type 1 (Th1) granulomas can be studied in mice sensitized with mycobacterium antigens followed by challenge of agarose beads covalently coupled to purified protein derivative. TLR9 is known to play a role in the regulation of Th1 responses; thus, we investigated the role of TLR9 in granuloma formation during challenge with mycobacterium antigens and demonstrated that mice deficient in TLR9 had increased granuloma formation, but a dramatically altered cytokine phenotype. Th1 cytokine levels of IFN-gamma and IL-12 in the lungs were decreased in TLR9(-/-) mice when compared to wild-type mice. In contrast, Th2 cytokine levels of IL-4, IL-5, and IL-13 were increased in TLR9(-/-) mice. The migration of CD4(+) T cells in the granuloma was impaired, while the number of F4/80(+) macrophages was increased in TLR9(-/-) mice. Macrophages in the lungs of the TLR9-deficient animals with developing granulomas expressed significantly lower levels of the classically activated macrophage marker, nitric oxide synthase, but higher levels of the alternatively activated macrophage markers such as 'found in inflammatory zone-1' antigen and Arginase-1. These results suggest that TLR9 plays an important role in maintaining the appropriate phenotype in a Th1 granulomatous response.

Allergic inflammatory reaction is involved in necrosis of human pulmonary dirofilariasis

AIMS

To determine whether, in view of the massive inflammatory cell infiltration and the rounded rather than wedge-shaped character of pulmonary lesions in dirofilariasis, the inflammatory response against the worm contributes to the coagulative necrosis, in addition to an ischaemic process.

METHODS AND RESULTS

The histopathological features of 13 resected dirofilariasis cases with well-defined nodules ranged from 10 to 30 mm were analysed. On routine histology and using immunohistochemistry, the peripheral encapsulating wall showed mild to severe infiltration of eosinophils, lymphocytes and plasma cells and a histiocytic reaction in all cases, often with necrotic eosinophils seen within the necrosis (84.6%) and inflammatory changes in the adjacent lung (38.5%). The CD4+ lymphocyte count (80.8 +/- 33.4) was greater than that of CD8+ lymphocytes (24.5 +/- 16.9) in the central necrosis and vice versa in the wall. In the necrotic regions, disruption of the pulmonary artery (61.5%) and extravasation of the torn worm (23.1%) could be seen.

CONCLUSIONS

These findings indicate that an allergic inflammatory reaction, mediated by eosinophils and lymphocytes, is involved in the formation of the dirofilarial necrotizing granuloma rather than infarction caused simply by embolism.

Expression and role of CCR6/CCL20 chemokine axis in pulmonary sarcoidosis

We have shown previously that the chemokine receptors CXCR3 and CXCR6 are coexpressed by Th1 cells infiltrating the lung and the granuloma of patients with sarcoidosis. In this study, we evaluated the role of CCL20/CCR6 interaction in the pathogenesis of acute and chronic pulmonary sarcoidosis. By flow cytometry and molecular analyses, we have demonstrated that Th1 cells isolated from the bronchoalveolar lavage (BAL) of patients with sarcoidosis and T cell alveolitis are equipped with CCR6. Furthermore, CCR6(+) T cells coexpressed the chemokine receptors CXCR3 and CXCR6. Immunohistochemical analysis of lung specimens has shown that CCR6(+) T cells infiltrate lung interstitium and surround the central core of the granuloma. It is interesting that CCR6 was never detected on the alveolar macrophage (AM) surface, and it is observed in the cytoplasm of AMs from patients with sarcoidosis and alveolitis. The CCR6 ligand CCL20 was expressed by macrophages, multinucleated giant cells, and epithelioid cells infiltrating the granuloma. Furthermore, detectable levels of CCL20 protein are seen in the BAL fluid components of patients with active sarcoidosis, and sarcoid AMs release the CCR6 ligand in vitro. From a functional point of view, sarcoid Th1 cells were able to respond to CXCL10, CXCL16, and CCL20 in migratory assays. In vitro kinetic studies demonstrated that CCR6 is induced rapidly by IL-2, IL-18, and IFN-gamma. In conclusion, T cells expressing CCR6, CXCR3, and CXCR6 act coordinately with respective ligands and Th1 inflammatory cytokines in the alveolitic/granuloma phases of the disease.

Milk fermented by Lactobacillus helveticus R389 and its non-bacterial fraction confer enhanced protection against Salmonella enteritidis serovar Typhimurium infection in mice

Bacterial infections in the gastrointestinal tract represent a major global health problem, even in the presence of normally effective mucosal immune mechanisms. Milk fermented by Lactobacillus helveticus R389 (FM) or its non-bacterial fraction obtained by milk fermentation at controlled pH 6 (NBF) are able to activate the small intestine mucosal immune response according to previous studies. In this work we aimed at comparing their protection capacity against an infection by Salmonella enteritidis serovar Typhimurium and at studying the mechanisms involved. In a completely randomized design, BALB/c mice received FM or NBF for 2, 5 or 7 consecutive days, followed by a single oral challenge with S. Typhimurium (10(7) cells/mouse). The increase in the number of IgA+ cells in the lamina propria of the small intestine, after the feeding periods, was accompanied by an increase in the luminal content of total S-IgA. However, no antibodies were produced against the NBF. In mice given the FM or the NBF for 7 consecutive days, lower levels of liver colonization on day 7 post-challenge with S. Typhimurium, higher luminal contents of specific anti-Salmonella S-IgA, higher percentages of survival to infection and lower numbers of MIP-1alpha+ cells in the lamina propria were observed. In this work we observed that in both the FM or the NBF there are active principles that confer enhanced protection against S. Typhimurium infection. However, the mechanisms underlying mucosal immunomodulation and protection are different. In those mechanisms, the mucosal immune response would seem to be more involved than the competitive or exclusion mechanisms between L. helveticus R389 and S. enteritidis serovar Typhimurium.

The role of CC chemokine receptor 6 in host defense in a model of invasive pulmonary aspergillosis

RATIONALE

Invasive aspergillosis is a severe fungal infection afflicting immunocompromised patients, particularly patients with neutrophil defects. CCR6, a beta-chemokine receptor, mediates migration of dendritic cells (DCs) and several lymphocyte subsets to sites of epithelial inflammation, but its role in infections has not been examined extensively.

OBJECTIVES

To test the hypothesis that CCR6-mediated leukocyte recruitment is necessary for effective host defense in neutropenic hosts with invasive pulmonary aspergillosis.

METHODS

Neutropenic wild-type mice and mice with targeted deletion of CCR6 were infected with Aspergillus fumigatus. The host responses to the infection were compared in vivo and leukocyte responses to the fungus were examined in vitro.

MEASUREMENTS AND MAIN RESULTS

In the context of infection, immature myeloid DCs were the major population of CCR6-expressing cells in the lungs. As compared with wild-type animals, CCR6-deficient mice developed a more severe infection when challenged with A. fumigatus conidia, as documented by a higher mortality rate and greater lung fungal burden. This was associated with reduced accumulation of DCs in the lungs. CCR6-deficient and wild-type DCs did not differ in their phagocytosis of conidia, cytokine response, or maturation in vitro. In adoptive transfer experiments, however, DCs from CCR6-deficient donors showed lesser accumulation in the lungs of infected mice as compared with wild-type cells, and transfer of wild-type, but not CCR6-deficient, DCs resulted in attenuated severity of infection in CCR6-deficient recipients.

CONCLUSIONS

Taken together, these results implicate CCR6-mediated DC influx into the lung in the initial host defense in invasive aspergillosis.

Ingested (oral) SIRS peptide 1–21 inhibits acute EAE by inducing Th2-like cytokines

OBJECTIVE

Ingested type I IFN inhibits clinical attacks, relapses and inflammation in murine chronic relapsing EAE by inhibiting Th1-like cytokines. Type I IFN activates human suppressor T cells that produce SIRS.

METHODS

We examined whether oral (ingested) SIRS peptide inhibits EAE by decreasing Th1-like cytokines.

RESULTS

Parenteral SIRS peptide 1-21 showed a significant inhibition of disease severity in murine EAE. Ingested SIRS peptide at 10 and 100 microg SIRS peptide showed a significant inhibition of disease severity but also a prolonged delay in the onset of disease compared to placebo. There were significantly less inflammatory foci in the SIRS peptide fed group compared to the control mock fed group. Splenocytes from SIRS peptide 1-21 fed mice showed increased production of Th2-like CD30L, IL-13, TCA-3 cytokines/chemokines and decreased production of Th1-like cytokine lymphotactin.

INTERPRETATION

Ingested (oral) SIRS peptide significantly inhibits both clinical EAE and inflammation predominately via counter-regulatory type 2-like cytokines/chemokines IL-13, CD30L and TCA-3.

Virally activated CD8 T cells home to Mycobacterium bovis BCG-induced granulomas but enhance antimycobacterial protection only in immunodeficient mice

The effect of secondary infections on CD4 T-cell-regulated chronic granulomatous inflammation is not well understood. Here, we have investigated the effect of an acute viral infection on the cellular composition and bacterial protection in Mycobacterium bovis strain bacille Calmette-Guérin (BCG)-induced granulomas using an immunocompetent and a partially immunodeficient murine model. Acute lymphocytic choriomeningitis virus (LCMV) coinfection of C57BL/6 mice led to substantial accumulation of gamma interferon (IFN-gamma)-producing LCMV-specific T cells in liver granulomas and increased local IFN-gamma. Despite traffic of activated T cells that resulted in a CD8 T-cell-dominated granuloma, the BCG liver organ load was unaltered from control levels. In OT-1 T-cell-receptor (TCR) transgenic mice, ovalbumin (OVA) immunization or LCMV coinfection of BCG-infected mice induced CD8 T-cell-dominated granulomas containing large numbers of non-BCG-specific activated T cells. The higher baseline BCG organ load in this CD8 TCR transgenic animal allowed us to demonstrate that OVA immunization and LCMV coinfection increased anti-BCG protection. The bacterial load remained substantially higher than in mice with a more complete TCR repertoire. Overall, the present study suggests that peripherally activated CD8 T cells can be recruited to chronic inflammatory sites, but their contribution to protective immunity is limited to conditions of underlying immunodeficiency.

Structural correlates of antimicrobial efficacy in IL-8 and related human kinocidins

Chemokines are small (8-12 kDa) effector proteins that potentiate leukocyte chemonavigation. Beyond this role, certain chemokines have direct antimicrobial activity against human pathogenic organisms; such molecules are termed kinocidins. The current investigation was designed to explore the structure-activity basis for direct microbicidal activity of kinocidins. Amino acid sequence and 3-dimensional analyses demonstrated these molecules to contain iterations of the conserved gamma-core motif found in broad classes of classical antimicrobial peptides. Representative CXC, CC and C cysteine-motif-group kinocidins were tested for antimicrobial activity versus human pathogenic bacteria and fungi. Results demonstrate that these molecules exert direct antimicrobial activity in vitro, including antibacterial activity of native IL-8 and MCP-1, and microbicidal activity of native IL-8. To define molecular determinants governing its antimicrobial activities, the IL-8 gamma-core (IL-8gamma) and alpha-helical (IL-8alpha) motifs were compared to native IL-8 for antimicrobial efficacy in vitro. Microbicidal activity recapitulating that of native IL-8 localized to the autonomous IL-8alpha motif in vitro, and demonstrated durable microbicidal activity in human blood and blood matrices ex vivo. These results offer new insights into the modular architecture, context-related deployment and function, and evolution of host defense molecules containing gamma-core motifs and microbicidal helices associated with antimicrobial activity.

Expression of macrophage-derived chemokine (MDC)/CCL22 in human lung cancer

BACKGROUND

Ligands for CXCR3 chemokines [IFN-gamma-inducible protein of 10 kD (IP-10/CXCL10), monokine induced by IFN-gamma (Mig/CXCL9), IFN-inducible T cell alpha chemoattractant (I-TAC/CXCL11)] and those for CCR4 [macrophage-derived chemokine (MDC/CCL22), thymus- and activation-regulated chemokine (TARC/CCL17)] have been shown to play the central roles for T helper-cell recruitment into the tissues. To examine the role of these chemokines in tumor progression of lung cancer, we investigated their expression in human lung cancer tissues to determine the possible relationship between their expression and the prognosis of patients.

METHODS

Total RNA was prepared from lung cancer tissues of 40 patients (24 adenocarcinoma and 16 squamous cell carcinoma). We measured gene expression levels of chemokines (IP-10, Mig, I-TAC, MDC and TARC) by real-time quantitative RT-PCR.

RESULTS

Higher gene expression of MDC in lung cancer was significantly correlated with longer disease-free survival time and lower risk of recurrence after tumor resection. We could not find any significant relationship of IP-10, Mig, I-TAC and TARC gene expression with disease-free survival or lower risk of recurrence after surgery.

CONCLUSIONS

These results suggest that increased gene expression of MDC in tumor tissues may be a predictive marker for improving the prognosis of lung cancer.

Antimicrobial peptides versus invasive infections

It has been estimated that there are more microorganisms within and upon the human body than there are human cells. By necessity, every accessible niche must be defended by innate mechanisms to prevent invasive infection, and ideally that precludes the need for robust inflammatory responses. Yet the potential for pathogens to transcend the integument actively or passively and access the bloodstream emphasizes the need for rapid and potent antimicrobial defense mechanisms within the vascular compartment. Antimicrobial peptides from leukocytes have long been contemplated as being integral to defense against these infections. Recently, platelets are increasingly recognized for their likely multiple roles in antimicrobial host defense. Platelets and leukocytes share many structural and functional archetypes. Once activated, both cell types respond in specific ways that emphasize key roles for their antimicrobial peptides in host defense efficacy: (a) targeted accumulation at sites of tissue injury or infection; (b) direct interaction with pathogens; and (c) deployment of intracellular (leukocyte phagosomes) or extracellular (platelet secretion) antimicrobial peptides. Antimicrobial peptides from these cells exert rapid, potent, and direct antimicrobial effects against organisms that commonly access the bloodstream. Experimental models in vitro and in vivo show that antimicrobial peptides from these cells significantly contribute to prevent or limit infection. Moreover, certain platelet antimicrobial proteins are multifunctional kinocidins (microbicidal chemokines) that recruit leukocytes to sites of infection, and potentiate the antimicrobial mechanisms of these cells. In turn, pathogens pre-decorated by kinocidins may be more efficiently phagocytosed and killed by leukocytes and their antimicrobial peptide arsenal. Hence, multiple and relevant interactions between platelets and leukocytes have immunologic functions yet to be fully understood. A clearer definition of these interactions, and the antimicrobial peptide effectors contributing to these functions, will significantly advance our understanding of antimicrobial host defense against invasive infection. In addition, this knowledge may accelerate development of novel anti-infective agents and strategies against pathogens that have become refractory to conventional antimicrobials.

Severe sepsis exacerbates cell-mediated immunity in the lung due to an altered dendritic cell cytokine profile

Severe sepsis leads to long-term alterations in the immune response of surviving individuals. We have modeled this alteration in host immunity by studying the survivors of severe experimental sepsis (murine cecal ligation and puncture), which were subsequently challenged with lung granuloma-inducing Schistosoma mansoni eggs. This granulomatous response is a well-studied cell-mediated immune reaction characterized by elevated levels of type-2 cytokines. Pulmonary granulomas induced by S. mansoni eggs in cecal ligation and puncture survivors were significantly larger and contained more eosinophils than granulomas in sham-operated mice. Significantly lower interleukin (IL)-12p40 mRNA and IL-12p70 protein levels were observed in the lungs of postseptic mice with developing granulomas, compared with controls. Postseptic mice had significantly fewer dendritic cells in the lungs during the granulomatous response. Isolated lung dendritic cells from postseptic mice at days 8 and 16 after S. mansoni egg challenge exhibited defective IL-12 synthesis but enhanced IL-10 synthesis after Toll-like receptor agonist challenge. Pulmonary transfection with an IL-12-expressing adenovirus in postseptic mice reversed the skewing of the pulmonary cytokine profile and normalized the lung granulomatous response. Our data indicate that severe sepsis shifts the pulmonary cytokine environment, presumably via effects on pulmonary dendritic cells, which in turn alters the lung cell-mediated immune response.

Elevated serum CCL2 concomitant with a reduced mycobacterium-induced response leads to disease dissemination in leprosy

Mycobacterium leprae and Mycobacterium tuberculosis are successful intracellular pathogens which down regulate host immune responses. T-cell interferon-gamma (IFNgamma) and macrophage tumour necrosis factor-alpha (TNFalpha) activate chemokines such as, C-C chemokine ligand-2 (CCL2) and CCL5, which play a role in granuloma formation. Lepromatous leprosy is characterized by defective granulomas with lowered T-cell- and macrophage-mediated responses. Tuberculosis (TB) can be localized to the lung, whereby discreet granulomas are formed. The role of chemokines in leprosy infections is as yet unclear. We compared chemokine responses in lepromatous leprosy and pulmonary tuberculosis patients. Circulating serum CCL2 was raised while CCL5 was lowered in leprosy, as compared with TB patients and healthy controls. However, both Mycobacterium bovis BCG- (P=0.08) and M. leprae-induced (P=0.05) CCL2 secretion was reduced in leprosy. In leprosy, BCG induced greater CCL2 (P=0.01), TNFalpha (P=0.02) and somewhat greater CCL5 (P=0.08) than M. leprae, while CXCL8 induction was comparable. Overall levels of Mycobacterium-induced CCL2, TNFalpha and CXCL8 were two to threefold lower, and CCL5 was 10-fold lower in leprosy as compared with TB. Reduced inducible CCL2 combined with a lowered TNFalpha response in lepromatous leprosy may contribute to the unrestricted growth and dissemination of mycobacteria found in the disease.