Single cell atlas of human gastric muscle immune cells and macrophage-driven changes in idiopathic gastroparesis.

Gastrointestinal immune cells, particularly muscularis macrophages (MM) interact with the enteric nervous system and influence gastrointestinal motility. Here we determine the human gastric muscle immunome and its changes in patients with idiopathic gastroparesis (IG). Single cell sequencing was performed on 26,000 CD45+ cells obtained from the gastric tissue of 20 subjects. We demonstrate 11 immune cell clusters with T cells being most abundant followed by myeloid cells. The proportions of cells belonging to the 11 clusters were similar between IG and controls. However, 9/11 clusters showed 578-11,429 differentially expressed genes. In IG, MM had decreased expression of tissue-protective and microglial genes and increased the expression of monocyte trafficking and stromal activating genes. Furthermore, in IG, IL12 mediated JAK-STAT signaling involved in the activation of tissue-resident macrophages and Eph-ephrin signaling involved in monocyte chemotaxis were upregulated. Patients with IG had a greater abundance of monocyte-like cells. These data further link immune dysregulation to the pathophysiology of gastroparesis.

Lactic acid induces transcriptional repression of macrophage inflammatory response via histone acetylation.

Lactic acid has emerged as an important modulator of immune cell function. It can be produced by both gut microbiota and the host metabolism at homeostasis and during disease states. The production of lactic acid in the gut microenvironment is vital for tissue homeostasis. In the present study, we examined how lactic acid integrates cellular metabolism to shape the epigenome of macrophages during pro-inflammatory response. We found that lactic acid serves as a primary fuel source to promote histone H3K27 acetylation, which allows the expression of immunosuppressive gene program including Nr4a1. Consequently, macrophage pro-inflammatory function was transcriptionally repressed. Furthermore, the histone acetylation induced by lactic acid promotes a form of long-term immunosuppression ("trained immunosuppression"). Pre-exposure to lactic acid induces lipopolysaccharide tolerance. These findings thus indicate that lactic acid sensing and its effect on chromatin remodeling in macrophages represent a key homeostatic mechanism that can provide a tolerogenic tissue microenvironment.

Blockade of CCR1 induces a phenotypic shift in macrophages and triggers a favorable antilymphoma activity.

Tumor-associated macrophages (TAMs) within the tumor microenvironment (TME) play an important role in tumor growth and progression. TAMs have been involved in producing immunosuppressive TME via various factors; however, the underlying mechanisms remain unclear in B-cell lymphoma, including mantle cell lymphoma (MCL). We identified that chemokine receptor-1 (CCR1) is highly expressed on monocytes (Mo) and macrophages (MΦ), and CCR1 pharmacological inhibition or CCR1 siRNA abolished lymphoma-mediated Mo/MΦ migration in a chemotaxis assay. The deficiency of host CCR1 (CCR1 KO) was associated with decreased infiltration of peritoneal-MΦ compared with WT-CCR1. Functional studies indicated that the genetic depletion of CCR1 or treatment inhibited protumor MΦ (M2-like) phenotype by decreasing CD206 and IL-10 expression. Moreover, CCR1 depletion reprogrammed MΦ toward an MHCII+/TNFα+ immunogenic phenotype. Mechanistically, protumor MΦ driven-IL-10 provides a positive feedback loop to tumor-CCL3 by regulating the CCL3 promoter via STAT1 signaling. Therapeutic in vivo targeting of CCR1 with CCR1 antagonist BX-471 significantly reduced FC-muMCL1 mouse tumors in the syngeneic MCL model by the depletion of M2-TAMs and increased infiltration of cytotoxic CD8+ T cells. Our study established that CCR1 exerts a pivotal role in macrophage programming, thus shaping protumor TME and lymphoma progression. CCR1 inhibition through CCR1 antagonists may be a promising therapeutic strategy to reprogram macrophages in lymphoma-TME and achieve better clinical outcomes in patients.

Long-Term Programming of CD8 T Cell Immunity by Perinatal Exposure to Glucocorticoids.

Early life environmental exposure, particularly during perinatal period, can have a life-long impact on organismal development and physiology. The biological rationale for this phenomenon is to promote physiological adaptations to the anticipated environment based on early life experience. However, perinatal exposure to adverse environments can also be associated with adult-onset disorders. Multiple environmental stressors induce glucocorticoids, which prompted us to investigate their role in developmental programming. Here, we report that perinatal glucocorticoid exposure had long-term consequences and resulted in diminished CD8 T cell response in adulthood and impaired control of tumor growth and bacterial infection. We found that perinatal glucocorticoid exposure resulted in persistent alteration of the hypothalamic-pituitary-adrenal (HPA) axis. Consequently, the level of the hormone in adults was significantly reduced, resulting in decreased CD8 T cell function. Our study thus demonstrates that perinatal stress can have long-term consequences on CD8 T cell immunity by altering HPA axis activity.

Evaluation of a multiplex flow immunoassay versus conventional assays in detecting autoantibodies in systemic lupus erythematosus.

INTRODUCTION: Conventional diagnostic assays are being replaced with automated multiplex assays, but their performance needs to be evaluated. We compared a multiplex flow immunoassay with conventional techniques in the detection of antinuclear antibodies (ANAs) and antibodies to specific extractable nuclear antigens (ENAs) in serum samples from patients with systemic lupus erythematosus. METHODS: A total of 140 consecutive Chinese patients with systemic lupus erythematosus and 41 healthy controls were included. The automated BioPlex 2200 ANA Screen assay (Bio-Rad Laboratories, Hercules [CA], US) was compared with indirect immunofluorescence. In addition, use of BioPlex 2200 to detect anti-ENA antibodies was compared with in-house assays of countercurrent immunoelectrophoresis (CIEP), enzyme-linked immunosorbent assay (ELISA), and line blot. RESULTS: The sensitivity and specificity of BioPlex in detecting ANAs (91.4% and 95.1%, respectively) were comparable to those of indirect immunofluorescence (90.7% and 85.4%, respectively). Overall, BioPlex achieved the best agreement with ELISA in detecting anti-ENA antibodies: agreement was >90% for most antibody types (κ=0.79-0.94). In contrast, agreement was poorest with CIEP, ranging from 85.6% (κ=0.33) for anti-Sm antibodies to 93.9% (κ=0.88) for anti-Ro antibodies. Overall, BioPlex and ELISA had the highest sensitivity, whereas CIEP had the highest specificity. In terms of disease association, anti-Sm detected by CIEP had the best positive predictive value and specificity for lupus nephritis. CONCLUSIONS: In a local lupus cohort, BioPlex showed comparable sensitivity to indirect immunofluorescence in detecting ANAs and comparable performance to ELISA in detecting anti-ENA antibodies. However, CIEP was the best method in terms of disease specificity.

Prevalence of neutralising antibodies to interferon-beta and clinical response in Chinese patients with relapsing multiple sclerosis.

BACKGROUND: There are no data on neutralising antibodies to interferon-beta and its clinical implications in Chinese patients with multiple sclerosis (MS). OBJECTIVES: The objectives of this study were to investigate the prevalence of neutralising antibodies among Chinese patients with relapsing MS receiving interferon-beta (1a or 1b) and to study the association between neutralising antibodies and the clinical-radiological response. METHODS: We performed a cross-sectional study on MS patients who received interferon-beta for 9 months or more, and evaluated the clinical response by relapses and magnetic resonance imaging lesions. Blood samples were evaluated for myxovirus resistance protein A (MxA) gene expression by polymerase chain reaction, anti-interferon-beta binding antibodies by enzyme-linked immunosorbent assay, and neutralising antibodies by cell-based MxA protein induction and luciferase reporter gene assays. Assay performances were evaluated by receiver operating characteristic analysis. RESULTS: Among 78 subjects recruited, 61/77 (79%) had anti-interferon-beta binding antibodies, and 22/78 (28%) had neutralising antibodies by MxA protein induction assay. The presence of high-titre neutralising antibodies was associated with poor clinical outcome (odds ratio 6.1, 95% confidence interval 1.5-25.6, P = 0.013). The sensitivity and specificity for neutralising antibodies using MxA gene expression assay (cut-off 0.20) was 80% and 68%, respectively (area under the curve 0.71). CONCLUSIONS: Neutralising antibodies are associated with poor clinical outcome in Chinese patients with relapsing MS. MxA gene expression and protein induction assays are complimentary assays for neutralising antibody detection.

Anti-inflammatory effect of IL-10 mediated by metabolic reprogramming of macrophages.

Interleukin 10 (IL-10) is an anti-inflammatory cytokine that plays a critical role in the control of immune responses. However, its mechanisms of action remain poorly understood. Here, we show that IL-10 opposes the switch to the metabolic program induced by inflammatory stimuli in macrophages. Specifically, we show that IL-10 inhibits lipopolysaccharide-induced glucose uptake and glycolysis and promotes oxidative phosphorylation. Furthermore, IL-10 suppresses mammalian target of rapamycin (mTOR) activity through the induction of an mTOR inhibitor, DDIT4. Consequently, IL-10 promotes mitophagy that eliminates dysfunctional mitochondria characterized by low membrane potential and a high level of reactive oxygen species. In the absence of IL-10 signaling, macrophages accumulate damaged mitochondria in a mouse model of colitis and inflammatory bowel disease patients, and this results in dysregulated activation of the NLRP3 inflammasome and production of IL-1ß.

Comparative evaluation of three new commercial immunoassays for anti-Müllerian hormone measurement.

STUDY QUESTION: How do the three new anti-Müllerian hormone (AMH) assay methods, manufactured by Beckman Coulter, Roche and Ansh Labs compare with each other and with the Gen II assay? SUMMARY ANSWER: The three new AMH assays are well correlated among themselves and with the Gen II assay, although differences in calibration do exist. WHAT IS KNOWN ALREADY: The Gen II assay has been the mainstay method for AMH measurement in the past few years. Recently, a few new AMH measurement methods have come to the market. STUDY DESIGN, SIZE, DURATION: This was a prospective assay evaluation performed on 178 human serum samples. PARTICIPANTS/MATERIALS, SETTING, METHODS: AMH concentration was measured in residual serum samples donated by female patients in a reproductive medicine centre. The three new assay methods were tested in parallel and the numerical values obtained were compared among themselves and with those obtained by the Gen II assay. The assay stability upon different sample storage conditions, intra-assay and inter-assay precision, linearity and dilution recovery, and diagnostic performance for polycystic ovary syndrome (PCOS) of the three new AMH assay methods were also compared. MAIN RESULTS AND THE ROLE OF CHANCE: AMH values measured by the Gen II kit and the three new assay methods have good correlations (R > 0.9 for all pairwise correlations). Values measured by the Ansh Labs assay were significantly higher, whereas those by the Roche assay were significantly lower, than those from the Gen II and Beckman-Coulter automated assays (P < 0.05). AMH values were significantly different when measured on the fresh and frozen-thawed serum sample (at -20oC and -80oC) for all three new methods (P < 0.05), but the magnitude of difference was very small with the Beckman-Coulter automated assay and Roche assay. The intra-assay coefficients of variation (CVs) were 0.7-2.2%, 0.5-1.4%, and 1.4-5.4% for the Beckman-Counter automated, Roche and Ansh Labs assays, respectively. Their inter-assay CVs were 0.9-2.5%, 0.7-1.9%, and 6.2-13.5%, respectively. All three new assay methods showed acceptable linearity, and provided excellent discrimination of PCOS from controls. LIMITATIONS, REASONS FOR CAUTION: The precision and dilution linearity experiments involved a small sample size, although these were not the primary outcome measures and have been properly evaluated in previous publications. The study was not designed or powered for determining diagnostic cut-off values. WIDER IMPLICATIONS OF THE FINDINGS: The results demonstrate that the three new AMH assay methods are all valid methods to be adopted in the field of reproduction and are a basis for further work on their clinical application. STUDY FUNDING/COMPETING INTERESTS: The authors have no competing interest to declare. The execution of this study was funded by the Department of Obstetrics and Gynaecology, The University of Hong Kong.

Macrophages monitor tissue osmolarity and induce inflammatory response through NLRP3 and NLRC4 inflammasome activation.

Interstitial osmolality is a key homeostatic variable that varies depending on the tissue microenvironment. Mammalian cells have effective mechanisms to cope with osmotic stress by engaging various adaptation responses. Hyperosmolality due to high dietary salt intake has been linked to pathological inflammatory conditions. Little is known about the mechanisms of sensing the hyperosmotic stress by the innate immune system. Here we report that caspase-1 is activated in macrophages under hypertonic conditions. Mice with high dietary salt intake display enhanced induction of Th17 response upon immunization, and this effect is abolished in caspase-1-deficient mice. Our findings identify an unknown function of the inflammasome as a sensor of hyperosmotic stress, which is crucial for the induction of inflammatory Th17 response.

Activation of caspase-1 by the NLRP3 inflammasome regulates the NADPH oxidase NOX2 to control phagosome function.

Phagocytosis is a fundamental cellular process that is pivotal for immunity as it coordinates microbial killing, innate immune activation and antigen presentation. An essential step in this process is phagosome acidification, which regulates many functions of these organelles that allow phagosomes to participate in processes that are essential to both innate and adaptive immunity. Here we report that acidification of phagosomes containing Gram-positive bacteria is regulated by the NLRP3 inflammasome and caspase-1. Active caspase-1 accumulates on phagosomes and acts locally to control the pH by modulating buffering by the NADPH oxidase NOX2. These data provide insight into a mechanism by which innate immune signals can modify cellular defenses and establish a new function for the NLRP3 inflammasome and caspase-1 in host defense.

Pathogen-derived effectors trigger protective immunity via activation of the Rac2 enzyme and the IMD or Rip kinase signaling pathway.

Although infections with virulent pathogens often induce a strong inflammatory reaction, what drives the increased immune response to pathogens compared to nonpathogenic microbes is poorly understood. One possibility is that the immune system senses the level of threat from a microorganism and augments the response accordingly. Here, focusing on cytotoxic necrotizing factor 1 (CNF1), an Escherichia coli-derived effector molecule, we showed the host indirectly sensed the pathogen by monitoring for the effector that modified RhoGTPases. CNF1 modified Rac2, which then interacted with the innate immune adaptors IMD and Rip1-Rip2 in flies and mammalian cells, respectively, to drive an immune response. This response was protective and increased the ability of the host to restrict pathogen growth, thus defining a mechanism of effector-triggered immunity that contributes to how metazoans defend against microbes with pathogenic potential.

Phagocytosis and phagosome acidification are required for pathogen processing and MyD88-dependent responses to Staphylococcus aureus.

Innate immunity is vital for protection from microbes and is mediated by humoral effectors, such as cytokines, and cellular immune defenses, including phagocytic cells (e.g., macrophages). After internalization by phagocytes, microbes are delivered into a phagosome, a complex intracellular organelle with a well-established and important role in microbial killing. However, the role of this organelle in cytokine responses and microbial sensing is less well defined. In this study, we assess the role of the phagosome in innate immune sensing and demonstrate the critical interdependence of phagocytosis and pattern recognition receptor signaling during response to the Gram-positive bacteria Staphylococcus aureus. We show that phagocytosis is essential to initiate an optimal MyD88-dependent response to Staphylococcus aureus. Prior to TLR-dependent cytokine production, bacteria must be engulfed and delivered into acidic phagosomes where acid-activated host enzymes digest the internalized bacteria to liberate otherwise cryptic bacterial-derived ligands that initiate responses from the vacuole. Importantly, in macrophages in which phagosome acidification is perturbed, the impaired response to S. aureus can be rescued by the addition of lysostaphin, a bacterial endopeptidase active at neutral pH that can substitute for the acid-activated host enzymes. Together, these observations delineate the interdependence of phagocytosis with pattern recognition receptor signaling and suggest that therapeutics to augment functions and signaling from the vacuole may be useful strategies to increase host responses to S. aureus.

Mannose-binding lectin and innate immunity.

Innate immunity is the earliest response to invading microbes and acts to contain infection in the first minutes to hours of challenge. Unlike adaptive immunity that relies upon clonal expansion of cells that emerge days after antigenic challenge, the innate immune response is immediate. Soluble mediators, including complement components and the mannose binding lectin (MBL) make an important contribution to innate immune protection and work along with epithelial barriers, cellular defenses such as phagocytosis, and pattern-recognition receptors that trigger pro-inflammatory signaling cascades. These four aspects of the innate immune system act in concert to protect from pathogen invasion. Our work has focused on understanding the protection provided by this complex defense system and, as discussed in this review, the particular contribution of soluble mediators such as MBL and phagocytic cells. Over the past two decades both human epidemiological data and mouse models have indicated that MBL plays a critical role in innate immune protection against a number of pathogens. As demonstrated by our recent in vitro work, we show that MBL and the innate immune signaling triggered by the canonical pattern-recognition receptors (PRRs), the Toll-like receptors (TLRs), are linked by their spatial localization to the phagosome. These observations demonstrated a novel role for MBL as a TLR co-receptor and establishes a new paradigm for the role of opsonins, which we propose to function not only to increase microbial uptake but also to spatially coordinate, amplify, and synchronize innate immune defenses mechanism. In this review we discuss both the attributes of MBL that make it a unique soluble pattern recognition molecule and also highlight its broader role in coordinating innate immune activation.

Low serum mannose-binding lectin level increases the risk of death due to pneumococcal infection.

BACKGROUND: Previous studies have shown associations between low mannose-binding lectin (MBL) level or variant MBL2 genotype and sepsis susceptibility. However, MBL deficiency has not been rigorously defined, and associations with sepsis outcomes have not been subjected to multivariable analysis. METHODS: We reanalyzed MBL results in a large cohort with use of individual data from 4 studies involving a total of 1642 healthy control subjects and systematically defined a reliable deficiency cutoff. Subsequently, data were reassessed to extend previous MBL and sepsis associations, with adjustment for known outcome predictors. We reanalyzed individual data from 675 patients from 5 adult studies and 1 pediatric study of MBL and severe bacterial infection. RESULTS: XA/O and O/O MBL2 genotypes had the lowest median MBL concentrations. Receiver operating characteristic analysis revealed that an MBL cutoff value of 0.5 microg/mL was a reliable predictor of low-producing MBL2 genotypes (sensitivity, 82%; specificity, 82%; negative predictive value, 98%). MBL deficiency was associated with increased likelihood of death among patients with severe bacterial infection (odds ratio, 2.11; 95% confidence interval, 1.30-3.43). In intensive care unit-based studies, there was a trend toward increased risk of death among MBL-deficient patients (odds ratio, 1.58; 95% confidence interval, 0.90-2.77) after adjustment for Acute Physiology and Chronic Health Enquiry II score. The risk of death was increased among MBL-deficient patients with Streptococcus pneumoniae infection (odds ratio, 5.62; 95% confidence interval, 1.27-24.92) after adjustment for bacteremia, comorbidities, and age. CONCLUSIONS: We defined a serum level for MBL deficiency that can be used with confidence in future studies of MBL disease associations. The risk of death was increased among MBL-deficient patients with severe pneumococcal infection, highlighting the pathogenic significance of this innate immune defence protein.

Mannose-binding lectin enhances Toll-like receptors 2 and 6 signaling from the phagosome.

Innate immunity is the first-line defense against pathogens and relies on phagocytes, soluble components, and cell-surface and cytosolic pattern recognition receptors. Despite using hard-wired receptors and signaling pathways, the innate immune response demonstrates surprising specificity to different pathogens. We determined how combinatorial use of innate immune defense mechanisms defines the response. We describe a novel cooperation between a soluble component of the innate immune system, the mannose-binding lectin, and Toll-like receptor 2 that both specifies and amplifies the host response to Staphylococcus aureus. Furthermore, we demonstrate that this cooperation occurs within the phagosome, emphasizing the importance of engulfment in providing the appropriate cellular environment to facilitate the synergy between these defense pathways.

Mannose-binding lectin and susceptibility to infection in Chinese patients with systemic lupus erythematosus.

OBJECTIVE: To test the hypothesis that low serum mannose-binding lectin (MBL) levels, as a result of the single-nucleotide polymorphisms in the promoter region (-221 X/Y) and exon 1 (codon 54 A/B) of the MBL2 gene, predispose to infection in Chinese patients with systemic lupus erythematosus (SLE). METHODS: Two hundred forty-five patients with SLE were prospectively followed for the development of major infective episodes that required hospitalization and antibiotic treatment during 1992-2005. MBL genotypes were determined by polymerase chain reaction and serum MBL levels were measured by ELISA. RESULTS: In total, 254 major infections developed in 130 patients. Serum MBL levels were shown to correlate inversely with the number of bacterial infections (r = -0.13, p = 0.03). The distribution of MBL genotypes was similar in patients with and without major infection (p = 0.84). Patients with major infection also had more major lupus exacerbations that required daily prednisolone dose > or = 15 mg. Logistic regression showed that log MBL level (odds ratio 0.516, 95% confidence interval 0.305-0.873; p = 0.01) and major lupus exacerbation (OR 1.382, 95% CI 1.154-1.654; p < 0.001) were independent risk factors to major bacterial infection after adjustment for age and disease duration. Multiple regression analysis showed an increase in risk of bacterial infection by 34.2% for every decrease in serum MBL level by one log, and by 22.8% for each increase in number of major lupus exacerbations. CONCLUSION: Low serum MBL level predisposes Chinese patients with SLE to more major infections, in particular bacterial ones.

Deficiency of mannan-binding lectin associated serine protease-2 due to missense polymorphisms.

Mannan-binding lectin (MBL) and ficolins distinguish between self, non-self and altered-self by recognizing patterns of ligands on the surface of microorganisms or aberrant cells. When this happens MBL-associated serine protease-2 (MASP-2) is activated and cleaves complement factors to start inflammatory actions. We examined human populations for MASP-2 levels, MASP-2 function and for the presence of mutations in coding exons of MASP2. The MASP-2 levels were lowest in Africans from Zambia (median, 196 ng/ml) followed by Hong Kong Chinese (262 ng/ml), Brazilian Amerindians (290 ng/ml) and Danish Caucasians (416 ng/ml). In the Chinese population, we uncovered a novel four amino-acid tandem duplication (p.156_159dupCHNH) associated with low levels of MASP-2. The frequency of this mutation as well as the SNPs p.R99C, p.R118C, p.D120G, p.P126L and p.V377A were analyzed. The p.156_159dupCHNH was only found in Chinese (gene frequency 0.26%) and p.D120G was found only in Caucasians and Inuits from West-Greenland. The p.P126L and p.R99Q were present in Africans and Amerindians only, except for p.R99Q in one Caucasian. The MASP-2 levels were reduced in individuals with p.V377A present. The MASP-2 present in individuals homozygous for p.377A or p.99Q had a normal enzyme activity whereas MASP-2 in individuals homozygous for p.126L was non-functional.

Induction of adhesion molecules upon the interaction between eosinophils and bronchial epithelial cells: involvement of p38 MAPK and NF-kappaB.

Eosinophils are principal effector cells of inflammation in allergic asthma, characterized by their infiltration and accumulation at inflammatory sites mediated by chemokine eotaxin, and interaction with adhesion molecules expressed on bronchial epithelial cells. In this study, tumor necrosis factor (TNF)-alpha and/or the interaction of eosinophils and bronchial epithelial BEAS-2B cells were found to up-regulate the cell surface expression of adhesion molecules intercellular adhesion molecule (ICAM)-1 and vascular adhesion molecule (VCAM)-1 on BEAS-2B cells, and ICAM-1 and leukocyte function-associated antigen-1 (LFA-1) on eosinophils. Interaction of eosinophils and BEAS-2B cells could induce the release of granulocyte macrophage colony-stimulating factor (GM-CSF) and activate both p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB activities in BEAS-2B cells but only NF-kappaB activity in eosinophils. Both proteasome inhibitor MG-132 and selective p38 MAPK inhibitor SB 203580 could significantly decrease the expression of ICAM-1 on BEAS-2B cells and CD18 on eosinophils upon co-culture with or without TNF-alpha treatment. However, the expression of VCAM-1 on BEAS-2B cells was only up-regulated by TNF-alpha-induced NF-kappaB activity. The interaction of eosinophils and bronchial epithelial cells therefore plays an important role in the up-regulation of adhesion molecules on eosinophils and epithelial cells via differential intracellular signalling pathways during allergic inflammation.

IL-25 regulates the expression of adhesion molecules on eosinophils: mechanism of eosinophilia in allergic inflammation.

BACKGROUND: Interleukin-25 (IL-25) is a novel T-helper-2 (Th2) cytokine of the IL-17 family that plays a key role in allergic inflammation. Recent studies reported that over-expression of IL-25 in mouse induces eosinophilia. We investigated the effect of IL-25 on the expression of several adhesion molecules on human eosinophils and the underlying intracellular mechanisms. METHODS: Viability of eosinophils was measured by annexin V-fluorescein isothiocyanate (FITC) assay. Gene expression and surface expression of intercellular adhesion molecule (ICAM)-1 (CD54), ICAM-3 (CD50), L-selectin (CD62L), leukocyte function-associated antigen (LFA-1) (CD11a/CD18) and very late antigen-4 (VLA-4, CD49d/CD29) on eosinophils were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry, respectively. Adhesion of eosinophils to fibronectin was assessed using the fibronectin-coated insert system. RESULTS: Viability of eosinophils was significantly enhanced by IL-25 from 41% to 76% dose-dependently. IL-25 could significantly upregulate the surface expression of ICAM-1, but suppress those of ICAM-3 and L-selectin on eosinophils in a dose-dependent manner. Adhesion of eosinophils to fibronectin was also significantly enhanced by IL-25. Besides, pre-incubation with p38 mitogen-activated protein kinases (MAPK) inhibitor SB203580, C-Jun NH2-terminal protein kinases (JNK) inhibitor SP600125 and proteosome inhibitor MG-132 could significantly restrain the effects of IL-25 on surface expression of L-selectin, ICAM-1 and ICAM-3, respectively, and also on the adhesion of eosinophils onto fibronectin (all P < 0.05). CONCLUSIONS: Our findings suggest an essential role of IL-25 in enhancing survival and regulating surface expression of ICAM-1, ICAM-3 and L-selectin on human eosinophils through the activation of p38 MAPK, JNK and nuclear factor (NF)-kappaB pathways, thereby shedding light on the molecular mechanisms of IL-25-induced eosinophilia in allergic inflammation.

Interleukin (IL)-4 and IL-13 up-regulate monocyte chemoattractant protein-1 expression in human bronchial epithelial cells: involvement of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase 1/2 and Janus kinase-2 but not c-Jun NH2-terminal kinase 1/2 signalling pathways.

The Th2 cytokines interleukin (IL)-4 and IL-13 and chemokine monocyte chemoattractant protein-1 (MCP-1) are significantly involved in bronchial hyperreactivity (BHR) and remodelling in allergic asthma. Although IL-4 and IL-13 can regulate a number of chemokines from bronchial epithelium, their regulatory effect on the expression of MCP-1 is as yet unproved. We aim to investigate the intracellular signalling mechanisms of IL-4 and IL-13 regulating the expression and secretion of MCP-1 from human bronchial epithelial cells. BEAS-2B cells, derived from a human bronchial epithelial cell line, were activated with or without IL-4 and/or IL-13 for different time intervals. MCP-1 gene expression and protein secretion were measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Activation of signalling molecules p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK) and Janus kinase-2 (JAK-2) was accessed by Western blotting. IL-4 and IL-13 were found to up-regulate gene expression and significantly increase the release of MCP-1 from BEAS-2B cells. Both cytokines could activate p38 MAPK, ERK and JAK-2, but not JNK activity. Inhibition of p38 MAPK, ERK and JAK-2 activities by pretreating the cells with their corresponding inhibitors SB203580, PD98059 and AG490, respectively, significantly suppressed IL-4- and IL-13-induced MCP-1 production in BEAS-2B cells. Together, the above results illustrate that the activation of p38 MAPK, ERK and JAK-2 but not JNK is crucial for IL-4- and IL-13-induced MCP-1 release in human bronchial epithelial cells. Our findings may provide insight into the future development of more effective therapeutic agents for treating allergic asthma.