Circulating neutrophils of septic patients constitutively express IL-10R1 and are promptly responsive to IL-10

Neutrophil responsiveness to IL-10 impairs clearance of Streptococcus pneumoniae from the lungs

The early immune response to bacterial pneumonia requires a careful balance between pathogen clearance and tissue damage. The anti-inflammatory cytokine interleukin (IL)-10 is critical for restraining otherwise lethal pulmonary inflammation. However, pathogen-induced IL-10 is associated with bacterial persistence in the lungs. In this study, we used mice with myeloid cell specific deletion of IL-10R to investigate the cellular targets of IL-10 immune suppression during infection with Streptococcus pneumoniae, the most common bacterial cause of pneumonia. Our findings suggest that IL-10 restricts the neutrophil response to S. pneumoniae, as neutrophil recruitment to the lungs was elevated in myeloid IL-10 receptor (IL-10R)-deficient mice and neutrophils in the lungs of these mice were more effective at killing S. pneumoniae. Improved killing of S. pneumoniae was associated with increased production of reactive oxygen species and serine protease activity in IL-10R-deficient neutrophils. Similarly, IL-10 suppressed the ability of human neutrophils to kill S. pneumoniae. Burdens of S. pneumoniae were lower in myeloid IL-10R-deficient mice compared with wild-type mice, and adoptive transfer of IL-10R-deficient neutrophils into wild-type mice significantly improved pathogen clearance. Despite the potential for neutrophils to contribute to tissue damage, lung pathology scores were similar between genotypes. This contrasts with total IL-10 deficiency, which is associated with increased immunopathology during S. pneumoniae infection. Together, these findings identify neutrophils as a critical target of S. pneumoniae-induced immune suppression and highlight myeloid IL-10R abrogation as a mechanism to selectively reduce pathogen burdens without exacerbating pulmonary damage.

Integrated Analysis of lncRNAs, mRNAs, and TFs to Identify Regulatory Networks Underlying MAP Infection in Cattle

Johne’s disease is a chronic infection of ruminants that burdens dairy herds with a significant economic loss. The pathogenesis of the disease has not been revealed clearly due to its complex nature. In order to achieve deeper biological insights into molecular mechanisms involved in MAP infection resulting in Johne’s disease, a system biology approach was used. As far as is known, this is the first study that considers lncRNAs, TFs, and mRNAs, simultaneously, to construct an integrated gene regulatory network involved in MAP infection. Weighted gene coexpression network analysis (WGCNA) and functional enrichment analysis were conducted to explore coexpression modules from which nonpreserved modules had altered connectivity patterns. After identification of hub and hub-hub genes as well as TFs and lncRNAs in the nonpreserved modules, integrated networks of lncRNA-mRNA-TF were constructed, and cis and trans targets of lncRNAs were identified. Both cis and trans targets of lncRNAs were found in eight nonpreserved modules. Twenty-one of 47 nonpreserved modules showed significant biological processes related to the immune system and MAP infection. Some of the MAP infection’s related pathways in the most important nonpreserved modules comprise “positive regulation of cytokine-mediated signaling pathway,” “negative regulation of leukocyte migration,” “T-cell differentiation,” “neutrophil activation,” and “defense response.” Furthermore, several genes were identified in these modules, including SLC11A1, MAPK8IP1, HMGCR, IFNGR1, CMPK2, CORO1A, IRF1, LDLR, BOLA-DMB, and BOLA-DMA, which are potentially associated with MAP pathogenesis. This study not only enhanced our knowledge of molecular mechanisms behind MAP infection but also highlighted several promising hub and hub-hub genes involved in macrophage-pathogen interaction.

Targeting STAT3: A crucial modulator of sepsis

Signal transducer and activator of transcription 3 (STAT3) is a cellular signal transcription factor that has recently attracted a great deal of attention. It can trigger a variety of genes transcription in response to cytokines and growth factors stimulation, which plays an important role in many cellular biological processes involved in anti/proinflammatory responses. Sepsis is a life-threatening organ dysfunction resulting from dysregulated host responses to infection. As a converging point of multiple inflammatory responses pathways, accumulating studies have presented the elaborate network of STAT3 in sepsis pathophysiology; these results generally indicate a promising therapeutic application for targeting STAT3 in the treatment of sepsis. In the present review, we evaluated the published literature describing the use of STAT3 in the treatment of experimental and clinical sepsis. The information presented here may be useful for the design of future studies and may highlight the potential of STAT3 as a future biomarker and therapeutic target for sepsis.

Time course of signaling profiles of blood leukocytes in acute pancreatitis and sepsis

Activation of intracellular signaling pathways in circulating leukocytes represents an early step in systemic immune-inflammatory response occurring e.g. in acute pancreatitis (AP) and sepsis. Previously, we found aberrations in the phosphorylation of leukocyte signaling proteins in patients with sepsis or AP (measured <48 h from hospital admission) resembling each other and associating with AP severity. Of these patients, those with sepsis or severe AP complicated by persistent organ dysfunction (OD+, n = 17) and patients with moderately severe AP (OD-, n = 6) were followed up in this study by measuring the phosphorylations at two additional time points (2-4 and 5-8 days after the initial sample) using phosphospecific whole blood flow cytometry. Twenty-eighty healthy subjects served as controls (HC). Constitutive STAT3 phosphorylation (pSTAT3) declined in monocytes and neutrophils of OD-/OD + and in lymphocytes of OD + and remained higher in OD- than HC. Monocytes of OD-/OD + showed low pSTAT3 and pSTAT1 levels in response to IL-6 through follow-up. Monocyte pNF-κB levels in response to TNF, LPS and E. coli in OD+, to E. coli in OD-, and lymphocyte pNF-κB levels in response to TNF in OD- increased during follow-up but remained lower than in HC, and neutrophil pNF-κB levels in response to TNF declined in OD-. Phorbol myristate acetate + Ca²⁺ ionophore-stimulated pERK1/2 decreased in neutrophils of OD-/OD+. To conclude, in patients with moderately severe or severe AP or sepsis, improvement and molecular events contributing to OD can be assessed at the level of blood leukocyte signaling.

Bone Marrow Mesenchymal Stromal Cells Induce Proliferative, Cytokinic and Molecular Changes During the T Cell Response: The Importance of the IL-10/CD210 Axis

BACKGROUND

Bone marrow mesenchymal stromal cells (BM-MSCs) display immunomodulatory features, representing a promising tool for cell-based therapies. However, the mechanisms used by MSCs to regulate T cell fate remain unclear.

AIMS

We investigated the potential of BM-MSCs to modulate T cell activation, proliferation, cytokine secretion and immunophenotype.

MATERIALS AND METHODS

T cells were co-cultured with BM-MSCs to assess their immunomodulatory impact. T cell characterization was performed using cell tracing, ELISA, intracellular and surface staining, flow cytometry analysis and qPCR.

RESULTS

The activation and proliferation of T cells were downregulated during coculture with BM-MSCs. We also observed that BM-MSCs upregulated IL-10 secretion as well as the expression of its receptor CD210 on T cells, thus creating a loop favoring the expansion of IL-10-producing T cells. IL-10 neutralization restored T cell proliferation, demonstrating that IL-10 is functionally relevant during immunomodulation. Moreover, BM-MSCs differently modulated CD4 and CD8 T-cell immunophenotype by inducing broad changes in their molecular pattern.

CONCLUSIONS

We provide a comprehensive functional and molecular characterization of T cells that are immunomodulated by BM-MSCs. Indeed, a better understanding of the immunological interplay between T cells and MSCs will facilitate the development of new efficient approaches to improve cell-based immune therapies.

Lack of interleukin-10-mediated anti-inflammatory signals and upregulated interferon gamma production are linked to increased intestinal epithelial cell apoptosis in pathogenic simian immunodeficiency virus infection

Interleukin-10 (IL-10) is an immunomodulatory cytokine that is important for maintenance of epithelial cell (EC) survival and anti-inflammatory responses (AIR). The majority of HIV infections occur through the mucosal route despite mucosal epithelium acting as a barrier to human immunodeficiency virus (HIV). Therefore, understanding the role of IL-10 in maintenance of intestinal homeostasis during HIV infection is of interest for better characterization of the pathogenesis of HIV-mediated enteropathy. We demonstrated here changes in mucosal IL-10 signaling during simian immunodeficiency virus (SIV) infection in rhesus macaques. Disruption of the epithelial barrier was manifested by EC apoptosis and loss of the tight-junction protein ZO-1. Multiple cell types, including a limited number of ECs, produced IL-10. SIV infection resulted in increased levels of IL-10; however, this was associated with increased production of mucosal gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α), suggesting that IL-10 was not able to regulate AIR. This observation was supported by the downregulation of STAT3, which is necessary to inhibit production of IFN-γ and TNF-α, and the upregulation of SOCS1 and SOCS3, which are important regulatory molecules in the IL-10-mediated AIR. We also observed internalization of the IL-10 receptor (IL-10R) in mucosal lymphocytes, which could limit cellular availability of IL-10 for signaling and contribute to the loss of a functional AIR. Collectively, these findings demonstrate that internalization of IL-10R with the resultant impact on IL-10 signaling and dysregulation of the IL-10-mediated AIR might play a crucial role in EC damage and subsequent SIV/HIV pathogenesis.

IMPORTANCE

Interleukin-10 (IL-10), an important immunomodulatory cytokine plays a key role to control inflammatory function and homeostasis of the gastrointestinal mucosal immune system. Despite recent advancements in the study of IL-10 and its role in HIV infection, the role of mucosal IL-10 in SIV/HIV infection in inducing enteropathy is not well understood. We demonstrated changes in mucosal IL-10 signaling during SIV infection in rhesus macaques. Disruption of the intestinal epithelial barrier was evident along with the increased levels of mucosal IL-10 production. Increased production of mucosal IFN-γ and TNF-α during SIV infection suggested that the increased level of mucosal IL-10 was not able to regulate anti-inflammatory responses. Our findings demonstrate that internalization of IL-10R with the resultant impact on IL-10 signaling and dysregulation of the IL-10-mediated anti-inflammatory responses might play a crucial role in epithelial cell damage and subsequent SIV/HIV pathogenesis.

Interleukin 10 receptor signaling: master regulator of intestinal mucosal homeostasis in mice and humans

Interleukin 10 (IL10) is a key anti-inflammatory cytokine that can inhibit proinflammatory responses of both innate and adaptive immune cells. An association between IL10 and intestinal mucosal homeostasis became clear with the discovery that IL10 and IL10 receptor (IL10R)-deficient mice develop spontaneous intestinal inflammation. Similarly, patients with deleterious mutations in IL10, IL10RA, or IL10RB present with severe enterocolitis within the first months of life. Here, we review recent findings on how IL10- and IL10R-dependent signaling modulates innate and adaptive immune responses in the murine gastrointestinal tract, with implications of their role in the prevention of inflammatory bowel disease (IBD). In addition, we discuss the impact of IL10 and IL10R signaling defects in humans and their relationship to very early-onset IBD (VEO-IBD).

The molecular basis of IL-10 function: from receptor structure to the onset of signaling

Assembly of the cell surface IL-10 receptor complex is the first step in initiating IL-10 signaling pathways that regulate intestinal inflammation, viral persistence and even tumor surveillance. The discovery of IL-10 homologs in the genomes of herpes viruses suggests IL-10 signaling pathways can be manipulated at the level of the receptor complex. This chapter will describe our current molecular understanding of IL-10 receptor assembly based on crystal structures and biochemical analyses of cellular and viral IL-10 receptor complexes.

Deficiency of the CGRP receptor component RAMP1 attenuates immunosuppression during the early phase of septic peritonitis

The neuropeptide CGRP contributes to the control of excessive cytokine production in endotoxemia models. However, the function of CGRP in sepsis caused by infection with viable pathogens is unknown. Here, we show that mice deficient for the CGRP receptor component RAMP1 have an improved anti-bacterial defense during the early, but not late, phase of polymicrobial septic peritonitis. The protective effect of Ramp1-deficiency was associated with reduced levels of IL-10 in plasma and peritoneal lavage fluid. Consistent with these findings, CGRP markedly increased IL-10 production of peritoneal and bone marrow-derived macrophages in response to short term stimulation with LPS in vitro. In addition, the lack of an intact CGRP receptor resulted in an increased recruitment and activation of neutrophils and caused an enhanced release of defensin-α1 in the peritoneal cavity. Considered together, our results identify the neuropeptide CGRP as a crucial immunosuppressive mediator impairing host defense during the early, but not late, phase of septic peritonitis.

STAT3 regulates monocyte TNF-alpha production in systemic inflammation caused by cardiac surgery with cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) surgery initiates a controlled systemic inflammatory response characterized by a cytokine storm, monocytosis and transient monocyte activation. However, the responsiveness of monocytes to Toll-like receptor (TLR)-mediated activation decreases throughout the postoperative course. The purpose of this study was to identify the major signaling pathway involved in plasma-mediated inhibition of LPS-induced tumor necrosis factor (TNF)-α production by monocytes.

METHODOLOGY/PRINCIPAL FINDINGS

Pediatric patients that underwent CPB-assisted surgical correction of simple congenital heart defects were enrolled (n = 38). Peripheral blood mononuclear cells (PBMC) and plasma samples were isolated at consecutive time points. Patient plasma samples were added back to monocytes obtained pre-operatively for ex vivo LPS stimulations and TNF-α and IL-6 production was measured by flow cytometry. LPS-induced p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB activation by patient plasma was assessed by Western blotting. A cell-permeable peptide inhibitor was used to block STAT3 signaling. We found that plasma samples obtained 4 h after surgery, regardless of pre-operative dexamethasone treatment, potently inhibited LPS-induced TNF-α but not IL-6 synthesis by monocytes. This was not associated with attenuation of p38 MAPK activation or IκB-α degradation. However, abrogation of the IL-10/STAT3 pathway restored LPS-induced TNF-α production in the presence of suppressive patient plasma.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that STAT3 signaling plays a crucial role in the downregulation of TNF-α synthesis by human monocytes in the course of systemic inflammation in vivo. Thus, STAT3 might be a potential molecular target for pharmacological intervention in clinical syndromes characterized by systemic inflammation.

Regulatory role of antigen-induced interleukin-10, produced by CD4(+) T cells, in airway neutrophilia in a murine model for asthma

It has been suggested that interleukin (IL)-10 exerts immunosuppressive effects on allergic inflammation, including asthma, mainly through inhibition of Th2 cell-mediated eosinophilic airway inflammation. In a model of experimental asthma utilizing multiple intratracheal antigen challenges in sensitized mice, IL-10 production as well as eosinophilia and neutrophilia in the lung were induced by the multiple challenges. In this study, we set out to reveal the cellular source of endogenously produced IL-10, and the roles of IL-10 in airway leukocyte inflammation using an anti-IL-10 receptor monoclonal antibody. Balb/c mice were sensitized i.p. with ovalbumin+Al(OH)(3), and then challenged by intratracheal administration of ovalbumin 4 times. Flow cytometric analyses revealed that the cellular source of IL-10 was CD4(+) T cells lacking the transcription factor, forkhead box P3. Treatment with anti-IL-10 receptor monoclonal antibody prior to the 4th challenge significantly augmented airway neutrophilia as well as the production of IL-1β, and CXC chemokines, keratinocyte-derived chemokine (KC) and macrophage inflammatory protein (MIP)-2, but not airway eosinophilia, Th2 cytokine (IL-4 and IL-5) production, or a late-phase increase in specific airway resistance. Approximately 40% of IL-10 receptor(+) cells expressed the macrophage marker F4/80, whereas only 3-4% of the IL-10 receptor(+) cells were granulocyte differentiation antigen (Gr)-1(high) cells (neutrophils). In conclusion, multiple airway antigen challenges induced the proliferation of IL-10-expressing CD4(+) T cells in regulating airway neutrophilia. Systemic blockade of IL-10 function coincided with increases in IL-1β and CXC chemokines. Thus, IL-1β and CXC chemokines may be targets for development of novel pharmacotherapy for neutrophilic asthma.

Innate transcriptional networks activated in bladder in response to uropathogenic Escherichia coli drive diverse biological pathways and rapid synthesis of IL-10 for defense against bacterial urinary tract infection

Early transcriptional activation events that occur in bladder immediately following bacterial urinary tract infection (UTI) are not well defined. In this study, we describe the whole bladder transcriptome of uropathogenic Escherichia coli (UPEC) cystitis in mice using genome-wide expression profiling to define the transcriptome of innate immune activation stemming from UPEC colonization of the bladder. Bladder RNA from female C57BL/6 mice, analyzed using 1.0 ST-Affymetrix microarrays, revealed extensive activation of diverse sets of innate immune response genes, including those that encode multiple IL-family members, receptors, metabolic regulators, MAPK activators, and lymphocyte signaling molecules. These were among 1564 genes differentially regulated at 2 h postinfection, highlighting a rapid and broad innate immune response to bladder colonization. Integrative systems-level analyses using InnateDB (http://www.innatedb.com) bioinformatics and ingenuity pathway analysis identified multiple distinct biological pathways in the bladder transcriptome with extensive involvement of lymphocyte signaling, cell cycle alterations, cytoskeletal, and metabolic changes. A key regulator of IL activity identified in the transcriptome was IL-10, which was analyzed functionally to reveal marked exacerbation of cystitis in IL-10-deficient mice. Studies of clinical UTI revealed significantly elevated urinary IL-10 in patients with UPEC cystitis, indicating a role for IL-10 in the innate response to human UTI. The whole bladder transcriptome presented in this work provides new insight into the diversity of innate factors that determine UTI on a genome-wide scale and will be valuable for further data mining. Identification of protective roles for other elements in the transcriptome will provide critical new insight into the complex cascade of events that underpin UTI.

An intracytoplasmic IL-10 receptor variant permits rapid reduction in STAT3 activation

Within the interleukin-10 receptor 1 (IL10R1) gene, two common variants are associated with certain diseases: single-nucleotide polymorphism 3 (SNP3), a serine-138 to glycine mutation is in linkage disequilibrium with SNP4, a glycine-330 to arginine mutation, both of which are considered loss-of-function alleles. However, the molecular consequence of G330R is unknown. We investigated possible roles of G330R on the dynamics of IL10R1 surface expression and signal transducer and activator of transduction (STAT) phosphorylation. HeLa cells expressing the respective IL10R1 haplotype were stimulated with IL-10. Significant reduction of IL10R1 surface expression was observed after ligand binding. Receptor expression remained low on continuous incubation with IL-10. In contrast, when treated with an IL-10 pulse, IL10R1 surface expression returned to its resting state within 3-9 h irrespective of the haplotype. STAT3 was rapidly phosphorylated both in cells with wild-type (WT) or variant IL10R1, and maintained phosphorylated when cells were cultured with IL-10. On IL-10 pulse, however, STAT3 phosphorylation declined rapidly in cells expressing IL10R1-G330R but not IL10R1-WT or S138G. Similar dynamics were observed with STAT1 phosphorylation at Tyr701. No differences in janus kinase 1 (JAK1) activation were observed in cells with WT or variant IL10R1. Our results indicate that IL10R1-G330R does not alter surface expression but duration of STAT phosphorylation, indicating that the position of G330 is important in stabilizing the STAT signal.

SH2-domain mutations in STAT3 in hyper-IgE syndrome patients result in impairment of IL-10 function

Autosomal-dominant hyper-IgE syndrome (AD-HIES) is a primary immunodeficiency caused by STAT3 mutations. This inherited condition is characterized by eczema, staphylococcal cold abscesses and recurrent pulmonary infections. Given that STAT3 is involved in IL-10 signaling, we examined the immunoregulatory role of IL-10 in inflammation by studying the effects of IL-10 on monocytes, neutrophils and monocyte-derived DCs from HIES subjects. Analysis of gene expression in PBMCs and neutrophils isolated from HIES patients and stimulated with LPS in the presence of IL-10 showed reduced expression of IL1RN, which encodes IL-1 receptor antagonist (IL-1ra), and SOCS3 mRNA but increased CXCL8 mRNA expression. Moreover, secretion of the anti-inflammatory protein IL-1ra was reduced in AD-HIES patients. DCs from HIES patients secreted higher levels of TNF-α, IL-6 and, to a lesser extent, IL-12 when these cells were cultured in the presence of IL-10. These results suggest that IL-10 activity is affected in myeloid cells (e.g. monocytes, DCs) of HIES patients. Impairment of IL-10 signaling in patients with AD-HIES might result in an altered balance between pro-inflammatory and anti-inflammatory signals and might lead to persistent inflammation and delayed healing after infections.

Understanding the molecular mechanisms of the multifaceted IL-10-mediated anti-inflammatory response: lessons from neutrophils

Analysis of the molecular mechanisms governing the ability of IL-10 to keep inflammation under control has highlighted the existence of a great degree of plasticity and specificity with regard to innate immune cells. In this respect, neutrophils represent a perfect example of innate immune cells conditioned by external signals (for instance, by LPS), as well as by intracellular regulatory pathways, that render them optimally responsive to IL-10 only when required. The focus of this review are the recent experimental findings that have uncovered the sophisticated and complex molecular mechanisms responsible for the modulation of pro- and anti-inflammatory cytokine production by IL-10 in neutrophils and other innate immune cells. Understanding how IL-10 exerts its anti-inflammatory response, particularly in the case of neutrophils, will provide novel clues leading, hopefully, to the therapeutic control of neutrophil-driven inflammatory reactions, such as septic infections, rheumatoid arthritis, osteoarthritis and chronic obstructive pulmonary disease.

Polymorphisms in the gene encoding bovine interleukin-10 receptor alpha are associated with Mycobacterium avium ssp. paratuberculosis infection status

Background

Johne's disease is a chronic inflammatory bowel disease (IBD) of ruminants caused by Mycobacterium avium ssp. paratuberculosis (MAP). Since this pathogen has been implicated in the pathogenesis of human IBDs, the goal of this study was to assess whether single nucleotide polymorphism (SNPs) in several well-known candidate genes for human IBD are associated with susceptibility to MAP infection in dairy cattle.

Methods

The bovine candidate genes, interleukin-10 (IL10), IL10 receptor alpha/beta (IL10RA/B), transforming growth factor beta 1 (TGFB1), TGFB receptor class I/II (TGFBR1/2), and natural resistance-associated macrophage protein 1 (SLC11A1) were sequenced for SNP discovery using pooled DNA samples, and the identified SNPs were genotyped in a case-control association study comprised of 242 MAP negative and 204 MAP positive Holstein dairy cattle. Logistic regression was used to determine the association of SNPs and reconstructed haplotypes with MAP infection status.

Results

A total of 13 SNPs were identified. Four SNPs in IL10RA (984G > A, 1098C > T, 1269T > C, and 1302A > G) were tightly linked, and showed a strong additive and dominance relationship with MAP infection status. Haplotypes AGC and AAT, containing the SNPs IL10RA 633C > A, 984G > A and 1185C > T, were associated with an elevated and reduced likelihood of positive diagnosis by serum ELISA, respectively.

Conclusions

SNPs in IL10RA are associated with MAP infection status in dairy cattle. The functional significance of these SNPs warrants further investigation.

Granulocyte colony-stimulating factor negatively regulates Toll-like receptor agonist-induced cytokine production in human neutrophils

We studied the effect of G-CSF on TLR agonist-induced cytokine production in human neutrophils. Human neutrophils produced IL-8 and TNF-alpha in response to stimulation with TLR agonists such as LPS and N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-(R)-cysteinyl-seryl-(lysyl)(3)-lysine. This response was dependent on activation of ERK, p38, and PI3K, but not JNK. TLR agonist-induced cytokine production in neutrophils was inhibited by G-CSF, whereas it was enhanced by GM-CSF, and GM-CSF-mediated enhancement was attenuated by G-CSF. G-CSF and GM-CSF did not affect TLR agonist-induced phosphorylation of ERK, p38, JNK, Akt, and IkappaBalpha. STAT3 activation was much greater in G-CSF-stimulated neutrophils than that in GM-CSF-stimulated cells. G-CSF-mediated STAT3 phosphorylation and inhibition of TLR agonist-induced cytokine production were prevented by pretreatment of cells with AG-490 (JAK2 inhibitor). These findings suggest that G-CSF and GM-CSF exert the opposite effects on TLR agonist-induced cytokine production, and G-CSF negatively regulates TLR agonist-induced cytokine production in neutrophils via activation of STAT3.

SNPs in the bovine IL-10 receptor are associated with somatic cell score in Canadian dairy bulls

Altering the balance between pro- and anti-inflammatory responses can influence an animal's susceptibility to acute or chronic inflammatory disease; bovine mastitis is no exception. Genetic variation in the form of single nucleotide polymorphisms (SNPs) may alter the function and expression of genes that regulate inflammation, making them important candidates for defining an animal's risk of developing acute or chronic mastitis. The objective of the present study was to identify SNPs in genes that regulate anti-inflammatory responses and test their association with estimated breeding values (EBVs) for somatic cell score (SCS), a trait highly correlated with the incidence of mastitis. These genes included bovine interleukin-10 (IL-10) and its receptor (IL-10R), and transforming growth factor beta1 (TGF-beta1) and its receptor (TGF-betaR). Sequencing-pooled DNA allowed for the identification of SNPs in IL-10 (n = 2), IL-10Ralpha (n = 6) and beta (n = 2), and TGF-beta1 (n = 1). These SNPs were subsequently genotyped in a cohort of Holstein (n = 500), Jersey (n = 83), and Guernsey (n = 50) bulls. Linear regression analysis identified significant SNP effects for IL-10Ralpha 1185C>T with SCS. Haplotype IL-10Ralpha AAT showed a significant effect on increasing SCS compared to the most common haplotype. The results presented here indicate that SNPs in IL-10Ralpha may contribute to variation in the SCS of dairy cattle. Although functional studies are necessary to ascertain whether these SNPs are causal polymorphisms or merely in linkage with the true causal SNP(s), a selection program incorporating these markers could have a beneficial influence on the average SCS and productivity of a dairy herd.

Cryptococcus neoformans directly stimulates perforin production and rearms NK cells for enhanced anticryptococcal microbicidal activity

NK cells, in addition to possessing antitumor and antiviral activity, exhibit perforin-dependent microbicidal activity against the opportunistic pathogen Cryptococcus neoformans. However, the factors controlling this response, particularly whether the pathogen itself provides an activation or rearming signal, are largely unknown. The current studies were performed to determine whether exposure to this fungus alters subsequent NK cell anticryptococcal activity. NK cells lost perforin and mobilized lysosome-associated membrane protein 1 to the cell surface following incubation with the fungus, indicating that degranulation had occurred. Despite a reduced perforin content during killing, NK cells acquired an enhanced ability to kill C. neoformans, as demonstrated using auxotrophs that allowed independent assessment of the killing of two strains. De novo protein synthesis was required for optimal killing; however, there was no evidence that a soluble factor contributed to the enhanced anticryptococcal activity. Exposure of NK cells to C. neoformans caused the cells to rearm, as demonstrated by increased perforin mRNA levels and enhanced loss of perforin when transcription was blocked. Degranulation alone was insufficient to provide the activation signal as NK cells lost anticryptococcal activity following treatment with strontium chloride. However, NK cells regained the activity upon prolonged exposure to C. neoformans, which is consistent with activation by the microbe. The enhanced cytotoxicity did not extend to tumor killing since NK cells exposed to C. neoformans failed to kill NK-sensitive tumor targets (K562 cells). These studies demonstrate that there is contact-mediated microbe-specific rearming and activation of microbicidal activity that are necessary for optimal killing of C. neoformans.

Oral glucocorticoid treatment decreases interleukin-10 receptor expression on peripheral blood leucocyte subsets

Glucocorticoids (GCS) are capable of stimulating the secretion of interleukin (IL)-10 by leucocytes; however, the potential of GCS to modulate leucocyte susceptibility to IL-10-mediated actions has not yet been studied. In the current paper, we performed a detailed cross-sectional analysis of IL-10 receptor (IL-10R) expression by CD4(+) and CD8(+) T cells, natural killer (NK) cells, monocytes and neutrophils. Next, we analysed the effects of short-term oral GCS treatment on surface IL-10R expression by various leucocyte subpopulations in asthmatic patients. All leucocyte subsets studied presented with substantial levels of surface IL-10R. The highest levels of IL-10R were found on monocytes, predominantly with CD14(2+)CD16(+) and CD14(+)CD16(+) phenotypes, and on CD4(+)CD25(high) T cells. In contrast, levels of IL-10R on CD8(+) T cells, NK cells and neutrophils were significantly lower and similar to each other in intensity. GCS treatment resulted in a significant decrease of IL-10R expression on all analysed peripheral blood leucocyte subsets. Our data suggest that down-regulation of IL-10R could counterbalance the otherwise suppressive action of GCS.