Superantigen-mediated differentiation of bovine monocytes into dendritic cells

DNA methylation and hydroxymethylation profiles reveal possible role of highly methylated TLR signaling on Fasciola gigantica excretory/secretory products (FgESPs) modulation of buffalo dendritic cells

BACKGROUND

Excretory/secretory products (ESPs) released by parasites influence the development and functions of host dendritic cells (DCs). However, little is known about changes of DNA (hydroxy)methylation on DC development during Fasciola gigantica infection. The present study aimed to investigate whether F. gigantica ESPs (FgESPs) affects the development and functions of buffalo DCs through altering the DNA (hydroxy)methylation of DCs.

METHODS

Buffalo DCs were prepared from peripheral blood mononuclear cells (PBMCs) and characterized using scanning and transmission electron microscopy (SEM/TEM) and quantitative reverse transcriptional PCR (qRT-RCR). DCs were treated with 200 μg/ml of FgESPs in vitro, following DNA extraction. The DNA methylome and hydroxymethylome were profiled based on (hydroxy)methylated DNA immunoprecipitation sequencing [(h)MeDIP-Seq] and bioinformatics analyses. qRT-RCR was also performed to assess the gene transcription levels of interest.

RESULTS

FgESPs markedly suppressed DC maturation evidenced by morphological changes and downregulated gene expression of CD1a and MHC II. Totals of 5432 and 360 genes with significant changes in the 5-methylcytosine (5-mC) and the 5-hydroxymethylcytosine (5-hmC) levels, respectively, were identified in buffalo DCs in response to FgESPs challenge. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these differentially expressed genes were highly enriched in pathways associated with immune response. Some cancer-related pathways were also indicated. There were 111 genes demonstrating changes in both 5-mC and 5-hmC levels, 12 of which were interconnected and enriched in 12 pathways. The transcription of hypermethylated genes TLR2, TLR4 and IL-12B were downregulated or in a decreasing trend, while the mRNA level of high-hydroxymethylated TNF gene was upregulated in buffalo DCs post-exposure to FgESPs in vitro.

CONCLUSIONS

To our knowledge, the present study provides for the first time a unique genome-wide profile of DNA (hydroxy)methylation for DCs that interact with FgESPs, and suggests a possible mechanism of FgESPs in suppressing DC maturation and functions that are involved in TLR signaling.

Bovine Derived in vitro Cultures Generate Heterogeneous Populations of Antigen Presenting Cells

Antigen presenting cells (APC) of the mononuclear phagocytic system include dendritic cells (DCs) and macrophages (Macs) which are essential mediators of innate and adaptive immune responses. Many of the biological functions attributed to these cell subsets have been elucidated using models that utilize in vitro-matured cells derived from common progenitors. However, it has recently been shown that monocyte culture systems generate heterogeneous populations of cells, DCs, and Macs. In light of these findings, we analyzed the most commonly used bovine in vitro-derived APC models and compared them to bona fide DCs. Here, we show that bovine monocyte-derived DCs and Macs can be differentiated on the basis of CD11c and MHC class II (MHCII) expression and that in vitro conditions generate a heterologous group of both DCs and Macs with defined and specific biological activities. In addition, skin-migrating macrophages present in the bovine afferent lymph were identified and phenotyped for the first time. RNA sequencing analyses showed that these monophagocytic cells have distinct transcriptomic profiles similar to those described in other species. These results have important implications for the interpretation of data obtained using in vitro systems.

Effect of a DNA-based immunostimulant on growth, performance, and expression of inflammatory and immune mediators in beef calves abruptly weaned and introduced to a complete ration

The effect of a DNA immunostimulant on inflammatory and immune responses, performance, and health in calves following abrupt weaning and introduction to a concentrate diet was tested. Sixty-four single source Angus crossbred steers were weaned on day 1 and assigned to receive a DNA immunostimulant (TRT) or saline (CON) on days 0, 2, 4, and 6. On day 0, steers received clostridial and respiratory vaccines and anthelmintic; they were then transported 2 h, allocated to pens (n = 8 per pen), and introduced to total mixed ration. Daily intake, ADG, and feed efficiency were measured. Serum haptoglobin, tumor necrosis factor-alpha (TNF-α), and interleukin-1 beta (IL-1β) were assayed by ELISA or AlphaLISA on days 0, 2, 4, 6, 14, and 28; serum-neutralizing antibodies (SNA) to bovine herpesvirus-1 and bovine viral diarrhea virus-1 (BVDV-1) were quantified on days 0, 28, 68, and 135. In a subset of cattle (n = 6 to 8 per treatment group), the percent macrophages and activated gamma delta (γδ) T cells in blood was determined by flow cytometry on days 2 and 6, and expression of mRNA for TNF-α, interferon-gamma (IFN-γ), IL-4, and IL-10 by stimulated blood mononuclear cells was assessed by real-time reverse transcriptase PCR on day 6. After 70 d, cattle were shipped 1,205 km to a feedlot and performance and health were followed. There was a significant effect of time on serum TNF-α, IL-1β, haptoglobin, and SNA (P < 0.001); the range in concentration among cattle on each day was large. The ratio of IFN-γ to IL-4 expression was significantly higher (P = 0.03) for TRT cattle, suggesting that treatment activated T-helper type 1 cells. There was a trend toward an improved feed conversion (P = 0.10) for TRT steers over the 70-d backgrounding period. There was no effect of treatment on feedlot performance or carcass merit (P > 0.10). During backgrounding, 1 TRT steer died of enterocolitis. In spite of backgrounding, cattle experienced an outbreak of bovine respiratory disease (BRD) in the feedlot and 1 of 31 TRT cattle and 5 of 32 CON cattle died of BRD. The immunostimulant modified some immune responses during backgrounding. Large variability in inflammatory responses during backgrounding indicated that events around weaning induce systemic inflammation that varies substantially among cattle.

Experimental Arthritis in the Rat Induced by the Superantigen Staphylococcal Enterotoxin A

The pathogenesis of rheumatoid arthritis (RA) is incompletely understood. Human endogenous retroviruses (HERVs) and their superantigenic envelope protein (env) have been implicated in the pathogenesis of RA. In the present investigation, the arthritogenic potential of the superantigen staphylococcal enterotoxin A (SEA) has been investigated. In the present investigation, the bacterial superantigen staphylococcal enterotoxin A (SEA) was injected into the right knee joint of 15 Lewis rats. Further nine animals received saline. Animals were sacrificed one, five and 10 days after the injection, respectively. The antigens CD3, CD4, CD8, MHC class I, MHC class II, Pax5 and CD138 were investigated by immunohistochemistry on cryo-sections. After intra-articular SEA injection, the inflammation was initially dominated by CD8+ T cells. In the course of the investigation, the numbers of CD4+, Pax5+, CD138+ and MHC class II+ cells increased. CD3 was expressed in low numbers as compared to CD8. After saline injection, no similar inflammatory response has been detected. The arthritis induced by the superantigen SEA may be a novel model for inflammatory joint diseases, that is rheumatoid arthritis or juvenile idiopathic arthritis.

Macrophage polarization in cattle experimentally exposed to Mycobacterium avium subsp. paratuberculosis

Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne's disease (JD) in cattle, has significant impacts on the livestock industry and has been implicated in the etiology of Crohn's disease. Macrophages play a key role in JD pathogenesis, which is driven by the manipulation of host immune mechanisms by MAP. A change in the macrophage microenvironment due to pathogenic or host-derived stimuli can lead to classical (M1) or alternative (M2) polarization of macrophages. In addition, prior exposure to antigenic stimuli has been reported to alter the response of macrophages to subsequent stimuli. However, macrophage polarization in response to MAP exposure and its possible implications have not been previously addressed. In this study, we have comprehensively examined monocyte/macrophage polarization and responsiveness to antigens from MAP-exposed and unexposed animals. At 3 years post-exposure, there was a heterogeneous macrophage activation pattern characterized by both classical and alternate phenotypes. Moreover, subsequent exposure of macrophages from MAP-exposed cattle to antigens from MAP and other mycobacterial species led to significant variation in the production of nitric oxide, interleukin-10 and tumour necrosis factor α. These results indicate the previously unreported possibility of changes in the activation state and responsiveness of circulating monocytes/macrophages from MAP-exposed cattle.

The retrovirus/superantigen hypothesis of multiple sclerosis

The pathogenesis of multiple sclerosis (MS) is as yet unknown. Commonly, MS is assumed to be due to an autoimmune inflammation of the central nervous system (CNS). Neurodegeneration is regarded to be a secondary reaction. This concept is increasingly being challenged. Human endogenous retroviruses (HERV) that could be locally activated in the CNS have been proposed as an alternative concept. HERV-encoded envelope proteins (env) can act as strong immune stimulators (superantigens). Thus, slow disease progression following neurodegeneration might be induced by re-activation of HERV expression directly, while relapses in parallel to inflammation might be secondary to the expression of HERV-encoded superantigens. It has been shown previously that T-cell superantigens are capable to induce a cellular inflammatory reaction in the CNS of experimental animals similar to that in MS. Furthermore, B-cell superantigens have been shown to activate blood leucocytes in vitro to produce immunoglobulin in an oligoclonal manner. It remains to be established, whether the outlined hypothesis accords with all known features of MS. Furthermore, anti-HERV agents may be taken into consideration to enrich and improve MS therapy.

Review: 2-mercaptoethanol alteration of in vitro immune functions of species other than murine

Descriptions that organosulfurs could alter biologically relevant cellular functions began some 40 years ago when cell mediated and humoral murine in vitro immune responses were reported to be dramatically enhanced by any of four xenobiotic, sulfhydryl compounds—2-mercaptoethanol (2-ME), dithiothreitol, glutathione, and l-cysteine; the most effective of the four was 2-ME. These findings triggered a plethora of reports defining 2-ME benefits for a multitude of immunological processes, primarily with murine models. This led to investigations on 2-ME alterations of (a) immune functions in other species, (b) activities of other cell-types, and (c) in situ diseases. In addition, the early findings may have been instrumental in the identification of the previously undefined anticarcinogenic chemicals in specific foods as organosulfurs. Outside the plant organosulfurs, there are no comprehensive reviews of these areas to help define mechanisms by which organosulfurs function as well as identify potential alternative uses. Therefore, the present review will focus on 2-ME alterations of in vitro immune functions in species other than murine; namely, fish, amphibian, reptile, avian, whales, dolphins, rat, hamster, rabbit, guinea pig, feline, canine, porcine, ovine, bovine, and human. Processes, some unique to a given species, were in general, enhanced and in some cases dependent upon the presence of 2-ME. The largest benefits occurred in media that were serum free, followed by those in autologous serum and then fetal bovine serum supplemented medium. Concentrations of 2-ME were generally in the low μM range, with exceptions of those for salamander (20 mM), turtles (70 mM) and dolphins (7 mM). The few studies designed to assess mechanisms found that changes induced by 2-ME were generally accompanied by alterations of reduced/oxidized glutathione cellular concentrations. The major benefit for most studies, however, was to increase the sensitivity of the culture environment, which permitted a specific process to be more easily dissected.

•

2-ME altered in vitro immune functions of species other than murine.

•

Benefits were found for species from fish to humans.

•

Enhancement occurred in serum-free and in autologous or fetal bovine serum.

•

Generally, optimal concentrations of 2-ME were in the low uM range.

•

Concentration exceptions were salamander (20 mM), turtles (70 mM), and dolphins (7 mM).

CXCL12/CXCR4 axis plays pivotal roles in the organ-specific metastasis of pancreatic adenocarcinoma: A clinical study

Pancreatic cancer is one of the most lethal types of cancer, and curative resection is only applicable to potentially limited cases due to early metastasis and local invasion. This study reports the influence of CXCL12 and its receptor CXCR4 on the progression of pancreatic cancer and highlights the correlation between the CXCL12/CXCR4 axis and the organ-specific metastasis of pancreatic adenocarcinoma (PAC). A total of 34 patients with pancreatic cancer participated in the current study. The expression of CXCL12 and CXCR4 in cancerous tissues, paracancerous tissues, normal pancreas and lymph nodes surrounding the pancreas were investigated using immunohistochemistry and RT-PCR; furthermore, their relationship with clinicopathological factors was explored (PV9000 method). The positive rate of CXCL12 protein was 13.3% (4/30), the positive rate of CXCR4 protein was 80% (24/30) in tumor tissues. Additionally, a significant correlation between the expression pattern of the CXCL12/CXCR4 axis with lymph node metastasis was identified (P<0.05), excluding gender, age, tumor node metastasis (TNM) stage and differentiation (all P>0.05). Also, the positive rate of CXCL12 protein was 50% (15/30), the positive rate of CXCR4 protein was 73.3% (22/30) in the lymphocytes in lymph nodes surrounding the pancreas. Furthermore, we found that CXCL12 and CXCR4 expression in paratumorous vessels and neural tissue were significantly strongly positive. The paratumorous vessels and neural tissue with positive CXCL12 and CXCR4 expression were invaded by CXCL12-positive pancreatic cancer cells. The chemotactic interaction between CXCR4 and its ligand CXCL12 may be a critical event during the progression of pancreatic cancer. The CXCL12/CXCR4 axis plays an important role in the progression and organ-specific metastasis of pancreatic adenocarcinoma.

Targeting mucosal immunity in the battle to develop a mastitis vaccine

The mucosal immune system encounters antigens that enhance and suppress immune function, and serves as a selective barrier against invading pathogens. The mammary gland not only encounters antigens but also produces a nutrient evolved to protect and enhance mucosal development in the neonate. Efforts to manipulate antibody concentrations in milk to prevent mastitis, an infection of the mammary gland, have been hampered both by complexity and variation in target pathogens and limited knowledge of cellular immunity in the gland. Successful vaccination strategies must overcome the natural processes that regulate types and concentrations of milk antibodies for neonatal development, and enhance cellular immunity. Furthermore, the need to overcome dampening of immunity caused by non-pathogenic encounters to successfully prevent establishment of infection is an additional obstacle in vaccine development at mucosal sites. A significant mastitis pathogen, Staphylococcus aureus, not only resides as a normal flora on a multitude of species, but also causes clinical disease with limited treatment options. Using the bovine model of S. aureus mastitis, researchers can decipher the role of antigen selection and presentation by mammary dendritic cells, enhance development of central and effector memory function, and subsequently target specific memory cells to the mammary gland for successful vaccine development. This brief review provides an overview of adaptive immunity, previous vaccine efforts, current immunological findings relevant to enhancing immune memory, and research technologies that show promise in directing future vaccine efforts to enhance mammary gland immunity and prevent mastitis.

The CXCR4-CXCL12 pathway facilitates the progression of pancreatic cancer via induction of angiogenesis and lymphangiogenesis

BACKGROUND

This study reports the influence of CXCL12 and its receptor CXCR4 on the progression of pancreatic cancer and illuminates the correlation between the CXCL12/CXCR4 axis and the angiogenesis and lymphangiogenesis of pancreatic adenocarcinoma (PAC).

METHODS

A total of 30 patients with pancreatic cancer participated in the current study. The expression of CXCL12 and CXCR4 in cancerous tissues, paracancerous tissues, normal pancreas, and lymph nodes surrounding the pancreas were investigated using real-time PCR and immunohistochemistry, respectively. In addition, we assessed microvessel density (MVD) and microlymphatic vessel density (MLVD) in tumor tissues using immunohistochemistry.

RESULTS

CXCL12 expression in tumor tissues was significantly lower than that of paracancerous tissues, normal pancreas, and lymph nodes. In contrast, CXCR4 expression in cancerous tissues was considerably higher than that of normal pancreas. Additionally, a significant correlation between the expression pattern of the CXCL12/CXCR4 axis and clinicopathologic features, such as lymph node metastasis, was identified. Furthermore, we found that CXCL12 expression was significantly associated with MVD but not significantly associated with MLVD, while CXCR4 expression was significantly associated with MLVD but not significantly associated with MVD.

CONCLUSIONS

The chemotactic interaction between CXCR4 and its ligand CXCL12 may be a critical event during the progression of pancreatic cancer. The underlying mechanism may be the induction of angiogenesis and lymphangiogenesis regulated by the interaction of CXCL12 and CXCR4.

Neutrophils are resistant to Yersinia YopJ/P-induced apoptosis and are protected from ROS-mediated cell death by the type III secretion system

Background

The human innate immune system relies on the coordinated activity of macrophages and polymorphonuclear leukocytes (neutrophils or PMNs) for defense against bacterial pathogens. Yersinia spp. subvert the innate immune response to cause disease in humans. In particular, the Yersinia outer protein YopJ (Y. pestis and Y. pseudotuberculosis) and YopP (Y. enterocolitica) rapidly induce apoptosis in murine macrophages and dendritic cells. However, the effects of Yersinia Yop J/P on neutrophil fate are not clearly defined.

Methodology/Principal Findings

In this study, we utilized wild-type and mutant strains of Yersinia to test the contribution of YopJ and YopP on induction of apoptosis in human monocyte-derived macrophages (HMDM) and neutrophils. Whereas YopJ and YopP similarly induced apoptosis in HMDMs, interaction of human neutrophils with virulence plasmid-containing Yersinia did not result in PMN caspase activation, release of LDH, or loss of membrane integrity greater than PMN controls. In contrast, interaction of human PMNs with the virulence plasmid-deficient Y. pestis strain KIM6 resulted in increased surface exposure of phosphatidylserine (PS) and cell death. PMN reactive oxygen species (ROS) production was inhibited in a virulence plasmid-dependent but YopJ/YopP-independent manner. Following phagocytic interaction with Y. pestis strain KIM6, inhibition of PMN ROS production with diphenyleneiodonium chloride resulted in a reduction of PMN cell death similar to that induced by the virulence plasmid-containing strain Y. pestis KIM5.

Conclusions

Our findings showed that Yersinia YopJ and/or YopP did not induce pronounced apoptosis in human neutrophils. Furthermore, robust PMN ROS production in response to virulence plasmid-deficient Yersinia was associated with increased PMN cell death, suggesting that Yersinia inhibition of PMN ROS production plays a role in evasion of the human innate immune response in part by limiting PMN apoptosis.

A quantitative real time PCR method to analyze T cell receptor Vbeta subgroup expansion by staphylococcal superantigens

Background

Staphylococcal enterotoxins (SEs), SE-like (SEl) toxins, and toxic shock syndrome toxin-1 (TSST-1), produced by Staphylococcus aureus, belong to the subgroup of microbial superantigens (SAgs). SAgs induce clonal proliferation of T cells bearing specific variable regions of the T cell receptor β chain (Vβ). Quantitative real time PCR (qRT-PCR) has become widely accepted for rapid and reproducible mRNA quantification. Although the quantification of Vβ subgroups using qRT-PCR has been reported, qRT-PCR using both primers annealing to selected Vβ nucleotide sequences and SYBR Green I reporter has not been applied to assess Vβ-dependent expansion of T cells by SAgs.

Methods

Human peripheral blood mononuclear cells were stimulated with various SAgs or a monoclonal antibody specific to human CD3. Highly specific expansion of Vβ subgroups was assessed by qRT-PCR using SYBR Green I reporter and primers corresponding to selected Vβ nucleotide sequences.

Results

qRT-PCR specificities were confirmed by sequencing amplified PCR products and melting curve analysis. To assess qRT-PCR efficiencies, standard curves were generated for each primer set. The average slope and R² of standard curves were -3.3764 ± 0.0245 and 0.99856 ± 0.000478, respectively, demonstrating that the qRT-PCR established in this study is highly efficient. With some exceptions, SAg Vβ specificities observed in this study were similar to those reported in previous studies.

Conclusions

The qRT-PCR method established in this study produced an accurate and reproducible assessment of Vβ-dependent expansion of human T cells by staphylococcal SAgs. This method could be a useful tool in the characterization T cell proliferation by newly discovered SAg and in the investigation of biological effects of SAgs linked to pathogenesis.