CD40 engagement strongly induces CD25 expression on porcine dendritic cells and polarizes the T cell immune response toward Th1

Interleukin-17 producing cells in swine induced by microbiota during the early postnatal period - a brief research report

Interleukin-17A (IL-17) is a pro-inflammatory cytokine involved in the immune response to many pathogens playing also a role in certain chronic and autoimmune diseases. The presented study focused on the early postnatal development of IL-17 producing cells in swine. In agreement with previous studies, αβ T-helper (CD3+CD4+) and γδ T (CD3+TCRγδ+) cells were found to be the major producers of IL-17. In newborn conventional piglets, αβ T-helper cells positive for IL-17 were almost undetectable, but their frequency increased markedly with age in all issues examined, i.e., blood, spleen, and mesenteric lymph nodes (MLN). Additional analyses of CD8 and CD27 expression showed that the main αβ T-helper producers of IL-17 has CD8+CD27- phenotype in all tissues. IL-17 positive CD8+CD27+ αβ T-helper subpopulation was found only in blood and spleen. The production of IL17 in CD8-CD27+ αβ T-helper cells was always minor. In contrast, γδ T cells positive for IL-17 did not show a similar age-dependent increase in blood and spleen, whereas they increased in MLN. Because of the age-dependent increase in conventional animals, we included a comparison with germ-free piglets to show that the increase in IL-17 positive cells was clearly depended on the presence of the microbiota as the production in germ-free animals was negligible without any age-dependent increase.

Interleukin-2 signals converge in a lymphoid-dendritic cell pathway that promotes anticancer immunity

Tumor-infiltrating dendritic cells (DCs) correlate with effective anticancer immunity and improved responsiveness to anti-PD-1 checkpoint immunotherapy. However, the drivers of DC expansion and intratumoral accumulation are ill-defined. We found that interleukin-2 (IL-2) stimulated DC formation through innate and adaptive lymphoid cells in mice and humans, and this increase in DCs improved anticancer immunity. Administration of IL-2 to humans within a clinical trial and of IL-2 receptor (IL-2R)-biased IL-2 to mice resulted in pronounced expansion of type 1 DCs, including migratory and cross-presenting subsets, and type 2 DCs, although neither DC precursors nor mature DCs had functional IL-2Rs. In mechanistic studies, IL-2 signals stimulated innate lymphoid cells, natural killer cells, and T cells to synthesize the cytokines FLT3L, CSF-2, and TNF. These cytokines redundantly caused DC expansion and activation, which resulted in improved antigen processing and correlated with favorable anticancer responses in mice and patients. Thus, IL-2 immunotherapy-mediated stimulation of DCs contributes to anticancer immunity by rendering tumors more immunogenic.

MHC class I and II peptide homology regulates the cellular immune response

Mammalian immune responses are initiated by "danger" signals--immutable molecular structures known as PAMPs. When detected by fixed, germline encoded receptors, pathogen-associated molecular pattern (PAMPs) subsequently inform the polarization of downstream adaptive responses depending upon identity and localization of the PAMP. Here, we report the existence of a completely novel "PAMP" that is not a molecular structure but an antigenic pattern. This pattern--the incidence of peptide epitopes with stretches of 100% sequence identity bound to both dendritic cell (DC) major histocompatibility (MHC) class I and MHC class II--strongly induces T_H 1 immune polarization and activation of the cellular immune response. Inherent in the existence of this PAMP is the concomitant existence of a molecular sensor complex with the ability to scan and compare amino acid sequence identities of bound class I and II peptides. We provide substantial evidence implicating the multienzyme aminoacyl-tRNA synthetase (mARS) complex and its AIMp1 structural component as the key constituents of this complex. The results demonstrate a wholly novel mechanism by which T-helper (T_H ) polarization is governed and provide critical information for the design of vaccination strategies intended to provoke cell-mediated immunity.

Toll-like receptor 5-mediated IL-17C expression in intestinal epithelial cells enhances epithelial host defense against F4+ ETEC infection

Enterotoxigenic Escherichia coli (ETEC) are an important cause of post-weaning diarrhea (PWD) in piglets. The IL-17 cytokine family is well known to play important roles in the host defense against bacterial infections at the mucosa. Previously, we reported the potential role of IL-17A in clearing an ETEC infection in piglets. IL-17C, another member of the IL-17 family, is highly expressed in the intestinal epithelium, however, its role during an ETEC infection is still unclear. In this study, we demonstrate that F4⁺ ETEC induce IL-17C mRNA and protein expression in intestinal tissues as well as in porcine intestinal epithelial cells (IPEC-J2). This IL-17C production is largely dependent on TLR5 signaling in IPEC-J2 cells. Both F4⁺ ETEC infection and exogenous IL-17C increased the expression of antimicrobial peptides and tight junction proteins, such as porcine beta-defensin (pBD)-2, claudin-1, claudin-2 and occludin in IPEC-J2 cells. Taken together, our data demonstrate that TLR5-mediated IL-17C expression in intestinal epithelial cells enhances mucosal host defense responses in a unique autocrine/paracrine manner in the intestinal epithelium against ETEC infection.

Physical Principles of Membrane Shape Regulation by the Glycocalyx

Cells bend their plasma membranes into highly curved forms to interact with the local environment, but how shape generation is regulated is not fully resolved. Here, we report a synergy between shape-generating processes in the cell interior and the external organization and composition of the cell-surface glycocalyx. Mucin biopolymers and long-chain polysaccharides within the glycocalyx can generate entropic forces that favor or disfavor the projection of spherical and finger-like extensions from the cell surface. A polymer brush model of the glycocalyx successfully predicts the effects of polymer size and cell-surface density on membrane morphologies. Specific glycocalyx compositions can also induce plasma membrane instabilities to generate more exotic undulating and pearled membrane structures and drive secretion of extracellular vesicles. Together, our results suggest a fundamental role for the glycocalyx in regulating curved membrane features that serve in communication between cells and with the extracellular matrix.

Induction of T cell-mediated immune response by dendritic cells pulsed with mRNA of sphere-forming cells isolated from patients with gastric cancer

Gastric cancer (GC) as the third most common cause of cancer-associated mortality worldwide is one of the cancers with very high heterogeneity. Cancer stem cells (CSCs) as a small subset of cancer cells in solid tumors with the self-renewal, differentiation and tumorigenic ability are responsible for tumor initiation, progression, recurrence, metastasis, and resistance to current treatments. Therefore, eradication of CSCs is very vital to cure cancer. Here, we first isolated and identified sphere-forming cells in tumor tissue from four GC patients and then analyzed T cell responses induced by monocyte-derived dendritic cells (DCs) loaded with total mRNA of sphere-forming cells in terms of interferon-gamma (IFN-γ) gene expression and specific cytotoxicity. Spheroid colonies were formed in serum-free media. Sphere-forming cells dissociated from tumorspheres heterogeneously expressed CD44, CD54, and epithelial cell adhesion molecule (EpCAM) markers and generated one tumor in nude mice. These results demonstrated that gastric CSCs were enriched in tumorspheres. Cytokine-matured DCs loaded with mRNA of sphere-forming cells were able to induce IFN-γ gene expression in T-lymphocytes after a 12-day co-culture. mRNA level of IFN-γ gene in these lymphocytes was more highly expressed compared to stimulated T-lymphocytes by DCs transfected with normal tissue (6.4-9.39 folds). Cytotoxic activity of primed T-lymphocytes with antigens of sphere-forming cells was significantly higher than normal tissue antigens and mock DCs (P ≤ 0.0001). Taken together, DCs loaded with mRNA of sphere-forming cells that elicit effectively specific T cell-mediated immune responses in vitro, may be considered as a promising therapeutic vaccination in GC patients in future.

Comparison of morphology, phenotypes and function between cultured human IL‑4‑DC and IFN‑DC

Dendritic cells (DCs) as professional antigen presenting cells, are important in the initiation of the primary immune response. The present study compared the morphology, phenotypes and function between monocyte‑derived human DCs produced from a conventional culturing system containing granulocyte‑macrophage colony‑stimulating factor (GM‑CSF) and IL‑4 (IL‑4‑DC) and DCs generated by the stimulation of GM‑CSF and interferon (IFN)‑α (IFN‑DC). When compared with IL‑4‑DC in morphology, IFN‑DC contained more organelles, including endoplasmic reticulum and myelin figures, whereas mature (m)IL‑4‑DC contained more vacuoles in the cells. The spikes of IFN‑DC were shorter and thicker. The expression of phenotypes between immature IFN‑DC and IL‑4‑DC were diverse. Following maturation with tumor necrosis factor‑α, IFN‑DC and IL‑4‑DC upregulated the expression of cluster of differentiation (CD) 11c and CD83. Conversely, immature IFN‑DC and IL‑4‑DC secreted few inflammatory cytokines including interleukin (IL)‑18, IL‑23, IL‑12p70, IL‑1β and anti‑inflammatory IL‑10. Following maturation, large amounts of the cytokines were secreted by these two DCs and mIFN‑DC secreted more cytokines compared with mIL‑4‑DC in general. Furthermore, immature IFN‑DC and IL‑4‑DC loaded with cytomegalovirus (CMV)‑pp65 protein were unable to induce the priming of T cells, as evaluated by the intracellular staining with IFN‑γ. Notably, mature DCs exhibited the ability to present CMV‑pp65 protein and activate T cells. The mIFN‑DC activated a greater proportion of autologous CD4+ T cells (0.91 vs. 0.31%, P<0.001) and CD8+ T cells (0.90 vs. 0.48%, P<0.001) to secret IFN‑γ compared with mIL‑4‑DC. The results suggested that the morphology, phenotypes and cytokine secretion of IFN‑DC and IL‑4‑DC were diverse. The mIFN‑DC were more effective in priming and cross‑priming T cells when compared with IL‑4‑DC.

Mechanisms of Adaptive Immunity to Porcine Reproductive and Respiratory Syndrome Virus

The adaptive immune response is necessary for the development of protective immunity against infectious diseases. Porcine reproductive and respiratory syndrome virus (PRRSV), a genetically heterogeneous and rapidly evolving RNA virus, is the most burdensome pathogen of swine health and wellbeing worldwide. Viral infection induces antigen-specific immunity that ultimately clears the infection. However, the resulting immune memory, induced by virulent or attenuated vaccine viruses, is inconsistently protective against diverse viral strains. The immunological mechanisms by which primary and memory protection are generated and used are not well understood. Here, we summarize current knowledge regarding cellular and humoral components of the adaptive immune response to PRRSV infection that mediate primary and memory immune protection against viruses.

Adiponectin inhibits oxidization-induced differentiation of T helper cells through inhibiting costimulatory CD40 and CD80

Adiponectin is a multifunctional adipokine that has several oligomeric forms in the blood stream, which broadly regulates innate and acquired immunity. Therefore, in this study, we aimed to observe the differentiation of T helper (Th) cells and expression of costimulatory signaling molecules affected by adiponectin. The mRNA and protein expression levels of adiponectin and its receptors in oxidized low density lipoprotein cholesterol-treated endothelial cells were assayed by real time PCR and immunofluorescence. The endothelial cells were then treated with adiponectin with or without adipoR1 or adipoR2 siRNA and co-cultured with T lymphocytes. The distribution of Th1, Th2 and Th17 subsets were assayed by flow cytometry. The effects of adiponectin on costimulatory signaling molecules HLA-DR, CD80, CD86 and CD 40 was also assayed by flow cytometry. The results showed that endothelial cells expressed adiponectin and its receptor adipoR1 and adipoR2, but not T-cadherin. Adiponectin suppressed Th1 and Th17 differentiation through adipoR1 receptor, contributed to the inhibition of CD80 and CD40, and inhibited differentiation of Th1 and Th17 by inhibiting antigen presenting action.

Establishing Porcine Monocyte-Derived Macrophage and Dendritic Cell Systems for Studying the Interaction with PRRSV-1

Monocyte-derived macrophages (MoMØ) and monocyte-derived dendritic cells (MoDC) are two model systems well established in human and rodent systems that can be used to study the interaction of pathogens with host cells. Porcine reproductive and respiratory syndrome virus (PRRSV) is known to infect myeloid cells, such as macrophages (MØ) and dendritic cells (DC). Therefore, this study aimed to establish systems for the differentiation and characterization of MoMØ and MoDC for subsequent infection with PRRSV-1. M-CSF differentiated MoMØ were stimulated with activators for classical (M1) or alternative (M2) activation. GM-CSF and IL-4 generated MoDC were activated with the well established maturation cocktail containing PAMPs and cytokines. In addition, MoMØ and MoDC were treated with dexamethasone and IL-10, which are known immuno-suppressive reagents. Cells were characterized by morphology, phenotype, and function and porcine MØ subsets highlighted some divergence from described human counterparts, while MoDC, appeared more similar to mouse and human DCs. The infection with PRRSV-1 strain Lena demonstrated different replication kinetics between MoMØ and MoDC and within subsets of each cell type. While MoMØ susceptibility was significantly increased by dexamethasone and IL-10 with an accompanying increase in CD163/CD169 expression, MoDC supported only a minimal replication of PRRSV These findings underline the high variability in the susceptibility of porcine myeloid cells toward PRRSV-1 infection.

F4+ ETEC infection and oral immunization with F4 fimbriae elicits an IL-17-dominated immune response

Enterotoxigenic Escherichia coli (ETEC) are an important cause of post-weaning diarrhea (PWD) in piglets. Porcine-specific ETEC strains possess different fimbrial subtypes of which F4 fimbriae are the most frequently associated with ETEC-induced diarrhea in piglets. These F4 fimbriae are potent oral immunogens that induce protective F4-specific IgA antibody secreting cells at intestinal tissues. Recently, T-helper 17 (Th17) cells have been implicated in the protection of the host against extracellular pathogens. However, it remains unknown if Th17 effector responses are needed to clear ETEC infections. In the present study, we aimed to elucidate if ETEC elicits a Th17 response in piglets and if F4 fimbriae trigger a similar response. F4⁺ ETEC infection upregulated IL-17A, IL-17F, IL-21 and IL-23p19, but not IL-12 and IFN-γ mRNA expression in the systemic and mucosal immune system. Similarly, oral immunization with F4 fimbriae triggered a Th17 signature evidenced by an upregulated mRNA expression of IL-17F, RORγt, IL-23p19 and IL-21 in the peripheral blood mononuclear cells (PBMCs). Intriguingly, IL-17A mRNA levels were unaltered. To further evaluate this difference between systemic and mucosal immune responses, we assayed the cytokine mRNA profile of F4 fimbriae stimulated PBMCs. F4 fimbriae induced IL-17A, IL-17F, IL-22 and IL-23p19, but downregulated IL-17B mRNA expression. Altogether, these data indicate a Th17 dominated response upon oral immunization with F4 fimbriae and F4⁺ ETEC infection. Our work also highlights that IL-17B and IL-17F participate in the immune response to protect the host against F4⁺ ETEC infection and could aid in the design of future ETEC vaccines.

LPS-induced systemic inflammation is more severe in P2Y12 null mice

Thienopyridines are a class of antiplatelet drugs that are metabolized in the liver to several metabolites, of which only one active metabolite can irreversibly antagonize the platelet P2Y12 receptor. Possible effects of these drugs and the role of activated platelets in inflammatory responses have also been investigated in a variety of animal models, demonstrating that thienopyridines could alter inflammation. However, it is not clear whether it is caused only by the P2Y12 antagonism or whether off-target effects of other metabolites also intervene. To address this question, we investigated P2Y12 KO mice during a LPS-induced model of systemic inflammation, and we treated these KO mice with a thienopyridine drug (clopidogrel). Contrary to the reported effects of clopidogrel, numbers of circulating WBCs and plasma levels of cytokines were increased in LPS-exposed KO mice compared with WT in this inflammation model. Moreover, both spleen and bone marrow show an increase in cell content, suggesting a role for P2Y12 in regulation of bone marrow and spleen cellular composition. Finally, the injury was more severe in the lungs of KO mice compared with WT. Interestingly, clopidogrel treatments also exerted protective effects in KO mice, suggesting off-target effects for this drug. In conclusion, the P2Y12 receptor plays an important role during LPS-induced inflammation, and this signaling pathway may be involved in regulating cell content in spleen and bone marrow during LPS systemic inflammation. Furthermore, clopidogrel may have effects that are independent of P2Y12 receptor blockade.

Molecular cloning and protein characterization of swine 4-1BB

4-1BB is expressed on activated T cells and other immune and non-immune cells. It plays important roles in human and mouse T cell function. However, the swine 4-1BB sequence remains unknown and its role in swine T cell response has not been studied. In the present study, we for the first time described the cloning of the swine 4-1BB gene and the property of the protein. Two 4-1BB variants were detected in swine. The coding sequences of variant 1 and variant 2 were 768 and 726 nucleotides in length, respectively, and both variants were coded by 7 exons in the swine genome. Comparison of nucleotide and amino acid sequences showed that both swine 4-1BB variants were more closely related to bovine and human sequences than to either the mouse or rat sequence. Prediction analysis showed that swine 4-1BB belonged to the tumor necrosis factor receptor (TNFR) superfamily like human and mouse 4-1BB and the tertiary structures of the swine 4-1BB variants were much more similar to mouse 4-1BB than to human 4-1BB. The 1556bp 5' regulatory sequence cloned by nested PCR efficiently induced green fluorescent protein expression in porcine peripheral blood mononuclear cells (PBMC) post nucleofection. Moreover, 4-1BB protein was widely expressed in pig tissues and both variants of swine 4-1BB protein were transmembrane proteins and expressed on the membrane of porcine PBMCs.

One-step spray-dried polyelectrolyte microparticles enhance the antigen cross-presentation capacity of porcine dendritic cells

Vaccination is regarded as the most efficient and cost-effective way to prevent infectious diseases. Vaccine design nowadays focuses on the implementation of safer recombinant subunit vaccines. However, these recombinant subunit antigens are often poor immunogens and several strategies are currently under investigation to enhance their immunogenicity. The encapsulation of antigens in biodegradable microparticulate delivery systems seems a promising strategy to boost their immunogenicity. Here, we evaluate the capacity of polyelectrolyte complex microparticles (PECMs), fabricated by single step spray-drying, to deliver antigens to porcine dendritic cells and how these particles affect the functional maturation of dendritic cells (DCs). As clinically relevant model antigen F4 fimbriae, a bacterial adhesin purified from a porcine-specific enterotoxigenic Escherichia coli strain was chosen. The resulting antigen-loaded PECMs are efficiently internalised by porcine monocyte-derived DCs. F4 fimbriae-loaded PECMs (F4-PECMs) enhanced CD40 and CD25 surface expression by DCs and this phenotypical maturation correlated with an increased secretion of IL-6 and IL-1β. More importantly, F4-PECMs enhance both the T cell stimulatory and antigen presentation capacity of DCs. Moreover, PECMs efficiently promoted the CD8(+) T cell stimulatory capacity of dendritic cells, indicating an enhanced ability to cross-present the encapsulated antigens. These results could accelerate the development of veterinary and human subunit vaccines based on polyelectrolyte complex microparticles to induce protective immunity against a variety of extra- and intracellular pathogens.

TNF-α promotes IFN-γ-induced CD40 expression and antigen process in Myb-transformed hematological cells

Tumour necrosis factor-α, interferon-γ and interleukin-4 are critical cytokines in regulating the immune responses against infections and tumours. In this study, we investigated the effects of three cytokines on CD40 expression in Myb-transformed hematological cells and their regulatory roles in promoting these cells into dendritic cells. We observed that both interleukin-4 and interferon-γ increased CD40 expression in these hematological cells in a dose-dependent manner, although the concentration required for interleukin-4 was significantly higher than that for interferon-γ. We found that tumour necrosis factor-α promoted CD40 expression induced by interferon-γ, but not by interleukin-4. Our data showed that tumour necrosis factor-α plus interferon-γ-treated Myb-transformed hematological cells had the greatest ability to take up and process the model antigen DQ-Ovalbumin. Tumour necrosis factor-α also increased the ability of interferon-γ to produce the mixed lymphocyte reaction to allogenic T cells. Furthermore, only cotreatment with tumour necrosis factor-α and interferon-γ induced Myb-transformed hematological cells to express interleukin-6. These results suggest that tumour necrosis factor-α plays a key regulatory role in the development of dendritic cells from hematological progenitor cells induced by interferon-γ.

Varying effects of different β-glucans on the maturation of porcine monocyte-derived dendritic cells

β-Glucans are well known for their immunomodulatory capacities in humans and mice. For this reason, together with the European ban on growth-promoting antibiotics, β-glucans are intensively used in pig feed. However, as shown in the present study, there is much variation in the stimulatory capacities of β-glucans from different sources. Since dendritic cells (DCs) are the first cells that are encountered after an antigen is taken up by the intestinal epithelial cell barrier, we decided to investigate the effect of two concentrations (5 and 10 μg/ml) of five commercial β-glucan preparations, differing in structure and source, on porcine monocyte-derived dendritic cells (MoDCs). Although all β-glucans gave rise to a significant reduction of the phagocytic activity of DCs, only Macrogard induced a significant phenotypic maturation. In addition to Macrogard, zymosan, another β-glucan derived from Saccharomyces cerevisiae, and curdlan also significantly improved the T-cell-stimulatory capacity of MoDCs. Most interesting, however, is the cytokine secretion profile of curdlan-stimulated MoDCs, since only curdlan induced significant higher expression levels of interleukin-1β (IL-1β), IL-6, IL-10, and IL-12/IL-23p40. Since the cytokine profile of DCs influences the outcome of the ensuing immune response and thus may prove valuable in intestinal immunity, a careful choice is necessary when β-glucans are used as dietary supplement.

Vaccination with immature dendritic cells combined with CD40mAb induces protective immunity against B lymphoma in hu-SCID mice

Dendritic cells (DCs) pulsed by tumor antigens have been widely used as tumor vaccines to specifically trigger the cytotoxicity of CD8+ T cells. But the tumor microenviroment with enriched immunosuppressants hampered DC maturation and co-stimulation. CD40/CD40L signaling, one of the most important co-stimulatory molecules is capable of effectively skewing the immune response by promoting DCs maturation and co-stimulation. To establish a novel specific immunotherapeutic approach for the use of DC vaccine in the treatment of B lymphoma, hu-SCID mice bearing B lymphoma were vaccinated by different combination of tumor antigen pulsed DC or imDC vaccines and immune-enhancing agencies such as agonist CD40mAb and T cells. The results of immature DCs combined with agonistic CD40mAb were encouraging with achievement of tumor regression and induction of antigen-specific immune responses. These findings demonstrated the potential utility of imDC-based tumor vaccination combining with agonistic CD40mAb in the treatment of malignant lymphoma.

Targeting of Escherichia coli F4 fimbriae to Fcgamma receptors enhances the maturation of porcine dendritic cells

F4(+) enterotoxigenic Escherichia coli (ETEC) infections are an important cause of postweaning diarrhoea in piglets and an oral immunization of piglets with purified F4 fimbriae protects them from a subsequent F4(+) ETEC infection. However, oral immunization of suckling piglets is hampered due to the immature status of their immune system. Targeting of antigens to Fcgamma receptors (FcgammaR) on human and murine dendritic cells (DC) has been shown to enhance DC maturation and both humoral and cellular immune responses. To investigate the effect of F4 fimbriae incorporated in immune complexes (F4-IC) on porcine DC, we used porcine monocytic-derived DC (MoDC) as a model system. The results in this study demonstrate that FcgammaRI, II and III mRNA is expressed by porcine MoDC. Furthermore, we show that FcgammaRII and III are expressed on the cell surface and that F4-IC are internalized by MoDC via FcgammaR. This FcgammaR ligation induced a significantly enhanced expression of Major Histocompatibility complex (MHCII) class II and the costimulatory molecules CD80/86 and CD40 by MoDC compared with immature MoDC. Furthermore, the phagocytic capacity of F4-IC stimulated MoDC was reduced as evidenced by a reduced uptake of DQ-ovalbumin and FITC-dextran. In an allogenic and autologous mixed lymphocyte reaction, these F4-IC-activated MoDC showed an improved T cell stimulatory capacity in comparison with immature MoDC. The F4-IC induced DC maturation correlated with significant higher expression levels of several pro-inflammatory cytokines such as interleukine (IL) 1beta, IL-6 and Tumor necrosis factor alpha, the chemokine IL-8 and IL-12p40 in comparison with immature MoDC. Altogether, these results clearly demonstrate that FcgammaR engagement enhances the maturation of porcine MoDC, which may suggest that antigen targeting to FcgammaR on DC could improve vaccine design against infections.

A comparison between isolated blood dendritic cells and monocyte-derived dendritic cells in pigs

Various dendritic cell (DC) populations exist that differ in phenotype and ability to present antigen to T cells. For example, plasmacytoid DCs (pDCs) are less potent T cell activators compared with conventional DCs (cDCs). Here, we compared porcine blood DCs (BDCs), containing pDCs and cDCs, and monocyte-derived DCs (MoDC), consisting of cDCs, in their phenotype, ability to uptake antigen, activation and maturation and their ability to present antigen to autologous T cells. Pigs represent an important animal model, whose immune system in many respects closely resembles that of humans. For example, the distribution of Toll-like receptors is similar to that of humans, in contrast to that of mice. Here we demonstrate that both populations endocytose foreign material. Following lipopolysaccharide stimulation, CD80/86 and chemokine receptor (CCR)7 expression was increased in both populations as was the expression of the chemokine ligands (CCL)-2, CCL-4, CCL-20 and CXCL-2. Although basal and post-stimulation protein concentrations of interleukins 6 and 8 and tumour necrosis factor-alpha were higher in MoDCs, protein concentrations showed a higher fold increase in BDCs. Antigen-specific proliferation of autologous T cells was induced by MoDCs and BDCs. Interestingly, while MoDCs induced stronger proliferation in naive T cells, no difference in proliferation was observed when primed T cells were studied. These results demonstrate that isolated porcine BDCs are highly responsive to stimulation with lipopolysaccharide and are functionally able to drive primed T-cell proliferation to the same extent as MoDCs.

Induction of Th1/Th17 immune response by Mycobacterium tuberculosis: role of dectin-1, Mannose Receptor, and DC-SIGN

Mtb influences DC activity and T cell-mediated immune responses. We show that the treatment of immature monocyte-derived DC with Mtb elicited the formation of mature DC, producing TNF-alpha, IL-1beta, IL-6, and IL-23 and instructing CD4(+) cells to secrete IFN-gamma and IL-17. Mtb-induced cytokine release by DC depended on dectin-1 receptor engagement, whereas MR or DC-SIGN stimulation inhibited this process. A selective dectin-1 binding by the receptor agonist glucan was sufficient to enable DC to generate Th1/Th17 lymphocytes, showing features comparable with those induced by Mtb-treated DC. Interestingly, DC-SIGN or MR engagement inhibited Th17 and increased Th1 generation by glucan- or Mtb-treated DC. Our results indicate that Mtb modulates the lymphocyte response by affecting DC maturation and cytokine release. Dectin-1 engagement by Mtb enables DC to promote a Th1/Th17 response, whereas DC-SIGN and MR costimulation limits dectin-1-dependent Th17 generation and favors a Th1 response, probably by interfering with release of cytokines.