Activation of Antigen-Specific CD8<Superscript>+</Superscript> T Cells by Poly-DL-Lactide/Glycolide (PLGA) Nanoparticle-Primed Gr-1<Superscript>high</Superscript> Cells

Purpose

The aim of this study was to investigate the induction of antigen-specific T cell activation and cell cycle modulation by a poly-DL-lactide/glycolide (PLGA) nanoparticle (NP)-primed CD11b⁺Gr-1^high subset isolated from mouse bone marrow.

Methods

PLGA NPs containing the ovalbumin (OVA) antigen were prepared using the double emulsion and solvent evaporation method, and protein release rate and cell viability were determined. The Lin2^¯CD11b⁺Gr-1^highLy6c^low (Gr-1^high) subset was sorted from the bone marrow of C57BL/6 J mice by fluorescence-activated cell sorting (FACS) and co-cultured with OT-I CD8⁺ splenic T cells. Proliferation of OT-I CD8⁺ T cells was monitored, and cell cycles were determined by 5-bromo-2′-deoxyuridine (BrdU) labeling.

Results

Treatment of Gr-1^high cells with PLGA/OVA NPs upregulated expression of the SIINFEKL-H2K^b complex in the context of MHC I. Co-cultures of OT-I CD8⁺ T cells with the PLGA/OVA NP-primed Gr-1^high cells induced the proliferation of T cells in vitro and modulated cell division and morphology. Treatment of Gr-1^high cells with PLGA/OVA NPs also induced cell apoptosis and necrosis.

Conclusion

This study demonstrated the function of PLGA/OVA NPs in the activation of OT-I CD8⁺ T cells and the capability of cross-presentation via the Gr-1^high polymorphonuclear subset from mouse bone marrow.

     

Co-immunizing with PD-L1 induces CD8+ DCs-mediated anti-tumor immunity in multiple myeloma

Tumor therapeutic vaccines have faced a challenge for effective protection against malignant tumors by inducing tumor-specific CD8⁺ T cell responses. Here, we designed a DNA vaccine containing a tumor-specific antigen of Dickkopf-1 (DKK-1) and an immune checkpoint of programmed death ligand 1 (PD-L1) delivered by PLGA/PEI nanoparticle-mediated delivery system for multiple myeloma therapy. Murine subcutaneous tumor model established with human DKK1 (hDKK-1)-SP2/0 cells were intramuscularly immunized with PLGA/PEI-pPD-L1/pDDK-1 vaccine and equal amount of control 3 times at 10 day-intervals. Compared with PLGA/PEI-pDKK1 immunization group, PLGA/PEI-pPD-L1/pDKK-1 co-immunization enhanced the induction and mature of CD11c⁺ DCs and CD8⁺CD11c⁺ DCs, and promoted antigen-specific Th1 responses and cytotoxic T lymphocyte (CTL) responses. The reduced tumor volume and weight as well as increased tumor inhibition rate were observed in PLGA/PEI-pPD-L1/pDKK-1 vaccine co-immunization group, indicated that the vaccine could effectively inhibit the tumor growth of multiple myeloma. The anti-tumor activity of PLGA/PEI-pPD-L1/pDKK-1 vaccine was abrogated by CD8 cell depletion accompanied with the reduced percentages of CD8⁺CD11c⁺ DCs and CD8⁺ T cells in the spleen and TILs. These results indicated that the anti-tumor efficacy of PLGA/PEI-pPD-L1/pDKK-1 vaccine was required for CD8⁺CD11c⁺ DCs-mediated CD8⁺ T cell immunity responses. This vaccine strategy may represent a potential and promising approach for hematological malignancy treatment.     

CD28 in thymocyte development and peripheral T cell activation in mice exposed to suspended particulate matter

The CD28:B7 signaling pathway is very important for the activity of mature peripheral T lymphocytes and thymocyte development. The proper development of thymocytes into mature single positive CD4⁺and CD8⁺ T cells is crucial for almost all immune functions. In naturally occurring conditions, T cells maturation in the thymus is influenced by environmental agents. The expression of CD28 and the distribution of CD28^low/high thymocytes have been examined at various stages of thymocyte development in BALB/c mice exposed to air-suspended particulate matter (ASM). Acute exposure to ASM resulted in the decrease of CD28 expression in the total thymocyte population. The increase of the percentage of CD28^low and the decrease of CD28^high thymocytes were observed, which may account for the acceleration of thymocyte development under the conditions of elevated risk resulting from the exposure of animals to environmental xenobiotics. ASM exposure resulted in the increase of the level of proliferation of lymph node T cells induced by anti-CD3 and anti-CD28 monoclonal antibodies activation despite normal expression of CD28 molecule. In contrast, the level of proliferation of spleen T cells was lowered or normal dependently of the concentration of stimuli used for activation. Results of these studies demonstrate that acute exposure of mice to ASM can result in the progression of two contrasting processes in the immune system: upregulation of thymocyte development, which contributes to the maintenance of peripheral T cell pool, and over-activation of lymph node lymphocytes, which may lead to uncontrolled immunostimulation.     

Dendritic cells transfected with indoleamine 2,3-dioxygenase gene suppressed acute rejection of cardiac allograft

BackgroundImmunomodulation by indoleamine 2,3-dioxygenase (IDO) has been documented in many studies yet its underlying mechanisms remain undefined, especially in solid organ transplantation. Recent research demonstrated that the active expression of IDO in dendritic cells (DCs) regulates immune reaction. This study assessed whether DCs transfected with IDO gene inhibit T cells responses and suppress cardiac allograft rejection.MethodsAdenovirus vector containing IDO gene was transfected into DCs to obtain IDO-positive DCs (IDO⁺ DCs). To evaluate the effect of IDO⁺ DCs on T cells in vitro, CD4⁺ T cell proliferation and apoptosis was assessed in mixed lymphocyte reactions and measured by flow cytometry, respectively. IDO⁺ DCs from C57BL/6 mice were injected into BALB/c recipients before heterotopic cardiac transplantation.ResultsSupernatant fluids from cultures of IDO⁺ DCs had decreased tryptophan and increased kynurenine levels, reflecting IDO activity. IDO⁺ DCs suppressed CD4⁺ T cell responses in vitro, as reflected by decreased proliferation and increased apoptosis. In the transplant model, IDO⁺ DCs prolonged survival and alleviated rejection of cardiac allograft in recipients injected with IDO⁺ DCs. In vivo, IDO⁺ DCs also significantly impaired CD4⁺ T cell responses promoting increased apoptosis and a Th2-dominant cytokine shift.ConclusionsIDO overexpression in DCs suppressed T cells alloresponses in vitro, and IDO⁺ DCs attenuated acute allograft rejection in vivo. Regulation of tryptophan catabolism by means of IDO overexpression in DCs may be a useful approach in cardiac transplantation and immunological tolerance.     

Nattectin a fish C-type lectin drives Th1 responses in vivo: licenses macrophages to differentiate into cells exhibiting typical DC function

Considerable efforts are currently focused on the biology of DC in view of their possible clinical use as adjuvant for the generation of antigen-specific immunity and lifelong immunologic memory or for the treatment of tumors. We assessed the role of Nattectin a C-type lectin identified in the Thalassophryne nattereri fish venom in DC maturation. Nattectin induced a significant neutrophilic recruitment into peritoneal cavity of mice, followed by macrophages, with lipidic mediators and IL-12 p70 synthesis. Macrophages derived from 7 day-Nattectin mice were CD11c + CD11b^lowLy6^highF4/80R^high and express high levels of MHC class II and CD80 molecules. Culture of peritoneal exudates derived macrophages from 7 day Nattectin-mice and immature BMDCs with Nattectin markedly increased the surface expression of CD40, CD80, CD86, and MHC class II in a dose-dependent manner, and the production of MMP-2 and MMP-9 distributed in nucleus and cytoplasm of cells, that was associated with strong activity in the culture supernatant. Nattectin treated DCs secreted IL-12 p70 and IL-10. The Nattectin-treated BMDC or macrophage-derived DCs were highly efficient at Ag capture. The specific immune response elicited by Nattectin was characterized by the production of specific antibodies IgG1 and mainly IgG2a with IL-10 and IFN-γ synthesis by splenic cells. These results enable us to address that Nattectin induces the recruitment of Ly6C^high monocytes into the peritoneum, which exhibit a pro-inflammatory profile, where they differentiate into proliferating F4/80R^high macrophages. Macrophage-derived DCs mature in the presence of the cytokine milieu generated against Nattectin, exhibiting T cell co-stimulatory molecule expression and induced a Th1 polarized response.     

Exploring the immunopotentiation of Chinese yam polysaccharide poly(lactic-co-glycolic acid) nanoparticles in an ovalbumin vaccine formulation in vivo

Biocompatible and biodegradable poly(lactic-co-glycolic acid) (PLGA) has been approved by the US Food and Drug Administration and has frequently been used to develop potential vaccine delivery systems. The immunoregulation and immunopotentiation of Chinese yam polysaccharide (CYP) have been widely demonstrated. In the current study, cell uptake mechanisms in dendritic cells (DCs) were monitored in vitro using confocal laser scanning microscopy, transmission electron microscopy, and flow cytometry. To study a CYP-PLGA nanoparticle-adjuvanted delivery system, CYP and ovalbumin (OVA) were encapsulated in PLGA nanoparticles (CYPPs) to act as a vaccine, and the formulation was tested in immunized mice. The CYPPs more easily underwent uptake by DCs in vitro, and CYPP/OVA could stimulate more effective antigen-specific immune responses than any of the single-component formulations in vivo. Mice immunized using CYPP/OVA exhibited more secretion of OVA-specific IgG antibodies, better proliferation, and higher cytokine secretion by splenocytes and significant activation of CD3⁺CD4⁺ and CD3⁺CD8⁺ T cells. Overall, the CYPP/OVA formulation produced a stronger humoral and cellular immune response and a mixed Th1/Th2 immune response with a greater Th1 bias in comparison with the other formulations. In conclusion, the data demonstrate that the CYPP-adjuvanted delivery system has the potential to strengthen immune responses and lay the foundation for novel adjuvant design.     

Analysis of the role of palmitoleic acid in acute anterior uveitis

PurposeTo study the role of palmitoleic acid (PA) in the pathogenesis of acute anterior uveitis (AAU).MethodsPA levels in feces from AAU patients were measured by gas chromatography coupled with a mass spectrometer (GC-MS) and compared with samples obtained from healthy individuals. Enzyme linked immunosorbent assay (ELISA) and flow cytometry (FCM) were used to assess the effect of PA on dendritic cells (DCs) and CD4⁺T cells obtained from mice, AAU patients and healthy individuals. C57BL/6 mice were fed with PA or vehicle and experimental autoimmune uveitis (EAU) was induced with a human retinal IRBP651-670 peptide. Disease severity of EAU was evaluated by clinical manifestation and histology. Differentiation of splenic Type 1 helper T cells (Th1) and Th17 cells was evaluated by FCM. Tandem mass tag (TMT)-based proteomics analysis was used to identify differentially expressed proteins following incubation of DCs with PA.ResultsThe fecal concentration of PA was increased in AAU patients as compared with healthy individuals. In vitro, PA promoted apoptosis of DCs and inhibited the secretion of TNF-α from mouse bone-marrow-derived dendritic cells (BMDCs) as well as in DCs from AAU patients and healthy individuals. It only decreased DCs surface marker expression and IL-12p70 secretion in BMDCs and healthy individuals DCs but not in AAU patient DCs. PA-treated BMDCs inhibited Th cell differentiation from mouse naïve CD4⁺T cells and IL-17 and IFN-γ secretion in co-culture supernatants. PA also inhibited the differentiation of Th cells and secretion of IFN-γ and IL-17 in CD4⁺T cells from mice, AAU patients and healthy individuals. In vivo, PA-treated EAU mice showed milder clinical and histopathological intraocular manifestations as compared with the control group. PA feeding inhibited differentiation of splenic Th17 cells, whereas Th1 cells were not affected. Up to 30 upregulated and 77 downregulated proteins were identified when comparing PA-treated DCs with controls.ConclusionAn increased expression of fecal PA was observed in AAU patients. PA was shown to have immunoregulatory effects on DCs and CD4⁺T cells and attenuated disease severity in EAU mice.     

Lactococcus lactis subsp. cremoris FC triggers IFN-γ production from NK and T cells via IL-12 and IL-18

Lactic acid bacteria (LAB) benefit health as probiotics in a strain-dependent way. In this study, we investigated the immunomodulatory effects of Lactococcus lactis subsp. cremoris FC (LcFC) on dendritic cells (DCs), natural killer (NK) cells and T cells. LcFC induced the production of cytokines such as IL-10, IL-12, IL-6 and TNF-α from murine bone marrow DCs (BMDCs) via MyD88-dependent pathway. In comparison with the type strain L. lactis subsp. cremoris ATCC 19257, LcFC induced particularly high production of IL-12 while induction of IL-6 was moderate. Consequently, LcFC triggered IFN-γ production in splenic NK, CD8⁺, and CD4⁺ cells. Most prominent effect of LcFC on IFN-γ production was observed in NK cells, followed by CD8⁺ cells, which was completely inhibited by combination of neutralizing anti-IL-12 and anti-IL-18 mAbs. Moreover, oral administration of LcFC enhanced the production of IFN-γ and IL-10 from splenocytes of treated mice. These findings suggest that this LAB strain is an efficient activator of protective cellular immunity via stimulation of myeloid cells including DCs.     

Effective stimulation of invariant natural killer T cells by oligomannose-coated liposomes

vThe in vitro and in vivo response of invariant natural killer T (iNKT) cells to alpha-galactosylceramide (αGC)-containing oligomannose-coated liposomes (αGC-OMLs) was examined to determine whether selective delivery of αGC to dendritic cells (DCs) and subsequent activation of iNKT cells could be achieved. Splenocytes stimulated with αGC-OMLs produced higher levels of IFN-γ compared to those stimulated with bare liposomes without an oligomannose coating (αGC-BLs). The ratio of IFN-γ/IL-4 produced from αGC-OML-treated splenocytes was higher than those produced from αGC-BL- and soluble αGC-treated cells. Depletion of CD3⁺-, DX5⁺- or CD11c⁺-cells from splenocytes almost completely abolished the αGC-OML-stimulated cytokine production, suggesting that both NKT cells and DCs were involved in the response to αGC-OML stimulation. In addition, αGC-OMLs were incorporated into both splenic and bone marrow-derived DCs more effectively than αGC-BLs. iNKT cells stimulated with DCs with ingested αGC-OMLs produced much higher levels of IFN-γ than those stimulated with DCs containing αGC-BLs or soluble αGC. Systemic administration of αGC-OMLs led to modification of the kinetics of IFN-γ production in vivo and also resulted in predominant production of IFN-γ from splenocytes over IL-4. In addition, iNKT cells proliferated and expanded upon in vivo activation of the cells with αGC-OMLs much more extensively than with αGC-BLs or soluble αGC. Collectively, our results suggest that αGC-OMLs can be used as a preferential delivery system for lipid antigens to DCs to activate iNKT cells in vivo and ex vivo.     

Maturation of dendritic cells by maitake α-glucan enhances anti-cancer effect of dendritic cell vaccination

Dendritic cells (DCs) play a primary role in antigen presentation to CD4⁺ and CD8⁺ T cells and induce acquired immune response against cancer cells. Therefore, determining positive modulators of DC activation to improve therapeutic approaches for cancer immunotherapy is greatly needed. In this study, we investigated the effect of maitake α-glucan YM-2A, isolated from Grifola frondosa, on the maturation and function of DCs and its adjuvant effect on a tumor-associated antigen (TAA)-loaded DC vaccine against murine tumor. We showed that YM-2A induced morphological changes and increased cell-surface maturation markers and cytokine production in DCs. In a mixed lymphocyte reactions assay, YM-2A-treated DCs increased proliferation and production of IFN-γ by allogeneic CD4⁺ and CD8⁺ T cells. These results indicate that YM-2A phenotypically and functionally activates DCs. Furthermore, YM-2A-treated TAA-loaded DC vaccine significantly reduced tumor growth and improved survival in two murine tumor models, CT-26 tumor-bearing BALB/c mice and B16 melanoma-bearing C57BL/6 mice. YM-2A-treated TAA-loaded DC vaccine increased splenic IFN-γ producing CD4⁺ and CD8⁺ T cells in CT-26 tumor-bearing BALB/c mice. Antibody neutralization studies indicated that YM-2A-induced DC maturation is mediated, in part, by the Dectin-1-dependent pathway. Overall, YM-2A-treatment with a TAA-loaded DC vaccine could be an excellent candidate for immunotherapy against cancer.     

Ageratina adenophora Inhibits Spleen Immune Function in Rats via the Loss of the FRC Network and Th1–Th2 Cell Ratio Elevation

The objective of this study was to determine the impact of Ageratina adenophora (A. adenophora) on splenic immune function in a rat model. Rats were fed with 10 g/100 g normal feed and an experimental feed, which was composed of 3:7 A. adenophora powder and normal feed for 60 days. On days 14, 28, and 60, subsets of rats (n = 8 rats/group/time point) were selected for blood and spleen tissue sample collection. The results showed that the proportion of CD3⁺ T cells in the spleen was decreased at day 60 (vs. control). Also, mRNA and protein expression of chemokines CCL21 and CCL19 and functional protein gp38 in spleen decreased significantly versus the control at day 60. In addition, ER-TR7 antigen protein expression was also decreased at day 60. Levels of T-helper (Th)1 cells significantly increased, whereas those of Th2 cells decreased significantly versus the control at day 60 in spleen. The finding revealed that A. adenophora could affect splenic immune function in rats by altering the fibroblast reticulocyte (FRC) network, as well as by causing an imbalance in Th1/Th2 cell ratios. This research provides new insights into potential mechanisms of spleen immunotoxicity due to exposures to A. Adenophora.     

Outer membrane protein A of Acinetobacter baumannii induces differentiation of CD4+ T cells toward a Th1 polarizing phenotype through the activation of dendritic cells

Acinetobacter baumannii is an increasing hospital-acquired pathogen that causes a various type of infections, but little is known about the protective immune response to this microorganism. Outer membrane protein A of A. baumannii (AbOmpA) is a major porin protein and plays an important role in pathogenesis. We analyzed interaction between AbOmpA and dendritic cells (DCs) to characterize the role of this protein in promoting innate and adaptive immune responses. AbOmpA functionally activates bone marrow-derived DCs by augmenting expression of the surface markers, CD40, CD54, B7 family (CD80 and CD86) and major histocompatibility complex class I and II. AbOmpA induces production of Th1-promoting interleukin-12 from DCs and augments the syngeneic and allogeneic immunostimulatory capacity of DCs. AbOmpA stimulates production of interferon-γ from T cells in mixed lymphocyte reactions, which suggesting Th1-polarizing capacity. CD4⁺ T cells stimulated by AbOmpA-stimulated DCs show a Th1-polarizing cytokine profile. The expression of surface markers on DCs is mediated by both mitogen-activated protein kinases and NF-κB pathways. Our findings suggest that AbOmpA induces maturation of DCs and drives Th1 polarization, which are important properties for determining the nature of immune response against A. baumannii.     

Paeoniflorin inhibits the maturation and immunostimulatory function of allergen-induced murine dendritic cells

Dendritic cells (DCs) as the front lines of defense play a crucial role in allergic contact dermatitis (ACD). Paeoniflorin (PF) has been clinically proven to be effective in the treatment of inflammatory skin diseases such as ACD. However, the mechanisms underlying the anti-inflammatory effect of PF remain unclear. The aim of this study was to explore the effect of PF on the maturation and immunostimulatory function of DCs in the murine model of ACD in vitro. Murine bone marrow-derived DCs were stimulated with the contact sensitizer 1-chloro-2, 4-dinitrobenze (DNCB) in vitro. Surface antigen expression of DCs (MHC II, CD40, CD80, and CD86), as an indicator of maturation DCs and cytokines (IL-12, IFN-γ, IL-10, and TGF-β) after DNCB stimulation in the absence or presence of PF at different doses, was detected. Then, we detected that PF-treated DCs stimulated T cells in response to DNCB. PF inhibited the up-regulation of MHC II, CD80, CD86, and CD40, decreased IL-12p70 secretion, while increased the production of IL-10 and TGF-β, and had no effect on IFN-γ cytokine production by murine bone marrow-derived DCs in response to DNCB. DCs exposed to PF had diminished capacity to stimulate allogeneic T cell proliferation and to activate IFN-γ-producing CD4⁺ T cells and induced CD4⁺CD25⁺Foxp3⁺ T cells and IL-10-producing T cell expansion from naïve CD4⁺ T cells. These results indicate that PF may be effective in preventing and treating ACD in vitro and other inflammatory responses possibly through inhibiting maturation of DCs and limiting their capacity to stimulate T cell responses.     

Biodegradable Nanoparticle Mediated Antigen Delivery to Human Cord Blood Derived Dendritic Cells for Induction of Primary T Cell Responses

Dendritic cells (DCs) in the peripheral tissues act as sentinels of the immune system. They detect and capture pathogens entering the body and present their antigens to T cells to trigger responses directed towards elimination of the pathogen. The induction of peripheral tolerance against self and certain foreign antigens is also believed to be mediated through DCs. The outcome of any immune response is largely controlled by the microenvironment of antigen capture, processing and presentation by DCs. The “context” of antigen delivery to DCs will directly influence the microenvironment of antigen presentation and hence the regulation of immune responses. We report here preliminary investigations describing the formulation of a pharmaceutically acceptable, biodegradable, and strategic nanoparticulate delivery system, and its application for efficient antigen loading of DCs to achieve antigen specific T cell activation. “Pathogen-mimicking” nanoparticles capable of interacting with DCs were fabricated by incorporating monophosphoryl lipid A (MPLA; toll-like receptor (TLR) 4 ligand) or CpG ODN (seq #2006; TLR9 ligand) in biodegradable copolymer, poly(_d,_l-lactic-co-glycolic acid) (PLGA). The uptake of PLGA nanoparticles by human umbilical cord blood derived DCs (DCs propagated from CD34₊ progenitors) was conclusively demonstrated by scanning electron microscopy (SEM), fluorescence activated cell sorting (FACS) and confocal laser scanning microscopy (CLSM). Cell phenotype at day 12 of cultures was determined as immature DC using specific cell surface markers, i.e. CD11c_hi (～90%), MHC-II₊ (～70%), CD86_low (～20%), CD83_low (～5%), CD80₊ (～40%), CD40₊ (～40%), and CCR7_low (～5%). Tetanus toxoid (TT), a model antigen, was encapsulated in nanoparticles along with an immunomodulator, i.e. either MPLA or CpG ODN. DCs pulsed with various antigen formulations were co-cultured with autologous naïve T cells at various cell ratios (DC: T cells were 1:5–20). The DCs pulsed with TT and MPLA together in nanoparticles induced significantly higher T cell proliferation (P<0.05) as compared to when DCs pulsed with TT and MPLA in solution were employed. A similar trend was observed when CpG ODN was used instead of MPLA in the TT nanoparticles. This strategy of antigen delivery to DCs was then tested with a cancer vaccine candidate, a MUC1 lipopeptide. The T cell proliferation observed in the presence of nanoparticulate MUC1 and MPLA pulsed-DCs was much higher than DCs pulsed with soluble antigen (P<0.0005). These results indicate that PLGA nanoparticles mimicking certain features of pathogens are efficient delivery systems for targeting vaccine antigens to DCs and activation of potent T cell responses.     

Polyactin A is a novel and potent immunological adjuvant for peptide-based cancer vaccine

Synthetic peptide cancer vaccines are poorly immunogenic sub-unit vaccines and thus essentially need adjuvants in their formulations to increase the efficacy by enhancing the peptide-specific immune response. However, aluminum-based compounds are almost dependent for clinical use at present. Therefore, the increasing use of peptide-based vaccines makes the need for novel and potent adjuvants. Polyactin A (PAA) has been used for the clinical treatment of impaired immunity in China for over 30 years. To figure out the adjuvant effects of PAA for E75 peptide breast cancer vaccine (Her2 p369-p377), the generation of mature dendritic cells (DCs) from peripheral blood monocytes (PBMCs) cultured with PAA, IL-4 and TNF-α was assessed by morphologic features and the expressions of special surface markers using flow cytometry. Then the functional features of PBMCs-derived DCs cultured with PAA, IL-4 and TNF-α were investigated by inducing E75-specific cytotoxicity. Finally, C57BL/6-Tg(HLA-A2.1)1Enge/J transgenic mice were immunized with E75 and various amounts of PAA, and splenic lymphocyte proliferation and the IFN-γ level were determined. The results showed that PAA, just like granulocyte-macrophage colony stimulating factor, with IL-4 and TNF-α efficiently induced mature DCs from PBMCs, and these DCs could trigger a potent E75 peptide-specific CD8⁺ T-cell response in vitro. Immunization with E75 and PAA significantly increased positive rates of CD4⁺ and CD8⁺ T lymphocytes, and enhanced splenocytes proliferation and levels of IFN-γ in splenocytes when induced by E75. Our results indicated that PAA could efficiently induce E75-specific immunologic responses in vitro and in vivo. Therefore, PAA possesses potent adjuvant effect on peptide-based cancer vaccine. Our study provides a safe, effective and novel adjuvant for clinical use.     

Regulatory T cells ameliorate acetaminophen-induced immune-mediated liver injury

The contribution of innate immune cells to acetaminophen (APAP)-induced liver injury has been extensively investigated. However, the roles of T cell populations among adaptive immune cells in APAP-induced liver injury remain to be elucidated. Herein, we found that distinct CD4⁺ T cell subsets but not CD8⁺ T cells modulated APAP-induced liver injury in mice. After APAP challenge, more CD62L^lowCD44^hiCD4⁺ T cells appeared in the liver, accompanied by increased IFN-γ. The removal of CD4⁺ T cells by either antibody depletion or genetic deficiency markedly compromised pro-inflammatory cytokine levels and ameliorated liver injury. Meanwhile, we also found that the frequency and absolute number of Treg cells also increased. Treg cell depletion increased hepatic CD62L^lowCD44^hiCD4⁺ T cells, augmented pro-inflammatory cytokines, and exacerbated liver injury, while adoptive transfer of Treg cells ameliorated APAP-induced liver injury. Furthermore, the recruitment of Treg cells into the liver through specific expression of CXCL10 in the liver could ameliorate APAP-induced liver injury. Our investigation suggests that Th1 and Treg subsets are involved in regulating APAP-induced liver injury. Thus, modulating the Th1/Treg balance may be an effective strategy to prevent and/or treat APAP-induced liver injury.     

IL-20 contributes to low grade inflammation and weight gain in the Psammomys obesus

The metabolic syndrome has been demonstrated in gene deficient animals, e.g. db/db mice, to include a systemic inflammation leading to insulin resistance, obesity and type 2 diabetes (T2D). To determine the importance of inflammation in obesity and diabetes, in a normal non-genetically modified species, an intervention study with neutralizing anti-IL-20 antibodies was conducted in the spontaneous T2D model Psammomys obesus.All IL-20 receptor chains were expressed on protein level in the Psammomys obesus. Neutralization of IL-20 did not modulate blood glucose, HbA1c, insulin levels or lymphocyte numbers after five weeks treatment although a trend to reduced weight gain rate was observed upon anti-IL-20 treatment. Inhibition of IL-20 significantly increased the number of CD11b^high/low cells and the CD11bGr-1^int myeloid derived suppressor cells in the spleen. Importantly, although the number of M1-like monocytes remained unchanged the M1-like marker CD11c expression level was reduced on the cells upon anti-IL-20 treatment. Anti-IL-20 treatment reduced both TLR4 and CCR2b expression on the macrophages upon treatment. Further, a marked shift in the protein signature in the pancreatic tissue after anti-IL-20 treatment was observed including enhanced expression of CXCL12, TIMP-1 and IL-10 while IL-1β, CXCL4, PEDF and ADAMTS1 were reduced.In conclusion, we describe for the first time the systemic immune response in the diabetic Psammomys obesus. Neutralizing IL-20 modulated the myeloid compartment, the adaptive immunity, and local expression of proteins in the diabetic pancreatic tissue as well as improved on weight gain and hence may place IL-20 as a cytokine to be considered in obesity.     

A humanized monoclonal antibody targeting the β7 integrin selectively blocks intestinal homing of T lymphocytes

BACKGROUND AND PURPOSE

rhuMAb Beta7 is a humanized anti-human β7 monoclonal antibody currently in phase I in inflammatory bowel disease. rhuMAb Beta7 binds the β7 subunit of the integrins α4β7 and αEβ7, blocking interaction with their ligands. These integrins play key roles in immune cell homing to and retention in mucosal sites, and are associated with chronic inflammatory diseases of the gastrointestinal tract. The goal of this study was to evaluate the mucosal specificity of rhuMAb Beta7.

EXPERIMENTAL APPROACH

We assessed the effect of murine anti-Beta7 on lymphocyte homing in mouse models of autoimmune disease. We also compared the effect of rhuMAb Beta7 on circulating mucosal-homing versus peripheral-homing T cells in naïve non-human primates.

KEY RESULTS

In cynomolgus monkeys, occupancy of β7 integrin receptors by rhuMAb Beta7 correlated with an increase in circulating β7⁺ mucosal-homing lymphocytes, with no apparent effect on levels of circulating β7^- peripheral-homing lymphocytes. rhuMAb Beta7 also inhibited lymphocyte homing to the inflamed colons of severe combined immunodeficient mice in CD45RB^high CD4⁺ T-cell transfer models. Consistent with a lack of effect on peripheral homing, in a mouse model of experimental autoimmune encephalomyelitis, anti-β7 treatment resulted in no amelioration of CNS inflammation.

CONCLUSIONS AND IMPLICATIONS

The results presented here suggest that rhuMAb Beta7 selectively blocks lymphocyte homing to the gastrointestinal tract without affecting lymphocyte trafficking to non-mucosal tissues. rhuMAb Beta7 provides a targeted therapeutic approach with the potential for a more attractive benefit : risk ratio than currently available inflammatory bowel disease therapies.