Induction Of Th1 Responses Research Articles

Evaluation of the sensitizing potential of food proteins using two mouse models

The current methodology to identify allergenic food proteins is effective in identifying those that are likely to cross-react with known allergens. However, most assays show false positive results for low/non-allergens. Therefore, an ex vivo/in vitro DC-T cell assay and an in vivo mouse model were used to distinguish known allergenic food proteins (Ara h 1, β-Lactoglobulin, Pan b 1, bovine serum albumin, whey protein isolate) from low/non allergenic food proteins (soy lipoxygenase, gelatin, beef tropomyosin, rubisco, Sola t 1).CD4+ T cells from protein/alum-immunized mice were incubated with corresponding protein-pulsed bone marrow-derived DC and analyzed for cytokine release. All known allergens induced Th2 responses in vitro, whereas soy lipoxygenase, gelatin or beef tropomyosin did not. Sola t 1 and rubisco induced a more generalized T cell response due to endotoxin contamination, indicating the endotoxin-sensitivity of the DC-T assay. To analyze responses in vivo, mice were orally sensitized on days 0 and 7. Known allergens induced IgE and mMCP-1 release upon oral challenge at day 16, whereas the low/non-allergens did not.Both the DC-T cell assay and the mouse model were able to distinguish 5 known allergens from 5 low/non-allergens and may be useful to identify novel allergenic food proteins.

Estradiol Enhances CD4+ T-Cell Anti-Viral Immunity by Priming Vaginal DCs to Induce Th17 Responses via an IL-1-Dependent Pathway.

Clinical and experimental studies have shown that estradiol (E2) confers protection against HIV and other sexually transmitted infections. Here, we investigated the underlying mechanism. Better protection in E2-treated mice, immunized against genital HSV-2, coincided with earlier recruitment and higher proportions of Th1 and Th17 effector cells in the vagina post-challenge, compared to placebo-treated controls. Vaginal APCs isolated from E2-treated mice induced 10-fold higher Th17 and Th1 responses, compared to APCs from progesterone-treated, placebo-treated, and estradiol-receptor knockout mice in APC-T cell co-cultures. CD11c+ DCs in the vagina were the predominant APC population responsible for priming these Th17 responses, and a potent source of IL-6 and IL-1β, important factors for Th17 differentiation. Th17 responses were abrogated in APC-T cell co-cultures containing IL-1β KO, but not IL-6 KO vaginal DCs, showing that IL-1β is a critical factor for Th17 induction in the genital tract. E2 treatment in vivo directly induced high expression of IL-1β in vaginal DCs, and addition of IL-1β restored Th17 induction by IL-1β KO APCs in co-cultures. Finally, we examined the role of IL-17 in anti-HSV-2 memory T cell responses. IL-17 KO mice were more susceptible to intravaginal HSV-2 challenge, compared to WT controls, and vaginal DCs from these mice were defective at priming efficient Th1 responses in vitro, indicating that IL-17 is important for the generation of efficient anti-viral memory responses. We conclude that the genital mucosa has a unique microenvironment whereby E2 enhances CD4+ T cell anti-viral immunity by priming vaginal DCs to induce Th17 responses through an IL-1-dependent pathway.

A central role for Type I IFN in the induction of Th2 responses by dendritic cells

Abstract Although dendritic cells (DCs) are critical for induction of Th2 immunity against helminths or allergens, relatively little is known about how they become activated and function in response to Th2-polarizing antigens. We have discovered a previously unrecognized role for Type I IFN (IFN-I) in the optimal activation and function of DCs following exposure to strongly Th2-polarizing antigens. To date, IFN-I has primarily been associated with anti-viral immunity, and its role in Th2 settings is currently unclear. DCs exposed to total egg antigens from the parasitic helminth Schistosoma mansoni, or the primary immunostimulatory component of S. mansoni eggs, omega-1, produced IFN-I in vitro. IFN-I was also detected in response to the common allergen house dust mite (HDM). DCs lacking the IFN-I receptor displayed a dramatically impaired ability to induce Th2 cytokines in vivo, but unimpaired ability to support CD4 T cell polarization in vitro. Further, Th2-promoting DCs depended on IFN-I signaling for optimal activation, efficient migration to the draining LN, and effective localization within the T cell zone. In vivo challenge of naïve mice with S. mansoni eggs or HDM in the absence of the IFN-I receptor induced significantly reduced levels of Th2 cytokines compared to controls. Together, our data suggest a key role for IFN-I to enable Th2 induction by DCs against Th2 Ag in vivo. Future work will address the wider role of IFN-I in Th2 inflammation, including during patent helminth infection in vivo.

DC-independent TSLP-mediated acute allergic airway inflammation via CD11c+ Interstitial Macrophages

Abstract Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine important for the development of type-2 inflammatory responses at mucosal surfaces. In humans, TSLP has been found to be elevated in the lungs of asthmatics, and in mouse models TSLP can promote type-2 airway inflammation. DC have been shown to respond directly to TSLP and subsequently promote the differentiation of Th2 cells. In addition, other lung-resident MHCII-expressing cells, such as Alveolar Macrophages (AM) and Interstitial Macrophages (IM), have been shown to regulate the activation of T cells. We have identified a subset of CD11c-expressing Interstitial Macrophages (CD11cIM) addition to AM and IM, which can directly induce proliferation and differentiation of CD4 T cells in a TSLP-dependent manner. Following exposure to TSLP, these cells are more potent then DC for expansion and Th2 cytokine production of CD4 T cells. More importantly, CD11cIM are necessary and sufficient for the induction of Th2 responses and downstream eosinophilic inflammation in the lungs. These findings indicate a novel unique and critical role for TSLP-signaling on CD11cIM in the development of acute Th2-dependent allergic airway inflammation in pulmonary microenvironment.

Cutaneous Leishmaniasis Vaccination: A Matter of Quality.

There have been exhaustive efforts to develop an efficient vaccine against leishmaniasis. Factors like host and parasite genetic characteristics, virulence, epidemiological scenarios, and, mainly, diverse immune responses triggered by Leishmania species make the achievement of this aim a complex task. It is already clear that the induction of a Th1, pro-inflammatory response, is important in the protection against Leishmania infection. However, many questions must still be answered to fully understand Leishmania immunopathology, especially regarding Leishmania-specific Th1 response induction, regulation, and persistence. A large number of Leishmania antigens able to induce pro-inflammatory response have been selected so far, but none of them demonstrated efficiency in protection assays. A possible explanation is that CD4 T cells display marked heterogeneity at a single-cell level especially regarding the production of Th1-defining cytokines and multifunctionality. It has been established in the literature that Th1 cells undergo a differentiation process, which can generate cells with diverse phenotypes and survival capabilities. Despite that, only a few studies evaluate this heterogenic response and the amount of multifunctional CD4 T cells induced by Leishmania vaccine candidates, missing what can be a crucial point in defining a correlate of protection after vaccination. Moreover, most of the knowledge involving the development of cutaneous leishmaniasis (CL) vaccines comes from the mouse model of infection with Leishmania major, which cannot be fully applied to New World Leishmaniasis. For this reason, the immune response triggered by infection with New World Leishmania species, as well as vaccine candidates, need further studies. In this review, we will reinforce the importance of evaluating the quality of immune response against Leishmania, using a multiparametric analysis in order to understand better this complex host-parasite interaction, discussing the differences in the responses triggered by different New World Leishmania species, as well as the impact on the development of an effective vaccine against CL.

Codelivery of DNA vaccination encoding LeIF gene and IL-12 increases protection against Leishmania major infection in BALB/c mice.

Previous studies have shown that Leishmania elongation initiation factor (LeIF) antigen causes a partial immunity against leishmaniasis. The antigen develops type I immunity by overexpression of inflammatory cytokines such as interleukin-12 (IL-12), IFN-γ and TNF-α. Therefore, We evaluated immune responses induced by the LeIF gene against Leishmania major infection. Immunization with LeIF gene alone or with IL-12 induced Th1 response and produced higher IFN-γ and lower IL-4 levels by splenocytes than control groups (P<0·05) and also ratios of IFN-γ/IL-4 were 11·68 to 18·53 times more in immunized groups than control groups after challenge. In addition, analysis of humoral immune response revealed that immunized mice had more IgG2a levels than both control groups (P<0·05). On the other hand, lesion size was less for immunized animals than control groups from 4th week after challenge (P<0·05). The percentage reduction in lesion size was 29·30% for LeIF and 51·98% for LeIF+ IL-12 than PBS at 12th week post-infection. Spleen parasite burden decreased in all immunized groups in comparison with control groups (P<0·05). The results indicated that LeIF gene induced partial immunity against L.major infection in BALB/c mice. However, LeIF plus IL-12 group showed more potent immunity with smaller lesions than other groups.

Blockade of Tim-1 and Tim-4 Enhances Atherosclerosis in Low-Density Lipoprotein Receptor-Deficient Mice.

T cell immunoglobulin and mucin domain (Tim) proteins are expressed by numerous immune cells, recognize phosphatidylserine on apoptotic cells, and function as costimulators or coinhibitors. Tim-1 is expressed by activated T cells but is also found on dendritic cells and B cells. Tim-4, present on macrophages and dendritic cells, plays a critical role in apoptotic cell clearance, regulates the number of phosphatidylserine-expressing activated T cells, and is genetically associated with low low-density lipoprotein and triglyceride levels. Because these functions of Tim-1 and Tim-4 could affect atherosclerosis, their modulation has potential therapeutic value in cardiovascular disease. ldlr(-/-) mice were fed a high-fat diet for 4 weeks while being treated with control (rat immunoglobulin G1) or anti-Tim-1 (3D10) or -Tim-4 (21H12) monoclonal antibodies that block phosphatidylserine recognition and phagocytosis. Both anti-Tim-1 and anti-Tim-4 treatments enhanced atherosclerosis by 45% compared with controls by impairment of efferocytosis and increasing aortic CD4(+)T cells. Consistently, anti-Tim-4-treated mice showed increased percentages of activated T cells and late apoptotic cells in the circulation. Moreover, in vitro blockade of Tim-4 inhibited efferocytosis of oxidized low-density lipoprotein-induced apoptotic macrophages. Although anti-Tim-4 treatment increased T helper cell (Th)1 and Th2 responses, anti-Tim-1 induced Th2 responses but dramatically reduced the percentage of regulatory T cells. Finally, combined blockade of Tim-1 and Tim-4 increased atherosclerotic lesion size by 59%. Blockade of Tim-4 aggravates atherosclerosis likely by prevention of phagocytosis of phosphatidylserine-expressing apoptotic cells and activated T cells by Tim-4-expressing cells, whereas Tim-1-associated effects on atherosclerosis are related to changes in Th1/Th2 balance and reduced circulating regulatory T cells.

A Fusion Protein Consisting of the Vaccine Adjuvant Monophosphoryl Lipid A and the Allergen Ovalbumin Boosts Allergen-Specific Th1, Th2, and Th17 Responses In Vitro.

Background. The detoxified TLR4-ligand Monophosphoryl Lipid A (MPLA) is the first approved TLR-agonist used as adjuvant in licensed vaccines but has not yet been explored as part of conjugated vaccines. Objective. To investigate the immune-modulating properties of a fusion protein consisting of MPLA and Ovalbumin (MPLA : Ova). Results. MPLA and Ova were chemically coupled by stable carbamate linkage. MPLA : Ova was highly pure without detectable product-related impurities by either noncoupled MPLA or Ova. Light scattering analysis revealed MPLA : Ova to be aggregated. Stimulation of mDC and mDC : DO11.10 CD4+ TC cocultures showed a stronger activation of both mDC and Ova-specific DO11.10 CD4+ TC by MPLA : Ova compared to the mixture of both components. MPLA : Ova induced both strong proinflammatory (IL-1β, IL-6, and TNF-α) and anti-inflammatory (IL-10) cytokine responses from mDCs while also boosting allergen-specific Th1, Th2, and Th17 cytokine secretion. Conclusion. Conjugation of MPLA and antigen enhanced the immune response compared to the mixture of both components. Due to the nonbiased boost of Ova-specific Th2 and Th17 responses while also inducing Th1 responses, this fusion protein may not be a suitable vaccine candidate for allergy treatment but may hold potential for the treatment of other diseases that require a strong stimulation of the host's immune system (e.g., cancer).

House Dust Mite-Derived Chitin Enhances Th2 Cell Response to Inhaled Allergens, Mainly via a TNF-α-Dependent Pathway.

PurposeChitin is a potent adjuvant in the development of immune response to inhaled allergens in the airways. According to other studies, chitin is known as multi-faced adjuvants which can induce Th2 responses. Recently, we found that TNF-α is a key mediator in the development of Th2 cell response to inhaled allergens. Here, we evaluated the immunologic mechanisms in the development of airway hypersensitivity to inhaled allergens, enhanced by house dust mite (HDM)-derived chitin.MethodsThe role of TNF-α and TLRs was evaluated in an airway hypersensitivity mouse model induced by a sensitization with an allergen (ovalbumin, OVA) and HDM-derived chitin using mice with the null mutation of target genes.ResultsThe present study showed that airway sensitization with HDM-derived chitin plus OVA enhanced OVA-induced airway inflammation v. OVA alone. This phenotype was associated with the increased expression of Th1, Th2, and Th17 cytokines and also with the enhanced production of OVA-specific IgE, IgG1, and IgG2a. As for T cell responses, OVA-specific Th2 cell response, enhanced by chitin, was abolished by the treatment of chitinase, whereas Th1 and Th17 cell responses enhanced by this treatment. Moreover, the null mutation of the TNF-α gene revealed similar effects as the chitinase treatment. In contrast, all the OVA-specific T cell responses, enhanced by chitin, were blocked by the absence of TLR2, but not of TLR1, TLR4, or TLR6.ConclusionsIn conclusion, these data suggest that HDM-derived chitin may enhance airway hypersensitivity to inhaled allergens, via the TLR2-dependent pathway, and that chitin-induced TNF-α can be a key mediator in the development of Th2 cell response to inhaled allergens.

Levamisole promotes murine bone marrow derived dendritic cell activation and drives Th1 immune response in vitro and in vivo

Our lab previously found that levamisole (LMS) as an adjuvant enhanced the efficacy of vaccine against infectious pathogens. However, the cellular and molecular mechanisms remain to be defined. In this study, we showed that BALB/c bone marrow-derived DC stimulated with LMS resulted in enhanced cell-surface expression of CD80, CD86, CD40 and MHC class II, as well as enhanced production of IL-12p70, TNF-α and IL-1β. Interestingly, the LMS activated DCs were able to stimulate CD4+ T cell proliferation and facilitated Th1 differentiation by increasing the secretion of IFN-γ in an allogeneic mixed leukocyte reaction. Furthermore, to confirm the in vitro data, we investigated the effect of LMS on antigen-specific antibody and cytokine production in BALB/c mice. Immunization with LMS plus OVA showed that anti-OVA IgG2a and IFN-γ were increased significantly compared with OVA alone in BALB/c mice. In conclusion, our results suggested that murine bone marrow-derived DC, played a crucial role in the effect of LMS on the induction of Th1 responses, which probably was due to its ability to promote DC maturation and secrete proinflammatory cytokines.

CpG Oligodeoxynucleotide Inhibits Cockroach-Induced Asthma via Induction of IFN-γ+Th1 Cells or Foxp3+Regulatory T Cells in the Lung

PurposeCpG oligodeoxynucleotide (CpG-ODN), a TLR9 agonist, activates innate immunity and induces Th1 response. Although the immune modulatory effect of CpG-ODN has been extensively studied, its function in cockroach extract-induced allergic asthma has not been studied. Here, we investigated the inhibitory function of CpG-ODN in cockroach extract-induced asthma in mice with different treatment schemes.MethodsScheme 1: BALB/C mice were intra-nasally co-administered by cockroach extract and CpG-ODN twice a week for 3 weeks; Scheme 2: The mice were intra-nasally pre-treated with CpG-ODN at day 0 and cockroach allergen challenge was performed from day 3 as in scheme 1. Scheme 3: Cockroach allergen challenge was performed as in scheme 1 and CpG-ODN was post-treated at day 21. Then, BAL cell count, flow cytometric analysis of alveolar macrophages, regulatory T cells, and lung tissue histology, Th1 and Th2 cytokines, serum IgE, cockroach specific IgE, IgG1/IgG2a ratio, and airway hyper-responsiveness were evaluated.ResultsMice with repeated intra-nasal exposure to CpG-ODN showed a dramatic decrease in eosinophilic inflammation, goblet cell hyperplasia, and airway hyper-responsiveness with reduction of IL-13, IL-5, and serum IgE, cockroach specific IgE and IgG1/IgG2a ratio. This inhibitory function might be related to the up-regulation of IL-10 and CD4+Foxp3+ regulatory T cells in the lung. Interestingly, one-time challenge of CpG-ODN either prior or posterior to cockroach extract exposure could modulate airway inflammation and hyper-responsiveness via increase of Th1 response.ConclusionsCollectively, our data suggest that CpG-ODN treatment modulates Th2 inflammation in the lung by induction of regulatory T cells or Th1 response in a cockroach-induced asthma model.

Inhaled house dust programs pulmonary dendritic cells to promote type 2 T-cell responses by an indirect mechanism.

The induction of allergen-specific T helper 2 (Th2) cells by lung dendritic cells (DCs) is a critical step in allergic asthma development. Airway delivery of purified allergens or microbial products can promote Th2 priming by lung DCs, but how environmentally relevant quantities and combinations of these factors affect lung DC function is unclear. Here, we investigated the ability of house dust extract (HDE), which contains a mixture of environmental adjuvants, to prime Th2 responses against an innocuous inhaled antigen. Inhalational exposure to HDE conditioned lung conventional DCs, but not monocyte-derived DCs, to induce antigen-specific Th2 differentiation. Conditioning of DCs by HDE was independent of Toll-like receptor 4 signaling, indicating that environmental endotoxin is dispensable for programming DCs to induce Th2 responses. DCs directly treated with HDE underwent maturation but were poor stimulators of Th2 differentiation. In contrast, DCs treated with bronchoalveolar lavage fluid (BALF) from HDE-exposed mice induced robust Th2 differentiation. DC conditioning by BALF was independent of the proallergic cytokines IL-25, IL-33, and thymic stromal lymphopoietin. BALF treatment of DCs resulted in upregulation of CD80 but low expression of CD40, CD86, and IL-12p40, which was associated with Th2 induction. These findings support a model whereby environmental adjuvants in house dust indirectly program DCs to prime Th2 responses by triggering the release of endogenous soluble factor(s) by airway cells. Identifying these factors could lead to novel therapeutic targets for allergic asthma.

Strategies to improve BCG vaccine efficacy.

Strategies to improve BCG vaccine efficacy.

Abstract A103: Intracellular immunotherapy of disseminated pancreatic cancer activates potent IFNγ and CD8+ T cell dependent anti-tumor responses

Abstract Innovative therapies with the ability to activate effective cellular-based immune mechanisms in conjunction with current treatment strategies have potential to combat highly aggressive solid and metastatic tumors such as pancreatic adenocarcinoma, which remains one of the most deadly cancers with an overall 5-year survival rate of 6% following diagnosis. In this study, we explored the immunotherapeutic mechanisms triggered by an avirulent and nonreplicating obligate intracellular parasite Toxoplasma gondii (cps strain), which preferentially invades myeloid cell types, in the disseminated pancreatic tumor environment. We hypothesized the strong induction of Th1 responses in the tumor environment triggered by cps may stimulate significant mechanisms that could halt or eliminate established pancreatic cancer. Pan02 cells were injected intraperitoneally into syngeneic C57BL/6 mice. Seven days later, these mice were treated with 2, 3, or 5 doses of cps or PBS, as a treatment control. Pan02 tumor-bearing mice treated with cps had a significant survival advantage over untreated mice. Additionally, treatment with heat-killed cps, which is unable to actively invade, led to loss of treatment efficacy. Following a single cps treatment CD11b+CD11c+ dendritic cell populations increased and CD11b+F4/80+CD11c- macrophage populations decreased in the peritoneum. Cps-invaded macrophages and dendritic cells in the tumor environment upregulated surface expression of CD80 and CD86, and there was an increase in local production of IL-12 up to 7 days post-treatment. Pan02 tumor-bearing mice unable to produce IL-12 lost protection mediated by cps treatment. Seven days post-cps treatment, both CD4+ and CD8+ T cells were significantly higher than within the tumor microenvironment of untreated mice. Local T cells had lower expression of CD62L and increased expression of CD44 and CD69 indicating activation of recruited T cells. Six and seven days post-cps treatment, local IFNγ production in Pan02 tumor-bearing mice increased and the numbers of IFNγ+ CD4+ and IFNγ+ CD8+ T cells were higher. Similar to IL-12, loss of IFNγ within the tumor microenvironment led to a loss of treatment efficacy. A lack of CD8+ T cells prior to and during therapy resulted in a loss of treatment efficacy, whereas CD4+ T cells and NK cells were not required for treatment efficacy. CD8+ T cells isolated from the spleens of treated animals 10 days after cps treatment robustly produced IFNγ ex-vivo when stimulated with Pan02 cells. This response appears to be tumor specific as stimulation with irrelevant tumor antigen did not induce an IFNγ response from the same CD8+ T cells. Cps-mediated activation of tumor-associated myeloid cells leads to increases in local IFNγ+ CD8+ T cells, which drive specific anti-tumor responses. Cps induction of host Th1 responses elicited in the tumor microenvironment demonstrates the capability of cps to be broadly applied as an immunotherapeutic against pancreatic tumors. Citation Format: Kiah L. Sanders, Barbara A. Fox, David J. Bzik. Intracellular immunotherapy of disseminated pancreatic cancer activates potent IFNγ and CD8+ T cell dependent anti-tumor responses. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr A103.

Vitamin D supplementation decreases Aspergillus fumigatus specific Th2 responses in CF patients with aspergillus sensitization: a phase one open-label study.

BackgroundPatients with cystic fibrosis (CF) complicated by allergic bronchopulmonary aspergillosis (ABPA) are vitamin D deficient and in vitro treatment with 1,25 (OH)2 vitamin D3 of CD4+ cells from CF patients with ABPA decreases Aspergillus fumigatus(Af)-induced Th2 responses. This Phase I clinical trial investigated the safety and effectiveness of daily vitamin D3 supplementation in CF patients with ABPA to reduce allergic responses and ABPA symptoms, and increase serum vitamin D levels.MethodsSeven patients ages 12 years and older with a clinical diagnosis of CF and ABPA with current evidence of Af sensitization received 4000 IU vitamin D3 (cholecalciferol) daily for 24 weeks. The primary outcome of the study was safety followed by the Aspergillus induced IL-13 response in CD4+ T cells to test the hypothesis that vitamin D supplementation is safe and reduces Aspergillus induced IL-13 responses in CD4+ T cells. Secondary outcomes included total IgE, Aspergillus- specific IgE, vitamin D levels, FEV1, urinary calcium/creatinine ratio, and cytokine production by Aspergillus-stimulated peripheral blood T cells.ResultsSix months of vitamin D3 supplementation resulted in significant increases in serum 25-(OH) vitamin D level, and the treatment was well tolerated without evidence of vitamin D toxicity or hypercalcemia. There were no serious adverse events. Daily vitamin D supplementation led to significantly decreased Aspergillus induced IL-13 responses between the baseline visit and that at 24 weeks (p = 0.04). Aspergillus-specific IgE level was also significantly decreased after 8 (p = 0.035) and 24 weeks of daily vitamin D supplementation (p = 0.04).Conclusions4000 IU vitamin D3 daily over a 24-week period is well tolerated in CF patients with a history ABPA and current evidence of Th2 immunity to Af. . Daily vitamin D supplementation was associated with reduced Aspergillus induced IL-13 responses from peripheral. . CD4+ T cells and Aspergillus-specific IgE levels, as well as increased serum vitamin D levels. This treatment was well tolerated and the study supports further investigation of the use of vitamin D supplementation in Th2 mediated diseases.Trial registrationThis trial was registered at www.clinicaltrials.gov as NCT01222273.

Looking beyond the induction of Th2 responses to explain immunomodulation by helminths.

Although helminth infections are characteristically associated with Th2-mediated responses that include the production of the prototypical cytokines IL-4, IL-5 and IL-13 by CD4(+) cells, the production of IgE, peripheral blood eosinophilia and mucus production in localized sites, these responses are largely attenuated when helminth infections become less acute. This modulation of the immune response that occurs with chronic helminth infection is often induced by molecules secreted by helminth parasites, by non-Th2 regulatory CD4(+) cells, and by nonclassical B cells, macrophages and dendritic cells. This review will focus on those parasite- and host-mediated mechanisms underlying the modulated T-cell response that occurs as the default in chronic helminth infections.

Dectin-1 activation unlocks IL12A expression and reveals the TH1 potency of neonatal dendritic cells

Early life is characterized by a high susceptibility to infection and a TH2-biased CD4 T-cell response to vaccines. Toll-like receptor (TLR) agonists are currently being implemented as new vaccine adjuvants for TH1 activation, but their translation to the field of pediatric vaccines is facing the impairment of neonatal innate TLR responses. We sought to analyze C-type lectin receptor pathways as an alternative or a coactivator to TLRs for neonatal dendritic cell activation for TH1 polarization. Neonatal monocyte-derived dendritic cells (moDCs) were exposed to various combinations of TLR agonists with or without Dectin-1 agonist. IL-12 and IL-23 responses were analyzed at the transcriptional and protein levels after stimulation. The intracellular pathways triggered by combined TLR plus Dectin-1 stimulation was determined by using pharmacologic inhibitors. The capacity of neonatal moDCs to differentiate naive CD4 TH cells was evaluated in cocultures with heterologous neonatal naive T cells. Curdlan was finally tested as an adjuvant within a subunit tuberculosis vaccine in neonatal mice. Simultaneous coactivation through Dectin-1 and TLRs induced robust secretion of IL-12p70 by neonatal moDCs by unlocking transcriptional control on the p35 subunit of IL-12. Both the spleen tyrosine kinase and Raf-1 pathways were involved in this process, allowing differentiation of neonatal naive T cells toward IFN-γ-producing TH1 cells. In vivo a Dectin-1 agonist as adjuvant was sufficient to induce TH1 responses after vaccination of neonatal mice. Coactivation of neonatal moDCs through Dectin-1 allows TLR-mediated IL-12p70 secretion and TH1 polarization of neonatal T cells. Dectin-1 agonists represent a promising TH1 adjuvant for pediatric vaccination.

Cytokine, antibody and proliferative cellular responses elicited by Taenia solium calreticulin upon experimental infection in hamsters.

Taenia solium causes two diseases in humans, cysticercosis and taeniosis. Tapeworm carriers are the main risk factor for neurocysticercosis. Limited information is available about the immune response elicited by the adult parasite, particularly the induction of Th2 responses, frequently associated to helminth infections. Calreticulin is a ubiquitous, multifunctional protein involved in cellular calcium homeostasis, which has been suggested to play a role in the regulation of immune responses. In this work, we assessed the effect of recombinant T. solium calreticulin (rTsCRT) on the cytokine, humoral and cellular responses upon experimental infection in Syrian Golden hamsters (Mesocricetus auratus). Animals were infected with T. solium cysticerci and euthanized at different times after infection. Specific serum antibodies, proliferative responses in mesenteric lymph nodes and spleen cells, as well as cytokines messenger RNA (mRNA) were analyzed. The results showed that one third of the infected animals elicited anti-rTsCRT IgG antibodies. Interestingly, mesenteric lymph node (MLN) cells from either infected or non-infected animals did not proliferate upon in vitro stimulation with rTsCRT. Additionally, stimulation with a tapeworm crude extract resulted in increased expression of IL-4 and IL-5 mRNA. Upon stimulation, rTsCRT increased the expression levels of IL-10 in spleen and MLN cells from uninfected and infected hamsters. The results showed that rTsCRT favors a Th2-biased immune response characterized by the induction of IL-10 in mucosal and systemic lymphoid organs. Here we provide the first data on the cytokine, antibody and cellular responses to rTsCRT upon in vitro stimulation during taeniasis.

Ferulic Acid Induces Th1 Responses by Modulating the Function of Dendritic Cells and Ameliorates Th2-Mediated Allergic Airway Inflammation in Mice.

This study investigated the immunomodulatory effects of ferulic acid (FA) on antigen-presenting dendritic cells (DCs) in vitro and its antiallergic effects against ovalbumin- (OVA-) induced Th2-mediated allergic asthma in mice. The activation of FA-treated bone marrow-derived DCs by lipopolysaccharide (LPS) stimulation induced a high level of interleukin- (IL-) 12 but reduced the expression levels of the proinflammatory cytokines IL-1β, IL-6, and tumor necrosis factor- (TNF-) α. Compared to control-treated DCs, FA significantly enhanced the expressions of Notch ligand Delta-like 4 (Dll4), MHC class II, and CD40 molecules by these DCs. Furthermore, these FA-treated DCs enhanced T-cell proliferation and Th1 cell polarization. In animal experiments, oral administration of FA reduced the levels of OVA-specific immunoglobulin E (IgE) and IgG1 and enhanced IgG2a antibody production in serum. It also ameliorated airway hyperresponsiveness and attenuated eosinophilic pulmonary infiltration in dose-dependent manners. In addition, FA treatment inhibited the production of eotaxin, Th2 cytokines (IL-4, IL-5, and IL-13), and proinflammatory cytokines but promoted the Th1 cytokine interferon- (IFN-) γ production in bronchoalveolar lavage fluid (BALF) and the culture supernatant of spleen cells. These findings suggest that FA exhibits an antiallergic effect via restoring Th1/Th2 imbalance by modulating DCs function in an asthmatic mouse model.

Targeted Immunology for Prevention and Cure of VL

Leishmaniasis is a neglected tropical disease caused by a group of protozoan parasites of the genus Leishmania. Clinical presentation of leishmaniasis can range from cutaneous, mucocutaneous, or visceral forms depending on the parasite species. Visceral leishmaniasis (VL) caused by L. donovani and L. infantum is the severest and one of the deadliest parasitic diseases of the tropics second only to malaria (1). Nearly, 20,000‐40,000 annual deaths are estimated due to this disease (2). Except for the Indian subcontinent and West Africa, VL is frequent in dogs, which serve as the major reservoir for zoonosis (3). Transmitted by the bite of an infected sandfly, Leishmania endure in the phagolysomal compartment of macrophages by evasion and attenuation of the microbicidal functions of the host (4, 5). Leishmania has evolved as a successful parasite chiefly by its ability to modulate the immunological and cyto-chemical responses of the host following infection. The key strategy for successful pathogenesis is to subvert the nitric oxide burst in the host macrophage. This opportunistic parasite thus establishes a safe niche in the inactivated phagocyte and uncontrolled parasitization in liver, spleen, and bone marrow leads to symptomatic VL characterized by fever, weight loss, hepatosplenomegaly, and anemia (3). Since the pathogenesis of the disease is based on subversion and modulation of both innate and adaptive arms of immunity, the disease is opportunistic to immuno-suppression (6). Hence, commencement of an appropriate immune response is a challenge for the control of VL infection. Indeed, therapeutic drugs like SSG and miltefosine are immuno-modulators that trigger Th1 responses essential for activation of oxidative burst in the macrophages (7, 8). However, major limitations of narrow therapeutic index and increasing incidence of resistance with currently used drugs for VL are encumbrances in effective disease management. Recent approaches like combination therapy, targeted delivery, and use of immune-adjunct are efforts to bring down the effective doses of these toxicity-associated drugs. Most promising are the prospects of various immune-targeted therapeutic approaches for treatment of VL (9). Various leishmanial antigens, cytokines, and antibodies that initiate protective Th1-biased cell-mediated immune responses used singly or as an adjunct to conventional chemotherapy are potent immuno-chemotherapeutic agents for the cure of VL (10, 11). Additionally, medicinal plants and their products have opened new dimensions in search of safer and cheaper anti-leishmanial immuno-modulators. These phytochemicals are not only promising as immuno-chemotherapeutic agents against VL but also have potential as immuno-adjuvants and adjuncts to chemotherapy for a number of other immuno-regulatory diseases (12). Since both cure and resilience to Leishmania infection depend on the immunological status of the host, the antigens that can trigger healing responses can also induce prophylactic immunity. Therefore, identification of immunogens that can induce Th1 responses is the critical aspect of vaccine search against VL (13). Although a number of defined antigens have been reported to impart protective immunity against experimental VL, recent trend of reverse vaccinology is a promising aspect for identification of key immunogens for a successful vaccine (13, 14). This requires rational inputs and algorithm for identification of a promising antigen from the whole proteome data analysis in silico (15). One of the key inputs is to identify the epitopes for activation of both CD4 C Th1 and CD8 C T cells.