Mechanisms that modulate the generation of Th17 cells are incompletely understood. We report that the activation of CK2 by CD5 is essential for the efficient generation of Th17 cells in vitro and in vivo. The CD5-CK2 signaling pathway enhanced TCR induced activation of AKT and promoted the differentiation of Th17 cells by two independent mechanisms: inhibiting GSK3, and activating mTOR. Genetic ablation of the CD5-CK2 signaling pathway attenuated TCR induced AKT activation and consequently increased activity of GSK3 in Th17 cells. This resulted in Th17 cells being more sensitive to IFN-γ mediated inhibition. In the absence of CD5-CK2 signaling, we observed decreased activity of S6K and attenuated nuclear translocation of RORγt. These results reveal a novel and essential function of CD5-CK2 signaling pathway and GSK3-IFNγ axis in regulating Th differentiation and provide a possible means to dampen Th17 responses in autoimmune diseases.

Additional supporting information may be found in the online version of this article at the publisher's web-site IntroductionUpon infection, T-cell activation and differentiation are initiated through TCR engagement of peptide-MHC molecules on the surface of APCs in the context of co-stimulation and inflammatory cytokines. These cues trigger numerous signal transduction cascades, whose integration is "translated" into changes in gene transcription, protein activity, and expression. This ultimately leads to the development of effector function and T-cell-mediated Correspondence: Dr. Mark A. Daniels e-mail: danielsma@missouri.edu immunity [1]. The MAPK SAPK/JNK cascade plays a major role in regulating a variety of fate decisions including activation, proliferation, differentiation, and death [2,3]. Three genes encode the JNK family members. JNK1 and JNK2 are ubiquitously expressed, whereas the expression of JNK3 is restricted to the brain, heart, and testis [2]. While each JNK isoform is ascribed a unique function, how activation of each is independently regulated is not well understood. Activation of JNK is important for shaping both the innate and adaptive immune response. For innate immune responses, the inflammatory cytokines TNF and IL-1 induce JNK activity [4]. JNK2 and IKKβ induce the production of proinflammatory cytokine response to viral dsRNA [5]. Inflammation-dependent activation of PLC-γ, JNK and NF-κB enhances the ability of DCs andwww.eji-journal.eu 3362 Cody A. Cunningham et al. Eur. J. Immunol. 2013. 43: 3361-3371 epithelium tissue to induce Th17 responses [6,7]. JNK signaling is implicated in regulating proinflammatory cytokine production, joint inflammation, and destruction in rheumatoid arthritis [8]. JNK is also required for polarization of proinflammatory macrophages, obesity-induced insulin resistance, and inflammation in adipose tissue [9]. For T lymphocytes, JNK activation plays different roles depending on the T-cell type, the maturation state, and the milieu of the responding cell [10]. For example, in developing thymocytes, JNK activation appears to have a role in negative selection and the induction of apoptosis [11,12] Together, these findings illustrate the extreme importance of JNK in an immune response and demonstrate the need to understand the specific regulation of JNK1 and JNK2 to control the outcome of these responses. The mechanisms that regulate the independent activation of the individual JNK isoforms are poorly understood. The functional specificity of a number of MAPK signaling pathways has been attributed to their regulation by scaffold molecules [20,21]. Scaffolds provide means for both spatial regulation and network formation that increase the number of outcomes possible when activating a given pathway [22] + T cells [27,28]. However, the scaffold proteins specific for TCR-mediated JNK1 activation is less clear. The TCR connects to JNK activation through the guanine exchange factor Vav1 and the adaptor/guanine exchange factor complex, Grb2/SOS. These molecules are ...

Background Cryptic Epitopes (CE) are peptides derived from the translation of one or more of the five alternative reading frames (ARFs; 2 sense and 3 antisense) of genes. Here, we compared response rates to HIV-1 specific CE predicted to be restricted by HLA-I alleles associated with protection against disease progression to those without any such association. Methods Peptides (9–11mer) were designed based on HLA-I binding algorithms for B*27, B*57 or B*5801 (protective alleles) and HLA-B*5301 or B*5501 (non-protective allele) in all five ARFs of the nine HIV-1 encoded proteins. Peptides with >50% probability of being an epitope (n=231) were tested for T cell responses in an IFN-γ ELISpot assay. PBMC samples from HIV-1 seronegative donors (n=42) and HIV-1 seropositive patients with chronic clade B infections (n=129) were used. Results Overall, 16%, 2%, and 2% of CHI patients had CE responses by IFN-γ ELISpot in the protective, non-protective, and seronegative groups, respectively (p=0.009, Fischer’s exact test). Twenty novel CE specific responses were mapped (median magnitude of 95 SFC/106 PBMC) and the majority were both anti-sense derived (90%) as well as represented ARFs of accessory proteins (55%). CE-specific CD8 T cells were multifunctional and proliferated when assessed by intracellular cytokine staining. Conclusions CE responses were preferentially restricted by the protective HLA-I alleles in HIV-1 infection suggesting that they may contribute to viral control in this group of patients.

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Due to the increasing amount of people afflicted worldwide with Chagas disease and an increasing prevalence in the United States, there is a greater need to develop a safe and effective vaccine for this neglected disease. Adenovirus serotype 5 (Ad5) is the most common adenovirus vector used for gene therapy and vaccine approaches, but its efficacy is limited by preexisting vector immunity in humans resulting from natural infections. Therefore, we have employed rare serotype adenovirus 48 (Ad48) as an alternative choice for adenovirus/Chagas vaccine therapy. In this study, we modified Ad5 and Ad48 vectors to contain T. cruzi’s amastigote surface protein 2 (ASP-2) in the adenoviral early gene. We also modified Ad5 and Ad48 vectors to utilize the “Antigen Capsid-Incorporation” strategy by adding T. cruzi epitopes to protein IX (pIX). Mice that were immunized with the modified vectors were able to elicit T. cruzi-specific humoral and cellular responses. This study indicates that Ad48-modified vectors function comparable to or even premium to Ad5-modified vectors. This study provides novel data demonstrating that Ad48 can be used as a potential adenovirus vaccine vector against Chagas disease.

While prior studies have demonstrated that CD8 T cell responses to cryptic epitopes (CE) are readily detectable during HIV-1 infection, their ability to drive escape mutations following acute infection is unknown. We predicted 66 CE in a Zambian acute infection cohort based on escape mutations occurring within or near the putatively predicted HLA-I-restricted epitopes. The CE were evaluated for CD8 T cell responses for patients with chronic and acute HIV infections. Of the 66 predicted CE, 10 were recognized in 8/32 and 4/11 patients with chronic and acute infections, respectively. The immunogenic CE were all derived from a single antisense reading frame within However, when these CE were tested using longitudinal study samples, CE-specific T cell responses were detected but did not consistently select for viral escape mutations. Thus, while we demonstrated that CE are immunogenic in acute infection, the immune responses to CE are not major drivers of viral escape in the initial stages of HIV infection. The latter finding may be due to either the subdominant nature of CE-specific responses, the low antigen sensitivity, or the magnitude of CE responses during acute infections. Although prior studies demonstrated that cryptic epitopes of HIV-1 induce CD8 T cell responses, evidence that targeting these epitopes drives HIV escape mutations has been substantially limited, and no studies have addressed this question following acute infection. In this comprehensive study, we utilized longitudinal viral sequencing data obtained from three separate acute infection cohorts to predict potential cryptic epitopes based on HLA-I-associated viral escape. Our data show that cryptic epitopes are immunogenic during acute infection and that many of the responses they elicit are toward translation products of HIV-1 antisense reading frames. However, despite cryptic epitope targeting, our study did not find any evidence of early CD8-mediated immune escape. Nevertheless, improving cryptic epitope-specific CD8 T cell responses may still be beneficial in both preventative and therapeutic HIV-1 vaccines.

Alternative reading frames (ARF) of HIV, in both sense and antisense directions, have been shown to produce polypeptides of unknown functions. These peptides, known as cryptic epitopes (CE), commonly induce CD8 T cell responses in HIV; however, their role in controlling HIV-1 infection remains unclear. We hypothesized that CD8 T-cells target CE shortly following acute HIV infection and force viral escape. Such a finding would indicate that CE may serve as viable immunogens for inclusion in preventative HIV-1 vaccines. Using an HLA-I binding prediction algorithm applied to fixed mutations in ARF during the first two years of infection in a Zambian patient cohort, we predicted 66 CD8 T-cell escape mutations within gag, pol, and nef, which we further tested for immunogenicity. 8/32 chronic patient samples responded to at least one predicted CE as shown by IFNγ ELISpot. Furthermore, all ten immunogenic CE identified in the study were derived from a single antisense reading frame within the coding region of pol. Longitudinal studies failed to show any evidence of early viral escape to CE, as evaluation of these CE-specific CD8 T-cells following acute infection was not temporally associated with the occurrence of potential escape mutations. Our data suggest that although T-cell responses to CE can be detected during early HIV infections, they rarely establish HIV-1 escape mutations. As such their contribution to viral control is likely limited. Potential reasons for their limitations in forcing escape mutations include their infrequent expression and the weak magnitude of T-cell responses generated. Nevertheless, these data indicate that cryptic epitopes are not optimal targets for a preventative HIV vaccine.

Alternative reading frames (ARF) of HIV, both sense and antisense directions, have shown to produce polypeptides of unknown functions. Although the roles of these polypeptides are unclear, they can still potentially act as HIV derived antigens, eliciting host T cell responses. These ARF derived epitopes, known as cryptic epitopes (CE), occur commonly in HIV, SIV, and other retroviruses through ribosomal frame-shifting, internal ribosomal entry sites, and alternative start codon initiation. We hypothesize that T cell responses to CE are capable of driving viral escape mutations at a population level. In order to identify CE of HIV capable of driving viral escape, sequence changes in gag, pol, and nef of HIV were identified during acute infection in a cohort of Zambian serodiscordant couples. HLA-I associated polymorphisms in ARF can thus be identified, predicting potentially immunogenic CE. Several CE were identified as a result (N=66), in which the majority appears to have been derived from antisense ARF. These CE were used to stimulate cryopreserved PBMC samples from HIV-1 patients in the chronic stage of infection. We found 8/32 patients responded to at least one predicted CE as shown by IFNγ ELISpot. Interestingly, all 10 immunogenic CEs found in this study were derived from a single antisense reading frame in the pol coding region. Furthermore, these CE were not only capable of eliciting CD8, but also CD4 responses. When examining alternative start codons in each reading frame, we found an enrichment of CUG in the antisense frame containing the immunogenic CE. Together, our results show HIV antisense CE can be targeted by T cells and may therefore have implications for T-cell vaccines.