Antigen degradation or presentation by MHC class I molecules via classical and non-classical pathways

Splicing neoantigen discovery with SNAF reveals shared targets for cancer immunotherapy

Immunotherapy has emerged as a crucial strategy to combat cancer by "reprogramming" a patient's own immune system. Although immunotherapy is typically reserved for patients with a high mutational burden, neoantigens produced from posttranscriptional regulation may provide an untapped reservoir of common immunogenic targets for new targeted therapies. To comprehensively define tumor-specific and likely immunogenic neoantigens from patient RNA-Seq, we developed Splicing Neo Antigen Finder (SNAF), an easy-to-use and open-source computational workflow to predict splicing-derived immunogenic MHC-bound peptides (T cell antigen) and unannotated transmembrane proteins with altered extracellular epitopes (B cell antigen). This workflow uses a highly accurate deep learning strategy for immunogenicity prediction (DeepImmuno) in conjunction with new algorithms to rank the tumor specificity of neoantigens (BayesTS) and to predict regulators of mis-splicing (RNA-SPRINT). T cell antigens from SNAF were frequently evidenced as HLA-presented peptides from mass spectrometry (MS) and predict response to immunotherapy in melanoma. Splicing neoantigen burden was attributed to coordinated splicing factor dysregulation. Shared splicing neoantigens were found in up to 90% of patients with melanoma, correlated to overall survival in multiple cancer cohorts, induced T cell reactivity, and were characterized by distinct cells of origin and amino acid preferences. In addition to T cell neoantigens, our B cell focused pipeline (SNAF-B) identified a new class of tumor-specific extracellular neoepitopes, which we termed ExNeoEpitopes. ExNeoEpitope full-length mRNA predictions were tumor specific and were validated using long-read isoform sequencing and in vitro transmembrane localization assays. Therefore, our systematic identification of splicing neoantigens revealed potential shared targets for therapy in heterogeneous cancers.

The Role of Genetic Risk Factors in Pathogenesis of Childhood-Onset Systemic Lupus Erythematosus

The pathogenesis of childhood-onset systemic lupus erythematosus (cSLE) is complex and not fully understood. It involves three key factors: genetic risk factors, epigenetic mechanisms, and environmental triggers. Genetic factors play a significant role in the development of the disease, particularly in younger individuals. While cSLE has traditionally been considered a polygenic disease, it is now recognized that in rare cases, a single gene mutation can lead to the disease. Although these cases are uncommon, they provide valuable insights into the disease mechanism, enhance our understanding of pathogenesis and immune tolerance, and facilitate the development of targeted treatment strategies. This review aims to provide a comprehensive overview of both monogenic and polygenic SLE, emphasizing the implications of specific genes in disease pathogenesis. By conducting a thorough analysis of the genetic factors involved in SLE, we can improve our understanding of the underlying mechanisms of the disease. Furthermore, this knowledge may contribute to the identification of effective biomarkers and the selection of appropriate therapies for individuals with SLE.

Secretogranin II influences the assembly and function of MHC class I in melanoma

Melanoma is the deadliest form of skin cancer showing rising incidence over the past years. New insights into the mechanisms of melanoma progression contributed to the development of novel treatment options, such as immunotherapies. However, acquiring resistance to treatment poses a big problem to therapy success. Therefore, understanding the mechanisms underlying resistance could improve therapy efficacy. Correlating expression levels in tissue samples of primary melanoma and metastases revealed that secretogranin 2 (SCG2) is highly expressed in advanced melanoma patients with poor overall survival (OS) rates. By conducting transcriptional analysis between SCG2-overexpressing (OE) and control melanoma cells, we detected a downregulation of components of the antigen presenting machinery (APM), which is important for the assembly of the MHC class I complex. Flow cytometry analysis revealed a downregulation of surface MHC class I expression on melanoma cells that showed resistance towards the cytotoxic activity of melanoma-specific T cells. IFNγ treatment partially reversed these effects. Based on our findings, we suggest that SCG2 might stimulate mechanisms of immune evasion and therefore be associated with resistance to checkpoint blockade and adoptive immunotherapy.

Delayed Diagnosis of Chronic Necrotizing Granulomatous Skin Lesions due to TAP2 Deficiency

Major histocompatibility complex class I (MHC-I) deficiency, also known as bare lymphocyte syndrome type 1 (BLS-1), is a rare autosomal recessively inherited immunodeficiency disorder with remarkable clinical and biological heterogeneity. Transporter associated with antigen processing (TAP) is a member of the ATP-binding cassette superfamily of transporters and consists of two subunits, TAP1 or TAP2. Any defect resulting from a mutation or deletion of these two subunits may adversely affect the peptide translocation in the endoplasmic reticulum, which is an important process for properly assembling MHC-I molecules. To date, only 12 TAP2-deficient patients were reported in the literature. Herein, we described two Iranian cases with 2 and 3 decades of delayed diagnosis of chronic necrotizing granulomatous skin lesions due to TAP2 deficiency without pulmonary involvement. Segregation analysis in family members identified 3 additional homozygous asymptomatic carriers. In both asymptomatic and symptomatic carriers, HLA-I expression was only 4-15% of the one observed in healthy controls. We performed the first deep immunophenotyping in TAP2-deficient patients. While total CD8 T cell counts were normal as previously reported, the patients showed strongly impaired naïve CD8 T cell counts. Mucosal-associated invariant T (MAIT) cells and invariant natural killer T (iNKT) cell counts were increased.

Tissue Transglutaminase but Not Microbial Transglutaminase Is Inhibited by Exogenous Oxidative Substances in Celiac Disease

Enzymatic modification of gliadin peptides by human transglutaminase 2 (TG2) is a central step in celiac disease (CD) pathogenesis. Microbial transglutaminase (mTG) mimics the enzymatic function of TG2 and might play a role in CD. TG2 is inhibited by endogenous oxidative endoplasmic reticulum-resident protein 57 (ERp57), but data about mTG are lacking. We investigated the localization of ERp57 in duodenal biopsies and examined inhibition of TG2, and mTG by competitive, and oxidative molecules. Localization of ERp57 was investigated in duodenal biopsies from CD, and control patients by electron microcopy. Inhibition of TG2 and mTG was analyzed on an in vitro level using a photometric assay. ERp57 was observed within the lamina propria and its abundance within the endoplasmic reticulum (ER) was reduced in CD patients. TG2 was oxidatively inhibited by up to 95% by PX12 (p < 0.001) and L-cystine (p < 0.001), whereas mTG remained unaffected. The reduced presence of ERp57 within the ER of CD biopsies suggests a regulatory function of this protein within CD pathogenesis. PX12 and L-cystine oxidatively inhibit TG2 and might serve as treatment options in CD. mTG is poorly regulated and could contribute to the accumulation of immunogenic peptides within the gut with potential pathogenic effects.

MHC class I antigen cross-presentation mediated by PapMV nanoparticles in human antigen-presenting cells is dependent on autophagy

Nanoparticles made of the coat protein of papaya mosaic virus (PapMV) and a single-strand RNA were previously shown to be an efficient antigen presentation system for the trigger of cellular immunity. Engineering of PapMV nano with a cytotoxic T lymphocyte epitope was previously shown activating specific T lymphocytes through a proteasome-independent major histocompatibility complex class I (MHC-I) cross-presentation. In this study, we provide new insights into the mechanism of the MHC-I cross-presentation mediated by PapMV nanoparticles. We demonstrate that PapMV nanoparticles do not require the transporter associated with antigen presentation (TAP), but rather depend on lysosome acidification and cathepsin S protease activity for presentation of the T cell epitope. We have also linked the induction of autophagy with this vacuolar MHC-I cross-presentation process. Interestingly, autophagy is induced in antigen-presenting cells after PapMV nanoparticles exposure and inhibition of autophagy reduce MHC-I cross-presentation. This study demonstrates that autophagy is associated with TAP- and proteasome-independent MHC-I cross-presentation. A deeper understanding of the autophagy-dependent MHC-I cross-presentation will be useful in designing vaccination platforms that aim to trigger an efficient cytotoxic T lymphocyte response.

Pathogenesis of Autoimmune Hepatitis-Cellular and Molecular Mechanisms

Pediatric autoimmune liver disorders include autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC), and de novo AIH after liver transplantation. AIH is an idiopathic disease characterized by immune-mediated hepatocyte injury associated with the destruction of liver cells, causing inflammation, liver failure, and fibrosis, typically associated with autoantibodies. The etiology of AIH is not entirely unraveled, but evidence supports an intricate interaction among genetic variants, environmental factors, and epigenetic modifications. The pathogenesis of AIH comprises the interaction between specific genetic traits and molecular mimicry for disease development, impaired immunoregulatory mechanisms, including CD4+ T cell population and Treg cells, alongside other contributory roles played by CD8+ cytotoxicity and autoantibody production by B cells. These findings delineate an intricate pathway that includes gene to gene and gene to environment interactions with various drugs, viral infections, and the complex microbiome. Epigenetics emphasizes gene expression through hereditary and reversible modifications of the chromatin architecture without interfering with the DNA sequence. These alterations comprise DNA methylation, histone transformations, and non-coding small (miRNA) and long (lncRNA) RNA transcriptions. The current first-line therapy comprises prednisolone plus azathioprine to induce clinical and biochemical remission. Further understanding of the cellular and molecular mechanisms encountered in AIH may depict their impact on clinical aspects, detect biomarkers, and guide toward novel, effective, and better-targeted therapies with fewer side effects.

Potent priming by inactivated whole influenza virus particle vaccines is linked to viral RNA uptake into antigen presenting cells

Current detergent or ether-disrupted split vaccines (SVs) for influenza do not always induce adequate immune responses, especially in young children. This contrasts with the whole virus particle vaccines (WPVs) originally used against influenza that were immunogenic in both adults and children but were replaced by SV in the 1970s due to concerns with reactogenicity. In this study, we re-evaluated the immunogenicity of WPV and SV, prepared from the same batch of purified influenza virus, in cynomolgus macaques and confirmed that WPV is superior to SV in priming potency. In addition, we compared the ability of WPV and SV to induce innate immune responses, including the maturation of dendritic cells (DCs) in vitro. WPV stimulated greater production of inflammatory cytokines and type-I interferon in immune cells from mice and macaques compared to SV. Since these innate responses are likely triggered by the activation of pattern recognition receptors (PRRs) by viral RNA, the quantity and quality of viral RNA in each vaccine were assessed. Although the quantity of viral RNA was similar in the two vaccines, the amount of viral RNA of a length that can be recognized by PRRs was over 100-fold greater in WPV than in SV. More importantly, 1000-fold more viral RNA was delivered to DCs by WPV than by SV when exposed to preparations containing the same amount of HA protein. Furthermore, WPV induced up-regulation of the DC maturation marker CD86 on murine DCs, while SV did not. The present results suggest that the activation of antigen-presenting DCs, by PRR-recognizable viral RNA contained in WPV is responsible for the effective priming potency of WPV observed in naïve mice and macaques. WPV is thus recommended as an alternative option for seasonal influenza vaccines, especially for children.

Type 1 Diabetes and Autoimmune Thyroid Disease-The Genetic Link

Type 1 diabetes (T1D) and autoimmune thyroid disease (AITD) are the most frequent chronic autoimmune diseases worldwide. Several autoimmune endocrine and non-endocrine disorders tend to occur together. T1D and AITD often cluster in individuals and families, seen in the formation of autoimmune polyendocrinopathy (AP). The close relationship between these two diseases is largely explained by sharing a common genetic background. The HLA antigens DQ2 (DQA1*0501-DQB1*0201) and DQ8 (DQA1*0301-DQB1*0302), tightly linked with DR3 and DR4, are the major common genetic predisposition. Moreover, functional single nucleotide polymorphisms (or rare variants) of various genes, such as the cytotoxic T-lymphocyte- associated antigen (CTLA4), the protein tyrosine phosphatase non-receptor type 22 (PTPN22), the interleukin-2 Receptor (IL2Ra), the Vitamin D receptor (VDR), and the tumor-necrosis-factor-α (TNF) that are involved in immune regulation have been identified to confer susceptibility to both T1D and AITD. Other genes including cluster of differentiation 40 (CD40), the forkhead box P3 (FOXP3), the MHC Class I Polypeptide-Related Sequence A (MICA), insulin variable number of tandem repeats (INS-VNTR), the C-Type Lectin Domain Containing 16A (CLEC16A), the Erb-B2 Receptor Tyrosine Kinase 3 (ERBB3) gene, the interferon-induced helicase C domain-containing protein 1 (IFIH1), and various cytokine genes are also under suspicion to increase susceptibility to T1D and AITD. Further, BTB domain and CNC homolog 2 (BACH2), C-C motif chemokine receptor 5 (CCR5), SH2B adaptor protein 3 (SH2B3), and Rac family small GTPase 2 (RAC2) are found to be associated with T1D and AITD by various independent genome wide association studies and overlap in our list, indicating a strong common genetic link for T1D and AITD. As several susceptibility genes and environmental factors contribute to the disease aetiology of both T1D and AITD and/or AP subtype III variant (T1D+AITD) simultaneously, all patients with T1D should be screened for AITD, and vice versa.

Epithelial cell dysfunction in coeliac disease

The intestinal epithelium limits host-luminal interactions and maintains gut homeostasis. Breakdown of the epithelial barrier and villous atrophy are hallmarks of coeliac disease. Besides the well characterized immune-mediated epithelial damage induced in coeliac mucosa, constitutional changes and early gluten direct effects disturb intestinal epithelial cells. The subsequent modifications in key epithelial signaling pathways leads to outnumbered immature epithelial cells that, in turn, facilitate epithelial dysfunction, promote crypt hyperplasia, and increase intestinal permeability. Consequently, underlying immune cells have a greater access to gluten, which boosts the proinflammatory immune response against gluten and positively feedback the epithelial damage loop. Gluten-free diet is an indispensable treatment for coeliac disease patients, but additional therapies are under development, including those that reinforce intestinal epithelial healing. In this chapter, we provide an overview of intestinal epithelial cell disturbances that develop during gluten intake in coeliac disease mucosa.

The Contribution of Major Histocompatibility Complex Class II Genes to an Association with Autoimmune Diseases

Genetic studies of patients with autoimmune diseases have shown that one of the most important roles in the developing of these diseases is played by a cluster of genes of the major histocompatibility complex (MHC), as compared with other genome areas. Information on the specific contribution of MHC alleles, mostly MHC class II ones, to the genetic predisposition to autoimmune diseases is crucial for understanding their pathogenesis. This review dwells on the most relevant aspects of this problem: namely, the correlation between carriage of certain MHC II alleles and an increased (positively associated allele) or reduced (negatively associated allele) probability of developing the most common autoimmune diseases, such as type 1 diabetes, rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, autoimmune thyroiditis, etc. The most universal haplotypes, DR3-DQ2 and DR4-DQ8, are positively associated with many of these diseases, while the universal allele HLA-DRB1*0701 is protective.

Cellular and Molecular Mechanisms of Autoimmune Hepatitis

Autoimmune hepatitis is an uncommon idiopathic syndrome of immune-mediated destruction of hepatocytes, typically associated with autoantibodies. The disease etiology is incompletely understood but includes a clear association with human leukocyte antigen (HLA) variants and other non-HLA gene variants, female sex, and the environment. Pathologically, there is a CD4+ T cell-rich lymphocytic inflammatory infiltrate with variable hepatocyte necrosis and subsequent hepatic fibrosis. Attempts to understand pathogenesis are informed by several monogenetic syndromes that may include autoimmune liver injury, by several drug and environmental agents that have been identified as triggers in a minority of cases, by human studies that point toward a central role for CD4+ effector and regulatory T cells, and by animal models of the disease. Nonspecific immunosuppression is the current standard therapy. Further understanding of the disease's cellular and molecular mechanisms may assist in the design of better-targeted therapies, aid the limitation of adverse effects from therapy, and inform individualized risk assessment and prognostication.

Intracellular Localization of Microbial Transglutaminase and Its Influence on the Transport of Gliadin in Enterocytes

OBJECTIVE

Celiac disease (CD) is a systemic inflammatory disorder, characterized by the destruction of duodenal epithelium. The CD8 T cells involved are associated with cross-presentation. In addition to other factors, the rising prevalence of CD might be induced by microbial transglutaminase (mTG) an enzyme frequently used in food production that shares enzymatic and antigenic properties of tissue transglutaminase (TG2), the autoantigen in CD. We hypothesized that mTG and gliadin are transported into the endoplasmic reticulum (ER), indicating cross-presentation of both antigens.

METHODS

Apical incubation of duodenal biopsies from CD and control patients was performed with mTG alone or with mTG and simultaneously with Frazer's fraction. Evaluation was carried out by immunofluorescence and electron microscopy.

RESULTS

Approximately 6% to 9% of the intracellular mTG and gliadin were transported to the ER of enterocytes. RACE cells (Rapid uptake of Antigen into the Cytosol of Enterocytes) displayed an enhanced antigen uptake into a dilated ER. mTG strongly localized at the basolateral membrane and the lamina propria.

CONCLUSIONS

mTG and gliadin are transported to the ER of enterocytes and to a greater extent to the ER of RACE cells, suggesting cross-presentation of exogenous antigens. The strong localization of mTG at the basolateral membrane and the lamina propria may also indicate a potential antigenic interaction with cells of the immune system. Since mTG may not only been taken up with food stuffs but could also be released by bacteria within the intestinal microbiota, further investigations are needed regarding the role of mTG in CD pathogenesis.

Dynamics of T Cells Repertoire During Trypanosoma cruzi Infection and its Post-Treatment Modulation

Chagas disease courses with different clinical phases and has a variable clinical presentation and progression. The acute infection phase mostly exhibits a non-specific symptomatology. In the absence of treatment, the acute phase is followed by a chronic phase, which is initially asymptomatic. This chronic asymptomatic phase of the disease is characterized by a fragile balance between the host's immune response and the parasite replication. The loss of this balance is crucial for the progression of the sickness. The virulence and tropism of the T. cruzi infecting strain together to the inflammation processes in the cardiac tissue are the main factors for the establishment and severity of the cardiomyopathy. The efficacy of treatment in chronic Chagas disease patients is controversial. However, several studies carried out in chronic patients demonstrated that antiparasitic treatment reduces parasite load in the bloodstream and leads to an improvement in the immune response against the Trypanosoma cruzi parasite. The present review is mainly focused on the cellular patterns associated to the clinical status and the evolution of the disease in chronic patients, as well as the effectiveness of the treatment related to T. cruzi infection control. Therefore, an emphasis is placed on the dynamics of specific-antigens T cell subpopulations, their memory and activation phenotypes, their functionality and their contribution to pathogenesis or disease control, as well as their association with risk of congenital transmission of the parasite.

Moving the Cellular Peptidome by Transporters

Living matter is defined by metastability, implying a tightly balanced synthesis and turnover of cellular components. The first step of eukaryotic protein degradation via the ubiquitin-proteasome system (UPS) leads to peptides, which are subsequently degraded to single amino acids by an armada of proteases. A small fraction of peptides, however, escapes further cytosolic destruction and is transported by ATP-binding cassette (ABC) transporters into the endoplasmic reticulum (ER) and lysosomes. The ER-resident heterodimeric transporter associated with antigen processing (TAP) is a crucial component in adaptive immunity for the transport and loading of peptides onto major histocompatibility complex class I (MHC I) molecules. Although the function of the lysosomal resident homodimeric TAPL-like (TAPL) remains, until today, only loosely defined, an involvement in immune defense is anticipated since it is highly expressed in dendritic cells and macrophages. Here, we compare the gene organization and the function of single domains of both peptide transporters. We highlight the structural organization, the modes of substrate binding and translocation as well as physiological functions of both organellar transporters.

Modulation of immune responses in lentiviral vector-mediated gene transfer

Lentiviral vectors (LV) are widely used vehicles for gene transfer and therapy in pre-clinical animal models and clinical trials with promising safety and efficacy results. However, host immune responses against vector- and/or transgene-derived antigens remain a major obstacle to the success and broad applicability of gene therapy. Here we review the innate and adaptive immunological barriers to successful gene therapy, both in the context of ex vivo and in vivo LV gene therapy, mostly concerning systemic LV delivery and discuss possible means to overcome them, including vector design and production and immune modulatory strategies.

Lactation-Based Maternal Educational Immunity Crosses MHC Class I Barriers and Can Impart Th1 Immunity to Th2-Biased Recipients

We have previously demonstrated lactational transfer of T cell-based immunity from dam to foster pup. In the short term, a significant part of transferred immunity is passive cellular immunity. However, as time progresses, this is replaced by what we have described as maternal educational immunity such that by young adulthood, all immune cells responding to a foster dam immunogen are the product of the foster pup's thymus. To reduce confounding factors, this original demonstration used congenic/syngeneic dam and foster pup pairs. In this study, we investigated lactational transfer of immunity to Mycobacterium tuberculosis in MHC class I-mismatched animals, as well as from Th1-biased dams to Th2-biased foster pups. Using immunized C57BL/6J dams, lactational transfer to nonimmunized BALB/cJ foster pups resulted in much greater immunity than direct immunization in 5-wk-old pups (ex vivo assay of pup splenocytes). At this age, 82% of immunogen-responding cells in the pup spleen were produced through maternal educational immunity. FVB/NJ nonimmunized foster recipients had a greater number of maternal cells in the spleen and thymus but a much larger percentage was Foxp3⁺, resulting in equivalent immunity to direct immunization. Depletion of maternal Foxp3⁺ cells from pup splenocytes illustrated a substantial role for lactationally transferred dam regulatory T cells in suppression of the ex vivo response in FVB/NJ, but not BALB/cJ, recipients. We conclude that lactational transfer of immunity can cross MHC class I barriers and that Th1 immunity can be imparted to Th2-biased offspring; in some instances, it can be greater than that achieved by direct immunization.

Immune Responses of Chickens Infected with Wild Bird-Origin H5N6 Avian Influenza Virus

Since April 2014, new infections of H5N6 avian influenza virus (AIV) in humans and domestic poultry have caused considerable economic losses in the poultry industry and posed an enormous threat to human health worldwide. In previous research using gene sequence and phylogenetic analysis, we reported that H5N6 AIV isolated in February 2015 (ZH283) in Pallas’s sandgrouse was highly similar to that isolated in a human in December 2015 (A/Guangdong/ZQ874/2015), whereas a virus (i.e., SW8) isolated in oriental magpie-robin in 2014 was highly similar to that of A/chicken/Dongguan/2690/2013 (H5N6). However, the pathogenicity, transmissibility, and host immune-related response of chickens infected by those wild bird-origin H5N6 AIVs remain unknown. In response, we examined the viral distribution and mRNA expression profiles of immune-related genes in chickens infected with both viruses. Results showed that the H5N6 AIVs were highly pathogenic to chickens and caused not only systemic infection in multiple tissues, but also 100% mortality within 3–5 days post-infection. Additionally, ZH283 efficiently replicated in all tested tissues and transmitted among chickens more rapidly than SW8. Moreover, quantitative real-time polymerase chain reaction analysis showed that following infection with H5N6, AIVs immune-related genes remained active in a tissue-dependent manner, as well as that ZH283 induced mRNA expression profiles such as TLR3, TLR7, IL-6, TNF-α, IL-1β, IL-10, IL-8, and MHC-II to a greater extent than SW8 in the tested tissues of infected chickens. Altogether, our findings help to illuminate the pathogenesis and immunologic mechanisms of H5N6 AIVs in chickens.

Varied Role of Ubiquitylation in Generating MHC Class I Peptide Ligands

CD8⁺ T cell immunosurveillance is based on recognizing oligopeptides presented by MHC class I molecules. Despite decades of study, the importance of protein ubiquitylation to peptide generation remains uncertain. In this study, we examined the ability of MLN7243, a recently described ubiquitin-activating enzyme E1 inhibitor, to block overall cytosolic peptide generation and generation of specific peptides from vaccinia- and influenza A virus-encoded proteins. We show that MLN7243 rapidly inhibits ubiquitylation in a variety of cell lines and can profoundly reduce the generation of cytosolic peptides. Kinetic analysis of specific peptide generation reveals that ubiquitylation of defective ribosomal products is rate limiting in generating class I peptide complexes. More generally, our findings demonstrate that the requirement for ubiquitylation in MHC class I-restricted Ag processing varies with class I allomorph, cell type, source protein, and peptide context. Thus, ubiquitin-dependent and -independent pathways robustly contribute to MHC class I-based immunosurveillance.

Ten novel MHC-DPB1 alleles identified in Tibetan macaque (Macaca thibetana)

Ten novel MHC-DPB1 alleles of Tibetan macaque, were identified by cloning and sequencing.

Characterization of the Canine MHC Class I DLA-88*50101 Peptide Binding Motif as a Prerequisite for Canine T Cell Immunotherapy

There are limitations in pre-clinical settings using mice as a basis for clinical development in humans. In cancer, similarities exist between humans and dogs; thus, the dog patient can be a link in the transition from laboratory research on mouse models to clinical trials in humans. Knowledge of the peptides presented on MHC molecules is fundamental for the development of highly specific T cell-based immunotherapies. This information is available for human MHC molecules but is absent for the canine MHC. In the present study, we characterized the binding motif of dog leukocyte antigen (DLA) class I allele DLA-88*50101, using human C1R and K562 transfected cells expressing the DLA-88*50101 heavy chain. MHC class I immunoaffinity-purification revealed 3720 DLA-88*50101 derived peptides, which enabled the determination of major anchor positions. The characterized binding motif of DLA-88*50101 was similar to HLA-A*02:01. Peptide binding analyses on HLA-A*02:01 and DLA-88*50101 via flow cytometry showed weak binding of DLA-88*50101 derived peptides to HLA-A*02:01, and vice versa. Our results present for the first time a detailed peptide binding motif of the canine MHC class I allelic product DLA-88*50101. These data support the goal of establishing dogs as a suitable animal model for the evaluation and development of T cell-based cancer immunotherapies, benefiting both dog and human patients.

Diverse HLA-I Peptide Repertoires of the APC Lines MUTZ3-Derived Immature and Mature Dendritic Cells and THP1-Derived Macrophages

Dendritic cells (DCs) and macrophages are specialized APCs that process and present self-Ags for induction of tolerance and foreign Ags to initiate T cell-mediated immunity. Related to differentiation states they have specific phenotypes and functions. However, the impact of these differentiations on Ag processing and presentation remains poorly defined. To gain insight into this, we analyzed and compared the HLA-I peptidomes of MUTZ3-derived human immature and mature DC lines and THP1-derived macrophages by liquid chromatography tandem mass spectrometry. We found that the HLA-I peptidomes were heterogeneous and individualized and were dominated by nonapeptides with similar HLA-I binding affinities and anchor residues. MUTZ3-derived DCs and THP1-derived macrophages were able to sample peptides from source proteins of almost all subcellular locations and were involved in various cellular functions in similar proportion, with preference to proteins involved in cell communication, signal transduction, protein metabolism, and transcription factor/regulator activity.

NLRC5 elicits antitumor immunity by enhancing processing and presentation of tumor antigens to CD8(+) T lymphocytes

Cancers can escape immunesurveillance by diminishing the expression of MHC class-I molecules (MHC-I) and components of the antigen-processing machinery (APM). Developing new approaches to reverse these defects could boost the efforts to restore antitumor immunity. Recent studies have shown that the expression of MHC-I and antigen-processing molecules is transcriptionally regulated by NOD-like receptor CARD domain containing 5 (NLRC5). To investigate whether NLRC5 could be used to improve tumor immunogenicity, we established stable lines of B16-F10 melanoma cells expressing NLRC5 (B16-5), the T cell co-stimulatory molecule CD80 (B16-CD80) or both (B16-5/80). Cells harboring NLRC5 constitutively expressed MHC-I and LMP2, LMP7 and TAP1 genes of the APM. The B16-5 cells efficiently presented the melanoma antigenic peptide gp100_25–33 to Pmel-1 TCR transgenic CD8⁺ T cells and induced their proliferation. In the presence of CD80, B16-5 cells stimulated Pmel-1 cells even without the addition of gp100 peptide, indicating that NLRC5 facilitated the processing and presentation of endogenous tumor antigen. Upon subcutaneous implantation, B16-5 cells showed markedly reduced tumor growth in C57BL/6 hosts but not in immunodeficient hosts, indicating that the NLRC5-expressing tumor cells elicited antitumor immunity. Following intravenous injection, B16-5 and B16-5/80 cells formed fewer lung tumor foci compared to control cells. In mice depleted of CD8⁺ T cells, B16-5 cells formed large subcutaneous and lung tumors. Finally, immunization with irradiated B16-5 cells conferred protection against challenge by parental B16 cells. Collectively, our findings indicate that NLRC5 could be exploited to restore tumor immunogenicity and to stimulate protective antitumor immunity.

Promiscuous Recognition of a Trypanosoma cruzi CD8+ T Cell Epitope among HLA-A2, HLA-A24 and HLA-A1 Supertypes in Chagasic Patients

Background

TcTLE is a nonamer peptide from Trypanosoma cruzi KMP-11 protein that is conserved among different parasite strains and that is presented by different HLA-A molecules from the A2 supertype. Because peptides presented by several major histocompatibility complex (MHC) supertypes are potential targets for immunotherapy, the aim of this study was to determine whether MHC molecules other than the A2 supertype present the TcTLE peptide.

Methodology/Principal Findings

From 36 HLA-A2-negative chagasic patients, the HLA-A genotypes of twenty-eight patients with CD8⁺ T cells that recognized the TcTLE peptide using tetramer (twenty) or functional (eight) assays, were determined. SSP-PCR was used to identify the A locus and the allelic variants. Flow cytometry was used to analyze the frequency of TcTLE-specific CD8⁺ T cells, and their functional activity (IFN-γ, TNFα, IL-2, perforin, granzyme and CD107a/b production) was induced by exposure to the TcTLE peptide. All patients tested had TcTLE-specific CD8⁺ T cells with frequencies ranging from 0.07–0.37%. Interestingly, seven of the twenty-eight patients had HLA-A homozygous alleles: A*24 (5 patients), A*23 (1 patient) and A*01 (1 patient), which belong to the A24 and A1 supertypes. In the remaining 21 patients with HLA-A heterozygous alleles, the most prominent alleles were A24 and A68. The most common allele sub-type was A*2402 (sixteen patients), which belongs to the A24 supertype, followed by A*6802 (six patients) from the A2 supertype. Additionally, the A*3002/A*3201 alleles from the A1 supertype were detected in one patient. All patients presented CD8⁺ T cells producing at least one cytokine after TcTLE peptide stimulation.

Conclusion/Significance

These results show that TcTLE is a promiscuous peptide that is presented by the A24 and A1 supertypes, in addition to the A2 supertype, suggesting its potential as a target for immunotherapy.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

CCR2+ Inflammatory Dendritic Cells and Translocation of Antigen by Type III Secretion Are Required for the Exceptionally Large CD8+ T Cell Response to the Protective YopE69-77 Epitope during Yersinia Infection

During Yersinia pseudotuberculosis infection of C57BL/6 mice, an exceptionally large CD8⁺ T cell response to a protective epitope in the type III secretion system effector YopE is produced. At the peak of the response, up to 50% of splenic CD8⁺ T cells recognize the epitope YopE_69-77. The features of the interaction between pathogen and host that result in this large CD8⁺ T cell response are unknown. Here, we used Y. pseudotuberculosis strains defective for production, secretion and/or translocation of YopE to infect wild-type or mutant mice deficient in specific dendritic cells (DCs). Bacterial colonization of organs and translocation of YopE into spleen cells was measured, and flow cytometry and tetramer staining were used to characterize the cellular immune response. We show that the splenic YopE_69-77-specific CD8⁺ T cells generated during the large response are polyclonal and are produced by a “translocation-dependent” pathway that requires injection of YopE into host cell cytosol. Additionally, a smaller YopE_69-77-specific CD8⁺ T cell response (~10% of the large expansion) can be generated in a “translocation-independent” pathway in which CD8α⁺ DCs cross present secreted YopE. CCR2-expressing inflammatory DCs were required for the large YopE_69-77-specific CD8⁺ T cell expansion because this response was significantly reduced in Ccr2^-/- mice, YopE was translocated into inflammatory DCs in vivo, inflammatory DCs purified from infected spleens activated YopE_69-77-specific CD8⁺ T cells ex vivo and promoted the expansion of YopE_69-77-specific CD8⁺ T cells in infected Ccr2^-/- mice after adoptive transfer. A requirement for inflammatory DCs in producing a protective CD8⁺ T cell response to a bacterial antigen has not previously been demonstrated. Therefore, the production of YopE_69-77-specific CD8⁺ T cells by inflammatory DCs that are injected with YopE during Y. pseudotuberculosis infection represents a novel mechanism for generating a massive and protective adaptive immune response.

Dendritic cells (DCs) direct host protective adaptive immune responses during infection. How different subpopulations of DCs contribute to the formation of antigen-specific CD8⁺ T cells is incompletely understood. Infection of C57BL/6 mice with the bacterial pathogen Yersinia pseudotuberculosis results in the production of an exceptionally large CD8⁺ T cell response to an epitope in the type III secretion system effector YopE. Here, we show that this large CD8⁺ T cell response requires translocation of YopE into inflammatory DCs, which express CCR2 and accumulate in infected tissues. In contrast, when mice are infected with a Y. pseudotuberculosis strain that can secrete but not translocate YopE, a smaller response is seen, and under these conditions the generation of YopE-specific CD8⁺ T cell requires CD8α⁺ DCs. Our results indicate that distinct DC subsets participate in constructing the CD8⁺ T cell response to secreted, versus translocated, YopE. Furthermore our data indicate that inflammatory DCs are a driving force behind the massive CD8⁺ T cell response to a protective epitope in a bacterial virulence factor that is translocated into host cells.

Association between LMP2 and LMP7 gene polymorphisms and the risk of gastric cancer: A case-control study

The integrality of low molecular weight protein (LMP)2/LMP7 function plays an important role in the processing of GC cell antigens. The purpose of the present hospital-based case-control study was to estimate the effect of polymorphisms in the LMP2 and LMP7 genes on the risk of GC. Polymerase chain reaction-restriction fragment length polymorphism analysis was used to distinguish the Arg to His substitution at codon 60 of LMP2 (LMP2-60) and the Gln to Lys substitution at codon 145 of LMP7 (LMP7-145) in 502 gastric cancer patients and 502 age and gender-matched cancer-free control individuals. The Lys allele of the LMP7-145 variant was more frequent in GC patients compared with control individuals [P=0.004; adjusted odds ratio (OR), 1.39; 95% confidence interval (CI), 1.11-1.74]. The Gln/Lys and Lys/Lys genotypes increased the risk of GC compared with the Gln/Gln genotype (P=0.049 and P=0.041, respectively; adjusted OR, 1.32 and 2.13, respectively; 95% CI, 1.00-1.73 and 1.03-4.39, respectively). Compared with the Gln/Gln genotype, the LMP7-145 Gln/Lys and Lys/Lys variants of the LMP7 gene were also associated with increased susceptibility to GC (P=0.017; adjusted OR, 1.38; 95% CI, 1.06-1.80). Haplotype analysis revealed that the LMP2 (Arg)-LMP7 (Lys) haplotype was associated with increased risk of GC (P=0.013, adjusted OR=1.34, 95% CI=1.06-1.70). Stratified analysis revealed that the association between the risk of GC and the variant genotypes of LMP7-145 was stronger in older individuals (>59 years), males and non-smokers. However, no association between the LMP2-60 polymorphism and the risk of GC was observed. The present results suggest that the LMP7-145 genetic variant contributes to increased susceptibility to GC, and the Lys allele is an independent risk factor for GC.

Molecular backgrounds of ERAP1 downregulation in cervical carcinoma

The antigen processing machinery (APM) plays an important role in immune recognition of virally infected and transformed cells. Defective expression of the APM component ERAP1 is associated with progression and poor clinical outcome in cervical carcinoma. However, the underlying mechanisms of ERAP1 protein downregulation remain to be established. We investigated ERAP1 mRNA expression levels in 14 patients with established ERAP1 protein downregulation. To further examine the possible pretranscriptional mechanisms of ERAP1 downregulation, ERAP1 DNA mutation status was analyzed alongside existing data on various single nucleotide polymorphisms. Moreover, loss of heterozygosity at various loci in the ERAP1 gene was investigated. In cases with ERAP1 protein downregulation, ERAP1 mRNA quantities were found to be significantly lower than in a cohort with normal ERAP1 protein expression (P = 0.001). Loss of heterozygosity was demonstrated to occur in up to 50% of tumors with ERAP1 downregulation. Our data indicate that ERAP1 downregulation is associated with loss of heterozygosity. These data provide the first insight into in vivo mechanisms of ERAP1 downregulation in cervical carcinoma.

Mechanisms of tumor-induced T cell immune suppression and therapeutics to counter those effects

The theory of tumor immune surveillance states that the host immune system has means to recognize transformed cells and kills them to prevent growth and spreading of those cells. Nevertheless, cancer cells often survive and outgrow to form a tumor mass and metastasize to other tissues or organs. During the stage of immune evasion of tumor, various changes takes place both in the tumor cells and the tumor microenvironment to divert the anti-tumor immune responses by T cells and natural killer cells. Advances in the basic science in tumor immunology have led to development of many creative strategies to overcome the immune suppression imposed during tumor progression, a few of which have been approved for the treatment of cancer patients in the clinic. In the first part of this review, mechanisms of tumor-induced T cell immune suppression resulting in immune evasion of tumors will be discussed. In the second part, emerging methods to harness the immune responses against tumors will be introduced.

An immunology primer for computational modelers

The immune system is designed to protect an organism from infection and damage caused by a pathogen. A successful immune response requires the coordinated function of multiple cell types and molecules in the innate and adaptive immune systems. Given the complexity of the immune system, it would be advantageous to build computational models to better understand immune responses and develop models to better guide the design of immunotherapies. Often, researchers with strong quantitative backgrounds do not have formal training in immunology. Therefore, the goal of this review article is to provide a brief primer on cellular immunology that is geared for computational modelers.

Nucleic acid recognition in dendritic cells

The immune system consists of specialized cell types with distinct functions in order to provide an effective innate and adaptive immune defense against harmful invading pathogens like bacteria, viruses, fungi, parasites, or other substances threatening the integrity of the organism. Once the immune system recognizes such pathogens via pattern recognition receptors (PRRs), they are taken up, processed, and presented as antigens on MHC class I and II to T lymphocytes by specialized cells called dendritic cells (DCs). At the same time pathogen components which bind to PRRs in DCs trigger potent cytokine and chemokine responses. Although other cell types like macrophages can also take up, process, and present antigens to naïve T lymphocytes, DCs are the cells with the greatest capacity to do so. Thus, DCs are also called professional antigen presenting cells (APCs), which induce a strong adaptive immune response and thereby act as a bridge between the innate and adaptive immune system. This chapter provides detailed instructions on how to generate various types of DCs from human peripheral blood mononuclear cells (PBMCs) and murine bone marrow, as well as stimulation conditions for activation of these cells by PRR ligands in vitro.

Effector CD8+ T cells are generated in response to an immunodominant epitope in type III effector YopE during primary Yersinia pseudotuberculosis infection

YopE is a virulence factor that is secreted into host cells infected by Yersinia species. The YopE C-terminal domain has GTPase-activating protein (GAP) activity. The YopE N-terminal domain contains an epitope that is an immunodominant CD8(+) T cell antigen during primary infection of C57BL/6 mice with Yersinia pseudotuberculosis. The characteristics of the CD8(+) T cells generated in response to the epitope, which comprises YopE amino acid residues 69 to 77 (YopE(69-77)), and the features of YopE that are important for antigenicity during primary infection, are unknown. Following intravenous infection of naïve C57BL/6 mice with a yopE GAP mutant (the R144A mutant), flow cytometry analysis of splenocytes by tetramer and intracellular cytokine staining over a time course showed that YopE69-77-specific CD8(+) T cells producing gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) were generated by day 7, with a peak at day 14. In addition, ∼80% of YopE(69-77)-specific CD8(+) T cells were positive for KLRG1, a memory phenotype marker, at day 21. To determine if residues that regulate YopE activity by ubiquitination or membrane localization affect the antigenicity of YopE(69-77), mice were infected with a yopE ubiquitination or membrane localization mutant (the R62K or L55N I59N L63N mutant, respectively). These mutants elicited YopE(69-77)-specific CD8(+) T cells producing IFN-γ and TNF-α with kinetics and magnitudes similar to those of the parental R144A strain, indicating that primary infection primes effector CD8(+) T cells independently of the ubiquitination or membrane localization of YopE. Additionally, at day 7, there was an unexpected positive correlation between the numbers of YopE(69-77)-specific CD8(+) T cells and CD11b(+) cells, but not between the numbers of YopE(69-77)-specific CD8(+) T cells and bacterial cells, in spleens, suggesting that the innate immune response contributes to the immunodominance of YopE(69-77).

Reduced expression of members of the mhc-i antigen processing machinery in ethnic Uighur women with cervical cancer in the Xinjiang region of China

OBJECTIVE

Cervical cancer is a major cause of mortality in Uighur women compared with Han women in the Xinjiang region of China. Although a reduction in the class i major histocompatibility complex (mhc-i) antigen processing machinery (apm) is associated with the development of cervical cancer, the mhc-i apm has not been studied in this particular group of women, who have the highest incidence rate of cervical cancer in China.

STUDY DESIGN

We used immunohistochemical staining and polymerase chain reaction amplification of viral dna from infection with the human papilloma virus (hpv) to study the expression of members of the mhc-i apm in cervical cancer sections collected from Uighur and Han women and in cervicitis samples from age-matched counterparts.

RESULTS

Expression of the molecules of interest was compared between two ethnic groups, and expression of transporter associated with antigen processing 1 and 2, heat shock protein 90, and calnexin were found to be reduced even more significantly in Han women with cervical cancer than in Uighur women with same disease. However, compared with Han women, Uighur women had a higher rate of infection with hpv 16.

CONCLUSIONS

The mhc-i apm were reduced in cervical cancer, with heterogeneity in the two ethnic groups. The reduction was more pronounced in Han women, who less frequently had hpv 16 infection, suggesting possible differences in the roles of members of the mhc-i apm and in the mechanisms of cervical cancer development in these two ethnic groups despite residence in the same region of China.

Alloprimed CD8(+) T cells regulate alloantibody and eliminate alloprimed B cells through perforin- and FasL-dependent mechanisms

While it is well known that CD4(+) T cells and B cells collaborate for antibody production, our group previously reported that CD8(+) T cells down-regulate alloantibody responses following transplantation. However, the exact mechanism involved in CD8(+) T cell-mediated down-regulation of alloantibody remains unclear. We also reported that alloantibody production is enhanced when either perforin or FasL is deficient in transplant recipients. Here, we report that CD8(+) T cell-deficient transplant recipient mice (high alloantibody producers) exhibit an increased number of primed B cells compared to WT transplant recipients. Furthermore, CD8(+) T cells require FasL, perforin and allospecificity to down-regulate posttransplant alloantibody production. In vivo CD8-mediated clearance of alloprimed B cells was also FasL- and perforin-dependent. In vitro data demonstrated that recipient CD8(+) T cells directly induce apoptosis of alloprimed IgG1(+) B cells in co-culture in an allospecific and MHC class I-dependent fashion. Altogether these data are consistent with the interpretation that CD8(+) T cells down-regulate posttransplant alloantibody production by FasL- and perforin-dependent direct elimination of alloprimed IgG1(+) B cells.

Seminal plasma peptides may determine maternal immune response that alters success or failure of pregnancy in the abortion-prone CBAxDBA/2 model

Spontaneous abortion (resorption) in the DBA/2-mated CBA/J mouse involves a deficiency in Treg cell activity against paternal antigens at the time of mating. Preimmunization of female CBA/J by BALB/c splenocytes, but not DBA/2 splenocytes, protects against subsequent abortions after a CBAxDBA/2 mating. Previous immunogenetic studies with BALB/cxDBA/2 recombinants have indicated that H-2(d)-restricted presentation of a single minor non-H-2(d) peptide might be responsible for protection, while the product of a second independent allele might promote abortions. Using brefeldin-treated BALB/c and DBA/2 splenocytes, we found that incubation in BALB/c seminal plasma rendered DBA/2 splenocytes protective and DBA/2 seminal plasma eliminated protection. The active protective moiety was <10 kD consistent with a peptide. DBA/2 seminal plasma contained a <10-kD peptide that boosted the abortion rate. Maternal H-2(k) CBA/J splenocytes were unable to present the protective activity. Amicon fractionation also unmasked a <10-kD activity in DBA/2 seminal plasma that could boost abortion rates when presented by BALB/c splenocytes. SELDI-TOF mass spectrometry proteomic analysis of <10-kD filtrates reproducibly detected 1416, 1468, 1774 D peptides in BALB/c that were reduced or absent in DBA/2, and the presence of 2662, 4559 and 5320 D molecules in DBA/2, the latter two definitely not present in BALB/c. Direct antigen presentation of paternal H-2(d)-restricted paternal peptides (600-1800 D) may prevent the rejection of the CBAxDBA/2 embryos, and larger sized peptides may bind to immunizing splenocytes and augment abortion mechanisms.

Immune responses in liver-directed lentiviral gene therapy

The use of lentiviral vectors (LV)s for in vivo gene therapy is an ideal platform for treating many types of disease. Since LVs can transduce a wide array of cells, support long-term gene expression, and be modified to enhance cell targeting, LVs are a powerful modality to deliver life-long therapeutic proteins. A major limitation facing the use of LVs for in vivo gene therapy is the induction of immune responses, which can reduce the transduction efficiency of LV, eliminate the transduced cells, and inhibit the effect of the therapeutic protein. LV strategies designed to restrict transgene expression to the liver to exploit its naturally tolerogenic properties have proven to significantly reduce the induction of pathogenic immune responses and increase therapeutic efficacy. In this review, we outline the immunological hurdles facing in vivo LV gene therapy and highlight the advantages and limitations of using liver-directed LV gene therapy.

The role of insulin-regulated aminopeptidase in MHC class I antigen presentation

Production of MHC-I ligands from antigenic proteins generally requires multiple proteolytic events. While the proteolytic steps required for antigen processing in the endogenous pathway are clearly established, persisting gaps of knowledge regarding putative cross-presentation compartments have made it difficult to map the precise proteolytic events required for generation of cross-presented antigens. It is only in the past decade that the importance of aminoterminal trimming as the final step in the endogenous presentation pathway has been recognized and that the corresponding enzymes have been described. This review focuses on the aminoterminal trimming of exogenous cross-presented peptides, with particular emphasis on the identification of insulin responsive aminopeptidase (IRAP) as the principal trimming aminopeptidase in endosomes and phagosomes.

Liposome-based polymer complex as a novel adjuvant: enhancement of specific antibody production and isotype switch

The aim of vaccination is to induce appropriate immunity against pathogens. Antibody-mediated immunity is critical for protection against many virus diseases, although it is becoming more evident that coordinated, multifunctional immune responses lead to the most effective defense. Specific antibody (Ab) isotypes are more efficient at protecting against pathogen invasion in different locations in the body. For example, compared to other Ab isotypes, immunoglobulin (Ig) A provides more protection at mucosal areas. In this study, we developed a cationic lipopolymer (liposome-polyethylene glycol-polyethyleneimine complex [LPPC]) adjuvant that strongly adsorbs antigens or immunomodulators onto its surface to enhance or switch immune responses. The results demonstrate that LPPC enhances uptake ability, surface marker expression, proinflammatory cytokine release, and antigen presentation in mouse phagocytes. In contrast to Freund’s adjuvant, LPPC preferentially activates Th1- immunity against antigens in vivo. With lipopolysaccharides or CpG oligodeoxynucleotides, LPPC dramatically enhances the IgA or IgG2A proportion of total Ig, even in hosts that have developed Th2 immunities and high IgG1 serum titers. Taken together, the results demonstrate that the LPPC adjuvant not only increases the immunogenicity of antigens but also modulates host immunity to produce an appropriate Ab isotype by combining with immunomodulators.

MHC class I-related antigen-processing machinery component defects in feline mammary carcinoma

Defects in HLA class I antigen-processing machinery (APM) component expression and/or function are frequent in human tumors. These defects may provide tumor cells with a mechanism to escape from recognition and destruction by HLA class I antigen-restricted, tumor antigen-specific cytotoxic T cells. However, expression and functional properties of MHC class I antigens and APM components in malignant cells in other animal species have been investigated to a limited extent. However, this information can contribute to our understanding of the mechanisms underlying the association of MHC class I antigen and APM component defects with malignant transformation of cells and to identify animal models to validate targeted therapies to correct these defects. To overcome this limitation in the present study, we have investigated the expression of the catalytic subunits of proteasome (Y, X, and Z) and of immunoproteasome (LMP2, LMP7, and LMP10) as well as of MHC class I heavy chain (HC) in 25 primary feline mammary carcinomas (FMCs) and in 23 matched healthy mammary tissues. We found a reduced expression of MHC class I HC and of LMP2 and LMP7 in tumors compared with normal tissues. Concordantly, proteasomal cleavage specificities in extracts from FMCs were different from those in healthy tissues. In addition, correlation analysis showed that LMP2 and LMP7 were concordantly expressed in FMCs, and their expression was significantly correlated with that of MHC class I HC. The abnormalities we have found in the APM in FMCs may cause a defective processing of some tumor antigens.

Induction of heterosubtypic cross-protection against influenza by a whole inactivated virus vaccine: the role of viral membrane fusion activity

BACKGROUND

The inability of seasonal influenza vaccines to effectively protect against infection with antigenically drifted viruses or newly emerging pandemic viruses underlines the need for development of cross-reactive influenza vaccines that induce immunity against a variety of virus subtypes. Therefore, potential cross-protective vaccines, e.g., whole inactivated virus (WIV) vaccine, that can target conserved internal antigens such as the nucleoprotein (NP) and/or matrix protein (M1) need to be explored.

METHODOLOGY/PRINCIPAL FINDINGS

In the current study we show that a WIV vaccine, through induction of cross-protective cytotoxic T lymphocytes (CTLs), protects mice from heterosubtypic infection. This protection was abrogated after depletion of CD8+ cells in vaccinated mice, indicating that CTLs were the primary mediators of protection. Previously, we have shown that different procedures used for virus inactivation influence optimal activation of CTLs by WIV, most likely by affecting the membrane fusion properties of the virus. Specifically, inactivation with formalin (FA) severely compromises fusion activity of the virus, while inactivation with β-propiolactone (BPL) preserves fusion activity. Here, we demonstrate that vaccination of mice with BPL-inactivated H5N1 WIV vaccine induces solid protection from lethal heterosubtypic H1N1 challenge. By contrast, vaccination with FA-inactivated WIV, while preventing death after lethal challenge, failed to protect against development of disease and severe body weight loss. Vaccination with BPL-inactivated WIV, compared to FA-inactivated WIV, induced higher levels of specific CD8+ T cells in blood, spleen and lungs, and a higher production of granzyme B in the lungs upon H1N1 virus challenge.

CONCLUSION/SIGNIFICANCE

The results underline the potential use of WIV as a cross-protective influenza vaccine candidate. However, careful choice of the virus inactivation procedure is important to retain membrane fusion activity and full immunogenicity of the vaccine.

Antiviral immune responses by human langerhans cells and dendritic cells in HIV-1 infection

The main route of human immunodeficiency virus-1 (HIV-1) infection is via unprotected sexual intercourse, and therefore, vaginal tissues and male foreskin are viral entry sites. Langerhans cells (LCs) and dendritic cells (DCs) are amongst the first immune cells encountering HIV-1 since these cells line these mucosal tissues. Both LCs and DCs are equipped with specific pattern recognition receptors that not only sense pathogens, but induce specific immune responses against these pathogens. LCs express the C-type lectin receptor langerin, which provides protection against HIV-1 infection. In contrast, DCs express the C-type lectin receptor DC-SIGN, which facilitates capture as well as infection of DCs and subsequent transmission to CD4(+) T cells. This chapter gives an update on immune responses elicited against viruses and sheds a light on different immune mechanisms that are hijacked by HIV-1 to infect the host. HIV-1 infection ultimately leads to the worldwide pandemic acquired immunodeficiency syndrome (AIDS).

Identification and characterization of novel immunomodulatory bursal-derived pentapeptide-II (BPP-II)

The bursa of Fabricius, the acknowledged central humoral immune organ, plays a vital role in B lymphocyte differentiation. However, there are few reports of the molecular basis of the mechanism on immune induction and potential antitumor activity of bursal-derived peptides. In this paper, a novel bursal-derived pentapeptide-II (BPP-II, MTLTG) was isolated and exerted immunomodulatory functions on antibody responses in vitro. Gene microarray analyses demonstrated that BPP-II regulated expression of 2478 genes in a mouse-derived hybridoma cell line. Immune-related gene ontology functional procedures were employed for further functional analysis. Furthermore, the majority of BPP-II-regulated pathways were associated with immune responses and tumor processes. Moreover, BPP-II exhibited immunomodulatory effects on antigen-specific immune responses in vivo, including enhancement of avian influenza virus (H9N2 subtype)-specific antibody and cytokine production and modification of T cell immunophenotypes and lymphocyte proliferation. Finally, BPP-II triggered p53 expression and stabilization and selectively inhibited tumor cell proliferation. These data identified the multifunctional factor, BPP-II, as a novel biomaterial representing an important linking between the humoral central immune system and immune induction, including antitumor. Information generated in this study elucidates further the mechanisms involved in humoral immune system and represents the potential basis of effective immunotherapeutic strategies for treating human tumors and immune improvement.

Genetic association analysis of TAP1 and TAP2 polymorphisms with aspirin exacerbated respiratory disease and its FEV1 decline

Aspirin exacerbated respiratory disease (AERD) induces bronchoconstriction in asthmatic patients characterized with a clinical condition of severe decline in forced expiratory volume in one second (FEV1) after ingestion of aspirin. Two genes consisting a heterodimer, transporter 1 and 2, ATP-binding cassette, sub-family B (MDR/TAP) (TAP1 and TAP2) within the major histocompatibility complex (MHC) region, have been implicated in immunodeficiency and bronchiectasis development. To investigate the associations of TAP1 and TAP2 genetic polymorphisms with AERD and phenotypic FEV1 decline, a total of 43 common single-nucleotide polymorphisms (SNPs) including 12 SNPs of TAP1 and 31 SNPs of TAP2 were genotyped in 93 AERD patients and 96 aspirin-tolerant asthma controls. Interestingly, regression analysis revealed that polymorphisms and haplotypes of TAP2 were associated with FEV1 decline by aspirin provocation (P=0.002-0.04), with about twofold decline rate of FEV1 in most of minor homozygotes compared with major homozygotes. In addition, nominal evidences of association between TAP2 and AERD development were observed (P=0.02-0.04). However, TAP1 polymorphisms showed no relations to both AERD and FEV1 decline after aspirin challenge (P>0.05). Although further functional evaluations and replications are required, our preliminary findings provide supporting information that variants of TAP2 might be predisposing factors for FEV1 decline-related symptoms.