Processing and presentation of (pro)-insulin in the MHC class II pathway: the generation of antigen-based immunomodulators in the context of type 1 diabetes mellitus

Series test of cluster and network analysis for lupus nephritis, before and after IFN-K-immunosuppressive therapy

AIM

The purpose was to screen potential targets of IFN-K-immunosuppressive therapy, which was used to offer effective information and resources for molecular targeted therapy.

METHODS

The gene expression profile of GSE72747 was used to screen out significant differently expressed genes (DEGs). Series Test of Cluster (STC) analysis for DEGs was performed. For all DEGs, the Database for Annotation, Visualization, and Integrated Discovery was performed for Gene Ontology (GO) enrichment analysis. Pathway enrichment analysis of DEGs was performed based on Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Pathway was constructed based on the interactions in the KEGG database. The coexpression network and gene signal expression networks were constructed and analyzed.

RESULTS

A total of 2193 DEGs were screened and eight significant profiles were identified. Significant GO terms included small molecule metabolic process, translation and apoptotic process. Metabolic pathways and Alzheimer's disease were significant KEGG pathways. Pathway relationship network of DEGs was constructed. MAPK signalling pathway, apoptosis and pathways in cancer were hub nodes. Gene co-expression network analysis was performed. VCP-interacting membrane protein and NADH dehydrogenase (ubiquinone) 1, alpha/beta subcomplex, 1, 8 kDa were the hub nodes. Gene signal network was constructed with 162 nodes and 254 edges. Hub nodes were phospholipase C, beta 2.

CONCLUSION

Screened DEGs including VIMP, NDUFAB1, SEC61G, PSMC2 might be potential targets for lupus nephritis treatment by involving in different functions and pathways, such as metabolic process and immune process.

Antibody responses to chimeric peptides derived from parasite antigens in mice and other animal species

Peptide vaccines constitute an interesting alternative to classical vaccines due to the possibility of selecting specific epitopes, easy of production and safety. However, an inadequate design may render these peptides poorly immunogenic or lead to undesirable outcomes (e.g., formation of B neoepitopes). As an approach to vaccine development, we evaluated the antibody response to chimeras composed of two or three known B epitopes from Trichinella and Fasciola, and several linkers (GSGSG, GPGPG and KK) in species as different as mice, sheep and turbot. All these species could mount an effective immune response to the short chimeric peptides. Nevertheless, this response depended on several factors including a favorable orientation of B-cell epitopes, adequateness of linkers and/or probability of formation of T neoepitopes. We also observed that, at least in mice, the inclusion of a decoy epitope may have favorable consequences on the antibody response to other epitopes in the chimera.

Systematic Evaluation of Genes and Genetic Variants Associated with Type 1 Diabetes Susceptibility

Genome-wide association studies have found >60 loci that confer genetic susceptibility to type 1 diabetes (T1D). Many of these are defined only by anonymous single nucleotide polymorphisms: the underlying causative genes, as well as the molecular bases by which they mediate susceptibility, are not known. Identification of how these variants affect the complex mechanisms contributing to the loss of tolerance is a challenge. In this study, we performed systematic analyses to characterize these variants. First, all known genes in strong linkage disequilibrium (r(2) > 0.8) with the reported single nucleotide polymorphisms for each locus were tested for commonly occurring nonsynonymous variations. We found only a total of 22 candidate genes at 16 T1D loci with common nonsynonymous alleles. Next, we performed functional studies to examine the effect of non-HLA T1D risk alleles on regulating expression levels of genes in four different cell types: EBV-transformed B cell lines (resting and 6 h PMA stimulated) and purified CD4(+) and CD8(+) T cells. We mapped cis-acting expression quantitative trait loci and found 24 non-HLA loci that affected the expression of 31 transcripts significantly in at least one cell type. Additionally, we observed 25 loci that affected 38 transcripts in trans. In summary, our systems genetics analyses defined the effect of T1D risk alleles on levels of gene expression and provide novel insights into the complex genetics of T1D, suggesting that most of the T1D risk alleles mediate their effect by influencing expression of multiple nearby genes.

Regulation of cathepsin G reduces the activation of proinsulin-reactive T cells from type 1 diabetes patients

Autoantigenic peptides resulting from self-proteins such as proinsulin are important players in the development of type 1 diabetes mellitus (T1D). Self-proteins can be processed by cathepsins (Cats) within endocytic compartments and loaded to major histocompatibility complex (MHC) class II molecules for CD4⁺ T cell inspection. However, the processing and presentation of proinsulin by antigen-presenting cells (APC) in humans is only partially understood. Here we demonstrate that the processing of proinsulin by B cell or myeloid dendritic cell (mDC1)-derived lysosomal cathepsins resulted in several proinsulin-derived intermediates. These intermediates were similar to those obtained using purified CatG and, to a lesser extent, CatD, S, and V in vitro. Some of these intermediates polarized T cell activation in peripheral blood mononuclear cells (PBMC) from T1D patients indicative for naturally processed T cell epitopes. Furthermore, CatG activity was found to be elevated in PBMC from T1D patients and abrogation of CatG activity resulted in functional inhibition of proinsulin-reactive T cells. Our data suggested the notion that CatG plays a critical role in proinsulin processing and is important in the activation process of diabetogenic T cells.

Routes to manipulate MHC class II antigen presentation

MHC class II molecules (MHC-II) present antigenic fragments acquired in the endocytic route to the immune system for recognition and activation of CD4+ T cells. This ignites a series of immune responses. MHC-II strongly correlates to most autoimmune diseases. Understanding the biology of MHC-II is therefore expected to translate into novel means of autoimmunity control or immune response improvement. Although the basic cell biology of MHC-II antigen presentation is well understood, many novel aspects have been uncovered in recent years including means of antigen delivery, preparation for MHC-II loading, transport processes and vaccination strategies. We will discuss past, present and future of these insights into the biology of MHC-II.