Revealing immune responses in the Mycobacterium avium subsp. paratuberculosis-infected THP-1 cells using single cell RNA-sequencing

Mycobacterium avium subsp. paratuberculosis (MAP) is a causative agent of Johne’s disease, which is a chronic and debilitating disease in ruminants. MAP is also considered to be a possible cause of Crohn’s disease in humans. However, few studies have focused on the interactions between MAP and human macrophages to elucidate the pathogenesis of Crohn’s disease. We sought to determine the initial responses of human THP-1 cells against MAP infection using single-cell RNA-seq analysis. Clustering analysis showed that THP-1 cells were divided into seven different clusters in response to phorbol-12-myristate-13-acetate (PMA) treatment. The characteristics of each cluster were investigated by identifying cluster-specific marker genes. From the results, we found that classically differentiated cells express CD14, CD36, and TLR2, and that this cell type showed the most active responses against MAP infection. The responses included the expression of proinflammatory cytokines and chemokines such as CCL4, CCL3, IL1B, IL8, and CCL20. In addition, the Mreg cell type, a novel cell type differentiated from THP-1 cells, was discovered. Thus, it is suggested that different cell types arise even when the same cell line is treated under the same conditions. Overall, analyzing gene expression patterns via scRNA-seq classification allows a more detailed observation of the response to infection by each cell type.

Investigation of Sensitization Potential of the Soybean Allergen Gly m 4 by Using Caco-2/Immune Cells Co-Culture Model

The soybean allergen Gly m 4 is known to cause severe allergic reactions including anaphylaxis, unlike other Bet v 1 homologues, which induce mainly local allergic reactions. In the present study, we aimed to investigate whether the food Bet v 1 homologue Gly m 4 can be a sensitizer of the immune system. Susceptibility to gastrointestinal digestion was assessed in vitro. Transport through intestinal epithelium was estimated using the Caco-2 monolayer. Cytokine response of different immunocompetent cells was evaluated by using Caco-2/Immune cells co-culture model. Absolute levels of 48 cytokines were measured by multiplex xMAP technology. It was shown that Gly m 4 can cross the epithelial barrier with a moderate rate and then induce production of IL-4 by mature dendritic cells in vitro. Although Gly m 4 was shown to be susceptible to gastrointestinal enzymes, some of its proteolytic fragments can selectively cross the epithelial barrier and induce production of Th2-polarizing IL-5, IL-10, and IL-13, which may point at the presence of the T-cell epitope among the crossed fragments. Our current data indicate that Gly m 4 can potentially be a sensitizer of the immune system, and intercommunication between immunocompetent and epithelial cells may play a key role in the sensitization process.

Identification of HLA-A*0201-restricted CTL Epitopes for MLAA-34-specific Immunotherapy for Acute Monocytic Leukemia

Our previous research has shown that monocytic leukemia-associated antigen-34 (MLAA-34) was a novel antiapoptotic molecule with unique expression in acute monocytic leukemia (M5), making it an ideal target for T-cell-based immunotherapy. Here, we sought to identify HLA-A*0201-restricted cytotoxic T-lymphocyte (CTL) epitope of MLAA-34 by reverse immunology. In all, 10 HLA-A*0201 restricted epitopes of MLAA-34 were predicted by bioinformatics. MLAA-34324-332, MLAA-34293-301, and MLAA-34236-244 showed the strongest HLA-A*0201-binding affinity. The percentages of HLA-A*0201-MLAA-34236-244 tetramer+ CD8+ T cells in MLAA-34236-244-induced CTLs were raised apparently. Enzyme-linked immunospot showed that MLAA-34236-244 and MLAA-34324-332-specific CTLs produced a higher amount of interferon-γ. MLAA-34236-244-induced CTLs presented a stronger cytotoxic effect on THP-1 cells (HLA-A*0201+MLAA-34+) at various effector to target ratios. MLAA-34236-244 peptide vaccine could inhibit the tumor growth and improve mean survival time of leukemia-bearing human peripheral blood lymphocyte reconstituting severe combined immunodeficient mice. Mice immunized with MLAA-34236-244 vaccine had increased percentages of MLAA-34236-244 tetramer+ CD8+ T cells in the spleen after each round of immunization. High-purity CD8+ and CD4+ T cells were sorted by Dynabeads as effector cells. The killing activity of CD8+ T cells was higher than that of CD4+ T cells. CTLs derived from the MLAA-34 peptide vaccine group were significantly higher than other therapeutic groups and showed specific cytotoxicity to THP-1 cells. Increased interferon-γ and interleukin (IL)-2 and decreased IL-10 and IL-4 were seen in the MLAA-34236-244 peptide vaccine group. MLAA-34236-244 peptide (ILDRHNFAI) is an effective HLA-A*0201-restricted CTL epitope and that it may serve as a promising strategy in designing antigen-specific immunotherapy against MLAA-34-positive acute monocytic leukemia.

Polyfunctional Tier 2-Neutralizing Antibodies Cloned following HIV-1 Env Macaque Immunization Mirror Native Antibodies in a Human Donor

Vaccine efforts to combat HIV are challenged by the global diversity of viral strains and shielding of neutralization epitopes on the viral envelope glycoprotein trimer. Even so, the isolation of broadly neutralizing Abs from infected individuals suggests the potential for eliciting protective Abs through vaccination. This study reports a panel of 58 mAbs cloned from a rhesus macaque (Macaca mulatta) immunized with envelope glycoprotein immunogens curated from an HIV-1 clade C-infected volunteer. Twenty mAbs showed neutralizing activity, and the strongest neutralizer displayed 92% breadth with a median IC50 of 1.35 μg/ml against a 13-virus panel. Neutralizing mAbs predominantly targeted linear epitopes in the V3 region in the cradle orientation (V3C) with others targeting the V3 ladle orientation (V3L), the CD4 binding site (CD4bs), C1, C4, or gp41. Nonneutralizing mAbs bound C1, C5, or undetermined conformational epitopes. Neutralization potency strongly correlated with the magnitude of binding to infected primary macaque splenocytes and to the level of Ab-dependent cellular cytotoxicity, but did not predict the degree of Ab-dependent cellular phagocytosis. Using an individualized germline gene database, mAbs were traced to 23 of 72 functional IgHV alleles. Neutralizing V3C Abs displayed minimal nucleotide somatic hypermutation in the H chain V region (3.77%), indicating that relatively little affinity maturation was needed to achieve in-clade neutralization breadth. Overall, this study underscores the polyfunctional nature of vaccine-elicited tier 2-neutralizing V3 Abs and demonstrates partial reproduction of the human donor's humoral immune response through nonhuman primate vaccination.

Key Vitamin D Target Genes with Functions in the Immune System

The biologically active form of vitamin D3, 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), modulates innate and adaptive immunity via genes regulated by the transcription factor vitamin D receptor (VDR). In order to identify the key vitamin D target genes involved in these processes, transcriptome-wide datasets were compared, which were obtained from a human monocytic cell line (THP-1) and peripheral blood mononuclear cells (PBMCs) treated in vitro by 1,25(OH)2D3, filtered using different approaches, as well as from PBMCs of individuals supplemented with a vitamin D3 bolus. The led to the genes ACVRL1, CAMP, CD14, CD93, CEBPB, FN1, MAPK13, NINJ1, LILRB4, LRRC25, SEMA6B, SRGN, THBD, THEMIS2 and TREM1. Public epigenome- and transcriptome-wide data from THP-1 cells were used to characterize these genes based on the level of their VDR-driven enhancers as well as the level of the dynamics of their mRNA production. Both types of datasets allowed the categorization of the vitamin D target genes into three groups according to their role in (i) acute response to infection, (ii) infection in general and (iii) autoimmunity. In conclusion, 15 genes were identified as major mediators of the action of vitamin D in innate and adaptive immunity and their individual functions are explained based on different gene regulatory scenarios.

Pro-inflammatory responses induced by A. fumigatus and A. versicolor in various human macrophage models

Exposure to mold-contaminated indoor air has been associated with various respiratory diseases, and there is a need for experimental data to confirm these associations. The pro-inflammatory properties of well-characterized aerosolized spores and hyphal fragments from Aspergillus fumigatus and Aspergillus versicolor were examined and compared using various human macrophage cell models including phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 macrophages (THP-1 Ma), primary peripheral blood monocyte-derived macrophages (MDM), and primary airway macrophages (AM) from induced sputum. X-ray treated samples of the two mold species induced different responses with A. fumigatus displaying the most potent induction of pro-inflammatory responses. While hyphal fragments from A. fumigatus were more potent than spores, similar responses were produced by the two growth stages of A. versicolor. THP-1 Ma was the most sensitive model releasing a broad range of cytokines/chemokines. MDM exhibited a similar cytokine/chemokine profile as THP-1 Ma, except for a low-quantity release of interleukin-1β (IL-1β). In contrast, AM appeared to be nonresponsive and yielded a different pattern of pro-inflammatory markers. Toll-like receptor (TLR)4, but also to a certain degree TLR2, was involved in several responses induced by spores and aerosolized hyphal fragments of A. fumigatus in MDM. Taken together, MDM seems to be the most promising experimental macrophage model. Abbreviations: AF: A. fumigatus, Aspergillus fumigatus; AV: A. versicolor, Aspergillus versicolor; AM: Airway Macrophage; CBA: Cytometric Bead Array; CD: Cluster of Differentiation; DTT: dithiothreitol; ELISA: Enzyme Linked Immunosorbent Assay; FBS: fetal bovine serum; GM-CSF: Granulocyte macrophage colony-stimulating factor; IL-1β: Interleukin-1beta; MDM: Monocyte-Derived Macrophages; NF-κB: Nuclear Factor kappa light chain enhancer of activated B cells; NLR: NOD-like Receptor; PAMP: Pathogen Associated Molecular Pattern; PMA: Phorbol 12-myristate 13-acetate; PRR: Pattern Recognition Receptor; THP-1: Human leukemia monocyte cell line; TLR: Toll-like Receptor; TNF-α: Tumor Necrosis Factor- alpha.