ImmunoHorizons最新文献

The obligate intracellular protozoan pathogen Toxoplasma gondii is estimated to infect a third of the world's population. Toxoplasmosis is considered a significant worldwide disease that can lead to morbidity or death in immunocompromised individuals. Host defense against T. gondii has been demonstrated to be dependent on a rapid myeloid cell and lymphocyte response working in concert to quickly eliminate the invading pathogen. Classically, T-bet-dependent group 1 innate lymphocytes (ILC1s), natural killer (NK) cells, and CD4+ T cell-derived interferon-γ (IFN-γ) are considered indispensable for host resistance against T. gondii. However, recent discoveries have illustrated that T-bet is not required for NK cell- or CD4+ T cell-derived IFN-γ. Yet, lack of T-bet still results in rapid mortality, pointing to a T-bet-dependent myeloid cell-mediated host defense pathway. This review summarizes the myeloid cell-mediated immune response against T. gondii and provides insights into the lesser known components of the T-bet-dependent myeloid cell-dependent host defense pathway for pathogen clearance.

Background: Tseek is a method of sequencing T cell receptor (TCR) repertoires with minimal bias. This work aimed to develop methods to characterize the TCR repertoire in dogs, identify influences such as genetic lineage and age, and evaluate the use of repertoires to monitor immune status in dogs.

Methods: Two studies were conducted to develop the techniques and characterize the effect of individual, breed, and age. One study analyzed RNA data from individuals (n = 32), 8 from each of 4 breeds, sampled at 2 time points a year apart. The second, lifestage study, used individuals within a single breed (Labrador Retriever) with ages dispersed across a broad range (0.2 to 12 yr, n = 50). Tseek was used to process samples for sequencing, to identify the V, and J segments to annotate the CDR3, which were then analyzed to draw inferences.

Results: The TCR repertoires had signatures of breeds, and of the individual, with stability over at least a year. Across the lifestage study, littermate-specific characteristics were not detected, but an age-related effect was observed: older dogs exhibited reduced diversity characterized by a greater abundance of individual-specific high-frequency clones, while puppies had a more diverse repertoire.

Conclusion: An individual's TCR repertoire includes stable information, indicative of the individual, breed, and age-related decline. The α and β chain repertoires had distinct properties in the breed-specific signatures, indicating differential influences on their selection, despite their pairing in each T cell. Consistent, age-related changes can be seen in the repertoire, but their impact on immune system needs to be delineated.

The pathology of severe COVID-19 is due to a hyperinflammatory immune response persisting after viral clearance. To understand how the immune response to SARS-CoV-2 is regulated to avoid severe COVID-19, we tested relevant immunoregulatory cytokines. Transforming growth factor β (TGF-β), interleukin (IL)-10, and IL-4 were neutralized upon infection with mouse-adapted SARS-CoV-2 (CMA3p20), a model of mild disease; lung inflammation was quantified by histology and flow cytometry at early and late time points. Mild weight loss and lung inflammation including consolidation and alveolar thickening were evident 3 d postinfection (dpi), and inflammation persisted to 7 dpi. Coinciding with early monocytic infiltrates, CCL2 and granulocyte colony-stimulating factor were transiently produced 3 dpi, while IL-12 and CCL5 persisted to 7 dpi, modeling viral and inflammatory phases of disease. Neutralization of TGF-β, but not IL-10 or IL-4, significantly increased lung inflammatory monocytes and elevated serum but not lung IL-6. Neutralization of IL-4 prolonged weight loss and increased early perivascular infiltration without changing viral titer. Anti-IL-4 reduced expression of Arg1, a gene associated with alternative activation of macrophages. Neutralizing TGF-β and IL-4 had differential effects on pathology after virus control. Lung perivascular infiltration was reduced 7 dpi by neutralization of IL-4 or TGF-β, and periairway inflammation was affected by anti-TGF-β, while alveolar infiltrates were not affected by either. Anti-IL-4 prolonged IL-12 to 7 dpi along with reduced IL-10 in lungs. Overall, the immunoregulatory cytokines TGF-β and IL-4 dampen initial inflammation in this mouse-adapted SARS-CoV-2 infection, suggesting that promotion of immunoregulation could help patients in early stages of disease.

Human and bovine respiratory syncytial virus (RSV) are significant causes of morbidity and mortality in human and cattle populations worldwide, respectively. RSV disease is characterized by deleterious inflammatory immune responses as well as generation of radical oxygen species in the airways. Recent reports have shown antiviral and anti-inflammatory activity of NRF2 agonists and immunometabolite derivatives 4-octyl-itaconate (4-OI) and dimethyl fumarate (DMF), suggesting their potential to protect against viral-induced inflammation. Here, we evaluated whether 4-OI or DMF impact human and bovine RSV replication and its associated inflammatory response in vitro and the efficacy of these NRF2 agonists in preventing RSV disease in a murine model. We observed that 4-OI and DMF inhibited the early inflammatory response to RSV as well as reduced infectious titers in epithelial cells. Moreover, mice treated with 4-OI or DMF were partially protected against RSV-induced weight loss and airway inflammation and showed reduced viral loads and interleukin-6 levels in the lung. Overall, these results support the use of NRF2 agonists 4-OI and DMF in the prevention of RSV disease in target populations.

The interactions between endogenous retroviruses (ERVs) and major histocompatibility complex molecules may significantly influence autoimmune diseases due to their common roles in the evolution and development of the adaptive immune system. Notably, regions within the Gag antigens of a specific group of ERVs, similar to murine leukemia retroviruses, exhibit patterns of sequence conservation, variation, and mutation. One highly conserved peptide of Gag, p5-13 (VTTPLSLTL), binds with high affinity to a nonclassic major histocompatibility complex molecule, Qa-1, and is preferentially recognized by T cells enriched in the pancreas of nonobese diabetic (NOD) mice, which spontaneously develop autoimmune type 1 diabetes. Interestingly, deep sequencing analysis of the Gag genes expressed in NOD mice has revealed numerous mutations flanking the conserved Qa-1-binding sequences. This includes 1 epitope, p310-328, which contains both conserved and mutated residues that can elicit autoreactive T cells in NOD mice. A specific residue, D316, within this epitope accumulates multiple mutations as the disease progresses, leading to a reduction in the consensus score in sequence alignment at this position during the later stages of prediabetes. Consistently, the substitution of the D316 residue with a dominant mutant, G316, enhances the antigenicity of this epitope, stimulating autoreactive T cells in prediabetic NOD mice to release interferon-γ . Thus, sequence variants of ERV Gag antigens encode overlapping conserved and highly mutated epitopes that can be recognized by T cells and utilized for biomarker discovery.

Sjögren's disease (SjD) is a chronic autoimmune disorder predominantly affecting females, characterized by exocrine gland dysfunction. This study investigates the therapeutic potential of 2-chloro-1-(4-hydroxy-phenyl)-ethanone (CHPE) and metformin in the C57BL/6.NOD-Aec1Aec2 mouse model, which closely mirrors human SjD. Molecular docking identified CHPE and metformin as high-affinity binders to the MHC class II I-Ab antigen-binding groove, suggesting their ability to inhibit antigen presentation and modulate immune responses. In-vitro assays confirmed their effectiveness in reducing T cell activation. In-vivo studies demonstrated that both preventative and therapeutic regimens of CHPE and metformin significantly reduced lymphocytic infiltration in the lacrimal glands, with metformin showing a more pronounced effect in females. Salivary gland infiltration was less responsive, though some reduction in focal scores was observed in male mice treated preventatively with CHPE. Both drugs altered the composition of lymphocytic infiltrates, particularly by reducing B cell populations, with notable sex-specific differences in response to treatment. CHPE and metformin also reduced anti-nuclear antibody levels, with CHPE showing stronger effects in females. Additionally, both drugs improved saliva and tear secretion, with metformin being more effective in the preventative regimen, especially in females. T cell receptor transductant assays revealed that CHPE and metformin exert their therapeutic effects through antigen-specific pathways, inhibiting T cell responses to SjD-associated autoantigens. Overall, this study provides compelling evidence that CHPE and metformin can modulate immune responses and improve gland function, with effectiveness varying by sex and age. These findings support the potential of these compounds as personalized treatments for SjD tailored to individual patient characteristics.

Thymocyte maturation is a tightly controlled and sequential process of T cell receptor (TCR) gene rearrangement that generates a broad repertoire of T cells with minimal self-reactivity. We previously generated TCR exchange (TRex) mice by targeting a mesothelin-specific "1045" TCR to the Trac locus in murine zygotes. While 1045 T cells from TRex mice display physiological development and function, some T cells coexpress endogenous TCRβ chains, suggesting that β-selection is required for 1045 T cell development. Here, we evaluate thymocyte maturation in the setting of compromised β-selection by deleting endogenous Tcrb or Rag2 in TRex mice. T cells readily form in TRex mice lacking Tcrb, though thymocytes mature through developmental trajectories that appear dependent on interleukin-7 and γδTCR. In contrast, mature T cells fail to form in the absence of Rag2. Maturation of αβ thymocytes bypassing β-selection is reduced by 100-fold, in part because γδTCR+ precursors are biased to form conventional γδ T cells. Nevertheless, in TRex mice, these unconventional β-selection-independent trajectories yield a mature αβ T cell population with uniform TCR expression and pronounced function.

The interleukin-1 receptor (IL-1R) plays an important role in mediating the inflammatory responses against pathogens. However, it is not clear whether a sustained IL-1R signaling following the loss of its endogenous inhibitor, IL-1R antagonist (IL-1RA), could improve mucosal immunity against the murine enteropathogen, Citrobacter rodentium. At basal levels, IL-1RA-deficient (IL1raKO) mice displayed an elevated inflammatory tone as indicated by their higher levels of circulating neutrophils, and the inflammatory marker, lipocalin-2, in both systemic and luminal contents. We reasoned that the heightened inflammatory tone of IL1raKO mice may be beneficial in clearing C. rodentium efficiently, but such was not the case. Oral challenge of C. rodentium (1 × 109 colony-forming units/mouse) resulted in luminal colonization, which peaked at day 7 postinfection, in both wild-type and IL1raKO mice. However, IL1raKO mice displayed a higher C. rodentium burden, and exacerbated colonic inflammation and hyperplasia. The aggravated infection in IL1raKO mice was corroborated using in vivo imaging of mice infected with a bioluminescent strain of C. rodentium. However, IL1raKO mice do not display any defect in their neutrophils with respect to their recruitment to the inflamed gut, generation of neutrophil extracellular traps and reactive oxygen species, or their ability to kill C. rodentium in vitro. In contrast, the macrophages of IL1raKO mice were able to upregulate more inducible nitric oxide synthase and produce more nitrite that wild-type macrophages; however, the former was less effective in mediating killing of C. rodentium in vitro. Together, our results suggest that IL-1RA plays a protective role in combating enteropathogen infection.

Bone marrow stromal cell antigen-1 (BST-1)/CD157 and CD38 are ectoenzymes belonging to the mammalian ADP-ribosyl cyclase family. Previous analyses of BST-1-deficient mice (Bst1KO) in a 129×C57BL/6J(B6) mixed background revealed that BST-1 is a positive regulator of humoral immunity. Murine BST-1 has recently been known to be an enteroneuroimmune regulator. To further clarify the functions of the ADP-ribosyl cyclase family in vivo, in this study, we generated CD38 and BST-1 double knockout mice (Cd38Bst1DKO) and compared them with Cd38KO, Bst1KO, and wild-type (WT) mice in B6 backgrounds. Flow cytometry analyses of the spleen revealed a decrease in B cells in Cd38KO mice, an increase in marginal zone (MZ) B cells of Bst1KO, and a decrease in neutrophils in Cd38Bst1DKO mice. Compared with WT mice, Cd38Bst1DKO mice showed decreased basal serum immunoglobulins and antigen-specific antibodies in memory responses to a thymus-dependent antigen. Because BST-1 is selectively expressed on WT MZ B cells responsive to lipopolysaccharide, enhanced antibody production in Bst1KO and increased growth responses of Bst1KO B cells to lipopolysaccharide stimulation suggest a suppressive role for BST-1 in Toll-like receptor 4 signaling in MZ B cells. Additionally, aged Cd38Bst1DKO mice displayed enlarged mesenteric lymph nodes and elongated small intestine; these phenotypes appeared only in Cd38Bst1DKO and not in Cd38KO or Bst1KO mice, indicating a cooperative role of CD38 and BST-1 in intestinal homeostasis regulation. Overall, these findings indicate the involvement of ADP-ribosyl cyclases CD38 and BST-1 in regulating humoral immune responses and small intestine homeostasis.

Dendritic cells (DCs) and natural killer (NK) cells engage in reciprocal interactions to trigger an efficient innate immune response while governing downstream adaptive immunity. Here, we used an ex vivo autologous human primary immune cell coculture system of DCs and NK cells to examine their impact on naïve CD4+ and CD8+ T cell (CD3+CD45RA+CD197+) activation in response to influenza A viral (IAV) infection. Using multiparameter flow cytometry, we observed that culturing T cells with both DCs and NK cells enhanced CD69 expression on CD4+ and CD8+ T cells, increased CD25 on CD4+ T cells, and promoted CD8+ T cell proliferation, compared with cultures with only NK cells or DCs. When DCs were exposed to the pandemic A/California/07/2009 (H1N1) strain or the A/Victoria/361/2011 (H3N2) strain, subsequent coculture with NK cells reduced the frequency of CD4+CD69+ and CD8+CD69+ naïve T cells. Notably, H3N2, but not H1N1, exposure also reduced CD4+CD25+ T cell frequencies. The IAV-mediated curtailment of T cell activation was dependent on viral replication because exposure to DCs with irradiated the H1N1 strain followed increased the frequency of CD4+CD69+, CD8+CD69+, CD4+CD25+, and CD8+CD25+ T cells, while irradiation of H3N2 increased the frequency of CD4+CD69+, CD8+CD69+ and proliferation of CD4+ and CD8+ T cells. These findings demonstrate that IAV can partially subvert DC-NK cell crosstalk to impair naïve T cell activation in a strain-dependent manner. This knowledge may guide the design of next-generation influenza vaccines to elicit robust cellular immune responses.