ImmunoHorizons最新文献

The inflammation resolution receptor lipoxin A4/formyl peptide receptor 2 (ALX/FPR2) plays a critical role in immune regulation by binding select oxylipins derived from n-6 and n-3 polyunsaturated fatty acids (PUFAs). While ALX/FPR2 is implicated in controlling inflammation initiation and resolution, its specific role in pulmonary inflammatory responses remains unclear. In this study, we investigated how genetic deletion of Alx/Fpr2 controls oxylipin levels, immune cell populations, and inflammatory cytokines under conditions of homeostasis and injury. Alx/Fpr2 knockout (KO) mice exhibited normal food intake and weight gain but showed impaired glucose and lipid metabolism. Targeted lipidomic analyses by liquid chromatography-tandem mass spectrometry revealed elevated pulmonary concentrations of n-6 and n-3 PUFA-derived oxylipins in KO mice compared to controls. Flow cytometry further demonstrated increased lung infiltration of NK cells, monocytes, and lymphoid cells, indicating a proinflammatory state in the absence of injury. Following 24 h of LPS-induced acute lung injury, IL-1β levels were elevated in KO mice, but pulmonary histopathology, immune cell numbers, and oxylipin levels were comparable to those of controls. These results suggested a protective role of ALX/FPR2 upon acute lung injury, which led us to further investigate the role of ALX/FPR2 upon 72 h of lung injury. Indeed, Alx/Fpr2 KO mice showed reduced bronchoalveolar lavage protein concentration and lower levels of IL-6 and TNF-α. Collectively, these findings demonstrate that ALX/FPR2 deficiency promotes basal pulmonary inflammation but protects against prolonged injury-induced inflammation, highlighting the context-dependent role of this receptor in pulmonary inflammation.

Using the parent-into-F1 mouse model, we compared in vivo sex differences in acute graft-vs-host (GVHD) disease, a Th1- response and in chronic GVHD, a T follicular helper cell (Tfh) lupus-like antibody response. Using a novel induction protocol standardized for donor CD8 content, we analyzed both a sub-threshold and a supra-threshold dose for twenty flow cytometry outcome variables encompassing splenic subsets and T cell activation markers. A large majority (≥16) of the outcome variables identified significant differences in the two phenotypes, many with very large effect sizes. In acute GVHD, B cells exhibited the greatest degree of depletion in both sexes; however, the male response was significantly stronger. Sex differences in chronic GVHD were more widespread; females exhibited significantly greater numbers of total splenocytes and host CD4 T cells, Tfh cells, B cells and CD8 T cells consistent with greater female autoantibody production in this model. The more potent male CTL response in acute GVHD conflicts with reports of greater female CTL responses following infections or vaccines possibly reflecting the absence of exogenous innate immune stimuli in the GVHD model. To our knowledge, this study is the first to compare sex differences in splenic cellular composition and T cell activation for acute and chronic GVHD mice at 2 wk post-induction using 2 different doses of donor splenocytes standardized to CD8 T cell numbers and using an expanded number of outcome variables. The implications for lupus pathogenesis are discussed.

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.

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.