Effective immunity requires the coordinated activation of innate and adaptive immune responses. Natural killer (NK) cells are central innate immune effectors, but can also affect the generation of ...acquired immune responses to viruses and malignancies. How NK cells influence the efficacy of adaptive immunity, however, is poorly understood. Here, we show that NK cells negatively regulate the duration and effectiveness of virus-specific CD4+ and CD8+ T cell responses by limiting exposure of T cells to infected antigen-presenting cells. This impacts the quality of T cell responses and the ability to limit viral persistence. Our studies provide unexpected insights into novel interplays between innate and adaptive immune effectors, and define the critical requirements for efficient control of viral persistence.
Objective
To use high‐density genotyping to investigate the genetic associations of acute anterior uveitis (AAU) in patients with and those without ankylosing spondylitis (AS).
Methods
We genotyped ...samples from 1,711 patients with AAU (either primary or combined with AS), 2,339 AS patients without AAU, and 10,000 control subjects on an Illumina Immunochip Infinium microarray. We also used data for AS patients from previous genome‐wide association studies to investigate the AS risk locus ANTXR2 for its putative effect in AAU. ANTXR2 expression in mouse eyes was investigated by real‐time quantitative reverse transcription–polymerase chain reaction.
Results
A comparison between all patients with AAU and healthy control subjects showed strong association over HLA–B, corresponding to the HLA–B27 tag single‐nucleotide polymorphism rs116488202. The association of 3 non–major histocompatibility complex loci, IL23R, the intergenic region 2p15, and ERAP1, reached genome‐wide significance (P < 5 × 10−8). Five loci harboring the immune‐related genes IL10–IL19, IL18R1–IL1R1, IL6R, the chromosome 1q32 locus harboring KIF21B, as well as the eye‐related gene EYS, were also associated, reaching a suggestive level of significance (P < 5 × 10−6). Several previously confirmed AS associations demonstrated significant differences in effect size between AS patients with AAU and AS patients without AAU. ANTXR2 expression varied across eye compartments.
Conclusion
These findings of both novel AAU‐specific associations and associations shared with AS demonstrate overlapping but also distinct genetic susceptibility loci for AAU and AS. The associations in IL10 and IL18R1 are shared with inflammatory bowel disease, suggesting common etiologic pathways.
Endothelial function and integrity are compromised after allogeneic bone marrow transplantation (BMT), but how this affects immune responses broadly remains unknown. Using a preclinical model of CMV ...reactivation after BMT, we found compromised antiviral humoral responses induced by IL-6 signaling. IL-6 signaling in T cells maintained Th1 cells, resulting in sustained IFN-γ secretion, which promoted endothelial cell (EC) injury, loss of the neonatal Fc receptor (FcRn) responsible for IgG recycling, and rapid IgG loss. T cell-specific deletion of IL-6R led to persistence of recipient-derived, CMV-specific IgG and inhibited CMV reactivation. Deletion of IFN-γ in donor T cells also eliminated EC injury and FcRn loss. In a phase III clinical trial, blockade of IL-6R with tocilizumab promoted CMV-specific IgG persistence and significantly attenuated early HCMV reactivation. In sum, IL-6 invoked IFN-γ-dependent EC injury and consequent IgG loss, leading to CMV reactivation. Hence, cytokine inhibition represents a logical strategy to prevent endothelial injury, thereby preserving humoral immunity after immunotherapy.
Ocular antigens are sequestered behind the blood-retina barrier and the ocular environment protects ocular tissues from autoimmune attack. The signals required to activate autoreactive T cells and ...allow them to cause disease in the eye remain in part unclear. In particular, the consequences of peripheral presentation of ocular antigens are not fully understood. We examined peripheral expression and presentation of ocular neo-self-antigen in transgenic mice expressing hen egg lysozyme (HEL) under a retina-specific promoter. High levels of HEL were expressed in the eye compared to low expression throughout the lymphoid system. Adoptively transferred naïve HEL-specific CD4
T cells proliferated in the eye draining lymph nodes, but did not induce uveitis. By contrast, systemic infection with a murine cytomegalovirus (MCMV) engineered to express HEL induced extensive proliferation of transferred naïve CD4
T cells, and significant uveoretinitis. In this model, wild-type MCMV, lacking HEL, did not induce overt uveitis, suggesting that disease is mediated by antigen-specific peripherally activated CD4
T cells that infiltrate the retina. Our results demonstrate that retinal antigen is presented to T cells in the periphery under physiological conditions. However, when the same antigen is presented during viral infection, antigen-specific T cells access the retina and autoimmune uveitis ensues.
Viral infection is a common, life-threatening complication after allogeneic bone marrow transplantation (BMT), particularly in the presence of graft-versus-host disease (GVHD). Using cytomegalovirus ...(CMV) as the prototypic pathogen, we have delineated the mechanisms responsible for the inability to mount protective antiviral responses in this setting. Although CMV infection was self-limiting after syngeneic BMT, in the presence of GVHD after allogeneic BMT, CMV induced a striking cytopathy resulting in universal mortality in conjunction with a fulminant necrotizing hepatitis. Critically, GVHD induced a profound dendritic cell (DC) defect that led to a failure in the generation of CMV-specific CD8+ T-cell responses. This was accompanied by a defect in antiviral CD8+ T cells. In combination, these defects dramatically limited antiviral T-cell responses. The transfer of virus-specific cells circumvented the DC defects and provided protective immunity, despite concurrent GVHD. These data demonstrate the importance of avoiding GVHD when reconstructing antiviral immunity after BMT, and highlight the mechanisms by which the adoptive transfer of virus-specific T cells overcome the endogenous defects in priming invoked by GVHD.
•GVHD elicits profound defects in DCs that prevent the priming of virus-specific T cells.•Transfer of polyclonal T cells from immune donors at transplant provides effective antiviral immunity despite the presence of active GVHD.
Microglial cells are the resident macrophages of the central nervous system and participate in both innate and adaptive immune responses but can also lead to exacerbation of neurodegenerative ...pathologies after viral infections. Microglia in the outer layers of the retina and the subretinal space are thought to be involved in retinal diseases where low-grade chronic inflammation and oxidative stress play a role. This study investigated the effect of systemic infection with murine cytomegalovirus on the distribution and dynamics of retinal microglia cells. Systemic infection with murine cytomegalovirus elicited a significant increase in the number of microglia in the subretinal space and an accumulation of iris macrophages, along with morphological signs of activation. Interferon γ (IFN-γ)–deficient mice failed to induce changes in microglia distribution. Bone marrow chimera experiments confirmed that microglial cells in the subretinal space were not recruited from the circulating monocyte pool, but rather represented an accumulation of resident microglial cells from within the retina. Our results demonstrate that a systemic viral infection can lead to IFN-γ–mediated accumulation of microglia into the outer retinal layers and offer proof of concept that systemic viral infections alter the ocular microenvironment and therefore, may influence the course of diseases such as macular degeneration, diabetic retinopathy, or autoimmune uveitis, where low-grade inflammation is implicated.
To validate the application of a known transgenic mouse line with green fluorescent cones (Chrnb4.EGFP) to study cone photoreceptor biology and function in health and disease.
Chrnb4.EGFP retinas ...containing GFP
cones were compared with retinas without the GFP transgene via immunohistochemistry, quantitative real-time polymerase chain reaction, electroretinograms, and flow cytometry. The Chrnb4.EGFP line was backcrossed to the mouse models of cone degeneration,
and
, generating the new lines
.GFP and
.GFP, which were also studied as described.
GFP expression spanned the length of the cone cell in the Chrnb4.EGFP line, as well as in the novel
.GFP and
.GFP lines. The effect of GFP expression showed no significant changes to outer nuclear layer cell death, cone-specific gene expression, and immune response activation. A temporal decrease in GFP expression over time was observed, but GFP fluorescence was still detected through flow cytometry as late as 6 months. Furthermore, a functional analysis of photopic and scotopic electroretinogram responses of the Chrnb4 mouse showed no significant difference between GFP
and GFP
mice, whereas electroretinogram recordings for the
.GFP and
.GFP lines matched previous reports from the original lines.
This study demonstrates that the Chrnb4.EGFP mouse can be a powerful tool to overcome the limitations of studying cone biology, including the use of this line to study different types of cone degeneration.
This work validates research tools that could potentially offer more reliable preclinical data in the development of treatments for cone-mediated vision loss conditions, shortening the gap to clinical translation.
As with human cytomegalovirus (HCMV) infection of humans, murine CMV (MCMV) infection is widespread in its natural host, the house mouse Mus domesticus, and may consist of mixed infection with ...different CMV isolates. The incidence and mechanisms by which mixed infection occurs in free-living mice are unknown. This study used two approaches to determine whether mixed infection with MCMV could be established in laboratory mice. The first utilized two naturally occurring MCMV strains, N1 and G4, into which the lacZ gene was inserted by homologous recombination. The lacZ gene was used to track recombinant and parental viruses in simultaneously coinfected mice. In the second approach, a real-time quantitative PCR (qPCR) assay was used to detect viral immediate-early 1 (ie1) gene sequences in mice successively coinfected with G4 and then with the K181 MCMV strain. In both systems, mixed infection was detected in the salivary glands and lungs of experimentally infected mice. MCMV-specific antibody in sera and G4 IE1-specific cytotoxic lymphocyte responses in the spleens of twice-infected mice did not prevent reinfection. Finally, the prevalence of mixed infection in free-living mice trapped in four Australian locations was investigated using real-time qPCR to detect ie1 DNA sequences of N1, G4 and K181. Mixed infection with MCMVs containing the G4 and K181 ie1 sequences was detected in the salivary glands of 34.2 % of trapped mice. The observations that mixed infections are common in free-living M. domesticus and are acquired by immunocompetent mice through simultaneous or successive infections are important for vaccine development.
The haematopoietic-specific RhoGTPase, Rac2, has been indirectly implicated in T-lymphocyte development and function, and as a pivotal regulator of T Helper 1 (T(H)1) responses. In other ...haematopoietic cells it regulates cytoskeletal rearrangement downstream of extracellular signals. Here we demonstrate that Rac2 deficiency results in an abnormal distribution of T lymphocytes in vivo and defects in T-lymphocyte migration and filamentous actin generation in response to chemoattractants in vitro. To investigate the requirement for Rac2 in IFN-gamma production and TH1 responses in vivo, Rac2-deficient mice were challenged with Leishmania major and immunized with ovalbumin-expressing cytomegalovirus. Despite a minor skewing towards a T(H)2 phenotype, Rac2-deficient mice displayed no increased susceptibility to L. major infection. Cytotoxic T-lymphocyte responses to cytomegalovirus and ovalbumin were also normal. Although Rac2 is required for normal T-lymphocyte migration, its role in the generation of T(H)1 responses to infection in vivo is largely redundant.
The haematopoietic‐specific RhoGTPase, Rac2, has been indirectly implicated in T‐lymphocyte development and function, and as a pivotal regulator of T Helper 1 (TH1) responses. In other haematopoietic ...cells it regulates cytoskeletal rearrangement downstream of extracellular signals. Here we demonstrate that Rac2 deficiency results in an abnormal distribution of T lymphocytes in vivo and defects in T‐lymphocyte migration and filamentous actin generation in response to chemoattractants in vitro. To investigate the requirement for Rac2 in IFN‐γ production and TH1 responses in vivo, Rac2‐deficient mice were challenged with Leishmania major and immunized with ovalbumin‐expressing cytomegalovirus. Despite a minor skewing towards a TH2 phenotype, Rac2‐deficient mice displayed no increased susceptibility to L. major infection. Cytotoxic T‐lymphocyte responses to cytomegalovirus and ovalbumin were also normal. Although Rac2 is required for normal T‐lymphocyte migration, its role in the generation of TH1 responses to infection in vivo is largely redundant.
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