Identification of multiple public TCR repertoires in chronic beryllium disease.

Chronic beryllium disease (CBD) is a granulomatous lung disease characterized by the accumulation of beryllium (Be)-specific CD4(+) T cells in bronchoalveolar lavage. These expanded CD4(+) T cells are composed of oligoclonal T cell subsets, suggesting their recruitment to the lung in response to conventional Ag. In the current study, we noted that all bronchoalveolar lavage-derived T cell lines from HLA-DP2-expressing CBD patients contained an expansion of Be-responsive Vß5.1(+) CD4(+) T cells. Using Be-loaded HLA-DP2-peptide tetramers, the majority of tetramer-binding T cells also expressed Vß5.1 with a highly conserved CDR3ß motif. Interestingly, Be-specific, Vß5.1-expressing CD4(+) T cells displayed differential HLA-DP2-peptide tetramer staining intensity, and sequence analysis of the distinct tetramer-binding subsets showed that the two populations differed by a single conserved amino acid in the CDR3ß motif. TCR Vα-chain analysis of purified Vß5.1(+) CD4(+) T cells based on differential tetramer-binding intensity showed differing TCR Vα-chain pairing requirements, with the high-affinity population having promiscuous Vα-chain pairing and the low-affinity subset requiring restricted Vα-chain usage. Importantly, disease severity, as measured by loss of lung function, was inversely correlated with the frequency of tetramer-binding CD4(+) T cells in the lung. Our findings suggest the presence of a dominant Be-specific, Vß5.1-expressing public T cell repertoire in the lungs of HLA-DP2-expressing CBD patients using promiscuous Vα-chain pairing to recognize an identical HLA-DP2-peptide/Be complex. Importantly, the inverse relationship between expansion of CD4(+) T cells expressing these public TCRs and disease severity suggests a pathogenic role for these T cells in CBD.

IL-17A-expressing T cells are essential for bacterial clearance in a murine model of hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HP) is an inflammatory lung disease characterized by a diffuse mononuclear cell infiltrate in the lung that can progress to pulmonary fibrosis with chronic exposure to an inhaled Ag. We previously reported that C57BL/6 mice repeatedly exposed to the ubiquitous microorganism Bacillus subtilis develop mononuclear infiltrates in the lung that contain Vgamma6/Vdelta1(+) gammadelta T cells. In the absence of this T cell subset, mice treated with B. subtilis had significantly increased collagen deposition in the lung, suggesting a regulatory role for Vgamma6/Vdelta1(+) gammadelta T cells. To further investigate the role of Vgamma6/Vdelta1(+) gammadelta T cells in B. subtilis-induced lung fibrosis, we exposed transgenic Vgamma6/Vdelta1 mice to this microorganism and found decreased collagen content in the lung compared with wild-type C57BL/6 mice. Cytokine analysis of lung homogenates from wild-type C57BL/6 mice demonstrated increased IL-17A concentrations with repeated exposure to B. subtilis. In the absence of IL-17 receptor signaling, IL-17ra(-/-) mice had delayed clearance of B. subtilis with increased lung inflammation and fibrosis. Although IL-17A was predominantly expressed by Vgamma6/Vdelta1(+) T cells, a compensatory increase in IL-17A expression by CD4(+) T cells was seen in the absence of gammadelta T cells that resulted in similar levels of IL-17A in the lungs of TCRdelta(-/-) and wild-type C57BL/6 mice. In combination, our data suggest an important role for IL-17A-expressing T lymphocytes, both gammadelta and alphabeta T cells, in eliminating this microorganism that prevents excessive inflammation and eventual lung fibrosis in this murine model of B. subtilis-induced hypersensitivity pneumonitis.

Th17-polarized immune response in a murine model of hypersensitivity pneumonitis and lung fibrosis.

Hypersensitivity pneumonitis is an environmental lung disease characterized by a diffuse mononuclear cell infiltrate in the lung that can progress to pulmonary fibrosis with chronic exposure to an inhaled Ag. Using a well-established murine model of hypersensitivity pneumonitis, we repeatedly exposed C57BL/6 mice to Saccharopolyspora rectivirgula to investigate whether T cells are required for lung fibrosis. In the absence of alphabeta T cells, TCRbeta(-/-) mice exposed to S. rectivirgula for 4 wk had markedly decreased mononuclear infiltrates and collagen deposition in the lung compared with wild-type C57BL/6 mice. In contrast to CD8(+) T cells, adoptive transfer of CD4(+) T cells reconstituted the S. rectivirgula-induced inflammatory and fibrotic response, suggesting that the CD4(+) T cell represents the critical alphabeta T cell subset. Cytokine analysis of lung homogenates at various time points after S. rectivirgula exposure failed to identify a predominant Th1 or Th2 phenotype. Conversely, IL-17 was found in the lung at increasing concentrations with continued exposure to S. rectivirgula. Intracellular cytokine staining revealed that 14% of CD4(+) T cells from the lung of mice treated with S. rectivirgula expressed IL-17A. In the absence of IL-17 receptor signaling, Il17ra(-/-) mice had significantly decreased lung inflammation and fibrosis compared with wild-type C57BL/6 mice. These data are the first to demonstrate an important role for Th17-polarized CD4(+) T lymphocytes in the immune response directed against S. rectivirgula in this murine model of hypersensitivity pneumonitis and pulmonary fibrosis.

Increased Serum Levels of Activated Caspases in Murine and Human Biliary Atresia.

In biliary atresia (BA), apoptosis is part of the pathomechanism, which results in progressive liver fibrosis. There is increasing evidence suggesting that apoptotic liver injury can be non-invasively detected by measuring the caspase activity in the serum. The purpose of this study was to investigate whether serological detection of caspase activation mirrors apoptotic liver injury in the infective murine BA-model and represents a suitable biomarker for BA in humans. Analysis showed increased caspase-3 activity and apoptosis in the livers of cholestatic BALB/c mice, which correlated significantly with caspase activation in the serum. We then investigated caspase activation and apoptosis in liver tissues and sera from 26 BA patients, 23 age-matched healthy and 11 cholestatic newborns, due to other hepatopathies. Compared to healthy individuals, increased caspase activation in the liver samples of BA patients was present. Moreover, caspase-3 activity was significantly higher in sera from BA infants compared to patients with other cholestatic diseases (sensitivity 85%, specificity 91%). In conclusion, caspase activation and hepatocyte apoptosis play an important role in experimental and human BA. We demonstrated that serological detection of caspase activation represents a reliable non-invasive biomarker for monitoring disease activity in neonatal cholestatic liver diseases including BA.

Cholangiocytes as immune modulators in rotavirus-induced murine biliary atresia.

BACKGROUND/AIMS: Biliary atresia (BA) is a progressive disease characterized by bile duct inflammation and fibrosis. The aetiology is unknown and may be due to a virus-induced, autoimmune-mediated injury of cholangiocytes. Cholangiocytes are not only targets of injury but may also modulate hepatic inflammation. The aim of this study was to determine the immune profile of murine cholangiocytes and the ability to function as antigen-presenting cells (APCs) in culture with Rhesus rotavirus (RRV), poly I:C (viral mimic) or interferon-gamma/tumour necrosis factor-alpha. METHODS/RESULTS: Both the cholangiocyte cell line (long-term culture) and fresh, ex vivo cholangiocytes expressed APC surface markers major histocompatibility complex (MHC)-class I and II and CD40, while only the cultured cell line expressed costimulatory molecules B7-1 and B7-2. Despite APC expression, cultured cholangiocytes were unable to function as competent APCs in T-cell proliferation assays. Furthermore, both cultured and ex vivo cholangiocytes expressed RNA transcripts for many pro-inflammatory cytokines and chemokines. CONCLUSIONS: Although cholangiocytes contain APC molecules, they are incompetent at antigen presentation and cannot elicit effective T-cell activation. Upregulation of MHC-class I and II found in BA mice may serve to prime the cholangiocyte as a target for immune-mediated injury. Cholangiocytes produced many pro-inflammatory cytokines and chemokines in the setting of RRV infection and T-helper type 1 cytokine milieu, suggesting a role of cholangiocytes as immune modulators promoting the ongoing inflammation that exists in RRV-induced BA.

Ingested partial denture mimicking perforated diverticular disease.

Denture ingestion is a rare clinical entity among foreign body ingestions. The caveat is that there is often no recollection of the event and that dentures are radiolucent and as such hard to identify on conventional imaging. To date not all dentures contain radiopaque marker. Here we present the case of a 52-year-old male who was admitted with clinical and radiological signs of perforated diverticular disease. A curvilinear metallic foreign body was picked up on repeat CT imaging at day 3, which was part of an unknowingly swallowed partial denture that became impacted and perforated the sigmoid colon. The patient underwent an uneventful laparoscopic anterior resection and was discharged home a week later. We conclude that all dentures should contain a radiopaque marker in order to avoid failure in radiological detection and thus prevent misdiagnosis and inappropriate treatment.

γδ T cells protect against LPS-induced lung injury.

γδ T lymphocytes are a unique T cell population with important anti-inflammatory capabilities. Their role in acute lung injury, however, is poorly understood but may provide significant insight into lung-protective mechanisms occurring after injury. In a murine model of lung injury, wild-type C57BL/6 and TCRδ(-/-) mice were exposed to Escherichia coli LPS, followed by analysis of γδ T cell and macrophage subsets. In the absence of γδ T cells, TCRδ(-/-) mice developed increased inflammation and alveolar-capillary leak compared with wild-type C57BL/6 mice after LPS exposure that correlated with expansion of distinct macrophage populations. Classically activated M1 macrophages were increased in the lung of TCRδ(-/-) mice at d 1, 4, and 7 after LPS exposure that peaked at d 4 and persisted at d 7 compared with wild-type animals. In response to LPS, Vγ1 and Vγ7 γδ T cells were expanded in the lung and expressed IL-4. Coculture experiments showed decreased expression of TNF-α by resident alveolar macrophages in the presence of γδ T cells that was reversed in the presence of an anti-IL-4-blocking antibody. Treatment of mice with rIL4 resulted in reduced numbers of M1 macrophages, inflammation, and alveolar-capillary leak. Therefore, one mechanism by which Vγ1 and Vγ7 γδ T cells protect against LPS-induced lung injury is through IL-4 expression, which decreases TNF-α production by resident alveolar macrophages, thus reducing accumulation of M1 macrophages, inflammation, and alveolar-capillary leak.

γδ T cells protect against lung fibrosis via IL-22.

Inflammation-induced pulmonary fibrosis (PF) leads to irreversible loss of lung function and is a predictor of mortality in numerous lung diseases. Why some subjects with lung inflammation but not others develop PF is unclear. In a mouse model of hypersensitivity pneumonitis that progresses to lung fibrosis upon repeated exposure to the ubiquitous microorganism Bacillus subtilis, γδ T cells expand in the lung and inhibit collagen deposition. We show that a subset of these γδ cells represents the predominant source of the Th17 cytokine IL-22 in this model. Preventing expression of IL-22, either by mutating the aryl hydrocarbon receptor (AhR) or inhibiting AhR signaling, accelerated lung fibrosis. Direct blockade of IL-22 also enhanced collagen deposition in the lung, whereas administration of recombinant IL-22 inhibited lung fibrosis. Moreover, the presence of protective γδ T cells and IL-22 diminished recruitment of CD4(+) T cells to lung. These data reveal a protective pathway that involves the inhibition of αß T cells by regulatory IL-22-secreting γδ T cells.