TCR V beta families in T cell clones from sarcoid lung parenchyma, BAL, and blood

Autoimmune comorbidities associated with sarcoidosis: a case-control study in the All of Us research program

Objective

The degree to which sarcoidosis patients are affected by autoimmune diseases is poorly understood. Prior studies of autoimmune co-morbidities in sarcoidosis have focused on populations outside the USA or have been impeded by small sample sizes and limited scope. This case-control study evaluated the association between sarcoidosis and autoimmune diseases in a large, diverse cohort based in the USA.

Methods

We used data from the All of Us research programme to conduct a case-control study involving patients ≥18 years old, from 2018 to the present, diagnosed with sarcoidosis. Sarcoidosis cases and age-, sex- and race-matched controls were identified in a 1:4 ratio. Autoimmune co-morbidities were compared between sarcoidosis patients and controls in univariable and multivariable analyses using logistic regression. The degree of association was measured using the odds ratio (OR).

Results

A total of 1408 sarcoidosis cases and 5632 controls were included in this study. Seven of 24 examined autoimmune diseases were significantly associated with sarcoidosis in our multivariable analysis (P < 0.05). The composite variable of any autoimmune disease was also significantly associated with sarcoidosis (OR = 2.29, P < 0.001).

Conclusion

We demonstrate an association between sarcoidosis and multiple autoimmune diseases in a large and diverse cohort based in the USA. These results underscore the need for careful screening of sarcoidosis patients for concomitant autoimmune disease.

Pathogenesis of sarcoidosis

Sarcoidosis is a systemic granulomatous disorder of unknown origin. Recent research uncovered underlying immunological and genetic mechanisms, which will pave the way for more effective pharmaceutical studies. At present some of this knowledge is clinically exploited to monitor therapy and expected genetic progress will allow the development of prognostic genetic patterns or molecular signatures. Moreover, it has become obvious that several etiologic agents and cofactors will exist. These will be of animate and inanimate nature and their interplay with host mechanisms discussed in this review determines disease phenotypes.

Sarcoidosis and molecular mimicry--important etiopathogenetic aspects: current state and future directions

Sarcoidosis is a disease of uncertainty in terms of its cause, presentation, and clinical course. The disease has a worldwide distribution and affects all ages, races, and both sex. Sarcoidosis of the skin may have an extremely heterogeneous clinical presentation, so that the definitions of 'great imitator' and 'clinical chameleon' have long been used. The factors that influence clinical picture and severity of the disease are probably linked to the etiopathogenesis of sarcoidosis, which continues to be shrouded in mystery. The current state of the art on the pathogenesis of sarcoidosis is that it is an immunological response in a genetically susceptible individual to an as-yet undefined antigenic stimulus. How exposure occurs in genetically predisposed patients is not completely clear, but the most likely explanation is that these agents or antigens are either inhaled into the lungs or enter through contact with the skin, as these are the common target organs that are constantly in contact with the environment. An autoimmune etiology of sarcoidosis could possibly occur through a process of molecular mimicry of infectious or other environmental antigens to host antigens. This could lead to a cross-mediated immune response and induction of autoimmune disease. This molecular mimicry may probably be responsible for the heterogeneous clinical presentations of the disease. Several investigations and studies have provided valuable evidence on the etiopathogenesis of sarcoidosis, which may lead to the future development of targeted and innovative treatment strategies. Nevertheless, we are still a long way from unravelling the underlying cause of this mysterious disease.

Dendritic cells in the pathogenesis of sarcoidosis

Sarcoidosis is a noncaseating granulomatous disease, likely of autoimmune etiology, that causes inflammation and tissue damage in multiple organs, most commonly the lung, but also skin, and lymph nodes. Reduced dendritic cell (DC) function in sarcoidosis peripheral blood compared with peripheral blood from control subjects suggests that blunted end organ cellular immunity may contribute to sarcoidosis pathogenesis. Successful treatment of sarcoidosis with tumor necrosis factor (TNF) inhibitors, which modulate DC maturation and migration, has also been reported. Together, these observations suggest that DCs may be important mediators of sarcoidosis immunology. This review focuses on the phenotype and function of DCs in the lung, skin, blood, and lymph node of patients with sarcoidosis. We conclude that DCs in end organs are phenotypically and functionally immature (anergic), while DCs in the lymph node are mature and polarize pathogenic Th1 T cells. The success of TNF inhibitors is thus likely secondary to inhibition of DC-mediated Th1 polarization in the lymph node.

Immunopathogenesis of sarcoidosis

The immunopathogenesis of sarcoidosis has been difficult to charaterize given the heterogeneity of disease, the elusiveness of the causative antigen, and the lack of an adequate animal model. However, by examining well-defined clinical cohorts, the interplay between genetic predisposition and immunologic response has been increasingly informative. Technological advances in cellular analysis have allowed researchers to characterize the immune responses important in the maintenance of granulomatous inflammation. Finally, "new" clinical observations such as granuloma responsiveness to targeted biological therapies, sarcoid developing during immune restoration, and the relationship between sarcoidosis and Hepatitis C will provide future insight to the immunopathogenesis of sarcoidosis.

Immunization of volunteers with Salmonella enterica serovar Typhi strain Ty21a elicits the oligoclonal expansion of CD8+ T cells with predominant Vbeta repertoires

CD8(+) T cells are likely to play an important role in host defense against Salmonella enterica serovar Typhi by several effector mechanisms, including lysis of infected cells (cytotoxicity) and gamma interferon (IFN-gamma) secretion. In an effort to better understand these responses, we studied the T-cell receptor (TCR) repertoire of serovar Typhi-specific CD8(+) T cells in humans. To this end, we determined the TCR beta chain (Vbeta) usage of CD8(+) T cells from three volunteers orally immunized with Ty21a typhoid vaccine by flow cytometry using a panel of monoclonal antibodies. Although TCR Vbeta usage varied among volunteers, we identified oligoclonal Vbeta subset expansions in individual volunteers (Vbeta 2, 5.1, 8, 17, and 22 in volunteer 1; Vbeta 1, 2, 5.1, 14, 17, and 22 in volunteer 2; and Vbeta 3, 8, 14, and 16 in volunteer 3). These subsets were antigen specific, as shown by cytotoxicity and IFN-gamma secretion assays on Vbeta sorted cells and on T-cell clones derived from these volunteers. Moreover, eight-color flow cytometric analysis showed that these clones exhibited a T effector memory phenotype (i.e., CCR7(-) CD27(-) CD45RO(+) CD62L(-)) and coexpressed gut homing molecules (e.g., high levels of integrin alpha4beta7, intermediate levels of CCR9, and low levels of CD103). In conclusion, our results show that long-term T-cell responses to serovar Typhi in Ty21a vaccinees are oligoclonal, involving multiple TCR Vbeta families. Moreover, these serovar Typhi-specific CD8(+) T cells bearing defined Vbeta specificities are phenotypically and functionally consistent with T effector memory cells with preferential gut homing potential.

Characterization of the Interstitial Lung and Peripheral Blood T Cell Receptor Repertoire in Cigarette Smokers

T lymphocytes modulate the pulmonary inflammatory response. The aim of this study was to evaluate the clonality within the interstitial lung and peripheral blood T cell receptor (TCR) repertoire in smokers. Interstitial T lymphocytes were isolated from surplus tissue of 16 patients (63 +/- 9 [+/- SD] yr old, 11 male) undergoing surgery due to lung cancer (n = 15) or emphysema. TCR clonality was assessed by PCR amplification followed by spectratyping. Nearly all TCR of interstitial lung lymphocytes showed oligoclonal bands (CD4(+) subset 13/16 patients, 81%; CD8(+) 100%) indicating a specific differentiation. Peripheral blood T lymphocytes (PBL) TCR (especially CD4(+)) had less oligoclonal bands (CD4(+) 31%, CD8(+) 88%). Likewise, more oligoclonal bands were seen in lung TCR (total of 168 bands; 37 CD4(+); 131 CD8(+)), compared with 59 bands in PBL TCR (13 CD4(+); 46 CD8(+)). Intraindividual comparison revealed a more prominent difference in TCR oligoclonality between lung and blood in CD8(+) T cells (median of difference lung minus blood 5; interquartile range 1-10; P = 0.002) compared with CD4(+) T cells (median 2, 0-3, P = 0.039). Thus, TCR oligoclonality is preferentially found in the CD8(+) T cell subset, most distinctive in the lung. These findings indicate a specific interstitial T cell differentiation in response to local stimuli.

Conserved CDR 3 region of T cell receptor BV gene in lymphocytes from bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an inflammatory lung disease characterized by the accumulation of inflammatory cells and deposition of collagen, resulting in lung remodelling. High numbers of T cells are present in bronchoalveolar lavage fluid (BALF) of IPF patients, although the characteristics of these cells are yet to be determined. To elucidate the pathogenic mechanisms of IPF, we analysed the T cell receptor (TCR) of BALF lymphocytes in three patients with IPF and three healthy subjects as control. TCR repertoire of BALF lymphocytes and T cell clonality were examined by family PCR and Southern blot analysis, and single-strand conformation polymorphism (SSCP), respectively. We observed that the TCR repertoire in the lung was heterogeneous, both in the control subjects and three patients with IPF. SSCP analysis demonstrated an increase in the number of accumulated T cell clones in BALF of two of the three patients, but not in the healthy subject. Furthermore, junctional sequence analysis showed the presence of conserved amino acid motifs (ETGRSG, LAxG, QGQ, GxQP, GRxG, VAR, PGT, GTI, GGT, TGR, LxLxQ, SGQ) in the TCR-CDR 3 region of BAL lymphocytes in patients with IPF, whereas only two amino acid motifs (VTTG, GGE) were found in the control. Our findings suggest that T cells in BALF of patients with IPF expand oligoclonally in the lung, suggesting antigen stimulation of these cells.

Expression of thioredoxin in granulomas of sarcoidosis: possible role in the development of T lymphocyte activation

BACKGROUND

Activated T lymphocytes are one of the characteristic features of sarcoidosis. The mechanism of T cell activation, expressing various activation markers including interleukin 2 receptor (IL-2R), has been extensively investigated but the precise mechanism remains unknown. Although thioredoxin (TRX) displays a number of biological activities including IL-2R inducing activity, its role in the induction of IL-2R expression on T cells in sarcoidosis has not been determined. The expression of TRX and IL-2R in granulomas of patients with sarcoidosis has been studied to clarify a possible role for TRX in the induction of IL-2R expression.

METHODS

Granulomas in specimens of lung tissue and lymph nodes from five patients with sarcoidosis were immunohistochemically stained with anti-TRX antibody and anti-IL-2Ralpha chain antibody and the concentration of TRX in the bronchoalveolar lavage (BAL) fluid from 20 patients with pulmonary sarcoidosis was measured.

RESULTS

Granulomas in lung and lymph node tissue from patients with sarcoidosis showed strong reactivity with anti-TRX antibody. Positive staining was present in the macrophages, epithelioid cells, and Langhans' type giant cells but not in lymphocytes. IL-2R was expressed on lymphocytes in the same granulomas. By contrast, positive immunoreactivity was not found in lung tissue specimens from 12 control subjects. Concentrations of TRX in BAL fluid were higher in patients with pulmonary sarcoidosis (median (range) 122.6 (20.9-303.3) ng/ml) than in control subjects (32.9 (16.8-52.8) ng/ml, p<0.05).

CONCLUSIONS

TRX is highly expressed and is locally produced by granulomas in patients with sarcoidosis. The coexistence of immunoreactive TRX and IL-2R in the same granulomas suggests that TRX might act as a local inducing factor for IL-2R expression on T cells.

T-cell receptor gene usage in patients with fibrosing alveolitis and control subjects

BACKGROUND

Fibrosing alveolitis is characterized by inflammation, fibrosis and increased numbers of activated CD4+ T-cells in the lower respiratory tract. The aims of this study were to compare the T-cell antigen receptor repertoire in the lungs of subjects with fibrosing alveolitis systemic sclerosis (FASSc) with cryptogenic fibrosing alveolitis (CFA) and normal control subjects, to determine whether FASSc is driven by a specific T-cell trigger and is determined by a T-cell driven immune response, and to assess the clonality of CD4+ and CD8+ TcR usage in subjects with FASSc.

MATERIALS AND METHODS

We used reverse transcription polymerase chain reaction with specific V alpha- and V beta-chain primers to identify the TcR gene usage in biopsy material, bronchoalveolar lavage fluid or peripheral blood from our subjects.

RESULTS

We found individual-specific restriction of V alpha- and V beta-chain usage in lung biopsies from patients and control subjects. To establish whether this was due to expression bias in the CD4+ or CD8+ T-cells and was restricted to the lung, the alpha beta-T-cell receptor chain usage was assessed in T-cell subsets separated from the lungs of patients with fibrosing alveolitis and was compared with that of the peripheral blood. There was no consistent difference in the expression of any variable family chain among the population studied, although there was a significant difference between lung and peripheral blood lymphocyte V beta-families in CD8+ T-cells (P = 0.0007).

CONCLUSION

We conclude that there is individual TcR V alpha- and V beta-expression bias in subjects with fibrosing alveolitis.