Spontaneous activation of transforming growth factor-beta gene transcription in broncho-alveolar mononuclear cells of individuals with systemic autoimmune diseases with lung involvement

Deltex1 suppresses T cell function and is a biomarker for diagnosis and disease activity of systemic lupus erythematosus

OBJECTIVE

Deletion of Deltex1 (DTX1) in mice caused hyperactivation of T cells and lupus-like autoimmune syndromes, however, the association of DTX1 with human autoimmune diseases is totally unknown. This study investigated the role of DTX1 in human T cell functions and its correlation with disease activity in patients with SLE.

METHODS

The influence of DTX1 on T cell function was evaluated using human primary cells. DTX1 expression in peripheral blood mononuclear cells (PBMCs) from healthy controls and SLE patients was measured by quantitative real-time PCR and the SLEDAI was used to assess disease activity.

RESULTS

After stimulation with anti-CD3 and anti-CD28, silencing of DTX1 expression enhanced IFN-γ secretion by human T cells. The expression of DTX1 in PBMCs was significantly lower in 100 SLE patients than in 50 age- and sex-matched healthy controls (DTX1/glyceraldehyde 3-phosphate dehydrogenase, 0.452 vs 1.269, P < 0.001). The area under the receiver operator characteristics curve of the model was 0.737 (95% CI 0.658, 0.815). Intriguingly, a low DTX1 level in T cells led to high IFN-γ production in SLE patients and had a correlation with severe disease activity. In addition, low DTX1 expression in SLE patients was associated with active LN, lung involvement or hypocomplementaemia.

CONCLUSION

Knockdown DTX1 expression in human T cells reduced IFN-γ secretion. DTX1 expression in the PBMCs was significantly lower in SLE patients and had an inverse correlation with disease activity, indicating that the DTX1 level may be a good disease marker of SLE.

Constitutive ALK5-independent c-Jun N-terminal kinase activation contributes to endothelin-1 overexpression in pulmonary fibrosis: evidence of an autocrine endothelin loop operating through the endothelin A and B receptors

The signal transduction mechanisms generating pathological fibrosis are almost wholly unknown. Endothelin-1 (ET-1), which is up-regulated during tissue repair and fibrosis, induces lung fibroblasts to produce and contract extracellular matrix. Lung fibroblasts isolated from scleroderma patients with chronic pulmonary fibrosis produce elevated levels of ET-1, which contribute to the persistent fibrotic phenotype of these cells. Transforming growth factor beta (TGF-beta) induces fibroblasts to produce and contract matrix. In this report, we show that TGF-beta induces ET-1 in normal and fibrotic lung fibroblasts in a Smad-independent ALK5/c-Jun N-terminal kinase (JNK)/Ap-1-dependent fashion. ET-1 induces JNK through TAK1. Fibrotic lung fibroblasts display constitutive JNK activation, which was reduced by the dual ETA/ETB receptor inhibitor, bosentan, providing evidence of an autocrine endothelin loop. Thus, ET-1 and TGF-beta are likely to cooperate in the pathogenesis of pulmonary fibrosis. As elevated JNK activation in fibrotic lung fibroblasts contributes to the persistence of the myofibroblast phenotype in pulmonary fibrosis by promoting an autocrine ET-1 loop, targeting the ETA and ETB receptors or constitutive JNK activation by fibrotic lung fibroblasts is likely to be of benefit in combating chronic pulmonary fibrosis.

Cytokine regulation of pulmonary fibrosis in scleroderma

Pulmonary fibrosis occurs in up to 70% of scleroderma patients and progresses to cause severe restrictive lung disease in about 15% of patients. The mechanisms that cause pulmonary fibrosis in scleroderma remain incompletely understood. Increased amounts of mRNA or protein for multiple profibrotic cytokines and chemokines have been identified in lung tissue or broncholveolar lavage samples from scleroderma patients, when compared to healthy controls. These cytokines include transforming growth factor (TGF)-beta, connective tissue growth factor (CTGF), platelet-derived growth factor (PDGF), oncostatin M (OSM), monocyte chemotactic factor-1 and pulmonary and activation-regulated chemokine (PARC). Potential cellular sources of these profibrotic cytokines and chemokines in scleroderma lung disease include alternatively activated macrophages, activated CD8+ T cells, eosinophils, mast cells, epithelial cells and fibroblasts themselves. This review summarizes the literature on involvement of cytokines and chemokines in the development of pulmonary fibrosis in scleroderma.

Immunomodulatory cytokines in asthmatic inflammation

The development of asthmatic inflammation involves a complex array of cytokines that promote the recruitment and activation of a number of different immune cells. While factors involved in initiating and establishing inflammation are well characterized, the process by which this pro-inflammatory cascade is regulated is less well understood. The identification and characterization of immunomodulatory cytokines in asthma has been a difficult proposition. Many of the putative regulatory factors have pleiotropic bioactivities and have been characterized as pro-inflammatory in association with certain pathologic conditions. This chapter addresses the potential role of several endogenous factors which appear to attenuate asthmatic inflammation. Understanding the integration of these factors into the regulation of the inflammatory process will likely result in novel therapeutic approaches.

Interstitial lung disease in scleroderma

Pulmonary fibrosis occurs most patients who have scleroderma. It progresses to severe restrictive lung disease in about 15% of patients and remains a major cause of death in this disease. Risks for developing pulmonary fibrosis include diffuse cutaneous scleroderma and anti-Scl-70 antibodies, and risks for developing progressive pulmonary fibrosis and death include low pulmonary function test results at presentation and lung inflammation. Early evaluation of the extent and severity of pulmonary fibrosis and the presence of lung inflammation is key, so that therapy can be given to patients who are at higher risk of progressive pulmonary fibrosis before they develop severe functional impairment occurs. Evaluation often includes pulmonary function tests, HRCT of the lungs, Doppler echocardiogram, and bronchoalveolar lavage. For patients who are unwilling or unable to participate in therapeutic trials that target pulmonary fibrosis in scleroderma, therapy with oral or intravenous cyclophosphamide is often given.

Elevation of bioactive transforming growth factor-beta in serum from patients with chronic fatigue syndrome

The level of bioactive transforming growth factor-beta (TGF-beta) was measured in serum from patients with chronic fatigue syndrome (CFS), healthy control subjects, and patients with major depression, systemic lupus erythematosis (SLE), and multiple sclerosis (MS) of both the relapsing/remitting (R/R) and the chronic progressive (CP) types. Patients with CFS had significantly higher levels of bioactive TGF-beta levels compared to the healthy control major depression, SLE, R/R MS, and CP MS groups (P < 0.01). Additionally, no significant differences were found between the healthy control subjects and any of the disease comparison groups. The current finding that TGF-beta is significantly elevated among patients with CFS supports the findings of two previous studies examining smaller numbers of CFS patients. In conclusion, TGF-beta levels were significantly higher in CFS patients compared to patients with various diseases known to be associated with immunologic abnormalities and/or pathologic fatigue. These findings raise interesting questions about the possible role of TGF-beta in the pathogenesis of CFS.