CCL13 is a promising diagnostic marker for systemic sclerosis.

BACKGROUND: Previous studies suggest that CCL13 may have some role in the pathogenesis of systemic sclerosis (SSc). OBJECTIVES: To determine serum levels of CCL13 and its clinical associations in patients with SSc. METHODS: Serum CCL13 levels were examined by enzyme-linked immunosorbent assay in 80 patients with SSc, 20 patients with systemic lupus erythematosus (SLE), 20 patients with dermatomyositis (DM), 29 patients with atopic dermatitis (AD) and 50 healthy individuals. RESULTS: Mean + or - SD serum CCL13 levels were elevated in patients with SSc (81.3 + or - 55.8 pg mL(-1)) compared with healthy controls (15.0 + or - 9.9 pg mL(-1); P < 0.001) and patients with SLE (22.0 + or - 6.9 pg mL(-1); P < 0.001), DM (24.4 + or - 36.1 pg mL(-1); P < 0.001) and AD (18.0 + or - 6.4 pg mL(-1); P < 0.001). Among patients with SSc, there were no differences in serum CCL13 levels between limited cutaneous SSc and diffuse cutaneous SSc. In a longitudinal study, CCL13 levels were generally unchanged during the follow-up. CONCLUSIONS: Serum CCL13 was specifically increased in patients with SSc, but not in patients with SLE, DM or AD or in healthy controls. CCL13 could be a promising serological marker for SSc.

Autoantibody against activating transcription factor-2 in patients with systemic sclerosis.

OBJECTIVES: To determine the prevalence and clinical correlation of autoantibody to activating transcription factor (ATF)-2, a transcription factor of ATF/CREB family, in patients with systemic sclerosis (SSc). METHODS: Anti-ATF-2 Ab was examined by ELISA and immunoblotting using human recombinant ATF-2. ATF-2 activity to bind target DNA was evaluated by ELISA using a plate coated with oligonucleotide containing the consensus binding site for ATF-2. RESULTS: IgG anti-ATF-2 Ab levels in SSc patients (n=69) were significantly higher than those in normal controls (n=26). SSc patients positive for IgG anti-ATF-2 Ab had significantly longer disease duration, more frequent presence of decreased %VC and %DLco, and elevated levels of serum IgG, serum IgA, and erythrocyte sedimentation rates than those negative. More-over, IgG anti-ATF-2 Ab levels correlated inversely with %VC or %DLco. The presence of anti-ATF-2 Ab in SSc patients was confirmed by immunoblotting analysis. IgG isolated from serum samples of SSc patients positive for IgG anti-ATF-2 Ab by ELISA slightly but significantly inhibited ATF-2 activity compared with normal controls. CONCLUSIONS: These results suggest that anti-ATF-2 Ab is a new autoantibody in SSc and that it serves as a novel serological marker for inflammation and lung involvement in SSc.

Serum levels of heat shock protein 70, a biomarker of cellular stress, are elevated in patients with systemic sclerosis: association with fibrosis and vascular damage.

OBJECTIVE: To determine the clinical significance of heat shock protein (Hsp) 70, a sensitive biomarker for monitoring cellular stress, in systemic sclerosis (SSc), we investigated the prevalence and clinical correlation of serum Hsp70 levels in SSc patients. METHODS: Serum Hsp70 levels were examined in 48 patients with SSc by enzyme-linked immunosorbent assay. RESULT: Serum Hsp70 levels were significantly elevated in SSc patients compared to normal controls (n=30), and were similar between patients with diffuse cutaneous SSc (n=26) and those with limited cutaneous SSc (n=22). Serum Hsp70 levels were elevated in 27% of total SSc patients with 30% of diffuse cutaneous SSc patients and 23% of limited cutaneous SSc patients. Hsp70 levels were significantly increased in SSc patients with pulmonary fibrosis or contracture of phalanges compared with those without pulmonary fibrosis or contracture of phalanges. Serum Hsp70 levels correlated positively with modified Rodnan total skin thickness score, renal vascular resistance, serum levels of monocyte chemotactic protein-1, C-reacting protein, and serum levels of 8-isoprostane. CONCLUSION: Serum Hsp70 levels were increased in SSc patients and were associated with pulmonary fibrosis, skin sclerosis, renal vascular damage, oxidative stress, and inflammation. These results suggest that Hsp70 is a useful serological marker for evaluating cellular stresses and the disease severity in SSc.

Involvement of gaseous low molecular monoxides in the cutaneous reverse passive Arthus reaction: cytoprotective action of carbon monoxide.

The deposition of immune complexes (IC) induces an acute inflammatory response with tissue injury, for which the involvement of nitric oxide (NO) and carbon monoxide (CO) has been suggested. NO is induced by NO synthase (NOS) and CO is generated by haeme oxygenase (HO). Among HO isoenzymes, HO-1 is an induced type. To assess the role of NO and CO in the pathogenic process, the cutaneous reverse passive Arthus reaction was examined using NOS inhibitor, HO-1 stimulator and HO-1 inhibitor. To evaluate the reaction we considered oedema, tumour necrosis factor-alpha, interleukin-6, and neutrophil number. The values of these four parameters were significantly reduced in mice treated with HO-1 stimulator as compared with the positive control mice. Quite the reverse was observed in mice treated with HO-1 inhibitor. These results suggest that the HO-1/CO signalling pathway is a therapeutic target for human IC-mediated disease.

Autoantibody against a protease domain of caspase-8 in patients with systemic sclerosis.

BACKGROUND: Systemic sclerosis (SSc) is characterized by autoantibodies against various cellular components. OBJECTIVE: To determine the presence or levels of antibodies (Abs) against a protease domain (PD) of caspase-8 and their clinical relevance in SSc. METHODS: Anti-caspase-8 PD Ab was examined by enzyme-linked immunosorbent assay and immunoblotting using human recombinant caspase-8 PD. Caspase-8 activity was evaluated by spectrophotometric detection of cleavage from p-nitroanilide-labeled IETD, a substrate of caspase-8. RESULTS: IgG anti-caspase-8 PD Ab levels in patients with SSc, systemic lupus erythematosus, or dermatomyositis were higher than in normal controls (CTL). Furthermore, anit-caspase-8 PD Ab levels in limited cutaneous SSc (ISSc) patients were elevated compared to diffuse cutameous SSc (dSSc) patients. To investigate the clinical correlation, laboratory findings were compared between SSc patients with high levels (>the mean+2SD of CTL) of anti-caspase-8 PD Ab and those with low levels. SSc patients with high level exhibited lower frequency of male and decreased C-reactive protein levels relative to those with low levels. Immunoblotting showed the anit-caspase-8 PD Ab was present in all SSc patients examined, while it was also detected in 75% of CTL. Caspase-8 activity was inhibited by IgG isolated from sera of SSc patients and CTL, although inhibitory effect was greater in SSc patients than CTL. CONCLUSION: These results suggest that immune response to caspase-8 occurs in healthy individuals, although it is greater in patients with systemic autoimmune diseases including SSc. Furthermore, high level of anti-caspase-8 PD Ab may be a serological indicator for a milder SSc subset.

Increased serum levels of nitrotyrosine, a marker for peroxynitrite production, in systemic sclerosis.

OBJECTIVE: To determine serum levels of nitrotyrosine (NT), an end product of peroxynitrite (ONOO-), and its clinical association in patients with systemic sclerosis (SSc). METHODS: Serum NT levels from 25 patients with limited cutaneous SSc (lSSc) and 34 patients with diffuse cutaneous SSc (dSSc) were examined by enzyme-linked immunosorbent assay. RESULTS: Serum NT levels were elevated in SSc patients compared with normal controls (n = 27), the levels being similar between lSSc and dSSc patients (P < 0.001). SSc patients with elevated NT had higher serum levels of anti- agalactosyl IgG Ab, IgG and IgA than those with normal NT levels (P < 0.05). NT levels correlated inversely with the percentage diffusion capacity for carbon monoxide (DLco) (P < 0.02, r = -0.414, n = 47). CONCLUSION: These results suggest that ONOO- may play an important role in the clinical manifestations of SSc, especially vascular damage to the lungs, and that ONOO- may be related to immunological abnormalities in SSc.

Autoantibody against peroxiredoxin I, an antioxidant enzyme, in patients with systemic sclerosis: possible association with oxidative stress.

OBJECTIVES: To determine the prevalence and clinical correlation of autoantibody to peroxiredoxin (Prx) I, an antioxidant enzyme, in patients with systemic sclerosis (SSc). METHODS: Serum samples from SSc patients (n = 70) and healthy controls (n = 23) were examined by ELISA using human recombinant Prx I. The presence of anti-Prx I antibody was further evaluated by immunoblotting analysis. To determine the functional relevance of anti-Prx I antibody in vivo, we assessed whether anti-Prx I antibody was able to inhibit Prx I enzymatic activity using yeast thioredoxin reductase system. RESULTS: IgG anti-Prx I antibody levels in SSc patients were significantly higher than healthy controls and this autoantibody was detected in 33% of SSc patients. The presence of IgG anti-Prx I antibody was associated with longer disease duration, more frequent presence of pulmonary fibrosis, heart involvement, and anti-topoisomerase I antibody and increased levels of serum immunoglobulin and erythrocyte sedimentation rates. IgG anti-Prx I antibody levels also correlated positively with renal vascular damage and negatively with pulmonary function tests. Furthermore, anti-Prx I antibody levels correlated positively with serum levels of 8-isoprostane, a marker of oxidative stress. Immunoblotting analysis confirmed the presence of anti-Prx I antibody. Remarkably, Prx I enzymatic activity was inhibited by IgG isolated from SSc sera containing IgG anti-Prx I antibody. CONCLUSIONS: These results suggest that elevated IgG anti-Prx I autoantibody is associated with the disease severity of SSc and that anti-PrxI antibody may enhance the oxidative stress by inhibiting Prx I enzymatic activity.

Serum levels of 8-isoprostane, a marker of oxidative stress, are elevated in patients with systemic sclerosis.

OBJECTIVE: To determine serum levels and clinical correlation of 8-isoprostane, which is produced in vivo through free radical-catalysed peroxidation of arachidonic acid and reflects oxidative stress, in patients with systemic sclerosis (SSc). METHODS: Serum 8-isoprostane levels from 32 patients with diffuse cutaneous SSc (dSSc) and 25 patients with limited cutaneous SSc (lSSc) were examined by enzyme-linked immunosorbent assay. RESULTS: Serum 8-isoprostane levels were elevated in dSSc and lSSc patients by 75-fold compared with normal controls (n=32). Serum 8-isoprostane levels correlated negatively with pulmonary function, such as percentage vital capacity and diffusion capacity for carbon monoxide, and correlated positively with renal vascular damage determined by colour flow Doppler ultrasonography. Serum 8-isoprostane levels also correlated positively with serum levels of IgG and anti-agalactosyl IgG autoantibody. CONCLUSION: Increased 8-isoprostane levels correlated with the severity of pulmonary fibrosis, the extent of renal vascular damage and immunological abnormalities in SSc, suggesting that enhanced oxidative stress is related to the development of SSc.