Proprotein convertase enzyme FURIN is upregulated in primary Sjögren's syndrome

OBJECTIVES

The proprotein convertase enzyme FURIN is a critical regulator of the anti-inflammatory TGFβ-1 cytokine and peripheral immune tolerance. In T cells, FURIN is co-regulated with IFN-γ and thus highly expressed in T helper 1 type cells. Previous studies have demonstrated that FURIN is upregulated in inflammatory conditions, including atherosclerosis, rheumatoid arthritis and systemic lupus erythematosus. Here, we evaluated the levels of FURIN in the plasma and peripheral blood mononuclear cells (PBMCs) of patients with primary Sjögren's syndrome (pSS) and in healthy controls.

METHODS

FURIN plasma levels were determined by ELISA, and the mRNA expression in PBMCs was quantitated using qPCR. FURIN levels in the plasma were correlated with the clinical and demographic characteristics of the patients.

RESULTS

FURIN was found to be significantly upregulated at both the protein and mRNA level in pSS patients compared to healthy controls. In pSS patients, high FURIN protein levels were significantly associated with elevated IFN-γ levels in the plasma as well as a longer duration of sicca symptoms in the eyes. pSS patients with high FURIN levels in their plasma showed a trend towards lower levels of serum beta-2 microglobulin, ESR and a lower systemic disease activity index ESSDAI.

CONCLUSIONS

The proprotein convertase FURIN is significantly upregulated in pSS. Elevated FURIN levels associate with high levels of the Th1 type cytokine IFN-γ and long duration of dry eye symptoms. Patients with high FURIN levels show signs of lower disease activity suggesting that FURIN might have a protective role in pSS.

Cytokine-induced STAT1 activation is increased in patients with primary Sjögren's syndrome

Limited data are available regarding the intracellular responses to different cytokines in primary Sjögren's syndrome (pSS). We studied the signal transducer and activator of transcription (STAT) activation profile in response to cytokine stimulations in peripheral blood mononuclear cells (PBMCs) from pSS patients by multicolor flow cytometry. The expression of the suppressors of cytokine signaling (SOCS), and interferon (IFN)-γ target genes in PBMCs was studied using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). The induction of STAT1 phosphorylation in response to stimulation with IFN-α, IFN-γ or interleukin (IL)-6 was significantly increased in B cells and monocytes from pSS patients. Accordingly, the STAT1-mediated gene responses were significantly enhanced in PBMCs from pSS patients. Finally, the expression of SOCS1 and SOCS3 mRNA was increased in pSS patients. The results indicate increased sensitivity of immune cells from pSS patients to STAT1-activating signals, and may partly explain the IFN signature observed in pSS.

STAT-5 is activated constitutively in T cells, B cells and monocytes from patients with primary Sjögren's syndrome

The expression and phosphorylation of signal transducer and activator of transcription-1 (STAT-1) have been shown to be markedly increased in the salivary gland epithelial cells of patients with primary Sjögren's syndrome (pSS). The present aim was to investigate the activation status of different STAT proteins in peripheral blood (PB) lymphocytes and monocytes, and their correlations with clinical parameters in patients with pSS. To this end, PB samples were drawn from 16 patients with active pSS and 16 healthy blood donors, and the phosphorylation of STAT-1, -3, -4, -5 and -6 proteins was studied in T cells, B cells and monocytes using multi-colour flow cytometry. In addition, mRNA expression of STAT molecules in PB mononuclear cells (PBMC) was studied with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Basal phosphorylation of STAT-5 was found to be significantly higher in PB T cells, B cells and monocytes in patients with pSS than in healthy controls. The expression of STAT-5 mRNA was not increased in PBMC. pSTAT-5 levels in B cells and monocytes showed a significant correlation with serum immunoglobulin (Ig)G levels and anti-SSB antibody titres. Constitutive STAT-5 activation in monocytes and CD4(+) T cells was associated with purpura. There were no major differences in the activation of other STATs between pSS patients and healthy controls. In conclusion, STAT-5 is activated constitutively in PB leucocytes in patients with pSS, and basal STAT-5 phosphorylation seems to associate with hypergammaglobulinaemia, anti-SSB antibody production and purpura.

ESSPRI and other patient-reported indices in patients with primary Sjogren's syndrome during 100 consecutive outpatient visits at one rheumatological clinic

OBJECTIVE

A European League Against Rheumatism (EULAR) SS disease activity index (ESSDAI) and a patient-reported index (ESSPRI) have recently been developed and validated. In our previous study the ESSDAI correlated significantly with serum β2 microglobulin concentration. We now aim to establish whether the ESSPRI is also associated with serum β2 microglobulin or with other patient-reported indices.

METHODS

The data on 100 consecutive visits of patients with primary SS (pSS) were reviewed from the patient charts. Patients who had filled out the ESSPRI questionnaire and fulfilled at least four of the revised American-European consensus group criteria for pSS were included. Data were gathered on the ESSPRI (0-10 cm) and on the patient's global health assessment [visual analogue scale (VAS) 0-10 cm] (PGH-VAS), pain-VAS (0-10 cm) and HAQ (range 0-3).

RESULTS

The ESSPRI correlated significantly with the PGH-VAS (r = 0.753, P < 0.0001), pain-VAS (r = 0.656, P < 0.0001) and HAQ (r = 0.542, P < 0.0001) (Spearman's correlation). It also correlated weakly with serum β2 microglobulin (r = 0.214, P = 0.043) and ESR levels (r = 0.235, P = 0.019).

CONCLUSION

The ESSPRI correlated significantly with other patient-reported indices, serum β2 microglobulin and ESR in patients with pSS. Our results support the view that the ESSPRI is a useful tool in the follow-up of patients with pSS.

Novel carbonic anhydrase autoantibodies and renal manifestations in patients with primary Sjogren's syndrome

OBJECTIVE

Anti-carbonic anhydrase II (anti-CA II) antibodies have been related to renal manifestations of primary SS (pSS), and animal studies have even suggested a pathogenic role for them. However, not all pSS patients with renal tubular acidosis (RTA) present with anti-CA II antibodies. Recently, several novel CA isoenzymes have been recognized and we aimed to investigate whether antibodies to these are associated with renal manifestations of pSS.

METHODS

We examined anti-CA II antibodies as well as anti-CA I, VI, VII and XIII antibodies by ELISA tests in 74 pSS patients on whom detailed nephrological examinations had been performed and, as controls, in 56 subjects with sicca symptoms, but no pSS.

RESULTS

The levels of anti-CA I, II, VI and VII antibodies were significantly higher in patients with pSS compared with subjects with sicca symptoms but no pSS. None of the anti-CA antibodies was associated with the presence of complete or incomplete RTA or proteinuria or urinary α₁m excretion in patients with pSS. However, levels of anti-CA II, VI and XIII antibodies correlated significantly with urinary pH, and inversely with serum sodium concentrations. The degree of 24-h urinary protein excretion correlated weakly with levels of anti-CA VII antibodies.

CONCLUSION

Not only antibodies to CA II, but also anti-CA VI and XIII antibodies seem to be associated with renal acidification capacity in patients with pSS.

Serum amyloid A and C-reactive protein concentrations are differently associated with markers of autoimmunity in patients with primary Sjögren's syndrome

OBJECTIVE

Primary Sjögren's syndrome (pSS) is an autoimmune disease in which the concentration of the acute-phase protein serum C-reactive protein (CRP) is low. We investigated whether levels of another acute-phase protein, serum amyloid A (SAA), are increased in patients with pSS and whether the immunological markers in patients with pSS are associated with variation in SAA levels.

METHODS

Serum SAA concentrations were measured by ELISA in 74 patients with pSS and in 56 control subjects with sicca symptoms.

RESULTS

Median SAA levels did not differ significantly between patients with pSS and subjects with sicca symptoms. In patients with pSS SAA concentrations correlated significantly with age, leukocyte count, CRP, interleukin 6, and C4. Unlike CRP, there was a significant inverse correlation between SAA and serum IgG levels and anti-SSA antibody titers, as well as a trend towards an inverse correlation between SAA and antinuclear antibody and rheumatoid factor titers.

CONCLUSION

Our data imply that high SAA production could constitute a protective element in pSS: high SAA levels inhibit in particular various signs of B cell hyperreactivity, i.e., IgG and autoantibody production.

Autoimmunity and atherosclerosis: the presence of antinuclear antibodies is associated with decreased carotid elasticity in young women. The Cardiovascular Risk in Young Finns Study

OBJECTIVE

There is ample evidence demonstrating that accelerated atherosclerosis prevails in autoimmune rheumatic diseases, particularly in SLE, and that the risk is due not only to traditional cardiovascular risk factors but also to the disease itself. ANAs are a hallmark of SLE and are known even to antedate the development of SLE. Our aim was to investigate whether positive ANAs in young adults are associated with risk factors for atherosclerosis or subclinical markers of atherosclerosis.

METHODS

ANAs were examined by IIF using HEp-2 cells as substrate in 2278 participants in the Cardiovascular Risk in Young Finns Study for whom detailed data on cardiovascular risk factors and markers of subclinical atherosclerosis (including brachial flow-mediated dilatation, carotid compliance and carotid intima-media thickness) were available.

RESULTS

In multivariate analyses, adjusted for age, BMI, serum concentrations of CRP, triglycerides, high-density lipoprotein and low-density lipoprotein cholesterol, blood pressure and smoking habits, ANA positivity (titre > 160) was inversely associated (beta = -0.145; P = 0.034) with carotid compliance in women.

CONCLUSIONS

Our results indicate that ANA positivity is associated with decreased carotid elasticity in women, suggesting that mechanisms resulting in ANA production may be involved in the development of early atherosclerosis.

Serum amyloid A is independently associated with metabolic risk factors but not with early atherosclerosis: the Cardiovascular Risk in Young Finns Study

BACKGROUND

Serum amyloid A (SAA) is a sensitive marker of inflammation and its elevation has been implicated in obesity and in cardiovascular disease, yet data on its regulation in young adults or on its role in early atherosclerosis is scarce. We investigated which factors explain the variation in SAA and analysed whether SAA could be associated with preclinical atherosclerosis.

METHODS

Serum amyloid A levels were measured in participants of the Cardiovascular Risk in Young Finns Study (n = 2280, n = 1254 women, n = 1026 men). Correlates and determinants of SAA were analysed and the effect of SAA on subclinical atherosclerosis, measured as intima-media thickness (IMT) and carotid artery compliance, was evaluated with risk-factor adjusted models.

RESULTS

Serum amyloid A correlated directly and independently of BMI with C-reactive protein (CRP), waist circumference and leptin in both sexes, with total cholesterol, LDL cholesterol and ApolipoproteinA1 (ApoA1) in women and with triglycerides, insulin levels and insulin resistance in men. Use of combined oral contraceptives and intrauterine device was also associated with SAA levels. Determinants for SAA included CRP, leptin and ApoA1 in women, and CRP, leptin and HDL cholesterol in men. SAA levels correlated with carotid compliance in both sexes and with IMT in men, yet SAA had no independent effect on IMT or carotid compliance in multivariable analysis.

CONCLUSIONS

Serum amyloid A was associated with several metabolic risk factors but was not an independent predictor of IMT or carotid artery compliance. Further longitudinal studies will show whether SAA holds a prognostic value as a risk marker, analogously to CRP.

Indoleamine 2,3-dioxygenase activity associates with cardiovascular risk factors: the Health 2000 study

Indoleamine 2,3-dioxygenase (IDO) is an important immunomodulator suppressing the activation of T lymphocytes, and its level in blood is increased in several autoimmune and inflammatory diseases. We have previously shown that this activity associates with several signs and risk factors of atherosclerosis in 24 to 39-year-old females. Now we repeat this analysis in an older population (n = 921, age range 46-76 years), i.e. in a population with more advanced atherosclerosis. IDO activity had a significant positive correlation in both sexes with carotid artery intima/media thickness (IMT), an early marker of atherosclerosis. In females, a significant negative correlation with HDL cholesterol and a positive correlation with triglycerides levels was observed. The association with IMT did not remain significant after adjustment with classical risk factors of atherosclerosis. It is thus concluded that IDO is a sensitive marker of atherosclerosis--or the inflammatory response associated with it--but does not have an independent role in the pathogenesis of this disease.

Indoleamine 2,3-dioxygenase activity is increased in patients with systemic lupus erythematosus and predicts disease activation in the sunny season

Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-degrading enzyme which suppresses T lymphocyte activity. IDO activity can be determined by relating kynurenine, the main metabolite of tryptophan, to tryptophan (kyn/trp). We have demonstrated recently that systemic lupus erythematosus (SLE) is activated during the sunny season as measured by the European Consensus Lupus Activity Measurement Index (ECLAM) activity score. Our aim here was to establish whether IDO-dependent mechanisms are involved in the activation process of SLE. Kyn/trp was measured by reverse-phase high-performance liquid chromatography (HPLC) in 33 (30 female, three male) SLE patients in winter, spring and summer and in 309 healthy control subjects. At the same time-points the SLE patients were examined by a rheumatologist and a dermatologist and the activity of SLE assessed by the ECLAM score. IDO activity was higher in SLE patients than in healthy subjects. There was no seasonal variation in IDO activity in SLE patients and it did not correlate with the ECLAM activity score in winter. However, there was a significant correlation between IDO activity and the ECLAM score both in spring and in summer. High IDO activity in winter predicted subsequent activation of SLE in spring and summer. Our results indicate that IDO-dependent immunosuppressive mechanisms are activated in SLE patients. Exposure to sunlight or another factor causing seasonal variation in SLE activity leads to insufficiency of this suppression in a subgroup of patients, causing activation of SLE. High IDO activity in winter predicts activation of SLE in the sunny season.

CRP gene is involved in the regulation of human longevity: a follow-up study in Finnish nonagenarians

Chronic low-grade inflammation is involved in the pathogenesis of many disease conditions in humans and it is frequently quantified by measuring the blood concentration of C-reactive protein (CRP). Here we show that the CRP concentration in old people (nonagenarians) is, at least partially, genetically determined, and that the high producer genotype is associated with a shorter life expectancy during follow-up. Thus, the data imply that the CRP gene may be a longevity gene in humans.

Indoleamine 2,3-dioxygenase enzyme activity correlates with risk factors for atherosclerosis: the Cardiovascular Risk in Young Finns Study

Indoleamine 2,3 dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, suppresses T cell activity and is up-regulated by various inflammatory stimuli. The ratio of kynurenine, the main metabolite of tryptophan, to tryptophan (kyn/trp) reflects IDO activity. We calculated IDO activity and measured carotid intima-media thickness (IMT), a presymptomatic predictor of atherosclerosis, in 986 young adults (544 female, 442 male) for whom data on levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride, high sensitive C-reactive protein (CRP), body mass index (BMI), waist circumference, waist-to-hip ratio, systolic and diastolic blood pressure and smoking habits were available. IDO activity correlated significantly with IMT in female subjects, but not in males. In a multivariate linear regression model, IDO did not correlate independently with IMT in female subjects. However, IDO activity correlated significantly with several risk factors for atherosclerosis in females, i.e. with age, LDL-C, BMI, weakly with CRP and inversely with HDL-C and triglyceride. In males IDO activity correlated significantly with CRP and inversely with HDL-C. In conclusion, our results suggest that the IDO enzyme is involved in the immune regulation of early atherosclerosis, particularly in young female adults, and could constitute a novel marker of immune activation in early atherosclerosis in females.

Autoimmunity and longevity: Presence of antinuclear antibodies is not associated with the rate of inflammation or mortality in nonagenarians

There are reports demonstrating elevated levels of autoantibodies in elderly people. We now analyzed whether the strong inflammatory response associated with aging is interrelated with the production of autoantibodies, antinuclear antibodies (ANA). In a cohort of 284 nonagenarians the rate of ANA positivity was 12.3%, which is significantly (p<0.001) higher than that in the middle-aged controls (2.8%). The mortality data of this cohort was collected after a 4-year follow-up. The ANA positivity at the age of 90 did not have any effect on the rate of survival, or on the levels of serum markers of inflammation.

Autoimmunity and atherosclerosis: functional polymorphism of PTPN22 is associated with phenotypes related to the risk of atherosclerosis. The Cardiovascular Risk in Young Finns Study

There is a growing body of evidence attesting the significance of inflammation in the pathogenesis of atherosclerosis. Protein tyrosine phosphate PTPN22 C/T single nucleotide polymorphism (SNP) at + 1858 has been identified recently as a susceptibility factor for various inflammatory autoimmune diseases. We hypothesized that data on the genetic polymorphism of the PTPN22 enzyme associated with an increased risk of autoimmunity could also provide insight into the possible role of autoimmunity in the pathogenesis of atherosclerosis. Therefore we analysed the PTPN22 + 1858 C/T polymorphism in a population of young Finnish adults (n = 2268) for whom data on carotid artery intima-media thickness (IMT), a presymptomatic predictor of atherosclerosis, and risk factors for atherosclerosis were available. In males carriage of the T allele of PTPN22 + 1858 was associated significantly with IMT in univariate and multivariate analyses, while in females it was associated with several risk factors for atherosclerosis (BMI, waist circumference, waist-to-hip ratio, serum concentrations of C-reactive protein and triglycerides) but not with IMT. Our results indicate that the genetic polymorphism of PTPN22 + 1858 known to predispose to autoimmunity also enhances the development of atherosclerosis and thereby links the genetics of autoimmunity and atherosclerosis.

The activity of the immunoregulatory enzyme indoleamine 2,3-dioxygenase is decreased in smokers

Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the degradation of the essential amino acid tryptophan (trp) to its main metabolite kynurenine (kyn), suppresses T cell activity. Smoking has marked immunomodulatory effects, above all immunosuppressive, causing a reduction in the levels of immunoglobulins and an increased risk of infections. The immunostimulatory effects of smoking are manifested, for example, in increased autoantibody production. We sought to establish whether IDO activity is involved in the immunomodulatory effects of smoking. To this end we measured the ratio of kyn to trp, reflecting IDO activity, by reverse-phase high-performance liquid chromatography (HPLC) in 784 (464 female, 230 male) subjects of a population-based sample of the adult Finnish population. Serum cotinine concentration as an indicator of active smoking was measured in the patients by radioimmunoassay and detailed data gathered on smoking habits. IDO activity was lower in smokers in this population-based sample compared with non-smokers when active smoking was classified according to serum cotinine concentration or history of smoking habits. Moreover, serum IDO activity correlated inversely with serum cotinine concentration. In conclusion, the activity of the IDO enzyme is decreased in smoking subjects, and the reduction in IDO-dependent immunosuppression could thus be responsible for the known immunostimulatory effects of smoking.

The association between burnout and physical illness in the general population--results from the Finnish Health 2000 Study

OBJECTIVE

The association between burnout and physical diseases has been studied very little. The purpose of this study was to examine the relationship between burnout and physical illness in a representative nationwide population health study.

METHODS

As a part of the "Health 2000 Study" in Finland, 3368 employees aged 30-64 years were studied. Burnout was assessed with the Maslach Burnout Inventory-General Survey. Physical diseases were diagnosed in a comprehensive health examination by research physicians.

RESULTS

Physical illness was more common among subjects with burnout than others (64% vs. 54%, P<.0001), and the prevalence of diseases increased with the severity of burnout (P<.0001). Burnout was an important correlate of cardiovascular diseases among men (OR=1.35; 95% CI, 1.13-1.61) and musculoskeletal disorders among women (OR=1.22, 95% CI, 1.07-1.38) when adjusted for age, marital status, education, socioeconomic status, physical strenuousness of work, smoking, physical activity, alcohol consumption, body mass index, and depressive symptoms. The prevalence of musculoskeletal disorders and cardiovascular diseases increased with the severity of all three dimensions of burnout, that is, exhaustion (P<.0001 and P<.001, respectively), cynicism (P=.0001 and P<.001, respectively), and lack of professional efficacy (P<.01 and P<.0001, respectively).

CONCLUSIONS

Burnout is associated with musculoskeletal diseases among women and with cardiovascular diseases among men. These associations are not explained by sociodemographic factors, health behavior, or depression. Physical illnesses are associated with all three dimensions of burnout and not only with the exhaustion dimension. In the future, the causal relationships between burnout and physical diseases need to be investigated in prospective studies.

Indoleamine 2,3-dioxygenase activity in nonagenarians is markedly increased and predicts mortality

Indoleamine 2,3-dioxygenase (IDO), an enzyme degrading tryptophan (trp) to kynurenine (kyn), suppresses T cell activity. Ageing of the immune system, immunosenescence, includes a decline in T cell function. We therefore sought to establish whether IDO activity is involved in immunosenescence and whether it predicts mortality in aged subjects. We measured kyn/trp, reflecting IDO activity, in 284 nonagenarians and 309 blood donor controls. IDO activity was significantly higher in nonagenarians compared with controls and IDO activity at study entry predicted subsequent mortality in nonagenarians. Thus, increased IDO activity might be a mechanism involved in the decline of T cell responses in immunosenescence.

Mechanisms dependent on tryptophan catabolism regulate immune responses in primary Sjögren's syndrome

To investigate the possible role of tryptophan metabolism in immune regulation of primary Sjögren's syndrome (pSS) the serum concentrations of tryptophan and its metabolite kynurenine were measured by reverse-phase high-performance liquid chromatography (HPLC) in 103 patients with pSS, 56 patients with sicca symptoms and 309 healthy blood donors. The kynurenine per tryptophan ratio (kyn/trp), which reflects the activity of the indoleamine-pyrrole 2,3-dioxygenase (IDO) enzyme involved in tryptophan catabolism, was calculated. Both female and male patients with pSS had significantly higher serum kynurenine concentrations and kyn/trp than subjects with sicca symptoms or healthy blood donors. The median (quartile range) concentration of kynurenine in female patients with pSS was 2.41 micromol/l (1.86-3.26) compared with 1.85 micromol/l (1.58-2.38, P < 0.0001) in subjects with sicca symptoms and 1.96 micromol/l (1.65-2.27, P < 0.0001) in healthy blood donors. Their kyn/trp x 1000 was 34.0 (25.1-44.3) compared with 25.3 (21.1-31.5, P < 0.0001) in subjects with sicca symptoms and 24.3 (21.0-28.9, P < 0.0001) in healthy blood donors. Female pSS patients with high IDO activity (kyn/trp x 1000 > or = 34.0) had significantly higher ESR, serum C-reactive protein, serum IgA and serum beta-2 microglobulin concentrations as well as higher serum creatinine levels, and they had positive antinuclear antibodies more frequently and presented with more American-European consensus group criteria than those with low IDO activity (kyn/trp x 1000 < 34.0). These data suggest that mechanisms dependent on tryptophan catabolism regulate immune responses in pSS. Tryptophan degradation is enhanced in patients with pSS, and high IDO activity is associated with severity of pSS.

Th2 cytokine genotypes are associated with a milder form of primary Sjogren's syndrome

BACKGROUND

Immunohistological studies on salivary and lacrimal glands have yielded conflicting results on the Th1/Th2 balance in primary Sjögren's syndrome (pSS).

OBJECTIVE

To establish whether pSS is a Th1 or Th2 directed autoimmune disease by analysing the polymorphism of the genes encoding for cytokines involved in the regulation of Th1/Th2 differentiation.

METHODS

The polymorphisms of the genes encoding for interleukin 4 (IL4) -590 C/T, interleukin 13 (IL13) +2044 G/A, and interferon gamma (IFNG) +874 T/A were analysed in 63 white Finnish patients with pSS (61 female, two male) and in 63 healthy controls. The clinical and immunological data on the pSS patients were analysed in relation to these cytokine gene polymorphisms.

RESULTS

There were no significant differences in the genotype or allele frequencies of IL4 -590, IL13 +2044, or IFNG +874 between pSS patients and controls. The erythrocyte sedimentation rate and concentrations of serum IgA and serum beta2 microglobulin were lower in pSS patients carrying the IL4 -590 T allele or the IL13 +2044 A allele than in those not carrying the respective alleles. The IL4 -509 T allele and IL13 +2044 A allele carriers less often had purpura than the corresponding non-carriers.

CONCLUSIONS

The frequencies of the cytokine genotypes regulating Th1/Th2 differentiation did not differ between pSS patients and controls. However, the presence of cytokine genotypes with increased susceptibility to atopic and other Th2 diseases was associated with signs of a milder form of pSS. This finding would favour a hypothesis envisaging pSS as primarily a Th1 mediated autoimmune disease.

Association of interferon-gamma +874(T/A) single nucleotide polymorphism with the rate of tryptophan catabolism in healthy individuals

Abstract Mechanisms induced by tryptophan (trp) catabolism are important in the regulation of both normal and pathogenetic immune responses. The key enzyme is indoleamine-pyrrole 2,3-dioxygenase (EC 1.13.11.42) (IDO) which converts trp to kynurenine (kyn), the main toxic metabolite. It is known that interferon-gamma (IFN-gamma) is able to activate IDO. We wanted to analyse whether the strength of this mechanism would be under genetic control. To this end, we analysed the IFN-gamma+874(T/A) genotypes, which are known to have an effect on IFN-gamma production, of 309 healthy blood donors and correlated these to the levels of trp and kyn in their blood. The data obtained demonstrate that the presence of the high producer T allele was associated with increased IDO activity (i.e. elevated kyn and kyn/trp levels), but this effect was observed only in females. These data show that trp catabolism is genetically controlled by the IFN-gamma gene and may thus be operative in those disease conditions associated with the polymorphisms of the IFN-gamma gene.

IgA levels are predictors of mortality in Finnish nonagenarians

It has been demonstrated that in obviously healthy, very old people increased levels of inflammatory markers as well as some defects in T lymphocyte populations are strong predictors of mortality. Very little is known about the role of possible functional defects in antibody formation. To examine this, we now measured IgM, IgG and IgA concentrations in a cohort of 285 nonagenarians (67 males, 218 females). IgG and IgA levels were significantly higher than those of healthy middle-aged controls. The analyzed serum samples were taken at the age of 90-91 years. After 4 years, 20 males and 94 females had survived. To analyze the role in predicting mortality, the immunoglobulin data (as well as the measured CRP and IL-6 concentrations) were stratified according to this survival data. IgA levels (and CRP and IL-6 levels) were clearly higher in the nonsurvivors than in the survivors. These data imply that elevated serum IgA level, i.e. indicator of intestinal inflammation and/or defect in mucosal defence, is a strong mortality predicting factor.

Seasonal variation of disease activity of systemic lupus erythematosus in Finland: a 1 year follow up study

OBJECTIVES

To study the role of different seasons in the disease activity of patients with systemic lupus erythematosus (SLE). Additionally, to evaluate whether the outdoor behaviour during the summer or a photoprovocation test affects disease activity.

METHODS

33 patients with SLE were examined by a rheumatologist and a dermatologist at a university hospital in winter, spring, and summer. The activity of SLE was assessed by the ECLAM index. Their outdoor behaviour was recorded by a questionnaire during the summer. In the winter, 12 patients were photoprovoked by ultraviolet A and B radiation on a small skin area.

RESULTS

The ECLAM scores were higher in spring and tended to be higher in summer than in winter (p = 0.006 and p = 0.051). This finding, as well as the outdoor behaviour, were independent of the patients' own impression of their photosensitivity. Overall, the sun protection actions were inadequate. The photoprovocation had no statistical effect on disease activity, but one patient had a violent exacerbation of SLE manifestations shortly after the photoprovocation.

CONCLUSIONS

In the northern climate SLE may be activated during the sunny season. Therefore, more effort should be focused on sun protection of patients with SLE.

Long-term follow-up study of pulmonary findings in patients with primary Sjögren's syndrome

BACKGROUND

In a previous study pulmonary hyperinflation was observed frequently in patients with primary Sjogren's syndrome (pSS) and elevated serum beta-2 microglobulin (beta2m) concentrations were associated with hyperinflation.

OBJECTIVE

To evaluate the significance of baseline serum beta2m concentration and to identify other possible risk factors for pulmonary involvement in long-term follow-up of patients with pSS.

METHODS

Nineteen pSS patients whose pulmonary function tests (PFTs) had been previously studied were reexamined after a median follow-up of 10 years. Pulmonary symptoms were recorded, chest radiograph, and high-resolution computed tomography (HRCT) were evaluated and methacholine provocation and PFTs including flow-volume spirometry, body plethysmography, and diffusing capacity performed.

RESULTS

Baseline serum beta2m concentrations correlated inversely with follow-up total lung capacity (TLC), vital capacity (VC), and diffusing capacity (DL), and positively with residual volume (RV), all expressed as percentage of predicted values. Diminished airways resistance (Raw) and, correspondingly, elevated specific conductance (SGaw) were frequent findings in pSS patients at follow-up, indirectly implying stiffness of the lungs and a restrictive decrease in lung volumes. Baseline serum protein concentration was higher and IgG concentration tended to be higher in pSS patients who at follow-up had elevated SGaw compared with others. Interstitial changes in HRCT were found more frequently in patients with elevated SGaw than in those without.

CONCLUSION

Our results suggest that subtle restrictive changes in pulmonary function are more prone to develop in the long term in pSS patients with elevated serum beta2m concentration and other signs of immunological activity at baseline.

Immunoglobulin KM and GM gene polymorphisms modify the clinical presentation of primary Sjögren's syndrome

OBJECTIVE

To investigate whether polymorphism of immunoglobulin (Ig) genes affects susceptibility to or severity of primary Sjogren's syndrome (pSS).

METHODS

Ig gene kappa (KM) and gamma (GM) polymorphisms were analyzed by a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) based method in 65 Finnish Caucasian patients with pSS and in 66 healthy controls matched for sex, ethnic origin, and area of residence. Clinical and immunological data on the pSS patients were analyzed in relation to Ig genotypes.

RESULTS

The genotype frequencies of Ig KM and GM genes did not differ between pSS patients and controls. Anti-SSB antibodies were encountered significantly more frequently in pSS patients carrying the KM1 allele than in those without (100% vs 48%, p = 0.016). The pSS patients with the KM1 allele had several signs of immunologically active disease: they had significantly higher erythrocyte sedimentation rate, serum IgA, serum beta2-microglobulin (beta2-m), and plasma IgG1 concentrations than patients without this allele. The pSS patients carrying the GM z allele had a milder form of pSS than those without this determinant. They had less severe labial salivary gland histological findings (grade 3-4 in 60% vs 93%, p = 0.004) and lower plasma IgG3 and serum beta2-m concentrations than those without GM z allele.

CONCLUSIONS

Ig KM and GM genes do not contribute to susceptibility to pSS. The Ig KM1 allele is associated with several markers of immunologically active disease, whereas the Ig GM z allele is associated with milder pSS.

Presence of apolipoprotein E epsilon4 allele predisposes to early onset of primary Sjogren's syndrome

BACKGROUND

Apolipoprotein E (apoE) polymorphism plays a central role in lipid metabolism, but has recently also been suggested to regulate inflammation, as judged by levels of serum C-reactive protein (CRP).

OBJECTIVE

To establish whether polymorphism of the apoE genes affects susceptibility to primary Sjogren's syndrome (pSS), degree of inflammation or age of onset of pSS.

METHODS

ApoE genotype distribution and allelic frequencies were analysed using PCR and the TaqMan system in 63 Finnish Caucasian patients with pSS and in 64 healthy controls matched for sex, ethnic origin and area of residence. The clinical and immunological data on the pSS patients were analysed in relation to the apoE genotypes.

RESULTS

There was no difference between pSS patients and controls in apoE genotype and allelic frequencies. The apoE epsilon4 allele was significantly associated with early onset of pSS in the entire population and in female patients (Kaplan-Meier log rank test, P = 0.0407 and P = 0.0168, respectively). The average age (+/- S.D.) of onset of pSS in all apoE epsilon4 allele carriers was 46 +/- 12 and in other genotypes it was 53 +/- 10 yr (P = 0.031, t-test). ApoE polymorphism was not associated with signs of inflammation evaluated by such markers as concentration of plasma CRP, plasma interleukin-6, plasma TNF-alpha, immunoglobulin G and haemoglobin, or leucocyte count or ESR.

CONCLUSIONS

ApoE polymorphism does not affect susceptibility to pSS or levels of plasma inflammatory indices in patients with pSS. However, a clear association prevails between apoE epsilon4 and early onset of pSS.

Matrix metalloproteinase 9 (MMP-9) gene polymorphism and MMP-9 plasma levels in primary Sjogren's syndrome

OBJECTIVES

To determine whether plasma matrix metalloproteinase 9 (MMP-9) and MMP9 (-1562C-->T) polymorphism have an effect on the disease phenotype in primary Sjogren's syndrome (pSS).

METHODS

Plasma MMP-9 concentrations and polymorphism of the MMP9 gene were analysed in 66 patients with pSS. These data were studied in relation to the clinical data of the patients. The genetic data of patients were compared with the data of 66 healthy subjects.

RESULTS

Plasma MMP-9 was higher in patients with definite pSS than in patients with possible pSS. This association was principally caused by higher plasma MMP-9 in patients with a positive Schirmer test and keratoconjunctivitis sicca. pSS patients with purpura, SS-A autoantibodies and RF had significantly lower plasma MMP-9 than patients without these characteristics. The overall MMP9 (-1562C-->T) allele frequencies were similar in patients and control subjects. The frequency of the allele T was higher in patients without Raynaud's phenomenon than in the control group.

CONCLUSIONS

MMP9 (-1562C-->T) could not be used for risk assessment in pSS. The presence of the rarer allele T may decrease the risk of Raynaud's phenomenon in pSS. High plasma MMP-9 is indicative of definite pSS but may paradoxically have a preventive effect on the eruption of purpura and on the development of autoantibody reaction in pSS.

Mapping the binding domain of the F18 fimbrial adhesin

F18 fimbrial Esherichia coli strains are associated with porcine postweaning diarrhea and pig edema disease. Recently, the FedF subunit was identified as the adhesin of the F18 fimbriae. In this study, adhesion domains of FedF were further studied by constructing deletions within the fedF gene and expressing FedF proteins with deletions either together with the other F18 fimbrial subunits or as fusion proteins tagged with maltose binding protein. The region essential for adhesion to porcine intestinal epithelial cells was mapped between amino acid residues 60 and 109 of FedF. To map the binding domain even more closely, all eight charged amino acid residues within this region were independently replaced by alanine. Three of these single point mutants expressing F18 fimbriae exhibited significantly diminished capabilities to adhere to porcine epithelial cells in vitro. In addition, a triple point mutation and a double point mutation completely abolished receptor adhesiveness. The result further confirmed that the region between amino acid residues 60 and 109 is essential for the binding of F18 fimbriae to their receptor. In addition, the adhesion capability of the binding domain was eliminated after treatment with iodoacetamide, suggesting the formation of a disulfide bridge between Cys-63 and Cys-83, whereas Cys-111 and Cys-116 could be deleted without affecting the binding ability of FedF.

Mapping the binding domain of the F18 fimbrial adhesin

F18 fimbrial Esherichia coli strains are associated with porcine postweaning diarrhea and pig edema disease. Recently, the FedF subunit was identified as the adhesin of the F18 fimbriae. In this study, adhesion domains of FedF were further studied by constructing deletions within the fedF gene and expressing FedF proteins with deletions either together with the other F18 fimbrial subunits or as fusion proteins tagged with maltose binding protein. The region essential for adhesion to porcine intestinal epithelial cells was mapped between amino acid residues 60 and 109 of FedF. To map the binding domain even more closely, all eight charged amino acid residues within this region were independently replaced by alanine. Three of these single point mutants expressing F18 fimbriae exhibited significantly diminished capabilities to adhere to porcine epithelial cells in vitro. In addition, a triple point mutation and a double point mutation completely abolished receptor adhesiveness. The result further confirmed that the region between amino acid residues 60 and 109 is essential for the binding of F18 fimbriae to their receptor. In addition, the adhesion capability of the binding domain was eliminated after treatment with iodoacetamide, suggesting the formation of a disulfide bridge between Cys-63 and Cys-83, whereas Cys-111 and Cys-116 could be deleted without affecting the binding ability of FedF.

The significance of mannan-binding lectin gene alleles in patients with primary Sjögren's syndrome

OBJECTIVE AND METHODS

To investigate the significance or mannan-binding lectin (MBL) gene alleles in patients with primary Sjogren's syndrome (pSS). Genotypes were determined in 65 pSS patients and 138 controls.

RESULTS

No difference in MBL genotype or allele frequencies was detected between the pSS patients and controls. However, when the effect of MBL genotypes on the diagnostic findings in pSS patients was assessed, none of the eight patients with 52/w genotype fulfilled four (definite) Californian criteria (P = 0.007). Among these eight the Chisholm-Mason histological grade was > or = 3 in only three (P = 0.017). Furthermore, the MBL concentration was lower in patients with 52/w genotype compared to those with wild-type (w/w) genotype (P = 0.035).

CONCLUSION

Our findings suggest that MBL structural gene polymorphisms do not influence on susceptibility to pSS. However, MBL may be associated with salivary gland destruction in pSS, and its concentration may be comparable with the intensity of inflammatory reaction. Further studies are warranted to clarify the possible mechanisms involved.

Factors predictive of renal involvement in patients with primary Sjögren's syndrome

AIM

To identify clinical and immunological risk factors underlying the development of renal involvement in primary Sjögren's syndrome (pSS).

SUBJECTS AND METHODS

Seventy-eight patients (75 females, 3 males) with pSS were carefully interviewed and clinical and laboratory data from the time of diagnosis recorded. The baseline data on patients shown to have either latent or overt distal renal tubular acidosis (dRTA), mild proteinuria or increased urinary excretion of alpha-1 microglobulin (alpha1m) after a mean disease duration of 9 +/- 4 years, were compared to the baseline data on those who did not have these manifestations at follow-up.

RESULTS

Patients with subsequent latent or overt dRTA were found to have significantly higher baseline levels of serum total gamma-globulin (24 +/- 7 vs. 19 +/- 6 g/l, p = 0.011) and serum protein (84 +/- 7 vs. 79 +/- 7 g/l, p = 0.024) compared to those with normal renal acidification capacity. The baseline levels of serum beta-2 microglobulin (beta2m) were higher in patients with an acidification defect than in those with normal acidification capacity (3.1 +/- 1.1 vs. 2.6 +/- 0.8 mg/l, p = 0.072). In those with subsequent proteinuria the levels of serum beta2m were almost significantly higher at baseline as compared to those with normal urinary protein excretion (3.1 +/- 1.4 vs. 2.5 +/- 0.8 mg/l, p = 0.052). The subgroup of pSS patients who had increased urinary alpha1m excretion as a sign of tubular proteinuria, had higher baseline levels of ESR (55 +/- 27 mm/h vs. 40 +/- 23 mm/h, p = 0.076) and significantly higher baseline levels of serum beta2m (4.6 +/- 1 .8 vs. 2.6 +/- 0.8 mg/l, p = 0.029) as compared to those with normal urinary alpha1m excretion.

CONCLUSIONS

High levels of serum total gamma-globulin, serum protein and serum beta2m were the best predictors of the development of dRTA in pSS patients. High baseline levels of serum beta2m were also associated with the subsequent occurrence of mild proteinuria and increased urinary alpha1m excretion in patients with pSS.

Elevated interleukin-6 plasma levels are regulated by the promoter region polymorphism of the IL6 gene in primary Sjögren's syndrome and correlate with the clinical manifestations of the disease

OBJECTIVES

To determine whether plasma interleukin-6 (IL-6) and G/C base exchange polymorphism at position -174 of the IL6 gene have an effect on the clinical manifestations of primary Sjögren's syndrome (pSS).

METHODS

Levels of circulating IL-6 protein and polymorphism of the IL6 gene were analysed in 66 patients with pSS and in 400 healthy subjects. These data were studied in relation to clinical data on the pSS patients.

RESULTS

Plasma IL-6 was elevated in pSS patients compared with healthy controls. pSS patients with coeliac disease, pulmonary fibrosis or alveolitis or peripheral nervous system symptoms had significantly higher IL-6 levels than patients without these manifestations. IL-6 levels increased in parallel with the histological grade of minor salivary gland biopsy and the number of pSS criteria fulfilled. IL6 allele frequencies were similar in patients and normal subjects. Plasma IL-6 levels were regulated by the IL6 genotype in pSS patients.

CONCLUSIONS

The G/C polymorphism of the IL6 gene does not predispose patients to pSS, but the circulating IL-6 concentration is related to specific manifestations of the disease and the levels of IL-6 are regulated by the IL6 promoter polymorphism in pSS.

A longitudinal cohort study of Finnish patients with primary Sjögren's syndrome: clinical, immunological, and epidemiological aspects

OBJECTIVE

To evaluate outcome in a cohort of Finnish patients with primary Sjögren's syndrome (pSS).

METHODS

Clinical and laboratory data from the time of diagnosis and follow up were collected from 110 patients with pSS (107 women, three men) diagnosed in 1977-1992 in central Finland. The standardised incidence ratio for cancers was determined as the ratio of the observed number of cases to the expected number based on regional population rates. Eighty one of the 93 patients still alive were interviewed, and clinical and laboratory examinations performed in 1994-1997.

RESULTS

The mean (SD) erythrocyte sedimentation rate (33 (22) v 45 (28) mm/1st h), serum IgG (18.8 (7.4) v 22.5 (8.5) g/l), and serum IgM (1.6 (1.1) v 2.0 (1.2) g/l) at the control visit were significantly (p<0.0001) lower than those at baseline. A similar change was observed in a subgroup of patients never treated with glucocorticosteroids or disease modifying antirheumatic drugs. Three non-Hodgkin's lymphomas were diagnosed (standardised incidence ratio 13; 95% confidence interval 2.7 to 38). In a logistic regression model, the patients with pSS with subsequent lymphoma were found to have higher baseline levels of serum beta2 microglobulin than the others (odds ratio 1.9; 95% confidence interval 1.1 to 3.4).

CONCLUSION

The results suggest that mean concentrations of serum IgG and IgM in patients with pSS decline with time, possibly reflecting diminishing inflammatory activity. As in previous studies, the incidence of non-Hodgkin's lymphomas in this cohort of patients with pSS was significantly higher than in the reference population.

Genetic association between interleukin-10 promoter region polymorphisms and primary Sjögren's syndrome

OBJECTIVE

To determine whether the haplotypes formed on the basis of single-base-exchange polymorphisms at positions -1082, -819, or -592 of the interleukin-10 (IL-10) gene predispose subjects to primary Sjögren's syndrome (SS).

METHODS

The frequency of IL-10 polymorphisms was analyzed in 62 patients with primary SS and in 400 healthy subjects. These data were assessed for correlations with the concentration of IL-10 in the plasma.

RESULTS

The frequency of the IL-10 GCC haplotype (G at position -1082, C at position -819, and C at position -592 of the IL-10 gene) was increased (P < 0.05, odds ratio [OR] 1.90, 95% confidence interval [95% CI] 0.955-3.62) and the frequency of the ACC haplotype decreased (P < 0.05, OR 0.443, 95% CI 0.257-0.764) in primary SS patients compared with healthy controls. Moreover, the frequency of the ATA haplotype was similar in primary SS patients and healthy controls, but the incidence of the GCC/ATA genotype was elevated in the primary SS patients (P < 0.05, OR 2.19, 95% CI 1.19-4.03). The concentration of plasma IL-10 was significantly higher in patients carrying the GCC haplotype than in non-carriers of GCC.

CONCLUSION

These results suggest that the presence of the GCC haplotype or the GCC/ATA genotype and the absence of the ACC haplotype of the IL-10 gene are associated with an increased susceptibility to primary SS. This effect is probably mediated by the increased capability to produce IL-10 among carriers of the GCC haplotype.

The occurrence of renal involvement in primary Sjögren's syndrome: a study of 78 patients

OBJECTIVE

To ascertain the occurrence of renal involvement in patients with primary Sjögren's syndrome (pSS).

METHODS

Urinary total protein excretion from 24 h urine collection, as well as urinary excretion rates of albumin, alpha-1 microglobulin (alpha1m) and IgG from overnight 8 h collections, were determined from 78 pSS patients (75 females, three males). Urine acidification capacity after oral ammonium chloride load was tested in 55 of these patients.

RESULTS

Mild proteinuria (0.15-0.42 g/24 h) was observed in 34 patients (44%). Increased urinary excretion rates of albumin (>/=20 microgram/min), alpha1m (>/=7.0 microgram/min) or IgG (>/=5.0 microgram/min) were detected in nine (12%), nine (12%) and 11 patients (14%), respectively. Latent or overt distal renal tubular acidosis (dRTA) was observed in 18 out of 55 patients with pSS (33%). These patients had a longer duration of the disease (10+/-4 vs 8+/-4 yr; P</=0.05); they also had proteinuria (67 vs 27%; P</=0.025) and hypertension (44 vs 14%; P</=0.05) more frequently, and significantly higher serum creatinine (92+/-39 vs 78+/-13 micromol/l; P</=0.025) and serum beta-2 microglobulin (beta2m) levels (3.3+/-1.6 g/l vs 2.6+/-0. 6 g/l; P</=0.025) as compared to patients with normal urine acidification capacity.

CONCLUSIONS

Inadequate renal acidification capacity, as well as mild proteinuria, were frequently found in patients with pSS. Those with dRTA had longer disease duration, a higher level of serum beta2m, and they had proteinuria and hypertension more frequently than those with normal renal acidification capacity.

Clinical follow up study of 87 patients with sicca symptoms (dryness of eyes or mouth, or both)

OBJECTIVE

To assess the prognosis of patients with sicca symptoms and to identify the clinical and immunological factors that most sensitively predict the later development of primary Sjögren's syndrome (SS) or other connective tissue diseases.

METHODS

Eighty seven patients (72 female, 15 male) with sicca symptoms were re-evaluated after a median follow up time of 11 years (range 8-17). The clinical examination included ophthalmological examination (Schirmer's test, break up time and Rose-Bengal staining). Labial salivary gland biopsy was performed and histological findings graded according to the Chisholm-Mason scale. The immunoserological tests included determination of rheumatoid factor (RF), antinuclear antibodies (ANA), anti-extractable nuclear antigen-antibodies (ENA), serum immunoglobulins IgA, IgG, and IgM, and serum beta2-microglobulin (beta2m).

RESULTS

At follow up 31 patients (36%) fulfilled modified Californian criteria (salivary flow measurements were not performed and Chisholm-Mason grades 3-4 were regarded as diagnostic histological findings) for possible or definite SS. Likewise, a significant progression of the histological findings was observed. Labial salivary gland re-biopsy was performed in 42 patients with grade 0-2 findings at baseline, progression to grades 3-4 being observed in 21 (50%) at follow up. The patients who later developed SS were at baseline significantly older (mean (SD) 52 (9) v 44 (14) years, p</=0.005) compared with those not fulfilling the SS criteria at follow up; they also had significantly higher serum beta2m (p</=0.0005) and IgG concentrations (p</=0.005), and they had positive ANA more frequently (p</=0.01).

CONCLUSION

These results suggest that high age, increased values of serum beta2m, ANA positivity and increased concentrations of serum IgG, might be useful indicators for the subsequent development of SS in patients with sicca symptoms. The prognosis of patients with these symptoms was favourable, and the clinical course was benign even in the 36% of patients who developed SS. No cases of lymphoma were observed.