AB0552 ELEVATED KYNURENINE LEVELS IN PATIENTS WITH PRIMARY SJÖGREN’S SYNDROME

Background

Sjögren’s syndrome (SS) is a chronic autoimmune systemic inflammatory disease of unknown origin that predominantly affects the exocrine glands (mainly salivary and lacrimal glands). Primary Sjögren’s syndrome (pSS) is a disease whose etiology is not yet fully understood, as in most autoimmune diseases, where genetic, epigenetic and environmental factors are hypothesized to play to the pathogenesis of the disease. Metabolism of tryptophan (Trp) via the kynurenine (Kyn) pathway has been proposed to act a substantial role in inflammatory processes.

Objectives

In the present study, we investigated levels of Trp and its metabolites in the Kyn pathway in patients with pSS and in healthy controls. Also, the relationship between Trp metabolites and laboratory parameters, disease activity was evaluated in patients with pSS.

Methods

The study included 34 pSS patients and 42 healthy individuals, and serum Trp and Kyn concentrations were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Trp degradation was predicted using the ratio of Kyn and Trp concentrations (Kyn/Trp). The EULAR Sjögren’s syndrome disease activity index (ESSDAI) and the EULAR Sjögren’s Syndrome Patient Reported Index (ESSPRI) were used to evaluate pSS activity.

Results

In our study, the mean serum Trp concentration was found to be considerably lower in the pSS group compared to the control group (p= 0.001). The levels of Kyn (p= 0.019) and Kyn/Trp ratio (p <0.001) were significantly higher in the pSS group compared to the control group (Table 1). Trp concentration was negatively correlated with physician global assessment (r=-0.568, p<0.001), positively correlated with albumin (r=0.384, p=0.025) and hemoglobin (p=0.396, r=0.020). The Kyn/Trp ratio was negatively correlated with CRP (r=-0.369, p=0.032). There was no correlation between the Trp pathway and disease activity parameters ESSDAI and ESRPI.

Table 1.

Comparison of the kynurenine pathway results of patients with Sjögren’s syndrome and the controls

Sjögren’s syndrome (n=34) median (IQR)Control(n=42) median (IQR)pKynurenine (ng/ml)485 (378-601)386 (356-496)0.019Tryptophan (ng/ml)10660 (9160- 12282)12258 (11442-14711)0.001Kynurenine/tryptophan ratio (%)4 (3-6)3 (3-4)<0.001

*Mann-Whitney U test

Conclusion

In conclusion, we found that kynurenine pathway metabolism was altered in patients with pSS. This suggests that tryptophan metabolism may be closely linked to the disease pathogenesis of pSS.

References

[1]Stefanski A-L, Tomiak C, Pleyer U, Dietrich T, Burmester GR, Dörner T. The diagnosis and treatment of Sjögren’s syndrome. Deutsches Ärzteblatt International. 2017;114(20):354.

[2]Maldini C, Seror R, Fain O, Dhote R, Amoura Z, De Bandt M, et al. Epidemiology of primary Sjögren’s syndrome in a French multiracial/multiethnic area. Arthritis care & research. 2014;66(3):454-63.

[3]Moffett JR, Namboodiri MA. Tryptophan and the immune response. Immunology and cell biology. 2003;81(4):247-65.

[4]Schroecksnadel K, Winkler C, Duftner C, Wirleitner B, Schirmer M, Fuchs D. Tryptophan degradation increases with stage in patients with rheumatoid arthritis. Clinical rheumatology. 2006;25(3):334-7.

Disclosure of Interests

None declared

AB0161 THE RELATIONSHIP OF TRYPTOPHAN CATABOLISM WITH RHEUMATOİD ARTHRITIS DİSEASE ACTİVİTY ABSTRACT

Background

Tryptophan (Trp) is an essential amino acid. The immunosuppressive effect caused by Kynurenine (Kyn) and its metabolites formed by the catabolism of Trp is thought to be an important physiological mechanism.

Objectives

This study aims to evaluate the relationship of Kyn and its metabolites formed in Trp catabolism with rheumatoid arthritis (RA) disease activation and to investigate the usability of these markers in the diagnosis and treatment of RA.

Methods

50 RA patients followed in our rheumatology clinic and 41 healthy controls without chronic disease were included in this study. Disease Activity Score 28 (DAS28) was used to evaluate the association of Kyn metabolites and Indolamine 2,3 dioxygenase (IDO) enzyme activity with RA disease activity. The task of this enzyme is to provide Kyn formation with Trp catabolism.

Results

In this study, lower Trp levels were found in the RA group compared to the control group (11285.47±2318.93-13320.31±3771.27, respectively) compared to the Trp mean (p<0.01). In terms of the Kyn/Trp ratio, a significantly higher Kyn/Trp ratio (4.42±1.77-3.27±0.71, respectively) was found in the RA compared to the control group (p<0.001). There was no significant difference between the study groups in terms of Kyn averages (p>0.05). A significant correlation was found between Trp levels and morning stiffness (r: -0.321, p<0.05) and the DAS28 score (r:-0.566, p<0.01). A significant positive correlation was found between the Kyn/Trp ratio and C-reactive protein (r:0.317, p<0.05), sedimentation (r:0.319, p<0.05), morning stiffness (r:0.287, p<0.05) and DAS28 score (r:0.322, p<0.01).

Table 1.

Comparison of study parameters between RA and control group.

ParameterRheumatoid arthritisControl groupP-ValueTryptophan (ng/ml)11285,47±2318,9313320,31±3771,27<0.01Kynurenine (ng/ml)477,68±158,38437,51±162,10>0.05Kyn/Trp ratio4,42±1,773,27±0,71<0.001

All values were expressed as mean ± SD. All values were calculated using independent sample t-test for normal distribution.

Figure 1.

Correlation relationship between DAS 28 and Trp levels (r: -0,321, p < 0.01)

Conclusion

In this study, we observed that RA has a significant relationship with Trp levels and Kyn/Trp ratio. In addition to the literature, we found that RA activation indicator DAS28 score and Kyn/Trp ratio and Trp level showed a statistically significant correlation. Our study has shown that the Trp catabolic pathway can be an important field of study for more effective and safe treatment of RA.

References

[1]Smolen JS, Aletaha D, Barton A, Burmester G, Emery P, et al. Rheumatoid arthritis. Nat Rev Dis Primers. 2018;4:18001. doi:10.1038/nrdp.2018.1

[2]Choy EH, Panayi GS. Cytokine pathways and joint inflammation in rheumatoid arthritis. N Engl J Med

[3]Murray PJ. Amino acid auxotrophy as a system of immunological control nodes. Nature immunology, 2016;17.2: 132-139. doi:10.1038/ni.3323

[4]Frumento G, Rotondo R, Tonetti M, Damonte G, Benatti U, et al. Tryptophan-derived catabolites are

[5]De Jong RA, Nijman HW, Boezen HM, Volmer M, Ten Hoor KA, et al. Serum tryptophan and kynurenine concentrations as parameters for indoleamine 2, 3-dioxygenase activity in patients with endometrial, ovarian, and vulvar cancer. International Journal of Gynecologic Cancer, 2011;21.7. doi:10.1097/IGC.0b013e31822017fb

[6]Aletaha D, Neogi T, Silman AJ, Funovits J, Felson DT., et al. 2010 rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis & Rheumatism, 2010;62.9:2569-2581. doi:10.1002/art.27584.

[7]Ozkan Y, Mete G, Sepici-Dincel A, Sepici V, Simsek B. Tryptophan degradation and neopterin levels in treated rheumatoid arthritis patients. Clinical rheumatology; 2012;31.1:29-34. doi:10.1007/s10067-011-1767-5

Trp: Tryptophan, DAS28: Disease Activity Score

Acknowledgements

This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK). The authors thank TUBITAK for its financial support

Disclosure of Interests

None declared

High sensitivity detection of salivary 8-hydroxy deoxyguanosine levels in patients with chronic periodontitis

BACKGROUND

Inflammation is associated with hydroxyl radical damage to DNA as a result of oxidative stress. 8-Hydroxy deoxyguanosine (8-OHdG) is a marker of this process and its levels in saliva could be linked to the severity of periodontal inflammation. The aim of this study was to test the sensitivity of liquid chromatography with tandem mass spectrometry (LC-MS/MS) in comparison to enzyme-linked immune sorbent assay (ELISA) for the detection of 8-OHdG in saliva in patients with chronic periodontitis before and after periodontal treatment.

METHODS

Saliva samples were collected from 23 patients (eight females and 15 males; 46.1 ± 5.1 years of age) with generalized chronic periodontitis and 25 (15 females and 10 males; 44.9 ± 6.8 years of age) periodontally healthy individuals. Patients received initial periodontal treatment consisting of scaling and root planing and were evaluated at baseline and after 6 wk of completion of non-surgical therapy. Salivary 8-OHdG levels were measured using ELISA and LC-MS/MS before and after the treatment. Clinically, plaque index, gingival index, clinical attachment level, bleeding on probing, gingival recession and probing pocket depth were measured at baseline and after 6 wk.

RESULTS

Salivary levels of 8-OHdG decreased significantly after the non-surgical periodontal treatment (p < 0.001). Statistically significant positive correlations were observed between plaque index, gingival index, probing pocket depth, clinical attachment level, bleeding on probing values and LC-MS/MS and ELISA levels of 8-OHdG (p < 0.001).

CONCLUSION

LC-MS/MS is a reliable and sensitive method for evaluating salivary 8-OHdG levels to monitor the treatment response of periodontitis.

The effects of analytical factors on second trimester risk estimations

OBJECTIVE

Triple test with measured maternal serum alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol combination as a routine procedure for fetal Down's syndrome, trisomy 18 and neural tube defect screening has some intrinsic problems, such as precision. The aim of this study was to evaluate the effect of analytical variation of triple test on prenatal risk estimation.

METHOD

Five different serum pools were prepared and triple test was performed seven times for within run and five times for between run precision determination.

RESULT

Within run and between run, precision values of risk estimations by measuring the same sample for Triple test were calculated to be 7.9-21.4% and 14.1-31.0% for trisomy 21, 13.2-23.7% and 14.2-15.1% for trisomy 18, 47.2 and 42.0 % for neural tube defect, respectively.

CONCLUSION

These results demonstrated that analytical variations have great impact on second trimester risk estimation procedures; therefore, triple test analyses should be carried out in laboratories using strict internal and external quality control programs. Moreover, triple test results should always be interpreted by considering analytical and biological variations.

In vitro IL-1beta release from gingival fibroblasts in response to pure metals, dental alloys and ceramic

Little information is available on the immunological basis for side-effects of dental materials. The objective of this study is to evaluate effects of pure metals, dental alloys and ceramic on cell viability and interleukin-1 beta (IL-1beta) release in three-dimensional human gingival fibroblast cultures as an indicator of their biological performance in gingival tissues. The gingival fibroblast cultures were exposed to test specimens fabricated from nickel, iron, molybdenum, copper, indium, gold, Ni-Cr-Mo alloy (Remanium CS), Au-Pt-In alloy (Pontostar) and a dental ceramic (In-ceram). Cell viability was determined by the MTT method 24 and 48 h after exposure. Assays for IL-1beta were carried out by ELISA. Statistical analysis was performed applying the non-parametric Mann-Whitney pairwise test. Dental ceramic and gold did not influence cell viability after 24 and 48 h. Cell viability was determined after 24 and 48 h to nickel (79-77%), iron (92-90%), molybdenum (86-83%), copper (48-36%), indium (90-90%), Remanium CS (83-80%), Pontostar (94-91%) compared with control cultures. Dental ceramic, Pontostar and gold had no significant influence on IL-1beta secretion. The highest amounts of IL-1beta (10-fold) levels were determined in cell cultures exposed to copper. Indium, molybdenum and iron induced twofold IL-1beta levels compared with untreated control cultures. These results support that some metals may alter immune responses and thereby contribute to a variety of dental pathological conditions and three-dimensional cell culture models for gingival fibroblasts appear to be suitable for in vitro studies.

A practical approach to glomerular filtration rate measurements: creatinine clearance estimation using cimetidine

Determination of creatinine clearance (Ccr) is not a reliable indicator of glomerular filtration rate (GFR), owing to tubular secretion of creatinine. It has been reported that Ccr measurements can approximate true GFR after cimetidine (Ci) administration. In this study, GFR was estimated by Cockcroft and Gault's equation (C(C-G)) based on measurement of plasma creatinine, and Ccr was determined by the standard clearance equation using 4- and 24-hr urine samples (Ccr4 and Ccr24, respectively) in 17 patients and 10 healthy controls. After cimetidine administration (800 mg, 3 times daily), GFR values were recalculated at the same time periods (C(CiC-G), CcrCi4 and CcrCi24, respectively). The results were all compared to those obtained by the 99mTc-DTPA protein-free double-sample method (C(DTPA)), which is a reference method for GFR determination. The coefficient of variation (CV%) for Ccr24/C(DTPA) was high before cimetidine administration; Ccr24 and CcrCi24 values were significantly different from C(DTPA) (CV 23.1%, Ccr24/C(DTPA) = 1.17, p 0.005; and CV 14.1%, CcrCi24/C(DTPA) = 0.92, p 0.006, respectively). Ccr4 values obtained before cimetidine ingestion showed large variation and were significantly different from C(DTPA) (CV 15.5%, Ccr4/C(DTPA) = 1.11, p 0.001). CcrCi4 values after cimetidine were similar to CDTPA (CV 6.9%, CcrCi4/C(DTPA) = 1.01, p 0.28). C(C-G) estimates were higher before cimetidine intake (CV 12.4%, C(C-G)/C(DTPA) = 1.21, p <0.001), whereas C(CiC-G) values were not significantly different from C(DTPA) values (CV 7.0%, C(CiC-G)/C(DTPA) = 1.01, p 0.67). This study shows that GFR estimations by C(C-G), Ccr4, Ccr24, or CcrCi24 are insufficiently reliable. On the other hand, C(CiC-G) and CcrCi4 results are acceptable for true GFR estimations.

Brainstem auditory-evoked potentials in iron-deficiency anemia

Slight-to-moderate impairments may be observed in mental and motor developments of infants with iron- deficiency anemia. Brainstem auditory-evoked potentials provide a noninvasive means of examining the auditory aspect of the central nervous system functions. In this study the effect of iron-deficiency anemia on auditory functions was investigated by using brainstem auditory-evoked potentials. Brainstem auditory-evoked potentials of the 20 iron-deficient infants were not significantly different from those of the control group that included 20 healthy age-matched infants. Furthermore, there was not a statistically significant difference between the brainstem auditory-evoked potentials of the study group performed before and 3 months after oral iron therapy. Although we could not demonstrate a hearing loss in infants with moderate iron-deficiency anemia in this study, the relationship between severe iron-deficiency anemia and hearing loss or auditory dysfunction remains to be determined.

The role of erythrocyte protoporphyrin in the diagnosis of iron deficiency anemia of children

The values of erythrocyte protoporphyrin, ferritin and mean corpuscular volume (MCV) measurements in diagnosing iron deficiency anemia were investigated in 72 iron deficient and in 25 healthy control infants. Receiver operator curve, sensitivity and specificity of erythrocyte protoporphyrin, ferritin and mean corpuscular volume were compared between the study and control groups. In the study group mean corpuscular volume, hemoglobin and ferritin concentrations were significantly lower, and erythrocyte protoporphyrin was significantly higher when compared to the control group. In the iron deficient study group, erythrocyte protoporphyrin was the most sensitive test and ferritin was the most specific test, whereas ferritin was the most diagnostic test and mean corpuscular volume was the least diagnostic test. A significant correlation between erythrocyte protoporphyrin and hemoglobin values was determined. We conclude that erythrocyte protoporphyrin is a more sensitive but less specific test than ferritin, and it can be used as a first-line diagnostic test in the evaluation of iron deficiency and in diagnosing iron deficiency anemia in infants.

The value of first-day bilirubin measurement in predicting the development of significant hyperbilirubinemia in healthy term newborns

OBJECTIVE

The recognition, follow-up, and early treatment of neonatal jaundice has become more difficult, since the earlier discharge of newborns from hospitals has become common practice. This prospective study was undertaken to identify the newborns at risk for developing significant hyperbilirubinemia later during the first days of life by measuring the serum bilirubin levels of the first 5 days of life to determine the critical predictive serum bilirubin value on the first day of life.

METHODOLOGY

A total of 498 healthy term newborns were followed with daily serum total bilirubin measurements for the first 5 days of life, and cases with serum bilirubin levels of >/=17 mg/dL after 24 hours of life were defined to have significant hyperbilirubinemia.

RESULTS

No newborns had a serum total bilirubin level of >/=17 mg/dL in the first 72 hours of life. Sixty of 498 cases (12.05%) had significant hyperbilirubinemia after 72 hours of life, and these cases had significantly higher bilirubin levels than those who did not develop significant hyperbilirubinemia on each of the first 5 days' measurements. Of the 206 newborns who had a serum bilirubin level of >/=6 mg/dL in the first 24 hours, 54 (26.21%) developed significant hyperbilirubinemia, whereas only 6 of the 292 newborns (2.05%) who had a serum bilirubin level of <6 mg/dL on the first day developed significant hyperbilirubinemia. A mean serum bilirubin level of >/=6 mg/dL on the first day had the highest sensitivity (90%). At this critical serum bilirubin value, the negative predictive value was very high (97.9%) and the positive predictive value was fairly low (26.2%). Furthermore, because no cases with a serum bilirubin level of <6 mg/dL in the first 24 hours of life required a subsequent phototherapy treatment and because all of those infants requiring a phototherapy treatment with serum bilirubin levels of >/=20 mg/dL were just among the cases whose first-day bilirubin levels were >/=6 mg/dL, the critical bilirubin level of 6 mg/dL on the first day made it possible, with the highest (100%) sensitivity and negative predictive value, to definitely predict all of the infants who would have a bilirubin level of >20 mg/dL, requiring a phototherapy treatment later during the first days of life.

CONCLUSIONS

A serum bilirubin measurement and the use of the critical bilirubin level of 6 mg/dL in the first 24 hours of life will predict nearly all of the term newborns who will have significant hyperbilirubinemia and will determine all those who will require a phototherapy treatment later during the first days of life.

Biochemical composition of benign thyroid cyst fluid

Although the availability of thyroid cyst fluid is easy by fine-needle aspiration, less is known about the biochemical composition of thyroid cyst fluid. The authors have, therefore, determined the biochemical composition of 18 benign thyroid cyst fluid specimens. They found that the activities of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and the concentrations of total protein, total bilirubin, and uric acid were highly increased in thyroid cyst fluid specimens when compared with normal human serum specimens. The concentrations of glucose, cholesterol, and triglycerides in cyst fluid were within normal serum limits. Selenium (Se) concentrations in most cyst fluids were low. Moreover, there was no correlation between Se and other biochemical parameters. Protein electrophoresis of cyst fluid specimens yielded high concentrations of alpha 1 and especially alpha 2 globulin fractions indicating an inflammation. The concentrations or activities of biochemical analytes were not significantly different in pure and mixed cysts. Those parameters were also not significantly different between cyst fluids of different colors. The gross appearance of the fluid and the presence of certain biochemical analytes were consistent with a hemorrhagic origin of most of the cyst fluid specimens. However, some biochemical markers indicate that autolysis or necrosis of thyroid tissue may also contribute the composition of thyroid cyst fluid. The reason for lower Se concentration in the thyroid cyst fluid may be the lower Se concentration in the Turkish population. These results also suggest that the fluid color or nature of cyst, e.g., pure or mixed cyst, is not a main determinant of biochemical composition of benign thyroid cyst fluid.