Interleukin-6 and interleukin-8 levels in children with aplastic anemia and its correlation with disease severity and response to immunosuppressive therapy.

Background: Aplastic anemia (AA) is an uncommon condition characterized by pancytopenia and hypocellular bone marrow. Interleukin (IL)-6 and IL-8 have been shown to inhibit myelopoiesis and are major mediators of tissue damage. The primary goal of this study was to determine the IL-6 and IL-8 levels in children with AA, as well as their relationship to illness severity and immunosuppressive medication response. Materials and Methods: The IL-6 and IL-8 levels were tested in 50 children aged 3-18 years who had AA. As controls, 50 healthy age and sex matched individuals were used. A sandwich enzyme-linked immunosorbent assay kit (solid-phase) was used to measure IL-6 and IL-8 levels quantitatively. The concentrations of IL-6 and IL-8 in pg/mL were used to represent the results. Immunosuppressive medication was given to the patients in accordance with the British Committee for Standards in Haematology Guidelines 2009. Results: The patients' average age was 11.3 ± 3.7 years. Patients with AA had significantly higher IL-6 and IL-8 levels than controls (278.88 ± 216.03 vs. 4.51 ± 3.26; P < 0.001) and (120.28 ± 94.98 vs. 1.79 ± 0.78; P < 0.001), respectively. The IL-6 and IL-8 levels were also investigated with respect to AA severity, with statistically significant differences (P < 0.01) between different grading strata. Patients with very severe AA (VSAA) had the highest IL-6 levels (499.52 ± 66.19), followed by severe AA (SAA) (201.28 ± 157.77) and non-SAA (NSAA) (22.62 ± 14.63). For IL-8 levels, a similar trend (P < 0.01) was detected, with values of 209.81 ± 38.85, 92.12 ± 78.0, and 9.29 ± 10.68 for VSAA, SAA, and NSAA, respectively. After 6 months of immunosuppressive treatment (IST), mean levels of IL-6 and IL-8 in responders and nonresponders were again assessed. The mean IL-6 level in the responders' group (46.50 ± 45.41) was significantly lower, when compared to the nonresponders' group (145.76 ± 116.32) (P < 0.001). Similarly, the mean IL-8 level in the responder's group (33.57 ± 27.14) was significantly lower, compared to the nonresponder's group (97.49 ± 69.00) (P < 0.001). Conclusions: Children with AA had higher IL-6 and IL-8 levels than normal age- and sex-matched controls. Increased levels were linked to the severity of the condition, suggesting that IL may have a role in AA. IL levels can be monitored in AA patients during IST, which can assist in predicting response to IST.

Résumé Contexte: L'anémie aplastique (AA) est une affection peu fréquente caractérisée par une pancytopénie et une moelle osseuse hypocellulaire. Il a été démontré que l'interleukine (IL)-6 et l'IL-8 inhibent la myélopoïèse et sont des médiateurs majeurs des lésions tissulaires. L'objectif principal de cette étude était de déterminer les niveaux d'IL-6 et d'IL-8 chez les enfants atteints d'AA, ainsi que leur relation avec la gravité de la maladie et la réponse aux médicaments immunosuppresseurs. Matériel et méthodes: Les niveaux d'IL-6 et d'IL-8 ont été testés chez 50 enfants âgés de 3 à 18 ans atteints d'AA. 50 témoins sains appariés par l'âge et le sexe ont été utilisés. Un kit de dosage immuno-enzymatique en sandwich (phase solide) a été utilisé pour mesurer quantitativement les niveaux d'IL-6 et d'IL-8. de manière quantitative. Les concentrations d'IL-6 et d'IL-8 en pg/mL ont été utilisées pour représenter les résultats. Des médicaments immunosuppresseurs ont été administrés aux patients conformément aux directives 2009 du British Committee for Standards in Haematology. Résultats: L'âge moyen des patients était de 11,3 ± 3,7 ans. Les patients atteints d'AA présentaient des taux d'IL-6 et d'IL-8 significativement plus élevés que les témoins (278,88 ± 216,03 contre 4,51 ± 3,26 ; P < 0,001) et (120,28 ± 94,98 contre 1,79 ± 0,78 ; P < 0,001), respectivement. Les taux d'IL-6 et d'IL-8 ont également été étudiés en fonction de la gravité de l'AA, avec des différences statistiquement significatives (P < 0,01) entre les différentes strates de classement. Les patients présentant une AA très sévère (VSAA) avaient les taux d'IL-6 les plus élevés (499,52 ± 66,19), suivis par les patients atteints d'AA sévère (SAA) (201,28 ± 157,77) et les patients non-SAA (NSAA) (22,62 ± 14,63). Pour les niveaux d'IL-8, une tendance similaire (P < 0,01) a été détectée, avec des valeurs de 209,81 ± 38,85, 92,12 ± 78,0, et 9,29 ± 10,68 pour les VSAA, SAA et NSAA, respectivement. Après 6 mois de traitement immunosuppresseur traitement immunosuppresseur (IST), les niveaux moyens d'IL-6 et d'IL-8 chez les répondeurs et les non-répondeurs ont été à nouveau évalués. Le taux moyen d'IL-6 dans le groupe des répondeurs (46,50 ± 45,41) était significativement plus faible, par rapport au groupe des non-répondeurs (145,76 ± 116,32) (P < 0,001). De même, le niveau moyen d'IL-8 dans le groupe des répondeurs (33,57 ± 27,14) était significativement plus faible que dans le groupe des non-répondeurs (97,49 ± 69,00) (P < 0,001). Conclusions: Les enfants atteints d'AA présentaient des niveaux d'IL-6 et d'IL-8 plus élevés que les témoins normaux appariés selon l'âge et le sexe. L'augmentation des taux était liée à la gravité de l'affection, suggérant que l'IL pourrait jouer un rôle dans l'AA. Les niveaux d'IL peuvent être surveillés chez les patients atteints d'AA pendant l'IST, ce qui peut aider à prédire la réponse à l'IST. Mots-clés: Anémie aplastique, traitement immunosuppresseur, interleukine-6, interleukine-8.

Aplastic anemia severity and IL-6 and IL-8 blood levels.

INTRODUCTION AND AIMS: Aplastic anemia is a rare, fatal bone marrow disorder that is presumed to be an autoimmune-mediated illness that actively destroys haematopoietic cells through a T helper type-1 cell response. Different cell types in the bone marrow and peripheral circulation produce chemokines, such as interleukin-6 (IL-6) and interleukin-8 (IL-8). The myelopoiesis that is profoundly impaired in aplastic anemia may be inhibited by these two, as critical and powerful inhibitors. Therefore, it is conceivable that their ongoing overproduction may contribute to aplastic anemia. We performed a quantitative enzyme-linked immunosorbent assay on the peripheral blood plasma to reveal the levels of IL-6 and IL-8 and their correlation to aplastic anaemia. MATERIALS AND METHODS: A total of 80 cases of aplastic anemia were included in this study, diagnosed according to the criteria laid down by the International Agranulocytosis and Aplastic Anemia study group. A total of 10 healthy individuals served as controls in this study. With the help of a commercial ELISA kit and the instructions from the kit's maker, the levels of IL-6 and IL-8 were measured in a quantitative way. RESULTS: Mean serum IL-6 and IL-8 levels in cases were 283.28±220.27 and 122.56±97.79 pg/ml, respectively, as compared to 7.52±1.43 and 3.42±1.73 pg/ml levels in controls. Statistically, mean IL-6, as well as IL-8 levels, were significantly higher in aplastic anemia patients than in controls (p< 0.001). Levels of interleukins were also assessed in relation to the severity of the disease. Patients with very severe aplastic anaemia had significantly higher mean IL-6 and IL-8 levels (516.71±36.73 and 220.50±23.45 pg/ml, respectively), followed by severe aplastic anaemia (198.84±150.39 and 89.82±77.18 pg/ml, respectively) and non-severe aplastic anaemia (26.71±33.40 and 10.29±2.63 pg/ml, respectively) (p<0.001). CONCLUSION: Blood serum levels of IL-6 and IL-8 were increased in aplastic anemia and showed a correlation with the severity of the disease. Hence, IL-6 and IL-8 may play an important role in the immune-mediated pathophysiology of aplastic anemia and their increasing levels are giving alarming signals for timely implementation of the appropriate treatment regimen to stop further progression of the disease. Additional studies are required in order to further investigate the exact involvement and role of IL-6 and IL-8 in aplastic anemia.