The Cytokine Polymorphisms Affect the Severity of Thrombocytopenia at Diagnosis in Chronic Immune Thrombocytopenia.
Authors: Saitoh Takayuki , Ushie Chiaki , Iwasaki Atsushi , Moriyama Norihiko , Takani Tomonori , Hikaru Hattori , Handa Hiroshi , Koiso Hiromi , Yokohama Akihiko , Tsukamoto Norifumi , Ogawara Hatsue , Murakami Hirokazu 
Published: October 2019

Abstract
Abstract 2194

Introduction:
The severity of immune thrombocytopenia (ITP) depends on the degree of the thrombocytopenia and the extent of bleeding. Some investigators have reported the association between the thrombocytopenia and cytokine dysregulation in ITP. We investigated the association between the severity of thrombocytopenia at diagnosis in ITP patients and several cytokine polymorphisms, including IL-10-1082A/G, -819T/C, -592A/C, IL-17F-7488T/C and IL-18-607A/C, −137G/C.

Patients and methods:
We examined 102 patients (male/female, 24/78; median age, 42) diagnosed with chronic ITP. The definition, response criteria, including complete response (CR)and response (R), loss of CR,and “corticosteroid-dependence” were assessed according to the criteria of the ITP International Working Group. ITP with severe thrombocytopenia (ST group)was defined as thrombocytopenia (platelet count < 10×109/L) at the initial diagnosis of ITP. Genotyping of IL-10 (rs1800870 − 1082 A/G, rs1800871 − 819 T/C, and rs1800872 − 592 A/C) and IL-17F (rs763780, 7488 T/C) polymorphisms were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the genotyping of the IL-18 polymorphism (rs187238 −137G/C and rs1946518−607 A/C) was determined by the allelic specific polymerase chain reaction technique. To confirm the accuracy of the assay, amplification products of several individuals were sequenced using an ABI Prism Genetic Analyzer. Genotype and allele frequencies were compared between the study groups using χ2-test. The characteristics and laboratory features of ITP patients with each polymorphisms were compared using χ2-tests and student t-tests. Odds ratios (OR) and 95% confidence intervals (CIs) were estimated for each study. All patients were provided written information about the study. This study was approved by the Institutional Research Board of Gunma University Hospital.

Results:

Clinical features of chronic ITP:
The platelet count ranged from 1×109/L to 98×109/L with a mean of platelet count of 32×109/L at the initial diagnosis. Fifty seven patients (49%) had bleeding tendency. Steroid treatment was given to 68 patients (66.7%) and eradication of Helicobacter pylori (H. pylori) was performed in 32 patients (31.4%), while splenectomy was performed in only 11 patients (10.8%).

Clinical features of ST group vs. non-ST group in chronic ITP:
Of these 102 patients, 17 (16.7%) had severe thrombocytopenia (platelet count < 10×109/L) (ST group). ST group were significantly older (ST group: median 59 years vs. non-ST group: 41 years, p<0.01) and had more severe bleeding tendency (ST group: 100% vs. non-ST group: 54%, p<0.0001). Steroid treatment was frequently given to ST group than to non-ST group (ST group: 100% vs. non-ST group: 59.5%, p<0.001). Though the response to corticosteroids treatment was not significantly different between ST group and non-ST group (CR rate, ST group: 50% vs. non-ST group: 51.0%, p=0.94), corticosteroid-dependent patients in ST group was significantly higher than in non-ST group (76.9% vs. 25.3%, p<0.005).

Polymorphism study of ST group vs. non-ST group in chronic ITP:
The frequencies of genotypes of cytokines in patients with chronic ITP according to the definition of criteria of ST were as follows: AA (93.3% vs. 97.1%) and AG (6.7% vs. 2.9%, p=0.48) for IL-10–1082; TT (46.7% vs. 33.3%), TC (33.3% vs.55 %) and CC (20% vs. 11.7%) for IL-10–819; AA (46.7% vs. 33.3%), AC (33.3% vs.55 %) and CC (12.2% vs. 11.5%) for IL-10–592; TT (100% vs. 81%) and TC (0% vs. 19%) for IL-17F; GG (82.4% vs. 74.4%), GC (17.6% vs. 23.2%) and CC (0% vs. 2.4%) for IL-18–137; AA (35.3% vs. 34.1%), AC (58.8% vs. 53.7%) and CC (5.9% vs 12.2%) for IL-18–607 loci (ST group vs. non-ST group, respectively). No significant difference was observed between ST group and non-ST group according to IL-10–1082A/G, −819T/C, −592A/C, and IL-18–607A/C, −137G/C polymorphism. However, the numbers of IL-17F 7488TT genotype (higher function type) in ST group were significantly higher than in non-ST group (ST group: 100% vs. non-ST group: 81% p<0.05).

Conclusion:
These findings suggest that severe thrombocytopenia at diagnosis have an impact of bleeding tendency and corticosteroid-dependency of chronic ITP. Furthermore, IL-17F polymorphism may affect the severity of thrombocytopenia of chronic ITP.

Disclosures:
No relevant conflicts of interest to declare.