Human Leukocyte Antigen B*14:01 and B*35:01 Are Associated With Trimethoprim-Sulfamethoxazole Induced Liver Injury

Abstract

Background and aims: Trimethoprim (TMP)-sulfamethoxazole (SMX) is an important cause of idiosyncratic drug-induced liver injury (DILI), but its genetic risk factors are not well understood. This study investigated the relationship between variants in the human leukocyte antigen (HLA) class 1 and 2 genes and well-characterized cases of TMP-SMX DILI.

Approach and results: European American and African American persons with TMP-SMX DILI were compared with respective population controls. HLA sequencing was performed by Illumina MiSeq (Illumina, San Diego, CA) for cases. The HLA genotype imputation with attribute bagging program was used to impute HLA alleles for controls. The allele frequency difference between case patients and controls was tested by Fisher's exact tests for each ethnic group. For European Americans, multivariable logistic regression with Firth penalization was used to test the HLA allelic effect after adjusting for age and the top two principal components. Molecular docking was performed to assess HLA binding with TMP and SMX. The European American subset had 51 case patients and 12,156 controls, whereas the African American subset had 10 case patients and 5,439 controls. Four HLA alleles were significantly associated in the European American subset, with HLA-B*14:01 ranking at the top (odds ratio, 9.20; 95% confidence interval, 3.16, 22.35; P = 0.0003) after covariate adjustment. All carriers of HLA-B*14:01 with TMP-SMX DILI possessed HLA-C*08:02, another significant allele (P = 0.0026). This pattern was supported by HLA-B*14:01-HLA-C*08:02 haplotype association (P = 1.33 × 10^-5 ). For the African American patients, HLA-B*35:01 had 2.8-fold higher frequency in case patients than in controls, with 5 of 10 patients carrying this allele. Molecular docking showed cysteine at position 67 in HLA-B*14:01 and phenylalanine at position 67 in HLA-B*35:01 to be the predictive binding sites for SMX metabolites.

Conclusions: HLA-B*14:01 is associated with TMP-SMX DILI in European Americans, and HLA-B*35:01 may be a potential genetic risk factor for African Americans.

Figure 1:

Consort diagram to outline the sample sizes used in this study

Figure 2:

HLA-B allele cluster from predicted peptide-binding specificity for European American (panel A) and African Americans (panel B). The color key was based on the distance between allele binding specificity. Red color (near 0) indicates high similarity on binding specificity between alleles, and white (near 1) indicates completely different binding specificity. Allele clusters tested for association with TMP-SMX DILI are marked by rectangles.

Figure 3:

Results of molecular docking. Panels A and B: HLA-B*14:01 exhibited an unpaired cysteine at position 67 with the potential to bind reactive SMX metabolite sulfonamide. The molecular surface of a model of HLA-B*14:01 is shown in light blue. Sulfonamide is shown as sticks, white for carbon, blue for nitrogen, red for oxygen. Cys⁶⁷, Trp⁹⁷, and Thr¹⁶³ are shown in red. Panels C and D: Molecular docking predicted interaction between SMX and the antigen binding cleft of HLA-B*35:01. The crystal structure of HLA-B*35:01 is shown (PDB code 6BJ8), colored based on sequence similarity to HLA-B*15:02. Blosum62 similarity values are: blue, 40–50, cyan, 50–60, green, 60–70, yellow, 70–80, orange 80–90, and red 90–100. Molecular docking (AutoDock Vina, ΔG=−7.6 kcal/mol) predicted SMX interaction with residues shared by HLA-B*35:01 and HLA-B*15:02 shown as sticks. Predicted H bond interactions are shown as black dashed lines. The position 67 (Phe⁶⁷), which we detected in our AA analysis, was not predicted to form contact with SMX by molecular docking.