Presence of Circulatory Autoantibodies Against ROS-Modified Histone H1 Protein in Lymphoma Patients

Naif K Binsaleh; Reem Eltayeb; Husam Qanash; Mohammad Azhar Aziz; Raid Albaradie; Mohd Wajid Ali Khan

doi:10.3389/fgene.2022.909903

Presence of Circulatory Autoantibodies Against ROS-Modified Histone H1 Protein in Lymphoma Patients

Front Genet. 2022 May 25:13:909903. doi: 10.3389/fgene.2022.909903. eCollection 2022.

Authors

Naif K Binsaleh¹, Reem Eltayeb¹, Husam Qanash^{1

2}, Mohammad Azhar Aziz³, Raid Albaradie⁴, Mohd Wajid Ali Khan^{2

5}

Affiliations

¹ Department of Medical Laboratory Science, College of Applied Medical Sciences, University of Ha'il, Ha'il, Saudi Arabia.
² Molecular Diagnostics and Personalized Therapeutics Unit, University of Ha'il, Ha'il, Saudi Arabia.
³ Interdisciplinary Nanotechnology Centre, Aligarh Muslim University, Aligarh, India.
⁴ Applied Medical Sciences College, Majmaah University, Al Majma'ah, Saudi Arabia.
⁵ Department of Chemistry, College of Sciences, University of Ha'il, Ha'il, Saudi Arabia.

Abstract

Lymphoma is a chronic inflammatory disease in which the immune system is highly affected. Increased oxidative stress is one of the common conditions of cancer and affects macromolecules. Histone modifications affect the chromatin structure and functions. In this study, histone H1 (His-H1) protein was modified by reactive oxygen species (ROS), and structural and chemical changes were studied. Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL) patients were selected, and oxidative stress markers, inflammatory cytokines, and serum autoantibodies were analyzed using biochemical and immunological assays. Furthermore, the formation of antigen-antibody immune complexes was assessed by the Langmuir plot. ROS-modified His-H1 (ROS-His-H1) showed substantial structural perturbation in protein (UV-hyperchromicity and increased intrinsic fluorescence) compared to the native His-H1 protein. A possible explanation for the changes is suggested by the exposure of the aromatic chromophore to the solvent. In-depth structural analysis by circular dichroism (CD) exhibited major changes in α-helix (-21.43%) and turns (+33%), reflecting changes in the secondary structure of histone H1 protein after ROS exposure. ELISA and competitive ELISA findings revealed high recognitions of serum autoantibodies to ROS-His-H1 from NHL, followed by HL subjects. Healthy controls showed negligible binding. Non-modified His-H1 did not show any binding with serum samples from either cohort. High apparent association constants (ACCs) were calculated for ROS-His-H1 using purified IgGs from NHL (1.46 × 10^-6 M) compared to HL (1.33 × 10^-6 M) patients. Non-modified His-H1 exhibited a hundred times less ACC for NHL (2.38 × 10^-8 M) and HL (2.46 × 10^-8 M) patients. Thus, ROS modifications of histone H1 cause structural changes and expose cryptic neo-epitopes on the protein against which autoantibodies were generated. These perturbations might affect the histone DNA interaction dynamics and potentially be correlated with gene dysregulation. These subtle molecular changes with an immune imbalance might further aggravate the disease.

Keywords: Hodgkin lymphoma; autoantibodies; histone H1; lymphoma; non-Hodgkin lymphoma; oxidative stress; reactive oxygen species.