Selective Silencing of Disease-Associated B Lymphocytes from Hashimoto’s Thyroiditis Patients by Chimeric Protein Molecules

Abstract

Hashimoto’s thyroiditis is one of the most common endocrine disorders, affecting up to 20% of the adult population. No treatment or prevention exists except hormonal substitution for hypothyroidism. We hypothesize that it may be possible to selectively suppress anti-thyroglobulin (Tg) IgG antibody-producing B lymphocytes from HT patients by a chimeric protein molecule containing a monoclonal antibody specific for the human inhibitory receptor CR1, coupled to peptide epitopes derived from Tg protein. We expect that this treatment will down-regulate B-cell autoreactivity by delivering a strong inhibitory signal. Three peptides—two epitope-predicted ones derived from Tg and another irrelevant peptide—were synthesized and then coupled with monoclonal anti-human CR1 antibody to construct three chimeric molecules. The binding to CD35 on human B cells and the effects of the chimeric constructs on PBMC and TMC from patients with HT were tested using flow cytometry, ELISpot assay, and immunoenzyme methods. We found that after the chemical conjugation, all chimeras retained their receptor-binding capacity, and the Tg epitopes could be recognized by anti-Tg autoantibodies in the patients’ sera. This treatment downregulated B-cell autoreactivity and cell proliferation, inhibited Tg-specific B-cell differentiation to plasmablasts and promoted apoptosis to the targeted cells. The treatment of PBMCs from HT patients with Tg-epitope-carrying chimeric molecules affects the activity of Tg-specific autoreactive B lymphocytes, delivering to them a strong suppressive signal.

The Role of the Immune System in the Course of Hashimoto’s Thyroiditis: The Current State of Knowledge

“…When discussing the importance of B lymphocytes, attention should also be paid to the influence of CD4+ T lymphocytes on their activity. It has been shown that, after binding to TG epitopes, they influence the process whereby B lymphocytes are differentiated into plasma cells [41]. Observations confirm the presence of B lymphocytes in the thyroid gland and their involvement in the development of the disease.…”

“…Observations confirm the presence of B lymphocytes in the thyroid gland and their involvement in the development of the disease. Patients with autoimmune thyroid diseases, including Hashimoto's thyroiditis, have also been observed to have reduced numbers in anergic TG-specific B cells in the blood [41]. Similar results were obtained in a study conducted by Smith et al, where a decreased total number of anergic B cells and those capable of reacting with TG and TPO, as well as higher levels of antibodies against self-antigens, were found in the blood of newly diagnosed patients compared to those with a longer history of the disease or those without the disease [40].…”

“…Although the impact of B lymphocytes on the development of Hashimoto's thyroiditis is becoming more thoroughly understood, there are still a lack of proposals on how knowledge of their activity can be implemented in the therapeutic process. Blocking or inhibiting the activity of B lymphocyte-recognizing autoantigens may be beneficial in eliminating disease symptoms, so it is worth considering these mechanisms when developing new therapeutic solutions [41]. In the study conducted by Ralchev et al, the authors suggest that the activity of B lymphocytes could be effectively reduced by using complement receptors [41].…”

“…Blocking or inhibiting the activity of B lymphocyte-recognizing autoantigens may be beneficial in eliminating disease symptoms, so it is worth considering these mechanisms when developing new therapeutic solutions [41]. In the study conducted by Ralchev et al, the authors suggest that the activity of B lymphocytes could be effectively reduced by using complement receptors [41]. Regulatory B cells may prove to be beneficial in the strategies in patients with autoimmune diseases; therefore, further research into the mechanisms affecting their production and activity is essential.…”

Advances in Antibody Design and Antigenic Peptide Targeting 2.0

“…In addition to this, specific antibodies conjugated with peptides may be used as therapeutics as well. In a study by Ralchev and coworkers, chimeric protein molecules composed of synthetic peptides coupled to a monoclonal antibody were able to inhibit B-cell-specific differentiation to plasmablasts and promote the apoptosis of targeted cells, each of which could aid in the treatment of Hashimoto Thyroiditis [12].…”