Recombinant Interferon Alpha-2b is a High-Affinity Antigen for Type 1 Diabetes Autoantibodies

Magnetic Relaxation Switching Assay Using IFNα-2b-Conjugated Superparamagnetic Nanoparticles for Anti-Interferon Antibody Detection

Type I interferons, particularly IFNα-2b, play essential roles in eliciting adaptive and innate immune responses, being implicated in the pathogenesis of various diseases, including cancer, and autoimmune and infectious diseases. Therefore, the development of a highly sensitive platform for analysis of either IFNα-2b or anti-IFNα-2b antibodies is of high importance to improve the diagnosis of various pathologies associated with the IFNα-2b disbalance. For evaluation of the anti-IFNα-2b antibody level, we have synthesized superparamagnetic iron oxide nanoparticles (SPIONs) coupled with the recombinant human IFNα-2b protein (SPIONs@IFNα-2b). Employing a magnetic relaxation switching assay (MRSw)-based nanosensor, we detected picomolar concentrations (0.36 pg/mL) of anti-INFα-2b antibodies. The high sensitivity of the real-time antibodies' detection was ensured by the specificity of immune responses and the maintenance of resonance conditions for water spins by choosing a high-frequency filling of short radio-frequency pulses of the generator. The formation of a complex of the SPIONs@IFNα-2b nanoparticles with the anti-INFα-2b antibodies led to a cascade process of the formation of nanoparticle clusters, which was further enhanced by exposure to a strong (7.1 T) homogenous magnetic field. Obtained magnetic conjugates exhibited high negative MR contrast-enhancing properties (as shown by NMR studies) that were also preserved when particles were administered in vivo. Thus, we observed a 1.2-fold decrease of the T2 relaxation time in the liver following administration of magnetic conjugates as compared to the control. In conclusion, the developed MRSw assay based on SPIONs@IFNα-2b nanoparticles represents an alternative immunological probe for the estimation of anti-IFNα-2b antibodies that could be further employed in clinical studies.

Endometrial cancer patients have high affinity antibodies for estrogen metabolite-receptor aggregate: A potential biomarker for EC

AIM

Elevated levels of 16α-hydroxyestrone (16α-OHE₁ ) have been described in endometrial cancer (EC) and estrogen receptors (ER) expressed in endometrial tissue, but research on their combined role is lacking. We aimed to investigate the affinity and binding specificity of EC antibodies against the 16α-OHE₁ -ERα aggregate in the serum of EC patients. Specificities of EC antibodies were also evaluated according to various clinical characteristics found in these cancer patients.

METHODS

The binding specificity and affinity of EC antibodies against 16α-OHE₁ -ERα in the serum of 120 EC patients were evaluated by direct binding and competition ELISA and quantitative precipitation titration. Binding of EC antibodies was also determined according to various clinical characteristics in EC patients through competition ELISA.

RESULTS

Antibodies from EC patients demonstrated high recognition of 16α-OHE₁ -ERα compared to ERα (P < 0.05) or 16α-OHE₁ (P < 0.001). The relative affinity of EC IgG was 1.49 × 10^-7  M, 1.34 × 10^-6  M and 1.13 × 10^-6  M for 16α-OHE₁ -ERα, ERα and 16α-OHE₁ , respectively. Several factors, such as obesity, postmenopausal status, use of hormonal therapy, ER and progesterone receptor (PR) status, low 2-OHE₁ /16α-OHE₁ ratio, chemotherapy and hypertension, augment the production of antibodies against 16α-OHE₁ -ERα in EC patients.

CONCLUSION

16α-OHE₁ -ERα is a high-affinity antigen for EC antibodies in the serum of EC patients and might function as a biomarker for this disease. Furthermore, several factors enhanced the production of antibodies against 16α-OHE₁ -ERα in the sera of these EC patients.

Estrogenization of insulin by catecholestrogen produced high affinity autoantibodies and altered the normal function of insulin in type 1 diabetes

AIMS

Insulin (Ins) covalently modified by catecholestrogens (CEs) was commonly found in diabetic patients who have developed insulin resistance. Estrogenization of insulin altered its molecular function and effect carbohydrates metabolisms in these patients. Insulin resistance is a common phenomenon in diabetes but the exact mechanism remains unknown. In this study, binding specificity and affinity of autoantibodies against estrogenized insulin (4-hydroxyestradiol-insulin; 4-OHE₂-Ins) were assayed in the serum of type 1 diabetes (T1D) patients in order to explain the phenomena behind insulin resistance.

MATERIALS AND METHODS

Specificity and affinity of autoantibodies from the sera of 66 T1D patients and 41 controls were analyzed by direct binding, competition ELISA and quantitative precipitin titration. Insulin was also estimated in the serum of T1D patients by ELISA.

KEY FINDING

Estrogenized insulin (4-OHE₂-Ins) exhibited high affinity and specificity to T1D autoantibodies in comparison to Ins (p < .05) or 4-OHE₂ (p < .001). Estrogenization of insulin alters its interaction with the insulin receptor (IR). The affinity constant of 4-OHE₂-Ins with the T1D autoantibodies was found to be 1.41 × 10^-7 M.

SIGNIFICANCE

Estrogenization of insulin by catecholestrogen makes these molecules highly antigenic and produced high-affinity autoantibodies in T1D patients. As a result, patients develop insulin resistance and presented this molecule as a potential biomarker for T1D.

16 α-Hydroxyestrone induced adduct generate high affinity autoantibodies in SLE

PURPOSE

Increased 16 α-hydroxyestrone (16 α-OHE₁) and autoantibodies against histone H1 (H₁) have been well described in systemic lupus erythematosus (SLE), but the combination effects of 16 α-OHE₁ and H₁ remains unclear. Here, we tried to assess the affinity and binding specificity of SLE autoantibodies against the 16 α-OHE₁-H₁ adduct. IgG was induced against this adduct and was also used as immunochemical probe for the estimation of 16 α-OHE₁ in the serum of SLE patients.

MATERIALS AND METHODS

The affinity and binding specificities of SLE autoantibodies against 16 α-OHE₁-H₁ were determined by direct binding and inhibition ELISA as well as quantitative precipitation titration in 60 patients and 30 control subjects.

RESULTS

Purified SLE autoantibodies showed greater recognition to 16 α-OHE₁-H₁ over H₁ (p < 0.05) or 16 α-OHE₁ (p < 0.001). The relative affinity of SLE autoantibodies for 16 α-OHE₁-H₁, H₁ and 16 α-OHE₁ was 1.41 × 10^-7, 1.31 × 10^-6, and 1.03 × 10^-6, respectively. The concentration of 16 α-OHE₁ in the sera of SLE patients was significantly higher than controls (p < 0.05) as estimated by anti-16 α-OHE₁-H₁ antibodies.

CONCLUSIONS

High affinity of 16 α-OHE₁-H₁ with SLE autoantibodies might suggest an antigenic role of this adduct in the production of these autoantibodies. The anti-16 α-OHE₁-H₁ antibody is a good immunochemical probe to measure 16 α-OHE₁ in different SLE sera.