Biochemical and aggregation analysis of Bence Jones proteins from different light chain diseases

Abstract

Deposition of immunoglobulin light chains is a result of clonal proliferation of monoclonal plasma cells that secrete free immunoglobulin light chains, also called Bence Jones proteins (BJP). These BJP are present in circulation in large amounts and excreted in urine in various light chain diseases such as light chain amyloidosis (AL), light chain deposition disease (LCDD) and multiple myeloma (MM). BJP from patients with AL, LCDD and MM were purified from their urine and studies were performed to determine their secondary structure, thermodynamic stability and aggregate formation kinetics. Our results show that LCDD and MM proteins have the lowest free energy of folding while all proteins show similar melting temperatures. Incubation of the BJP at their melting temperature produced morphologically different aggregates: amyloid fibrils from the AL proteins, amorphous aggregates from the LCDD proteins and large spherical species from the MM proteins. The aggregates formed under in vitro conditions suggested that the various proteins derived from patients with different light chain diseases might follow different aggregation pathways.

Aggregation of Full-length Immunoglobulin Light Chains from Systemic Light Chain Amyloidosis (AL) Patients Is Remodeled by Epigallocatechin-3-gallate

“…The independent unfolding of the two protein domains fails to explain the observed unfolding dynamics (28,29,63). Furthermore, thermodynamic instability is not sufficient for amyloid formation, suggesting the importance of kinetic factors (27,30). All studies suggest that the enhanced aggregation of the full-length protein results not only from the combined aggregating propensities of its variable and constant domain but also from the intramolecular interactions between these regions.…”

“…The significance of full-length LC for amyloid formation was only recently addressed (27)(28)(29)(30). These studies find that interactions between the constant and variable domain of LC alter the unfolding/folding pathways and that the unfolding of native state LC is a complex, often irreversible, process.…”

“…The significance of full-length LC for amyloid formation is not yet fully understood (27)(28)(29)(30).…”

“…AL patients also displayed MM markers in addition to AL pathology (AL ϩ MM in Table 1). Instead of a standard dialysis approach (27,36,37), we utilized sequential membrane ultrafiltration, which removed small molecule components and concentrated the LC by a factor of 40 -80 ( Fig. 1A) (38).…”

Urinary gamma-glutamyl transferase-to-creatinine ratio as an indicator of tubular function in Bence Jones Proteinuria

“…1 Acute kidney injury remains an important cause of morbidity and mortality in patients with multiple myeloma. 2 Severe cases are frequently a direct consequence of the high clonal production rates of immunoglobulin free light chains.…”