Interleukin-1 receptor (IL-1R) liquid formulation development using differential scanning calorimetry

Area of Science:

• Biochemistry
• Protein Stability
• Formulation Science

Background:

• Interleukin-1 Receptor (IL-1R) is a crucial protein in immune response.
• Understanding IL-1R stability in aqueous solutions is vital for therapeutic applications.
• Protein aggregation and degradation impact drug efficacy and safety.

Purpose of the Study:

• To determine solution conditions that enhance the stability of aqueous Interleukin-1 Receptor (IL-1R).
• To investigate the relationship between thermal unfolding and aggregation.
• To identify optimal excipients for IL-1R stabilization.

Main Methods:

• Differential Scanning Calorimetry (DSC) was used to assess thermal stability and melting transitions (Tm).
• SDS-PAGE monitored degradation products to determine optimal pH.
• SEC evaluated the correlation between thermal unfolding and aggregation.
• Circular Dichroism (CD) confirmed secondary structure content.

Main Results:

• IL-1R exhibits approximately 39% beta-sheet structure.
• DSC identified three melting transitions for IL-1R, with Tm values around 47°C and 66°C.
• Sodium chloride (NaCl) demonstrated significant stabilizing effects, shifting a transition to 53°C.
• Preservatives like phenol, m-cresol, and benzyl alcohol showed varying degrees of stabilization.

Conclusions:

• The three observed melting transitions correspond to the unfolding of IL-1R's three immunoglobulin-like domains.
• Optimal stability was achieved in 20 mM sodium citrate at pH 6, with NaCl for isotonicity.
• DSC effectively correlated predicted stability rankings with observed aggregation levels.