Probing the Protein-Excipient Interaction in the Orally Delivered Protein by Solid-State Hydrogen-Deuterium Exchange Mass Spectrometry and Molecular Dynamics

The oral administration of protein therapeutics in solid dosage form is gaining popularity due to its benefits, such as improved medication adherence, convenience, and ease of use for patients compared to traditional parental delivery. However, formulating oral biologics presents challenges related to pH barriers, enzymatic breakdown, and poor bioavailability. Therefore, understanding the interaction between excipients and protein therapeutics in the solid state is crucial for formulation development. In this Letter, we present a case study focused on investigating the role of excipients in protein aggregation during the production of a solid dosage form of a single variable domain on a heavy chain (VHH) protein. We employed solid-state hydrogen-deuterium exchange coupled with mass spectrometry (ssHDX-MS) at both intact protein and peptide levels to assess differences in protein-excipient interactions between two formulations. ssHDX-MS analysis revealed that one formulation effectively prevents protein aggregation during compaction by blocking β-sheets across the VHH protein, thereby preventing β-sheet-β-sheet interactions. Spatial aggregation propensity (SAP) mapping and cosolvent simulation from molecular dynamics (MD) simulation further validated the protein-excipient interaction sites identified through ssHDX-MS. Additionally, the MD simulation demonstrated that the interaction between the VHH protein and excipients involves hydrophilic interactions and/or hydrogen bonding. This novel approach holds significant potential for understanding protein-excipient interactions in the solid state and can guide the formulation and process development of orally delivered protein dosage forms, ultimately enhancing their efficacy and stability.

Function-structure approach reveals novel insights on the interplay of Immunoglobulin G 1 proteoforms and Fc gamma receptor IIa allotypes

Human Fc gamma receptor IIa (FcγRIIa) or CD32a has two major allotypes with a single amino acid difference at position 131 (histidine or arginine). Differences in FcγRIIa allotypes are known to impact immunological responses such as the clinical outcome of therapeutic monoclonal antibodies (mAbs). FcγRIIa is involved in antibody-dependent cellular phagocytosis (ADCP), which is an important contributor to the mechanism-of-action of mAbs by driving phagocytic clearance of cancer cells. Hence, understanding the impact of individual mAb proteoforms on the binding to FcγRIIa, and its different allotypes, is crucial for defining meaningful critical quality attributes (CQAs). Here, we report a function-structure based approach guided by novel FcγRIIa affinity chromatography-mass spectrometry (AC-MS) assays to assess individual IgG1 proteoforms. This allowed to unravel allotype-specific differences of IgG1 proteoforms on FcγRIIa binding. FcγRIIa AC-MS confirmed and refined structure-function relationships of IgG1 glycoform interactions. For example, the positive impact of afucosylation was higher than galactosylation for FcγRIIa Arg compared to FcγRIIa His. Moreover, we observed FcγRIIa allotype-opposing and IgG1 proteoform integrity-dependent differences in the binding response of stress-induced IgG1 proteoforms comprising asparagine 325 deamidation. The FcγRIIa-allotype dependent binding differences resolved by AC-MS were in line with functional ADCP-surrogate bioassay models. The molecular basis of the observed allotype specificity and proteoform selectivity upon asparagine 325 deamidation was elucidated using molecular dynamics. The observed differences were attributed to the contributions of an inter-molecular salt bridge between IgG1 and FcγRIIa Arg and the contribution of an intra-molecular hydrophobic pocket in IgG1. Our work highlights the unprecedented structural and functional resolution of AC-MS approaches along with predictive biological significance of observed affinity differences within relevant cell-based methods. This makes FcγRIIa AC-MS an invaluable tool to streamline the CQA assessment of therapeutic mAbs.

Investigating Saccharomyces cerevisiae alkene reductase OYE 3 by substrate profiling, X-ray crystallography and computational methods

Saccharomyces cerevisiae OYE 3 and OYE 1 share 80% sequence identity, but sometimes differ in stereoselectivities.

Clinical and Socio demographic profile of attendees at ART centre in a tertiary care hospital in Mangalore, India

Introduction: India has the third largest number of people living with HIV/AIDS. There is a need to study the profile of patients who come to ART centers and link their clinical and socio-demographic variables in the management. Moreover, it is important to understand the presentation of HIV disease in the local context and culture. The present study is aimed at identifying the socio-demographic characteristics, clinical presentations of HIV/AIDS patients, opportunistic infections and the possible risk factors for acquiring HIV infection at an ART centre of Government Wenlock hospital, situated in Karnataka state of India. Materials and Methods: In this study 102 HIV patients attending the HIV clinic were enrolled and they were followed for a period of one year with relevant investigations.Results: Of 102 patients 69 were males and 33 were females.The mean age of the study subjects at the time of diagnosis was 38.06. Heterosexual contact was the commonest mode of transmission in96 (94.12%) patients. History suggestive of a risk factor for HIV transmission could not be elicited in 4 (3.92%) patients. Fever (71.5%), weight loss (62.74%), cough (51.96%) and chronic diarrhea (43.9%) were the common presenting symptoms. The most common opportunistic infection was oral candidiasis (66.67%) followed bytuberculosis (22.54%) and pneumocystis pneumonia (13.72%). Significant number of patients (30.37%) developed Zidovudine induced anemia and females were more prone for Zidovudine induced anemia as compared to males. CD4 counts of the patients were significantly inversely correlated with the number of symptoms and the number of opportunistic infections. Conclusion: Majority of patients were of low socioeconomic status and in productive age group with heterosexual contact being commonest mode of transmission.Significant number of patients developed Zidovudine induced anemia and females were more prone. DOI: http://dx.doi.org/10.3126/ajms.v6i5.11622Asian Journal of Medical Sciences Vol.6(5) 2015 61-65