Fever as an evolutionary agent to select immune complexes interfaces

Fever exerts opposing effects on the binding affinities of two neutralizing monoclonal antibodies against Staphylococcal Enterotoxin B

RATIONALE

Infections with methicillin-resistant Staphylococcus aureus are a major source of morbidity and mortality worldwide. While no vaccines against this pathogen are yet available, passive therapy with neutralizing monoclonal antibodies against a key S. aureus toxin, the Staphylococcal Enterotoxin B (SEB), can be clinically effective. Further, fever response is a key symptom of this infection, and typically precedes or is concomitant to antibody therapy against SEB.

OBJECTIVE

To investigate the role of febrile temperatures on the formation of immune complexes between SEB and two therapeutic monoclonal antibodies, 6D3 and 14G8.

RESULTS

Using molecular dynamics simulations, free binding energy calculations and Surface Plasmon Resonance experiments, we reveal that at high fever (i.e. 312K (39 °C), compared to the physiologic body temperature of 310K (37 °C), the activity of 6D3 mAb is markedly reduced. In contrast, the binding affinity of antibody 14G8 benefits from the higher temperature.

CONCLUSIONS

Febrile temperatures differentially affect the binding affinities of monoclonal antibodies used in the therapy against S. aureus, and judicious control of the body temperature of the patients before their administration may potentiate their activity.

Molecular Basis of High-Blood-Pressure-Enhanced and High-Fever-Temperature-Weakened Receptor-Binding Domain/Peptidase Domain Binding: A Molecular Dynamics Simulation Study

The entry and infection of the Severe Acute Respiratory Syndrome Coronavirus 2 virus (SARS-CoV-2) involve recognition and binding of the receptor-binding domain (RBD) of the virus surface spike protein to the peptidase domain (PD) of the host cellular Angiotensin-Converting Enzyme-2 (ACE2) receptor. ACE2 is also involved in normal blood pressure control. An association between hypertension and COVID-19 severity and fatality is evident, but how hypertension predisposes patients diagnosed with COVID-19 to unfavorable outcomes remains unclear. High temperature early during SARS-CoV-2 infection impairs binding to human cells and retards viral progression. Low body temperature can prelude poor prognosis. In this study, all-atom molecular dynamics simulations were performed to examine the effects of high pressure and temperature on RBD/PD binding. A high blood pressure of 940 mmHg enhanced RBD/PD binding. A high temperature above 315 K significantly weakened RBD/PD binding, while a low temperature of 305 K enhanced binding. The curvature of the PD α1-helix and proximity of the PD β3β4-hairpin tip to the RBM motif affected the compactness of the binding interface and, hence, binding affinity. These findings provide novel insights into the underlying mechanisms by which hypertension predisposes patients to unfavorable outcomes in COVID-19 and how an initial high temperature retards viral progression.

Plasmodium Falciparum and mosquito vector IgG patterns across suspected malaria cases in Ghana

INTRODUCTION

Malaria, a widespread tropical disease, remains a significant global health issue, resulting in numerous deaths each year. In Ghana, malaria is a leading cause of illness, contributing to a large proportion of hospital outpatient visits. The study assessed the pattern of malaria and vector IgG antibody levels among suspected malaria patients seeking healthcare at selected health facilities across Ghana.

METHODS

Samples from a total of 823 participants aged 1 to 85 years with clinical malaria from the ten regions of Ghana were recruited into the study. Archived plasma obtained from each participant was used to assess antibody responses against MSP1 (19 k), MSP2 (FC27 & 3D7), MSP3, gSG6-P1, and GLURP-RO using ELISA. The data were categorized according to study site, age group, gender, and diagnostic tests. Data were analyzed using Kruskal-Wallis's statistics. The statistical significance was assessed at 0.05.

RESULTS

The mean ± standard error of the mean (S.E) of MSP3 IgG concentration for the different age groups were 16, 847 ± 3, 031 ng/mL for 0-4 years, 18, 973 ± 4,357 ng/mL for 5-10 years, 25,961 ± 5,436 ng/mL for 11-15 years and 76, 244 ± 8, 209 ng/mL for ≥ 16 years. A significant (Kruskal-Wallis statistic = 122.6, p < 0.0001) increase in P. falciparum MSP 3 (p < 0.0001) and gSG6-P1(p < 0.0001) IgG concentration was observed with increasing age categories. There were significant differences in antibody responses against MSP2 (FC27) IgG (Kruskal-Wallis statistic = 29.63, p = 0.0005), MSP3 IgG (Kruskal-Wallis statistic = 32.53, p = 0.0002), GLURP-RO IgG (Kruskal-Wallis statistic = 52.8, p < 0.0001) and gSG6-P1 IgG (Kruskal-Wallis statistic = 152.8, p < 0.0001) across the study regions.

CONCLUSION

The study reveals that IgG against merozoite surface proteins MSP3, GLURP-RO, and gSG6-P1 but not MSP1 and MSP2 antibodies increase with age. The mean IgG antibody concentrations varied in the selected regions of Ghana. A longitudinal study where confounding factors are controlled for is recommended to provide insights into the development of immunity and antibody efficacy, and to enhance the effectiveness of malaria prevention efforts in Ghana. This will help improve the overall understanding of malaria transmission.

ThermoPCD: a database of molecular dynamics trajectories of antibody-antigen complexes at physiologic and fever-range temperatures

Progression of various cancers and autoimmune diseases is associated with changes in systemic or local tissue temperatures, which may impact current therapies. The role of fever and acute inflammation-range temperatures on the stability and activity of antibodies relevant for cancers and autoimmunity is unknown. To produce molecular dynamics (MD) trajectories of immune complexes at relevant temperatures, we used the Research Collaboratory for Structural Bioinformatics (RCSB) database to identify 50 antibody:antigen complexes of interest, in addition to single antibodies and antigens, and deployed Groningen Machine for Chemical Simulations (GROMACS) to prepare and run the structures at different temperatures for 100-500 ns, in single or multiple random seeds. MD trajectories are freely available. Processed data include Protein Data Bank outputs for all files obtained every 50 ns, and free binding energy calculations for some of the immune complexes. Protocols for using the data are also available. Individual datasets contain unique DOIs. We created a web interface, ThermoPCD, as a platform to explore the data. The outputs of ThermoPCD allow the users to relate thermally-dependent changes in epitopes:paratopes interfaces to their free binding energies, or against own experimentally derived binding affinities. ThermoPCD is a free to use database of immune complexes' trajectories at different temperatures that does not require registration and allows for all the data to be available for download. Database URL: https://sites.google.com/view/thermopcd/home.

Rheumatoid arthritis autoantibodies benefit from inflammation temperatures

BACKGROUND

Symptoms of rheumatoid arthritis are associated with local inflammation and may include low-grade fever.

OBJECTIVE

To establish the role of fever/inflammation temperatures (38℃-39℃) on the activity of autoantibodies and therapeutic antibodies relevant for rheumatoid arthritis.

METHODS

Through the use of molecular dynamics and free energy calculations, we investigated the role of temperature on the formation of pertinent immune complexes.

RESULTS

Rheumatoid arthritis autoantibodies bind with higher affinity at febrile/inflammation temperatures.

CONCLUSIONS

Fever may modulate binding affinity of autoantibodies relevant for rheumatoid arthritis.

Febrile temperatures modulate the formation of immune complexes relevant for autoimmune diseases

BACKGROUND

Autoimmune disorders encompass a diverse subset of diseases whose common symptoms include, among others, fever. Fever of unknown origins, once an infectious or tumor agent have been ruled out as possible causes, may originate with an autoimmune disease.

OBJECTIVE

To determine the role of febrile temperatures on the stability of antigens pertinent to autoimmunity, and on the immune complexes they form with commercial therapeutic monoclonal antibodies.

METHODS

Using molecular dynamics simulations, the binding between four antigens belonging to a set of autoimmune diseases and their individual monoclonal antibodies was investigated under different febrile temperatures.

RESULTS

It was determined that at febrile temperatures, monoclonal antibodies used in the therapy of autoimmune diseases bind with higher binding free energy to pertinent antigens, once the autoimmune condition has been established and treatment is warranted.

CONCLUSION

Performing molecular dynamics simulations at fever temperatures may be important for delineating the role antibodies may play in other diseases, including in cancers and infections.

Fever temperatures modulate intraprotein dynamics and enhance the binding affinity between monoclonal antibodies and the Spike protein from SARS-CoV-2

Fever is a typical symptom of most infectious diseases. While prolonged fever may be clinically undesirable, mild reversible fever (<39℃, 312 K) can potentiate the immune responses against pathogens. Here, using molecular dynamics and free energy calculations, we investigated the effect of febrile temperatures (38℃ to 40℃, 311 K to 313 K) on the immune complexes formed by the SARS-CoV-2 spike protein with two neutralizing monoclonal antibodies. In analyzing the conformational dynamics of the interactions between the antibodies and the spike protein under different thermal conditions, we found that, at mild fever temperatures (311–312 K), the binding affinities of the two antibodies improve when compared to the physiological body temperature (37℃, 310 K). Furthermore, only at 312 K, antibodies exert distinct mechanical effects on the receptor binding domains of the spike protein that may hinder SARS-CoV-2 infectivity. Enhanced antibody binding affinity may thus be obtained using appropriate temperature conditions.