Immunomodulatory Effect of Phospholipid Nanoparticle, VBI-S for Treatment of Sepsis.

Authors:
Gracy Rosario, Gelilla Daniel, Benjamin Edwards, Cuthbert Simpkins

Body of Abstract:
Background:

Sepsis, a leading cause of morbidity and mortality in humans, is an inflammatory disease caused by a dysregulated host response to an infection. Increased antibiotic resistance and lack of FDA approved drugs significantly limits treatment options for sepsis. Recently, VBI-S, a phospholipid nanoparticle colloid, has proven effective in Phase 2a clinical trial for septic shock1. Efficacy of VBI-S for septic shock is currently being evaluated in Phase III open-label randomized controlled clinical trial.

In sepsis, macrophages play an important role in inflammation, which is one of the causes of multi-organ damage. As preliminary evidence indicates that VBI-S is effective in sepsis, we hypothesized that VBI-S is immunomodulatory in nature, and capable of reducing inflammation in septic patients. Hence, the present study initially evaluated the immunomodulatory potential of VBI-S on pro-inflammatory macrophage functions. The study analyzed the effect of VBI-S on pro-inflammatory gene expression by M1 macrophages in an in-vitro culture model.

Methods:

Human THP-1 monocytes were differentiated to M0 macrophages by treatment with 25nM phorbol-myristate-acetate (PMA) for 48h and then to M1 macrophages by treatment with 100 ng/ml lipopolysaccharide (LPS) and 20 ng/ml interferon gamma (IFN-γ) for 48h. Subsequently, the M1 cells were treated with different concentrations of VBI-S, (1%, 0.1%, 0.01%, 0.01%) for 24h in presence of LPS and IFN-γ for 24h. Control included M1 cells cultured in media with or without the aqueous phase. Expression of pro-inflammatory genes (CXCL10, CCR7 and IL-1b) were analyzed by quantitative SYBR Green RT-PCR. Viability of the VBI-S treated adherent M1 cells were studied by MTT assay and non-adherent floating M1 cells evaluated by Trypan blue staining. Statistical analysis was performed by Brown-Forsythe and Welsch ANOVA, nonparametric t-test and Mann Whitney U test (Graph Prism Software).

Results:

VBI-S significantly decreased the levels of candidate pro-inflammatory CXCL10, CCR7 and IL-1b genes in M1 cells at 1%, 0.1%, and 0.01% concentrations (P<0.05). Furthermore, the number of viable adherent or non-adherent dead cells were unaltered at 1%, 0.1%, 0.01% and 0.001% VBI-S as compared to the respective controls. Conclusion: VBI-S has immunomodulatory properties as it reduces pro-inflammatory cytokine/chemokine gene expression by M1 macrophages. This study points towards immunomodulation being a key mechanistic function of VBI-S in treatment of sepsis. Futuristic studies are aimed at assessing VBI-S uptake by M1 macrophages, and subsequent mechanistic actions on pro-inflammatory signaling events. 1 Simpkins C, et al., 2024: Efficacy and safety of phospholipid nanoparticles (VBI-S) in reversing intractable hypotension in patients with septic shock: a multicentre, open-label, repeated measures, phase 2a clinical pilot trial. EClinicalMedicine 68:102430.