Kinetics of Phenotypic and Functional Changes in Mouse Models of Sponge Implants: Rational Selection to Optimize Protocols for Specific Biomolecules Screening Purposes.

Mariana Ferreira Lanna,Ludmila Zanandreis De Mendonça,Reysla Maria Da Silveira Mariano,Olindo Assis Martins-Filho,Alexandre Barbosa Reis,Patricia Silveira,Lucilene Aparecida Resende,Denise Silveira-Lemos,Otoni Alves De Oliveira Melo Júnior,Marina Barcelos De Miranda,Rodolfo Cordeiro Giunchetti,Rodrigo Corrêa-Oliveira,Sandra Aparecida Lima De Moura,Rodrigo Dian De Oliveira Aguiar-Soares,Jaqueline Costa Leite,Walderez Ornelas Dutra

doi:10.3389/fbioe.2020.538203

Abstract

The sponge implant has been applied as an important in vivo model for the study of inflammatory processes as it induces the migration, proliferation, and accumulation of inflammatory cells, angiogenesis, and extracellular matrix deposition in its trabeculae. The characterization of immune events in sponge implants would be useful in identifying the immunological events that could support the selection of an appropriate experimental model (mouse strain) and time post-implant analysis in optimized protocols for novel applications of this model such as in biomolecules screening. Here, the changes in histological/morphometric, immunophenotypic and functional features of infiltrating leukocytes (LEU) were assessed in sponge implants for Swiss, BALB/c, and C57BL/6 mice. A gradual increase of fibrovascular stroma and a progressive decrease in LEU infiltration, mainly composed of polymorphonuclear cells with progressive shift toward mononuclear cells at late time-points were observed over time. Usually, Swiss mice presented a more prominent immune response with late mixed pattern (pro-inflammatory/anti-inflammatory: IL-2/IFN-γ/IL-4/IL-10/IL-17) of cytokine production. While BALB/c mice showed an early activation of the innate response with a controlled cytokine profile (low inflammatory potential), C57BL/6 mice presented a typical early pro-inflammatory (IL-6/TNF/IFN-γ) response with persistent neutrophilic involvement. A rational selection of the ideal time-point/mouse-lineage would avoid bias or tendentious results. Criteria such as low number of increased biomarkers, no recruitment of cytotoxic response, minor cytokine production, and lower biomarker connectivity (described as biomarker signature analysis and network analysis) guided the choice of the best time-point for each model (Day5/Swiss; Day7/BALB/c; Day6/C57BL/6) with wide application for screening purposes, such as identification of therapeutic biomolecules, selection of antigens/adjuvants, and follow-up of innate and adaptive immune response to vaccines candidates.

Highlights

The sponge implant has been applied as an important in vivo model for the study of inflammatory processes (Xavier et al, 2010; Pereira et al, 2012; Cassini-Vieira et al, 2014)
We studied the dynamics of phenotypic and functional changes in the sponge implant microenvironment that could support the selection of the best mouse lineage and time-point for screening assays as a relevant prerequisite to employing the sponge implant model for testing bioactive molecules
The sponge implant model is a feasible strategy for screening bioactive molecules

Summary

Introduction

The sponge implant has been applied as an important in vivo model for the study of inflammatory processes (Xavier et al, 2010; Pereira et al, 2012; Cassini-Vieira et al, 2014). The subcutaneous implantation of sponges has been used in several studies, since it is a model that induces an amplified inflammatory foreign body response that evolves into the formation of a highly vascularized granulation tissue in which various constituents can be analyzed (Andrade et al, 1997; Agrawal et al, 2011; Moura et al, 2011c; Alhaider et al, 2014b) Most of these studies are focused on the inflammatory angiogenesis model, since significant evidence indicates that angiogenesis and inflammation are key components to the maintenance of a variety of pathological conditions, whereas others seek to access the anti-angiogenic and/or anti-inflammatory outcomes of pharmacological compounds to prove its effects (Xavier et al, 2010; Agrawal et al, 2011; Moura et al, 2011a,c; Saraswati et al, 2011; Pereira et al, 2012; Alhaider et al, 2014a; Almeida et al, 2014; Cassini-Vieira et al, 2014, 2016; Michel et al, 2015). Regardless of the goal, the immunophenotypic characterization in the sponge implant was not employed in the analysis of LEU subsets

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Conclusion