Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature

Abstract

Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood vessels resulting in vascular leak, the development of purpuric rashes and eventual tissue necrosis. Studying the pathogenesis of this infection was previously limited by the human specificity of the bacteria, which makes in vivo models difficult. In this protocol, we describe a humanized model for this infection in which human skin, containing dermal microvessels, is grafted onto immunocompromised mice. These vessels anastomose with the mouse circulation while maintaining their human characteristics. Once introduced into this model, N. meningitidis adhere exclusively to the human vessels, resulting in extensive vascular damage, inflammation and in some cases the development of purpuric rash. This protocol describes the grafting, infection and evaluation steps of this model in the context of N. meningitidis infection. The technique may be applied to numerous human specific pathogens that infect the blood stream.

Unraveling Neisseria meningitidis pathogenesis: from functional genomics to experimental models

“…Experimental models of fulminant meningococcemia in human skin-grafted immune-compromised mice have recently been engineered 60 , 61 . Under these conditions, N. meningitidis adheres to implanted human vessels, triggering extensive vascular damage, similar to that observed in patients 62 . We expect that this kind of model, together with the increased accessibility to organoids and three-dimensional (3D) bioprinted organs, will be extensively exploited not only to confirm the current knowledge on N. meningitidis pathogenesis but to disclose the hidden pathways that are essential to bacterial fitness and that could be unraveled only by recreating a physiological environment.…”

Induced Pluripotent Stem Cell-Derived Brain Endothelial Cells as a Cellular Model to Study Neisseria meningitidis Infection

“…While HBMECs lack Claudin-5 expression, hCMEC/D3 cells express Claudin-5 but lack continuous Occludin and exhibit relatively low TEER (Weksler et al, 2005; Eigenmann et al, 2013). Alternatively, humanized mice have been used in vivo , but these must rely on known interactions and/or have limited translatability (Johswich et al, 2013; Melican et al, 2014). Here, we demonstrate a significant technical advance in the modeling of Nm interaction with human BECs by using iPSC-BECs.…”

Potential Pitfalls of the Humanized Mice in Modeling Sepsis

“…The multiple interactions between pathogen and host organs as well as between the host organs themselves are crucial for understanding the clinical trajectory [ 2 , 32 , 85 ]. Mesenchymal cells, the central nervous system, and endothelium are frequently quoted culprits of unfavorable outcomes in sepsis [ 57 , 85 , 86 ]. Several deficits in the crosstalk between the grafted human immune system and mice organs may create a translation barrier for implementation of humanized mice into sepsis research [ 73 ].…”

“…Several deficits in the crosstalk between the grafted human immune system and mice organs may create a translation barrier for implementation of humanized mice into sepsis research [ 73 ]. Their xenotransplant nature inherently limits their usefulness as it was already suggested in studies of hemorrhagic fever or meningitis [ 57 , 86 ]. Additionally, the endothelium is critical for immune system performance, and humanized mice are deemed a less favorable model for them unless significant modification is introduced [ 57 ].…”

“…Their xenotransplant nature inherently limits their usefulness as it was already suggested in studies of hemorrhagic fever or meningitis [ 57 , 86 ]. Additionally, the endothelium is critical for immune system performance, and humanized mice are deemed a less favorable model for them unless significant modification is introduced [ 57 ]. Moreover, on the level of immune system interaction between APC and effector cells is notably ineffective.…”