A MICROFLUIDIC PLATFORM TO INVESTIGATE THE CROSS-TALK BETWEEN IMMUNE CELLS IN RHEUMATOID ARTHRITIS

Jun 30, 2022, 4:30 PM
10m
Room: S3 B

Room: S3 B

Speaker

Palma, Cecilia (Politecnico di Milano )

Description

"INTRODUCTION
Rheumatoid arthritis (RA) is an autoimmune disease that affects diarthrodial joints, characterized by a systemic inflammatory response that leads to progressive joint destruction [1]. Various immune cells are involved, but the exact mechanism of RA development is still unknown, and it is well established that none of the currently available animal models fully represent human RA onset and progression [2]. In this scenario, organs-on-chip provide a valuable solution to evaluate the involvement and the interaction of different cell types in RA conditions. To this aim, we developed a novel microfluidic platform allowing to study the cross-talk between immune cells involved in RA.

METHODOLOGY
The platform consists of two separate culture areas, whose communication is controlled through normally closed valves. The first compartment is intended to host cells seeded in a 3D matrix, e.g. macrophages, while the second one is composed of a single channel designed to precisely locate and culture cells in suspension, e.g. T cells. The second compartment encompasses a novel technology, named “sieving valve”, which relies on normally closed valves with underneath microfluidic channels that allow perfusion of fluids but impair cell escaping when closed. CD14+ macrophages and CD4+ T cells isolated from human buffy coat were independently seeded in the two separate compartments and stimulated with TNFa and IL15, respectively. Upon central valve opening, recruitment of CXCR6+ T cells operated by inflamed macrophages expressing CXCL16 was evaluated [3].

RESULTS
A protocol was first optimized to seed and trap CD4+ T cells inside the microfluidic platform, taking advantage of the sieving valve technology. Cells were then successfully stimulated inside the platform exploiting the separation of the compartments. As proven by immunofluorescence staining, CXCL16 expression was enhanced in macrophages after treatment with TNF-α, while CXCR6 expression was up-regulated in T-cells after stimulation with IL-15. After stimulation, migration of T-cells towards macrophages occurred spontaneously upon opening of the communication valves, as quantified through live imaging.

CONCLUSIONS
The proposed device offers an innovative solution to trap immune cells inside microfluidic chips and to study the cross-talk between different cell types, having the possibility to stimulate them separately. The platform was validated replicating a known mechanism in RA, involving resident macrophages and T cells [3]. The use of the platform to elucidate the role of RA-patient specific circulating immune cells on synovial membrane is currently under evaluation, and will eventually increase the understanding about unknown mechanisms in RA progression. Moreover, the technology is highly versatile and can be potentially applied to assess the interaction of immune system in manifold diseases and more complex models.

REFERENCES
1. Lee et al, Lancet, 358, 903-911 (2001)
2. Paggi et al, Nat Rev Rheumatol (2022)
3. Tu et al, Front Immunol, 12, 1-8 (2021)

ACKNOWLEDGEMEBNTS
We thank Dr. Carlotta Catozzi for her technical help in the experiments. This work was supported by Fondazione Cariplo-uKNEEque - Rif. 2018/0551 and has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 841975."

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