T cells in microgravity: High resolution microscopy and deep gene expression profiling to find the T cell gravisensor

Cells of the immune system has evolved to undergo rapid dynamics of the cell cytoskeleton during cell migration and for cell-cell interaction.

We hypothesize that the force and tension of the cell cytoskeleton underneath the cell membrane is a gravity sensor for immune cells.

At normal gravity, activation of the T cell receptor for 5 minutes stimulates large rearrangement of the actin cytoskeleton that can be measured by advanced microscopy techniques.

The T cell change in shape from a round cell to a “fried egg” mimics the T cell immune synapse formation with other cells. Termed T cell spreading, this is the first critical step to induce changes in gene expression. We propose to compare the T cell spreading response in micro-g versus 1 g conditions during sounding rocket flight.

This is the ideal set up since we can examine rapid cytoskeletal changes in T cells on glass surfaces during 5 minutes of microgravity exposure.

T cells, wildtype or gene-edited to lack specific cytoskeletal proteins, will be loaded in fully-automated culture units capable of administrating cells that will be exposed to micro-g at 37ºC for 5 minutes and thereafter fixed. A setup as used in the BIM-2 experimental module in the Maser 12 sounding rocket can be employed.

In BIM-2, units are either placed on a static rack permissive of exposing cells to changes in gravity or on a centrifuge that maintained cells at 1 g throughout the experiment.

High resolution microscopy to image T cells and deep RNA sequencing for gene expression profiling will be performed in our laboratory at Karolinska Institutet using our already established assays.

We expect that our new and unique approach to use gene-edited T cells and combined microscopy and gene expression data will identify microgravity sensors and help in development of counter measures during space flights.