Trans-epithelial Electrical Resistance

Tight junctions regulate the movement of ions between neighboring epithelial cells. When these junctions restrict ion passage, less current crosses the monolayer and the measured resistance is higher. If junctional organization becomes compromised, ion movement increases and resistance falls. TEER therefore provides a quantitative readout of how effectively the epithelial layer maintains its intercellular barrier.

A decrease in TEER can indicate that a pathogen, inflammatory signal, or experimental treatment has disrupted epithelial barrier function. The measurement does not simply describe cell presence; it reflects altered restriction of ion movement across the layer. Conversely, a subsequent increase toward earlier values can suggest barrier repair, making repeated measurements useful for following damage and recovery.

Epithelial barriers must restrict some forms of passage while permitting others, so resistance changes provide information about barrier selectivity rather than only total tissue coverage. Tight junctions and cell membranes contribute to this electrical behavior. In immunology and infection studies, the resulting measurement helps connect structural barrier performance with the epithelial defense response to pathogens or inflammatory conditions.

Researchers grow an epithelial cell monolayer on a porous membrane and position electrodes so that a small electrical signal passes across the layer. They record the resulting resistance and use it as an indicator of barrier integrity. Repeating the measurement after exposing the model to pathogens, inflammatory signals, or treatments allows changes in barrier function to be tracked.

A baseline measurement establishes the electrical behavior of the epithelial monolayer before an experimental change. Lower values after exposure are consistent with impaired restriction of ion movement, whereas later recovery toward the starting level indicates restoration of barrier function. This time-dependent pattern helps investigators evaluate whether an intervention preserves the barrier or supports repair after disruption.

In host-pathogen experiments, TEER can show how exposure to a pathogen affects epithelial defenses over time. Researchers can compare untreated and exposed monolayers, then assess whether barrier function declines or recovers under different experimental conditions. The approach links pathogen-associated changes to epithelial integrity and supports investigation of infection-related damage without relying only on qualitative observations.

TEER helps researchers evaluate epithelial models used to study drug permeability and to test strategies intended to preserve or restore barrier function. Measurements can indicate whether a treatment maintains electrical resistance during a damaging condition or whether the barrier recovers afterward. This makes the method relevant to both assessing compound passage models and examining interventions that influence epithelial defenses.