NYC Healthcare News



Johns Hopkins researchers identify a key protein that triggers sarcoidosis

August 31, 2015

Further tests in patients' lung cell cultures showed that adding serum amyloid A spiked production of at least a half-dozen key inflammatory chemicals known to be involved in damaging tissue.

In another series of experiments in mice, the team discovered that granuloma formation in the lungs sped up when the mice were given injections of synthetic serum amyloid A. Mice had previously been injected with specially coated plastic beads designed to trigger sarcoidosis-like lesions. Adding the synthetic protein led to the same biochemical reactions in the mice as observed in humans, suggesting to the researchers that serum amyloid A played a key role in triggering sarcoidosis.

To better understand how serum amyloid A might be driving granuloma formation, the team used special antibodies to block various cell surface receptor sites where the protein would bind to the white blood cells and spur inflammation. Tests in human lung cells showed that blocking one particular receptor, toll-like receptor-2 (TLR2), inhibited the sustained inflammatory reaction typically associated with sarcoidosis. But when left to bind on its own, without an antibody blocking TLR2, the open receptor could attach to serum amyloid A, and raised production of inflammatory chemicals would ensue.

"Not only have we shown that serum amyloid A is a key protein trigger in sarcoidosis, but we also have evidence that the resulting inflammation is dependent on binding the protein at toll-like receptor-2, which opens up a host of possibilities that drugs blocking this binding site could prove an effective treatment for this disease," says Chen, an assistant professor at Johns Hopkins.

Source: Johns Hopkins Medical Institutions