Not without cause: Vibrio parahaemolyticus induces acute autophagy and cell death

Abstract

Vibrio parahaemolyticus (V. parahaemolyticus) is a gram-negative halophillic bacterium that causes worldwide seafood-borne gastroenteritis. The prevalence of V. parahaemolyticus in the environment and incidence of infection have been linked to rising water temperatures caused by global warming. Among its virulence factors, V. parahaemolyticus harbors two type III secretion systems (T3SS). Recently, we have shown that T3SS1 induces rapid cellular death that initiates with acute autophagy, as measured by LC3 lipidation and accumulation of early autophagosomal vesicles. While not the first characterized pathogen to usurp autophagy, this is the first example of an extracellular pathogen that exploits this pathway for its own benefit. Here we discuss possible roles for the induction of autophagy during infection and discuss how V. parahaemolyticus-induced autophagy provides insight into key regulatory steps that govern the decision between apoptosis and autophagy.

Figure 1

Electron microscopy image of HeLa cells infected at 3 hours with V. parahaemolyticus capable of secreting only from TTSS1 (POR3). Surrounded by bacteria (arrows), the nucleus (N) of the lysing cell remains intact. However, the lace-like appearance of the cytoplasm (C) reflects the proinflammatory release of cytosolic contents characteristic of V. parahaemolyticus infection. The scale bar represents 2 micrometers.