process is probably initiated in the epithelial cell when it comes into contact with bacteria, and further cellular activation, cytokine secretion, and inflammation may also contribute to elimination of pathogens from infected mucosa. Moreover, not all mutations in CFTR lead to a loss of membrane protein, and defects in CFTR genes that result in a membrane protein that is nonfunctional with regard to chloride ion secretion may also diminish the protein's ability to orchestrate the full epithelial cell response needed to remove P. aeruginosa from the tissue. The identification of CFTR as a protein that binds P. aeruginosa and coordinates the epithelial cell response leading to bacterial clearance indicates a direct connection between mutant CFTR genes and the clinical course of CF. Thus, in addition to its functions as a chloride ion channel, a regulator of sodium, and perhaps a regulator of other ion channels, CFTR is also a key component in innate immunity on mucosal surfaces, serving as a receptor to ingest and clear microbes and contribute to host resistance to infection.

I thank the following individuals from the Channing Laboratory who carried out the work described in this report: Alev Gerceker, Martha Grout, Kazue Hatano, Jeffrey Lyczak, Gloria Meluleni, and Tanweer Zaidi. Work described in this paper was carried out, in part, under National Institutes of Health Grants AI22535, AI22806, and HL58398 and under a Brigham and Women's Hospital Interdisciplinary Seed Grant.

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Front Matter (R1-R5)

Pathogens and Host: The Dance is the Same, the Couples are Different (1-2)

Striking a Balance: Modulation of the Actin Cytoskeleton by Salmonella (3-10)

Structure and Function of Pectic Enzymes: Virulence Factors of Plant Pathogens (11-18)

Pseudomonas syringae Hrp Type III Secretion System and Effector Proteins (19-26)

Molecular and Cell Biology Aspects of Plague (27-32)

A Framework for Interpreting the Leucine-rich Repeats of the Listeria Internalins (33-37)

Acyl-homoserine Lactone Quorum Sensing in Gram-negative Bacteria: A Signaling Mechanism Involved in Associations with Higher Organisms (38-42)

Phenotypic Variation and Intracellular Parasitism by Histoplasma capsulatum (43-47)

Exploitation of Host Cells by Enteropathogenic Escherichia coli (48-55)

Genetic Complexity of Pathogen Perception by Plants: The Example of Rcr3, a Tomato Gene Required Specifically by Cf-2 (56-63)

Plants and Animals Share Functionally Common Bacterial Virulence Factors (64-70)

Role of the Cystic Fibrosis Transmembrane Conductance Regulator in Innate Immunity to Pseudomonas aeruginosa Infections (71-77)

Bad Bugs and Beleaguered Bladders: Interplay Between Uropathogenic Escherichia coli and Innate Host Defenses (78-84)

AvrPto-dependent Pto-interacting Proteins and AvrPto-interacting Proteins in Tomato (85-89)

Reactive Oxygen and Nitrogen Intermediates in the Relationship Between Mammalian Hosts and Microbial Pathogens (90-97)

Nitric Oxide and Salicylic Acid Signaling in Plant Defense (98-104)

The Role of Antimicrobial Peptides in Animal Defenses (105-110)

Suramin Inhibits Initiation of Defense Signaling by Systemin, Chitosan, and a ß-glucan Elicitor in Suspension-cultured Lycopersicon Peruvianum Cells (111-116)