By binding SIRPalpha or calreticulin/CD91, lung collectins act as dual function surveillance molecules to suppress or enhance inflammation.
Surfactant proteins A and D (SP-A and SP-D) are lung collectins composed of two regions, a globular head domain that binds PAMPs and a collagenous tail domain that initiates phagocytosis. We provide evidence that SP-A and SP-D act in a dual manner, to enhance or suppress inflammatory mediator production depending on binding orientation. SP-A and SP-D bind SIRPalpha through their globular heads to initiate a signaling pathway that blocks proinflammatory mediator production. In contrast, their collagenous tails stimulate proinflammatory mediator production through binding to calreticulin/CD91. Together a model is implied in which SP-A and SP-D help maintain a non/anti-inflammatory lung environment by stimulating SIRPalpha on resident cells through their globular heads. However, interaction of these heads with PAMPs on foreign organisms or damaged cells and presentation of the collagenous tails in an aggregated state to calreticulin/CD91, stimulates phagocytosis and proinflammatory responses.
Gardai
Shyra J
SJ
Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA.
Xiao
Yi-Qun
YQ
Dickinson
Matthew
M
Nick
Jerry A
JA
Voelker
Dennis R
DR
Greene
Kelly E
KE
Henson
Peter M
PM
D000818:Animals; D000943:Antigens, Differentiation; D037282:Calreticulin / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D037222:Collectins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D015922:Complement C1q / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000166:cytology / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D039842:Neural Cell Adhesion Molecule L1 / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D037662:Pulmonary Surfactant-Associated Protein A / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D011971:Receptors, Immunologic; D048051:p38 Mitogen-Activated Protein Kinases
D000943:Antigens, Differentiation; D037282:Calreticulin; D037222:Collectins; D016207:Cytokines; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D; D011971:Receptors, Immunologic; D015922:Complement C1q; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C509248:Ptpn6 protein, mouse