Final Report Summary - HIIS (The humoral innate immune system: long pentraxins as a paradigm)
The general objective of this application was to use the long pentraxin PTX3 (discovered by the applicant) as a paradigm to understand the logic and molecular mechanisms of humoral innate immunity and its interplay with the cellular arm. Its non-redundant role in resistance against selected pathogens (uropathogenic Escherichia coli; Shigella flexneri, Neisseria meningitides, Pseudomonas aeruginosa), beside against Aspergillus fumigatus already established in previous works, has been defined during the project, as well as its role in autoimmunity. Novel unexpected cellular sources of PTX3 have been defined, beside lymphatic endothelial cells just found at the beginning of the project. Human colostrum has been shown to contain high levels of PTX3, and mammary epithelial cell and milk macrophages constitutively produce it. Oral administration of PTX3 provided protection against P. aeruginosa lung infection in neonate mice. Moreover PTX3 was detected in urine of patients infected with uropathogenic E. coli and amounts correlated with disease severity. The pathogen induces PTX3 in uroepithelial cells and it enhanced phagocytosis of the pathogen and phagosome maturation by neutrophils. The presence of PTX3 in milk and urine can be good examples that the cellular and humoral arms of innate immunity exert complementary functions in mediating resistance against pathogen infections. Correlative genetic evidence in humans now indicates the general validity of the functions of this molecule described through gene targeting in the mouse. Interestingly, we observed a correlation between specific PTX3 allelic variants and resistance to urinary tract infections and to susceptibility to A. fumigatus infection. Interestingly, an association between genetic polymorphisms in PTX3 and the occurrence of invasive aspergillosis after allogeneic hematopoietic stem-cell transplantation and with the susceptibility to acute pyelonephritis and cystitis has been found in these two clinical studies. The role of PTX3 as endogenous adjuvant, proposed on the basis of gene transcription profile after adjuvant administration, has been strengthened in vivo in vaccination protocols taking advantage of PTX3-deficient mice or exogenous PTX3 administration.
The interaction of PTX3 with ficolins and Mannose Binding Lectin (MBL) has shed new light on how humoral pattern recognition receptors interact and amplify their recognition and effector repertoire, interacting with the microenvironment.
The study on the role of the constitutive expression of PTX3 by lymphatic vessels showed that PTX3 is essential for the drainage of solutes and trafficking of dendritic cell. Besides the functional defects, lymphatic vessels in PTX3-deficient mice are characterized by morphometric alterations. Two strains of PTX3 conditional knock out mice have been generated, one with a complete functional deletion of the gene, and one with a deletion restricted to the C-terminal domain of the molecule. The availability of conditional KO will help to define PTX3 role in lymphatics. To further characterize the role of PTX3 in orchestration of hyaluronan (HA)-rich ECM we were involved in the development of a range of surface-sensitive techniques. An in vitro setting has been developed to study how PTX3 participates together with its known partners TSG-6 and Inter-alpha-Inhibitor (IαI), in the composition and cohesion of HA-rich ECM. We found that an essential requirement for successful incorporation of PTX3 in the matrix is the initial encounter of the protein with IαI. PTX3 and P-selectin double deficient animals were generated. However the absence of P-selectin did not modify the phenotype observed in PTX3-deficient animals in a model of peripheral artery disease. In contrast, in a model of kidney ischemia and reperfusion injury, the increased damage and inflammation observed in PTX3-deficient mice were inhibited by blocking P-selectin. The analysis of the functional role of PTX3 polymorphisms in terms of expression and functional activity, and on the regulation of the expression of PTX3 through microRNAs and epigenetic modifications opened new vistas on the complexity of the regulation of PTX3 expression through SNPs, miR and epigenetic modifications and its relevance in disease, including infections and cancer.
A novel long pentraxin (PTX4) has been identified and is under investigation for its functional activity, through the use of gene targeted mice and original reagents generated in this project.
In general these studies have shed new light on PTX3 as a functional ancestor of antibodies and on the interplay between the cellular and humoral arm of innate immunity. These studies have paved the way to the diagnostic and therapeutic exploitation of PTX3.
The interaction of PTX3 with ficolins and Mannose Binding Lectin (MBL) has shed new light on how humoral pattern recognition receptors interact and amplify their recognition and effector repertoire, interacting with the microenvironment.
The study on the role of the constitutive expression of PTX3 by lymphatic vessels showed that PTX3 is essential for the drainage of solutes and trafficking of dendritic cell. Besides the functional defects, lymphatic vessels in PTX3-deficient mice are characterized by morphometric alterations. Two strains of PTX3 conditional knock out mice have been generated, one with a complete functional deletion of the gene, and one with a deletion restricted to the C-terminal domain of the molecule. The availability of conditional KO will help to define PTX3 role in lymphatics. To further characterize the role of PTX3 in orchestration of hyaluronan (HA)-rich ECM we were involved in the development of a range of surface-sensitive techniques. An in vitro setting has been developed to study how PTX3 participates together with its known partners TSG-6 and Inter-alpha-Inhibitor (IαI), in the composition and cohesion of HA-rich ECM. We found that an essential requirement for successful incorporation of PTX3 in the matrix is the initial encounter of the protein with IαI. PTX3 and P-selectin double deficient animals were generated. However the absence of P-selectin did not modify the phenotype observed in PTX3-deficient animals in a model of peripheral artery disease. In contrast, in a model of kidney ischemia and reperfusion injury, the increased damage and inflammation observed in PTX3-deficient mice were inhibited by blocking P-selectin. The analysis of the functional role of PTX3 polymorphisms in terms of expression and functional activity, and on the regulation of the expression of PTX3 through microRNAs and epigenetic modifications opened new vistas on the complexity of the regulation of PTX3 expression through SNPs, miR and epigenetic modifications and its relevance in disease, including infections and cancer.
A novel long pentraxin (PTX4) has been identified and is under investigation for its functional activity, through the use of gene targeted mice and original reagents generated in this project.
In general these studies have shed new light on PTX3 as a functional ancestor of antibodies and on the interplay between the cellular and humoral arm of innate immunity. These studies have paved the way to the diagnostic and therapeutic exploitation of PTX3.