Specifc aims:
Our proposal aims at identifying which molecules can be targeted to enhance NK cell functions in WHIM
patients, with particular interest dedicated to those that are involved in the clearance of human papillomavirus (HPV) infected cells. Thus, we will:
1) analyze the phenotypic and functional characteristics of NK subsets in WHIM disease. To assess the mechanisms underlying NK cell phenotype, attention will be dedicated to the analysis of the crosstalk with other immune (neutrophils), or non-immune (stromal cells) components of the NK cell differentiation niche in BM.
2) assess the influence of WHIM mutation on the anti-viral activity mediated by NK cells during HPV
infection.
3) establish approaches to increase NK cell accumulation in skin virus lesions.
Background/rationale
WHIM syndrome is a rare congenital disorder characterized by warts, hypogammaglobulinemia, recurrent bacterial infections, and myelokathexis. Genetic defects leading to persistent activation of the chemokine receptor CXCR4 are at the basis of the syndrome and result in marked leucopenia due to immune cell retention in generative organs. The associated immune defect underlies the marked susceptibility to bacterial and HPV infection.
Research design and methods for achieving the stated objectives
Our research goals will be pursued by performing an intensive characterization of peripheral blood (PB)
NK cell subsets by flow cytometry. NK cell characteristics will be related to the level of disease signs and to the functional status of other immune and non-immune cells expressing the mutated CXCR4. Moreover, NK cell role against HPV will be established by analyzing their migration and function in skin lesions.
Anticipated output
Through NK cell characterization, we foresee to obtain unknown information on the role of those cells in
the HPV clearance in the WHIM syndrome and to generate important therapeutic tools
WHIM syndrome is an extremely rare disease, usually transmitted as an autosomal dominant trait but autosomal recessive or sporadic cases have also been described. Specific mutations identified in WHIM patients include heterozygous gain of function mutations in the CXCR4 gene encoding a chemokine receptor expressed on mature leukocytes and involved in many pathways controlling bone marrow cell adhesion and homing, myelopoiesis and lymphopoiesis. Recent reports of patients who do not have detectable mutations of CXCR4, raise the possibility that there is more than one genetic basis for WHIM.
The main clinical problem in WHIM patients is the unusual susceptibility to HPV infection that causes warts on any part of the body. Unfortunately, treatment of warts associated with WHIM syndrome, has proven to be difficult, with poor response to standard therapies and often requiring surgical resection. The main goal of this project is to convert our knowledge about NK cell functional maturation and trafficking capacity in WHIM syndrome into effective, targeted therapies to keep under control the viral infection. In particular, we will try identify key mechanisms of NK cell HPV evasion to ameliorate NK cell effector functions.
The only studies dealing with NK cells in WHIM patients refer to their numbers but not to their functional characterization and trafficking capacity. The main goal of our project is to fulfill an intensive characterization of the different NK cell subset in WHIM syndrome. With the increase of clinical cases, it has become apparent that susceptibility to HPV infection, inducing warts, condyloma acuminata and carcinomas, represents a major clinical problem for WHIM patients.
One of the aims of which we will deal with is the assessment of the influence of WHIM microenvironment on the anti-viral activity mediated by NK cells during HPV infection. Early vaccination may be able to prevent certain HPV infections and reduce HPV related cancer potentially associated with WHIM syndrome. However, the underlying immune defects associated with the disorder may lessen the effectiveness of such protection, thereby requiring periodic re-vaccination. New observations suggest that NK cells may play important roles in the development of efficacious vaccines (Rydyznski CE, Trends Immunol. 2015). To this regard, our findings will help to harness the power of NK cells for therapeutic aims, and to design new generation vaccine strategies based on engineering vaccines that can induce NK activation. Moreover, efforts to modulate NK cell trafficking into HPV infected tissues, and to counteract NK cell suppressors, might also prove fruitful in the clinic.