Immune Response Profiles From Humans Experimentally Exposed To Ph. Duboscqi Bites

IMMUNE RESPONSE PROFILES FROM HUMANS EXPERIMENTALLY EXPOSED TO Ph. duboscqi BITES 1Uniformed Services University of the Health Sciences, Bethesda, MD; 2Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD; 3Vector Molecular Biology Section, LMVR, National Institutes of Allergy and Infectious Diseases, NIH, Rockville, MD; 4Fundacao Oswaldo Cruz, Fortaleza, Brazil; 5Walter Reed National Military Medical Center, Bethesda, MD; 6Walter Reed Army Institute of Research, Silver Spring, MD Cutaneous leishmaniasis is a vector-borne neglected infectious disease prevalent in 92 countries with approximately one million infections annually. Interactions between vector saliva and the human host alter the response to infection and outcome of disease caused by Leishmania major . To understand the human immunological responses developed against saliva of the L. major vector, Phlebotomus duboscqi (Pd), we repeatedly exposed the arms of 14 healthy U.S. volunteers. IgG antibodies were determined and peripheral blood mononuclear cells (PBMCs) were cultured in the presence of SGH or recombinant proteins for IFN-g release assay. A punch skin biopsy of the arm from the bite site of some volunteers was used for histological staining for various markers and RNA extraction for transcriptome analysis. A variety of immediate site reactions with punctuate lesions, erythematous patches and induration were observed and late reactions were characterized by macular discoloration/pigmentation/erythematous papules. Hematoxylin and eosin staining showed moderate mononuclear infiltrate with occasional eosinophils. Immunohistochemistry analysis demonstrated a varied mild to moderate cellular infiltrate with CD3 T lymphocytes, macrophages, neutrophils and some eosinophils. Human RNA sequencing of these specimens revealed expression profile differences between control skin and the Pd bite site. Modest increases in plasma antigen-specific IgG responses to SGH were seen over time
RITM0025419
Cutaneous leishmaniasis is a vector-borne neglected infectious disease prevalent in 92 countries with approximately one million infections annually. Interactions between vector saliva and the human host alter the response to infection and outcome of disease caused by Leishmania major . To understand the human immunological responses developed against saliva of the L. major vector, Phlebotomus duboscqi (Pd), we repeatedly exposed the arms of 14 healthy U.S. volunteers. IgG antibodies were determined and peripheral blood mononuclear cells (PBMCs) were cultured in the presence of SGH or recombinant proteins for IFN-g release assay. A punch skin biopsy of the arm from the bite site of some volunteers was used for histological staining for various markers and RNA extraction for transcriptome analysis. A variety of immediate site reactions with punctuate lesions, erythematous patches and induration were observed and late reactions were characterized by macular discoloration/pigmentation/erythematous papules. Hematoxylin and eosin staining showed moderate mononuclear infiltrate with occasional eosinophils. Immunohistochemistry analysis demonstrated a varied mild to moderate cellular infiltrate with CD3 T lymphocytes, macrophages, neutrophils and some eosinophils. Human RNA sequencing of these specimens revealed expression profile differences between control skin and the Pd bite site. Modest increases in plasma antigen-specific IgG responses to SGH were seen over time. WB results showed volunteer plasma reactivity to Pd salivary proteins. Moreover, volunteers developed a cellular immunity exhibited by the secretion of IFN-g upon PBMC stimulation with Pd SGH and saliva recombinant antigens. Our results demonstrated that humans make a local and systemic immune response against Pd salivary proteins indicating that the further investigation of salivary recombinant proteins represents a crucial approach for future development of a potential Leishmania vaccine.