Microbiological, clinical, and epidemiological profile of Phaeohyphomycosis in a tertiary care hospital from Western India

Abstract

Background: Cryptococcus neoformans is an encapsulated fungal pathogen that causes severe complications primarily in immunocompromised populations. Monocytes and macrophages serve as first line of innate immune defence in tackling Cryptococcus neoformans infection.Nevertheless, the interplay between Cryptococcus neoformans with macrophages remain elusive. In this study, we investigated the interaction between C. neoformans and THP-1 monocyte derived macrophages, emphasising on the role of cryptococci capsule and the host cytoskeleton remodelling upon interactions.Methods and materials: Cryptococcus neoformans encapsulated H99 (ATCC 208821), Cap64 (ATCC 52816, acapsular mutant of B-3501) and B-3501 (ATCC 34873) strains were used in this study. THP-1 (TIB-202, human acute monocytic leukemia cell line) was induced into adherent, macrophage-like cells in the presence of phorbol myristate acetate. The association of Cryptococcus neoformans Cap64, B-3501 and H99 with THP-1 monocyte derived macrophage, particularly adherence and internalisation events, host actin and microtubule changes were examined using differential fluoresence assay. The images were acquisited using inverted epifluorescence microscope. Association indexes (adherence or internalised yeasts/100 host cells) from three independent experiments were calculated. Additionally, the role of actin and complement receptor type-3 (CR3) in the interaction between C.neoformans Cap64 and THP-1 monocyte derived macrophage were studied upon treatment of infected THP-1 monocyte derived macrophage with cytochalasin D and with a combination of anti-CD18 and anti-CD11b, respectively.Results: Acapsular C. neoformans cells were able to efficiently adhere to and become internalised into THP-1 cells without opsonisation and macrophage activation; while presence of capsule reduced the host-pathogen association. Infection by C. neoformans generally led to localised actin but not microtubule remodelling at the host-pathogen interface. Treatment with Cytochalasin D, an actin polymerisation inhibitor, confirmed that the integrity of actin microfilament is required for both adherence and internalisation of cryptococci into macrophage cells. We further demonstrated that antibody inhibition of complement receptor type 3 (CR3) in THP-1 reduced the association of acapsular cryptococci to the host cells. Conclusion:The results presented new insights on how C. neoformans co-opts professional phagocytic cells during primary infection.

Molecular epidemiology of clinical filamentous fungi in Qatar beyond Aspergillus and Fusarium with notes on the rare species

“…identified 27 cases of phaeohyphomycosis in SOT recipients in which Exophiala was the most recovered genus (11/27), followed by Ochroconis (3/11) and Alternaria (2/11). 67 Moreover, in studies from India 69 and Korea, 70 Exophiala was the most isolated genus causing phaeohyphomycosis (26% and 71%, respectively). However, we recovered only one case of Exophiala from a gastric aspirate specimen of a patient with obstructive jaundice admitted to the intensive care unit (ICU).…”