Which fungi classes cause disease in humans
3 phyla causing disease in humans Zygomycota Basidiomycota `Ascomycota (bottom 2 more closely related)
Give an example of ascomycota
Candida and Aspergillus
Give examples of basidiomycota
List Fungi causing infections
Aspergillus (ascomycota) Cryptococcus (basidiomycota) Candida albicans (ascomycota)
How can aspergillus cause problems
Have spores called conidium.Normally fine, most people inhale every day Only a problem if you have no neutrophils Can germinate (leading to fungal ball) and cause bleeding in LUNGS
How can Cryptococcus neoformans cause disease
Mushroom group (microscopic) .Fimbrae that allow it to adhere to surfaces .Commonest cause of death in HIV patients (subsaharan Africa) .Inhaled through lungs but can disseminate to brain if lack of CD4+ T cells. Leads to cryptococcal meningitis. Can then develop cryptococcomas (fungal ball) , and stroke like symptoms.
What is cryptococcoma
Ball of fungus which has germinated. CNS (cryptococcus neoformans)
How can candida albicans cause disease
Candida is commensal on skin and gut But in immunocompromised/catheterised, can develop invasive infeection. Can get into the back of the eye creates mass =candida endophthalmitis, for example
Outline cellular immunity to fungal infection
Innate immune system very important. Loss of neutrophils is a key risk factors .Most fungi encountered at mucosal surface (in gut, yeast or on lungs as moulds). Opsonisation, phagocytes and complemet all important. Dendritic cells present antigen to T cells Can lead to Th1, Th2 and Th17 responses(these then determine innate response-circle).
Why are NK cells important in cellular immunity to fungal infection
They produce IFN-g which primes macrophage to deal with fungus
Outline how fungi change shape Candida, cryptococcus and aspergillus
Can start as unicellular organisms then become mutlicellular ▪Candidal dimorphism (starts of as budding yeast but when it is involved in invasioive infections changes into hyphal forms, which are muticellular filamentoius structurees) allows tissue invasion ▪Crytpococcus divides in the host as a yeast. Forms a capsule to evade phagocytosis ▪Aspergillus species inhaled as conidia, invade tissues as hyphae
How can fungi be sensed
Toll like receptors (innate receptor). Losing the toll systems put you at high risk of fungal disease
What are c-type lectins
Part of immunoglobulin super family.Detect carbohydrate on fungal cell wall. Important for phagocytosis of fungi (TLR cannot do it alone, need c -type lectins).
What receptors are important in fungal infection
TLR, c-type lectins and scavenger receptors
T/F scavenger receptors normally phagocytose non-inflammatory materials
What deficiencies could result in chronic mucocutaneous candidasis
c-type lectin is really importnat in fungal immunity. Mutations and thus deficiency of Dectin 1[Dectin 1 (a c-type lectin). It binds candida. Without dectin 1 ,cannot produce IL-6 or bind ], and CARD9, a protein in the downstream signalling pathays for many c-type lectins, can result in chronic mucocutaneous candidiasis.
What is worse, dectin 1 or CARD9 deficiency
CARD9, because this is the signalling molecule for the actiation of many receptors