Fungal Immunity Flashcards

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1
Q

What are the four main phyla of fungi and which most commonly causes human fungal infection?

A

Ascomycota – MAIN ONE
Basidiomycota
Chytridiomycota
Zygomycota

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2
Q

Give examples of how the morphogesis of fungi contributes to its ability to cause disease in the host.

A
  1. Candida albicans dimorphism between spores but they and hyphae forms which allows tissue invasion
  2. Cryptococcus forms a capsule to evade phagocytosis
  3. Aspergillus sp. are inhaled as conidia and invade tissues as hyphae
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3
Q

Which pattern recognition receptors in Drosophilia flies are important in detection of fungal pathogens?

A

TLR

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4
Q

Name 2 deficiencies that are associated with an increased risk of mucocutaneous candidiasis.

A
  1. Dectin 1

2. CARD 9 (downstream of Dectin 1)

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5
Q

Name 3 factors that are associated with increased risk of Aspergillosis in transplantation.

A

TLR4 – loss of function
Dectin 1
Plasminogen alleles

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6
Q

Which PRR is actively recruited to Aspergillus fumigatusphagolysosomes?

A

TLR9

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7
Q

What can plasminogen directly bind to?

A

Aspergillus fumigatus conidia

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8
Q

Which cells are the most important in defence against an Aspergillus fungal infection?

A

Neutrophils

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9
Q

What do neutrophils release that enable them to trap Aspergillus?

A

NETs

chromatin nets to capture pathogens and act outside nucleus acts as danger signals and recruit more effector cells

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10
Q

Describe how fungal morphogenesis governs the dendritic cell modulation of adaptive immunity.

A

Hyphal forms = Th2 response

Conidium = Th1 response

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11
Q

What cytokine therapy has been shown to enhance clearance ofinvasive fungal infection?

A

IFN-gamma

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12
Q

Describe the principles of adoptive immunotherapy for fungal infection.

A

Generate anti-fungal T cells, which can be cultured in large numbers and administered to the patient

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13
Q

Give an example of gene therapy for chronic granulomatous disorder.

A

Restoration of gp91 function
This is involved in the generation of NADPH oxidase – this generates reactive oxygen species, which is required to kill microbes
NOTE: another type of gene therapy = restoration of neutrophil NET formation

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14
Q

What types of hypersensitivity reaction are associated with fungal allergies?

A

Type 1, 3 and 4

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15
Q

What are two predisposing conditions for allergic bronchopulmonary aspergillosis (ABPA)?

A
  1. Asthma

2. Cystic fibrosis

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16
Q

What is the obligatory criteria for ABPA?

A
  1. Total baseline serum IgE > 1000 IU/ml
  2. Positive immediate hypersensitivity skin test or
  3. Aspergillus-specific IgE
17
Q

List some supportive criteria for ABPA.

A
  1. Eosinophilia > 500 cells/ul
  2. IgG antibodies to Aspergillus fumigatus
  3. Consistent radiographic abnormalities
18
Q

List some radiological abnormalities/features of ABPA.

A
  1. Dilated bronchi with thick walls
  2. Proximal bronchiectasis
  3. Ring or linear opacities
  4. Upper or central region predilection
  5. Lobar collapse due to mucous impaction
  6. Fibrotic scarring
19
Q

What might be seen in a CT scan of a patient with ABPA?

A

Hyper dense mucous sign

20
Q

Describe the main treatment options for ABPA.

A
  1. Corticosteroids
  2. Itraconazole may be used as a steroid-sparing agent
    - indicated if not responding to steroids or steroid dependant
  3. Omalizumab (recombinant anti-IgE antibodies)
21
Q

List three other examples of fungal allergies, including associated features of each.

A
  1. Aspergillus rhinosinusitis
    - May be allergic or invasive
    - Obliterated sinuses
    - Treated with oral corticosteroids or surgical removal of nasal tissue
  2. Severe asthma with fungal sensitisation
    - Fungal sensitisation as a potential cause of severe asthma
    - Requires exclusion of ABPA
  3. Hypersensitivity pneumonitis (extrinsic allergic alveolitis)
    - Allergy requires long-term exposure to allergen (often occupational)
22
Q

What test is used to diagnose fungal allergies?

A

Skin prick testing

23
Q

Which type of hypersensitivity is each of the previously mentioned fungal allergies?

A

ABPA – type 1 or 4
Asthma – type 1
Rhinitis – type 1
Hypersensitivity pneumonitis – type 4

24
Q

Give specific example of mucocutaneous fungal infections due to Dectin- 1 deficiency and how this happens

A

Vulvovaginitis
Onchomycosis

the deficiency leads to

  1. impaired macrophage IL-6 production and binding in response to fungal infections
  2. increased susceptibility to IA (invasive aspergillosis) in stem cell transplants
25
Q

What specific mucocutaneous infection does a deficiency in CARD-9 lead to?

A

Chronic mucocutaneous candidiasis

26
Q

What is CARD-9 required for?

A
  1. TNFalpha production in response to B-glucan stimulation

2. T-cell TH17 differentiation

27
Q

What do polymorphisms in TLR4 lead to?

A

Increased risk of IA in transplantation (e.e haematopoietic stem cell transplants)

28
Q

What is Conclusion 1 in fungal immunity?

A

Mutations on Dectin-1, TLR4 and plasminogen confer increased susceptibility to fungal disease

29
Q

What disease are plasminogen alleles linked to?

A

Aspergillosis

30
Q

What is Fungal Morphogenesis?

A

fungi can transition between yeast, candida and hyphae forms (multicellular) which can drive a modulation of dendritic cell response and is bad for the immune system as it confuses it

31
Q

What innate defence do we have against fungal infections?

A

Mucosal immunity governs fungal tolerance and resistance

32
Q

What is Conclusion 2 in fungal immunity?

A
  1. Macrophages and neutrophils contribute to fungal immunity but for Aspergillus neutrophils are of a primary importance
  2. Dendritic cells modulate adaptive immune reponses
  3. Adaptive T-cell IFN gamma responses increase host immunity
  4. New treatments involve IFN gamma or adoptive T-cell therapy as well as gene therapy for primary immunodeficiencies
33
Q

What is the primary driver in fungal allergy, and what are the supporting fungi?

A

primary- Aspergillus

supporting- Alternarnia, Cladosporium, Penicillum

34
Q

What is Conclusion 4 in fungal allergy?

A
  1. variety of pulmonary allergies, but ABPA is best recognised
  2. evidence for fungal sensitisation in hypersensivity pneumonitis
  3. diagnosis driven by skin test, IgE and IgM in clinical relevant populations