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Microbiota On Mucosal > B6- Gut Parasites And Giardia SAV > Flashcards

B6- Gut Parasites And Giardia SAV Flashcards

1
Q

Which 2 gut parasites are common in the whole world because they are zoonotic

A

Cryptosporidium and giardia (micro is also zoonotic)

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2
Q

How does this compare to entamoeba histolytica

A

Low levels in eu and us more in developing countries eg due to poor sanitation of water

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3
Q

Which way do they all transmit

A

Faecal oral with resistant cysts

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4
Q

Although giardia is extracellular where is it

A

Close to epi surfaces (contacts with them)

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5
Q

What is acute vs chronic diarrhoea

A

Acute is below 14 days
Chronic is over 30 and seem more in immunocompromised

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6
Q

What are the 2 main cryptosporidium

A

Parvum and hominis

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7
Q

What do they cause if severe infections

A

Profuse watery diarrhoea, vomiting, malabsorption and death (in under 2 second biggest death after rv)

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8
Q

What proteases do they have for ezcystarion

A

Serine protease

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9
Q

What is gp900 and TRAP proteins for and found to be from

A

Found in invading sporozoites and required for host cell invasion

From microneme release of apical organelles

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10
Q

Which cells do they infect

A

Small intestine

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11
Q

What transporter in c.Parvum found for feeding on nutrients in the parasitophorous vacuole

A

CpABC transporters (another virulence factor)

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12
Q

Which pid affecting cd4 are eveidence for crucial role of cd4 cells in crypto

A

Scid and cd4 lymphophenia severity of disease

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13
Q

What cells induced by the th1 in particular also important in the crypto response

A

CD8 and NK cells potentially

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14
Q

What happens in hiv infection for collapse

A

Hiv load comes in
Not fully removed by your immune system so persists and replicates
High viral load causes loss first of mucosal cd4 and then blood cd4

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15
Q

Below what cell count of CD4 sees increased micro and crypto

A

100 mm^4

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16
Q

Where can excystarion occur to release 4 sporozoites in crypto

A

Stomach acid ph

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17
Q

What histological changes seen in infection

A

Villous atrophy and immune infiltration

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18
Q

Which neuropeptide triggered by crypto from monocytes/macrophages is released which increase Cl secretion for diarrhoea

A

Neuropeptide P

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19
Q

In what disease is neuropeptide p seen more of

A

AIDS

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20
Q

Give some examples of proteins crypto has which disrupts tj and cytoskeleton for permeability and proinflam responses (for diarrhoea)

A

Aminopeptidases

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21
Q

Recognition of c Parvum by enterocyte tlr important for the release of chemotactic cytokines for neutrophils like RANTES and il8, why?

A

Because macrophages are isolated from them since at the apical site

Need neutrophil response

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22
Q

Which hiv protein downrwgs the tlr4 responses of crypto

A

Tat protein

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23
Q

Which cytokines important for reduced crypto burden and is low in hiv and chronic uncontrolled cryptosporidiosis

A

Il15

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24
Q

What does it do and where from

A

Activated monocytes release it and
Induces the ilc1/NK response

causes NK cell prolif and crypto toxicity

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25
Q

How does malnutrition affect complement mediated opsonisation and phagocytosis

A

Reduced mbl which binds crypto needed for complement mediated opsonisation and phagocytosis

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26
Q

Which amp defensin is anticrypto

A

B defensin 2

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27
Q

Balance of th1 with what necessary to stop inflammatory induced diarrhoea

A

Th2 responses/ th2 cytokines eg il13 needed for m2 phenotype

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28
Q

How could this link to Microbiota potentially

A

Since they can release tslp and il25 from cells causing ilc2 responses

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29
Q

Which anti apoptotic gene upreg in crypto in infection as evasion mechanism for survival in enterocytes

A

Osteoprotegerin (acts as a decoy receptor for trail = antiapoptotic )

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30
Q

Where is EH usually situated

A

Outer mucus layer on the colon (not intracellular)

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31
Q

What % of cases are noninvasive amebiasis and what is this

A

90%
Where you get non dysenteric diarrhoea (non bloody) , might be asymptomatic or also get abdominal pain and spread cysts

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32
Q

What happens to invasive 10%

A

Induced colitis

Can either cause bloody diarrhoea with flask shaped lesions forming as they invade the submucosa (this can form chronic lesions)

Or can even disseminate into the portal circulation where it can reach liver and cause liver abscesses which you can die from

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33
Q

What immediate innate are important in EH which can be modulated by microbiota

A

Mucus barrier effective
Amps
Tj integrity
Iga

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34
Q

Which enzymes do eh have for degrading mucus

A

Glycosidases and cysteine proteinases

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35
Q

What can this be excacerbated by host dependant to therefore increase interaction with epi cells and inflam

A

Diet- low fibre = more mucin degrading

36
Q

What inflam response can occur if they make contact

A

Proinflam cytokines the usual leading to neutrophil and mac
Ifny also involved causing ros and no (antiparasitic)
Aswell as degranulation

37
Q

Which ilc is involved in response and can lead to so much inflammation and damage it will cause dissemination potentially

A

Ilc3

38
Q

Binding of what to epi cells leads to these inflam responses

A

Gal/galnac-lectins

39
Q

What does eh do to Microbiota that potentially exacerbates penetration

A

Dysbiosis eg increased p copri - makes sense due to inflammatory environment link with this (th17/3 inducing) - associated with RA commonly

Also reduced butyrate clostridium and bacteroides which are immunomod

40
Q

What is meant by contact dependant cell lysis which allows there dissemination/mucosal lesion formation

A

They insert an ion pore (amebopore) disrupting the membrane and causing death

41
Q

Why would il17 be important here (and Microbiota)

A

Potent Siga responses important for eh

42
Q

How is it suggested they can be resistant to ox stresses from inflammation they cause

A

Oxygen reductases they have

43
Q

How do they affect effective iga and complement

A

Cysteine protease mediated degradation

Degrade c3b and c3a

44
Q

Is Giardia invasive

A

No it will stay on the si lumen and interact with si by central sucking disc

45
Q

In most cases what are the symptoms

A

Asymptomatic or acute/cleared diarrhoea, cramps, nausea

46
Q

Can this become chronic / what chronic effects can happen

A

Yes it can,

Due to impairment of absorption

With recurring episodes of diarrhoea, can lead to cramps, anorexia/weight loss and nutritional disorders bc of malnutrition

47
Q

Why can trophozoites often unlike EH interact with epi cells

A

Because low mucus barrier in si

48
Q

Give some issues in so it can cause to histology and enzymes

A

Shortening of microvilli so malabsorption
Cell apoptosis via direct contact
Also affects enzymes like lactase gaining access to the si and therefore also causing increase diarrhoea due to water flow

49
Q

What can malabsorption and diarrhoea lead to in long run

A

IBS, cognitive impairment, tiredness and stunted development

50
Q

What ilc response is there like EH and which cytokines is particularly important

A

Ilc3
Il17 required for pigr expression as iga most important adaptive protection against Giardia

51
Q

Is the effects of the Microbiota dysbiosis Giardia causes known

A

No but it is present

52
Q

Why is flagella and adhesive disc essential

A

Peristalsis induced by NO release on surface = sm contraction

53
Q

What same proteases as EH do they have and disrupts tj and also appptosis of cells and most importantly degrades iga

A

Cysteine proteases

54
Q

Which amps essential for anti Giardia

A

Defensins and cathelicidins (showing role of il22 and also Microbiota)
cathelcidin ll37 speicfically induced by b producta and b theta via hif 1a

55
Q

What chemical from cells and immune cells inhibits excystation and trophozoites proliferation - particularly important innate control of Giardia

A

NO

56
Q

Which KO of mice caused chronic infection with increased trophozoites in small intestine

A

Iga, pigr and J chain (showing importance of Siga and the role of Microbiota)

57
Q

Other than vsp immune evasion, what do they have to control NO production

A

Arginine deaminases reducing levels of no

58
Q

Whcih genetic pid can therefore affect severity/chronic of Giardia

A

X linked b cell immunodeficiency

59
Q

VSP GIARDIA ANTIGEN SWITCH

A
60
Q

Explain the structure of vsp proteins on surface of Giardia

A

Intracellular C domain ( cytoplasmictail) and is conserved
Tmd

Then middle part of extracellular is semi conserved

N terminus is variable and has cxxc motifs

61
Q

How many expressed on trophozoites at once

A

1 or 2

62
Q

Why are they important

A

Very immunogenic (both cell and humoral)

63
Q

What enzymes does it protect parasite from

A

Intestinal and pancreatic proteases

64
Q

Around how many genes compared to trypanosoma

A

300 genes (all transcribed) vs 1000 vsg copies

65
Q

How is it similar only way to trypanosoma vsg

A

Called ‘true’ ag switch where there are homologous genes that can be expressed alternatively

66
Q

Explain the rnai process used for mono allelic exp

A

Hairpin premirna from rna dep rna pol is transcribed

This then goes to cytoplasm meeting dicer rnase which processes it to ds mirna

Dsmirna binds argonaute ago protein and form mirna-risc complex which either cleaves the transcript or blocks translation via complementary binding

67
Q

Downregulation of which proteins in this process of mirna silencing causes multiple allele expressions in Giardia showing rnai is important

A

Dicer ko or rdrp (ago would kill them)

Rdrp required for production of hairpin loop mirna

68
Q

What special motifs did a bioinformatics study find that 73 out of total vsp have which make them able to be presented on cell surface and complete switching

A

2 conserved motifs that were not present in around half (suggesting they don’t have effect)

69
Q

Why is using bio informatics on vsp difficult

A

Different studies will annotate diff proteins as vsp depending on the tools they use. Hard to figure out

70
Q

Give example of why 3’ utr specifically isn’t used in Giardia repression (saraiya 2014 study into whole coding sequence mirna binding to vsp)

A

Vsp-2 doesn’t even have a 3’ targeting site for mirna but still silenced

71
Q

What happened to vsp117 silenced by no overlapping 6mirna compared to only 2 non overlapping

A

There was additive effect where vsp 117 silenced to only 2% exp vs 48% for 2 mirna

72
Q

What does this indicate

A

Giardia relies on multiple mirna targeting sites within the orf to fully silence as only having 1 on 3’ utr is insufficient

73
Q

In comparison to vsg, are vsp in subtelmoeres?

A

No only 3 are out of 75 working

74
Q

Explain what they found in gerbils suggesting vsp could be used in future for vaccines

A

injection of trophozoites exp all of them (rnai mutants) protected from secondary infections

75
Q

What did using oral vaccines injecting all vsp protein repertoires (solely the proteins) done in dogs and cats also find

A

That they were protected from subsequent infections with giardiasis and chronic infection

and it also reduced spread to children from dogs in shanty towns ie affecting zoonotic transmission rates

76
Q

Why would using vsp- coated vlps with Ha and na be useful for influenza

A

Highly immunogenic ie
Found better igG and iga responses orally to HA and NA

Also it protects them from being degraded by enzymes

77
Q

How are these gut protozoans different to MICROSPORIDIA

A

MICROSPORIDIA is opportunistic- meaning that it won’t cause symptoms in healthy

These are obligate pathogens and can cause complications

78
Q

Which nutrient from diet could impact host ability to fight infection via redox activity in macrophages for example

A

Can be pumped into the phagosome and kill them via ros generation

79
Q

What vaccine was initially found worked for crypto in calves but wasn’t replicated

A

Y-irradiated oocysts

80
Q

Why would th1 cytokines like ifny be important for crypto

A

Can starve the vacuole of tryptophan via breakdown

Also induced production of NO/ROS VIA INOS = kill cells and crypto

81
Q

How would entamoeba even get to the liver

A

Trophozoites into the portal vein through intestinal lesions

82
Q

Which is the most common protozoan found in stool

A

Giardia

83
Q

How do Giardia excysting trophozoites replicate

A

They adhere close to surface and replicate extracellularly before encystation

84
Q

Which enzyme does Giardia have which maybe makes NO response less important

A

arginine deaminase which degrades arginine required for NO production

85
Q

How does mirna work in mammals

A

Mirna sites usually near 3’ utr and there is cleavage of the poly A tail causing de adenylation exonuclease activity

86
Q

Since b-defensin 2 is important for cryptococcus, which probiotic could be useful and why

A

Ecoli nissle 1917- shown to induce the release of b-defensin 2 via nfkb induction (similar to the tlr9 mediated degranulation)

Microbiota On Mucosal (22 decks)

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