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Mucosal Surfaces > L2 > Flashcards

L2 Flashcards

1
Q

Explain the mucosal layers for barriers

A

Outer lauer is the non aterile part where microbiota utilise the wf carbs from the mucin glycoprotein.
Inner layer is mroe sterile, fontains secretions like amps, cytokines, iga etc , lectins for mbl

Surface mucus is mucin which is o glycosylated part of the glycocalyx on epithelial cells surface

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2
Q

Whoch crlls ade in the crypt of villi

A

Paneth which wre singly differentiated

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3
Q

What did lei et al 2019 find aboout amps

A

2 groups defensins and cathelicidins

A defensins are the major troup in si by paneth cells

All stabilised cationic proteins wirh 3 s-s bonds

Anchor to membrqne to form pores

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4
Q

What did smith 2013 find about leukocytes role with goblet cells

A

Induce goblet cell hyperplasia eg via th1 and th2 xytokines allowing more mucus production

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5
Q

What did mcguckin et al 2011 find about mucins

A

Cell surface mucons are o glycosylated and prefent psthogen adhesion

Microbiota influence ratw of mucin production eg goblet cell proliferation

Mucin in small intestine usually muc2 producing mucus

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6
Q

What are inductive sites

A

Where ag is captured and presented to naive b and t cells wg in the peyers patch within the SI

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7
Q

Where do immune cells need to migrate to from inductive sites

A

Effector sites where its rhe place of origin eg lamina propria elsewhere or exocrine glands/salivary or mammary

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8
Q

What are epithelial cells due to tight junctions

A

Polarised apical facing thr air or gut lumen (villi)

Or basolateral side facing basement membrane and lamina propria and below blood circulation

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9
Q

What is the importwnce of lamina propria connective tissue

A

Parts of ecm like collagen needed to maintain the mcuosal epithelial barrier

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10
Q

Whoch deficeicy causes lack of collagen in LP

A

Vitamin c eg via scurvy

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11
Q

What is cell trafficking in mucosal battier

A

Transcytosis

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12
Q

Explain briefly how traffickint can occur eg from baso to apical when iga secreted

A

Receptor endocytosis, into early endosome then either dehrwded in lysosome, recycled or goes to apucal via transcyotsis in vesicle

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13
Q

Which 2 cells can do antigen sampling (presentint ag through the epithelial barrier to the malt)

A

M cells or cross epithelial dendritic cells

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14
Q

Ehat are m cells and how do they work

A

Specialised epi cells in the galt which endocytose or phagocytose ag. Then undergoes transcytosis to the basolateral side for ag presentation

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15
Q

How do cross epithelial crlls do antigen sampling

A

Theough their extensions can etebd to the gut lumen and then present them in basolateral side

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16
Q

What did miller 2007 find about m cells

A

They detect ag throygh cellular prion protein receptors

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17
Q

How is the barrier ovetcome by another solution in immune function

A

Iga, igm and igg and igd can be transcytosed to the lumen

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18
Q

What is malt

A

Mucosa associated lympoid tissue. Where adaptice response begins

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19
Q

Where is NALT

A

nasopharyngeal. Forms ring around mouth airway and gut.

In adenoids and tonsils

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20
Q

Which malt is onlt present in chuodren

A

BALT in respiratory tract bronchus

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21
Q

Where in the gut is malt

A

Peyers patch (below the epithelial barrier)

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22
Q

Which mucosa area has no malt to protect embryo

A

Urogenital tract

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23
Q

What is needed in mucosal immune sites to blockninflammation

A

Suppresive mechanisms eg by microbiota

24
Q

What did holmgren 2005 find about mucosal suppression

A

Insuction of t regs, anergy of T cells, cd8 IEC have tolerance , increased il 10 supprwssive cytokine

25
Q

What are homing mechanisms

A

Ways to specific mucsal immunocutes to their effector cites eg mammary gland, resp tract lamina propria

26
Q

How are lymphocytes drained into blood stream from the malt eg peyers patch after ag sampling

A

Theough lymphatic drainage system agter ag sampling

27
Q

Which chemokine is speicifc in muxosal homing to the small intestine and how

A

Teck/CCL25

Atteacrs cells onlt with ccr9. This is expressed only from mucosal immunocytes usuallt homing in small imtestine

28
Q

Which other cytokine is involved in eg homing from pp to the large bowel egfecgor site ot to mammary gland

A

Meck via the ccr10 on mucosal derived eg b homing yo mammary, or respiratort tract

29
Q

How do endothelial on mucosal tissue of effector sites also gatekeep in homing in gut specifically

A

Madcam1 which binds only a4:b7 expressinf cells allow extravasatipn from blood

Note these found only in gut homing cells populations eg cd4 and cd8

30
Q

Wht happens acter hpming yo rffector site

A

Iga secretion as plasma cells fully differentiate only in the effector site ti secrwte iga

31
Q

Which malt is connected to systemic and mucosal local immune system via systemic homing and local

A

Nalt - eg goes to nasal and salivary gland effector sites

32
Q

Which cells in ceullar mucosa reaponse are good for fighting ic pathogens like ciruses

A

Iec cd8 cells but type A : ab (ab is a dimer forming cd8)

33
Q

What do type B: aa cells do

A

Active against stressed or infected cells

34
Q

What is the mechanism called moving antibodies through mucosa barrier

A

Transporter mediated mechanisms

35
Q

Which receptor on basolateral epithelial cells important for iga and igm transport and how does jt bind

A

Polymeric ig receptor (pigar or pigmr)

Binds by the ec domain which is the secretory compmenet which recognaies j chain

36
Q

What happens to the polymeric pig receptors

A

Proteolytically cleaved in epithelial cells to release secrwtory component bound to iga or igm.

= secretort iga

37
Q

What joins iga into dimer wnd igm into pentamer in the lamina propria

A

Plasma cells join via the j chain

38
Q

What produces polymeric ig receptors

A

Epithelial cells (so responsible for iga secretion)

39
Q

What happens to diga-pigar

A

Recpetor mediated endocytosis

40
Q

What are the functions of iga/pigar ans the authors

A

1- inhibit microbial adherance at lumen eg by affecting mobility eg flagellin. Effectively neutralises toxins,viruses,bacteria

2- neutralise internalised ag which have peneetrated by direction into endosomes

3- reexport toxins etc from penetrated cells by viral etc infections from baso lateral back to lumen for excretion

4- when in iga:ag complex in lumen bind dectin1 which then gets recornsied by dc to release il10 to stop inflammatory response but still cause defence
(Rojas and apodaca 2002)

41
Q

What did rojas and apodaca 2002 find an example of a virus sropped by iga im adherance

A

Found hiv blocked by iga by adherance to the enevelope gp by iga

42
Q

Iga in a complex with what allows it to bind DC in Lp cuasing il10 release

A

Dectin 1

43
Q

Why is il10 importantly secreted by dc

A

It is antiinflammatory by blocking inflammatory cytokines (zhang 2007)

44
Q

How is igg birirectionally transported

A

Via fcr n on placental endothelial and epithelial cells. Allows igg transfer maternally into basolateral side for protection

Also can be transported to apical side in immune activation for secretory igg eg in reap tract and urogenital

45
Q

When does igg dissassemble from fcrn

A

Ar neutral ph after endocytosis/ transcyotiss

46
Q

What is the effector site of tonsil nalt (eg mouth stimulation) and which ab important

A

Gi tract

Iga increase

47
Q

What effector site is by adenoids (ef nasal spray)

A

Respiratoet tract and urogenital tract

Iga and igG increase

48
Q

Gut homeostasis is via galt- microbiota interactions. What is the author of these

A

Sekirov 2010

49
Q

Which microbiota increase AID expression in peyers patch b cells so increase iga

A

Bacteroides (sekirov 2010)

50
Q

How do microbial metabolites impact mucosal skin surfsce immunity

A

Scfa for example can induce cathelicidins ll-37 (sekirov 2010)

51
Q

How is tolerwnce ti microbiota built overtime

A

Exposure of lps to IEC causes the downreg of the tlr4 response overtime (sekirov 2010)

52
Q

Which area of the body holds mcirobiota to replenish and reculture after diarrhoea episodes

A

Appendix

53
Q

Where is igg important

A

Resp tract and urogenital tract. Eg when given a nasal spray it increases iga and igg

54
Q

When is iga downregulated

A

Diseases like ibd

55
Q

When is il10 downreg

A

Diseases like ibd

Mucosal Surfaces (33 decks)

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