Pseudomembranous colitis - necrosis or apoptosis?

[Phloston]

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I have annotated in my FA (I think from USMLE Rx): "Pseudomembranous colitis is due to APOPTOSIS, NOT necrosis." That probably means that a few months ago I had encountered a question on it and got it wrong because I thought it was necrosis, but I can't remember at this moment the actual mechanism, or if it is in fact one over the other.

Anyway, a gut feeling inside me just had a momentary doubt, so I double-checked on Google but hadn't come across anything definitive.

Has anyone come across this distinction at any point / does anyone know the precise mechanism of cell death here (apoptosis vs necrosis vs pyroptosis, etc.)?

Cheers,

 

[thinkenergy]

Apoptosis, C. difficile releases a toxin that causes cytoskeleton rearrangement, which results in apoptosis

 

[usmlesuccess]

Doesn't C. diff use the AB cytotoxin, similar to that used by other ADP ribosylating exotoxic bacteria? I would suspect that it would be necrosis, as there is a lot of inflammation associated, whereas apoptosis would not exhibit such inflammation.

Edit: it seems like the literature states that it is apoptosis, but why is that?

 

[thinkenergy]

C. difficile releases a cytotoxin that ribosylates of Rho (a GTPase), this leads to actin rearrangement, loss of tight junctions, cytokine release, and eventually apoptosis of GI epithelial cells. Inflammation, if present, I would think is from cytokine release not d/t necrosis or apoptosis itself.

 

[Phloston]

C. difficile releases a cytotoxin that ribosylates of Rho (a GTPase), this leads to actin rearrangement, loss of tight junctions, cytokine release, and eventually apoptosis of GI epithelial cells. Inflammation, if present, I would think is from cytokine release not d/t necrosis or apoptosis itself.

Cheers, mate. That's exactly what I needed.

I had actually encountered a practice question today btw that asked about actin in tight junctions binding specifically to claudins, not occludens or JAMs (maybe you already knew that).

 

[Genesea]

Necro thread (found this thread looking for clarification on the topic).
Had a UWorld question today that said: C diff. ToxinB induces actin depolymerization leading to mucosal cell death, necrosis of colonic mucosal surfaces, and pseudomembrane formation.

Is this contradictory to what is in this thread, or should it be interpreted as apoptosis of infected cells then necrosis of neighboring cells due CMI called in by cytokines?

Is apoptosis vs necrosis even something to be worrying about?

 

[coolforschool]

Necro thread (found this thread looking for clarification on the topic).
Had a UWorld question today that said: C diff. ToxinB induces actin depolymerization leading to mucosal cell death, necrosis of colonic mucosal surfaces, and pseudomembrane formation.

Is this contradictory to what is in this thread, or should it be interpreted as apoptosis of infected cells then necrosis of neighboring cells due CMI called in by cytokines?

Is apoptosis vs necrosis even something to be worrying about?

I agree with you (apoptosis first then necrosis of surrounding cells). It's shown up a few times for me, so I guess it's not nothing.