

This one has lots of clues for our understanding of #COVID19 and heavily implicates mononuclear phagocytes as central to severe pathology.
A thread....
https://www.biorxiv.org/content/10.1101/2020.04.08.029769v1
They sampled #PBMC from severe and recovery stage #COVID19 and integrated data with reference healthy #PBMC
Fairly standard cell type annotation.
Recovery stage samples are after Tocilizumab - anti-IL6R monoclonal Ab
Fairly standard cell type annotation.


Fairly standard cell type annotation.
This bit is easy for PBMC nowadays and can be semi automated...
Cluster 13 are clearly T-mono doublets. Maybe these are physiological? Evidence of physical interaction/crosstalk?
This bit is easy for PBMC nowadays and can be semi automated...












https://www.medrxiv.org/content/10.1101/2020.02.23.20026690v1.full.pdf inflammatory monocyte/macrophage population in bronchoalveolar lavage fluid

Back to the tocilizumab study...
They also see prominent plasma cells which recede during recovery, and are rare in health.
There are some proliferating and effector CD8 T cells expressing PRDM1.


Authors looked at putative interactions using CellPhoneDB -
tool developed by @teichlab @mirjana_e @roserventotormo 
Severe stage enriched for mono->lymphocyte signalling
Some IL6-IL6R signalling
after tocilizumab
severe stage monos signal -> plasma cells ++






Overall model is that in severe #COVID19, monocytes are v activated and signal to lymphocytes incl plasma cells to orchestrate the phenotype...
Tentative implications:
Need to break myeloid/innate activation - that seems proximal.
IL6 blockade seems well motivated given these data
Inflammasome blockade also worth trying


