Microscopic image of blood cells marked with illuminants in a comparison of healthy people and Long Covid patients. The latter are glowing green over a large area, the former are small green dots.

First indications of inflammatory micro-clots in the blood of people with Long COVID

New rese­arch shows that over­loading various inflamma­to­ry mole­cu­les liter­al­ly “trap­ped” in inso­lub­le micro­scopic blood clots (micro-clots) could be the cau­se of some of the per­sis­tent sym­ptoms indi­vi­du­als with Long COVID experience.

This unex­pec­ted fin­ding was made by Prof. Resia Pre­to­ri­us, a rese­ar­cher at the Insti­tu­te of Phy­sio­lo­gi­cal Sci­en­ces at Stel­len­bosch Uni­ver­si­ty (SU), when she star­ted stu­dy­ing micro­clots and their mole­cu­lar con­tent in blood sam­ples from peop­le with Long COVID. The results have sin­ce been peer-review­ed and publis­hed in the jour­nal Car­dio­vascu­lar Dia­be­to­lo­gy in August 2021.

“We found high levels of various inflamma­to­ry mole­cu­les trap­ped in micro-clots that are pre­sent in the blood of peop­le with Long COVID. Some of the trap­ped mole­cu­les con­tain coagu­la­ti­on pro­te­ins such as fibri­no­gen and alpha (2) anti­plas­min, ”exp­lains Prof. Pretorius.

Alpha (2) anti­plas­min is a mole­cu­le that pre­vents blood clots from brea­king down, while fibri­no­gen is the main clot­ting pro­te­in. Under nor­mal con­di­ti­ons, the body’s plas­min-anti­plas­min sys­tem main­tains a fine balan­ce bet­ween clot­ting (the pro­cess by which blood thi­c­kens and coagu­la­tes to pre­vent blood loss after an inju­ry) and fibri­no­ly­sis (the pro­cess of brea­king down fibrin in the coagu­la­ted Blood to pre­vent blood clots from forming).

With high levels of alpha (2) anti­plas­min in the blood of COVID-19 pati­ents and tho­se suf­fe­ring from Long COVID, the body’s abi­li­ty to break down the clots is signi­fi­cant­ly inhibited.

The inso­lu­b­i­li­ty of the micro-clots beca­me appa­rent when Dr. Maré Vlok, a seni­or ana­lyst in the mass spec­tro­me­try unit of the SU cen­tral ana­ly­ti­cal faci­li­ties, noted that after dilu­ti­on, blood plas­ma sam­ples from tho­se with Acu­te COVID and Long COVID con­ti­nued to depo­sit inso­lub­le pel­lets at the bot­tom of the tubes

He aler­ted Prof. Pre­to­ri­us to this obser­va­ti­on and inves­ti­ga­ted it fur­ther. They are now the first rese­arch group to report on fin­ding micro­clots in the blood sam­ples of peop­le with Long COVID by using fluo­re­scence micro­scopy and pro­teo­mic ana­ly­sis, sol­ving ano­t­her mys­te­ry rela­ted to the disease.

Of par­ti­cu­lar inte­rest is the simul­ta­ne­ous pre­sence of per­sis­tent abnor­mal micro-clots and a patho­lo­gi­cal fibri­n­o­ly­tic sys­tem, ”they wri­te in the rese­arch paper. This means that the plas­min and anti­plas­min balan­ce may be cen­tral to patho­lo­gies in Long COVID, and pro­vi­des fur­ther evi­dence that COVID-19 and now Long COVID have signi­fi­cant car­dio­vascu­lar and coagu­la­ti­on pathologies.

Fur­ther rese­arch into a the­ra­py regi­men to sup­port coagu­la­ti­on and fibri­n­o­ly­tic sys­tem func­tion in indi­vi­du­als with per­sis­tent long-term COVID sym­ptoms is recommended.

In coope­ra­ti­on with the vascu­lar inter­nist Dr. Jaco Laubs­cher from Medi­cli­nic Stel­len­bosch (co-aut­hor of the arti­cle) they are now plan­ning to car­ry out the same ana­ly­sis on a lar­ger pati­ent sam­ple. To date, they have collec­ted blood from a hund­red Long COVID peop­le who par­ti­ci­pa­ted in the Long COVID Regis­ter, which was laun­ched in May 2021, as well as from 30 healt­hy peop­le. The rese­arch is fun­ded by the Long COVID Rese­arch Cha­ri­ta­ble Trust, a trust estab­lis­hed with an initi­al dona­ti­on from Mr Koos Pre­to­ri­us of ENSa­fri­ca. It is inten­ded that this trust will be used as a vehi­cle to rai­se fur­ther funds for rese­arch into the cau­ses and effec­ti­ve tre­at­ment of peop­le with Long COVID.

The arti­cle “Per­sis­tent coagu­la­ti­on pro­te­in patho­lo­gy in long COVID / post-acu­te seque­lae of COVID-19 (PASC) is accom­pa­nied by incre­a­sed anti­plas­min levels” was publis­hed in August 2021 in car­dio­vascu­lar dia­be­to­lo­gy and is online at https://pubmed.ncbi.nlm.nih.gov /34425843/ available.

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