Researchers examine COVID fog and chemokine C–C motif ligand 11

In a latest examine printed in Cell, researchers assessed the traits of mind fog reported by some coronavirus illness 2019 (COVID-19) sufferers.

Study: COVID fog demystified. Image Credit: eamesBot/Shutterstock
Examine: COVID fog demystified. Picture Credit score: eamesBot/Shutterstock


In a majority of extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, affected person signs resolved inside two weeks of onset. Nonetheless, a big proportion of sufferers have reported the persistence of COVID-19 symptoms for a number of months. This syndrome is named long-COVID and has been reported to comprise substantial cognitive dysfunction.

Concerning the examine

Within the current examine, researchers reviewed the profile of COVID fog reported by COVID-19 sufferers.

The examine used a mice mannequin to precise human angiotensin-converting enzyme-2 (ACE-2), which is the receptor required for a profitable viral entry and subsequent COVID-19 an infection. Since ACE-2 expression was restricted to the lungs and trachea, the mice developed gentle SARS-CoV-2 which was restricted solely to the respiratory system and cleared inside per week of SARS-CoV-2 an infection.

The workforce famous exceptional similarities between COVID fog and a cognitive syndrome known as chemobrain. Chemobrain or most cancers therapy-related cognitive impairment (CRCI) is a neuroinflammatory situation skilled by sufferers after chemotherapy or radiation. In CRCI, a rise in reactive microglia and neurotoxic cytokines leads to antagonistic results on the plasticity of the white and grey matter that are important for wholesome cognition.

Following this framework, the examine evaluated the adjustments occurring within the microglial reactivity and cytokine ranges after SARS-CoV-2 an infection.


The examine outcomes confirmed that microglial reactivity was elevated within the hippocampal and the subcortical white matter in mice after a gentle COVID-19 an infection. This elevation was discovered to be persistent and detectable even seven weeks after SARS-CoV-2 an infection. The workforce additionally noticed elevated ranges of cytokines within the cerebrospinal fluid and serum of the examined mice. Variation was noticed within the focus of a number of cytokines, nonetheless, chemokine C–C motif ligand 11 (CCL11) ranges had been persistently elevated within the cerebrospinal fluid of the mice seven weeks after an infection. Curiously, elevated CCL11 ranges have been causally related to cognitive impairments famous in regular growing older.

Equally, reactive microglia had been elevated within the subcortical white matter in symptomatic COVID-19 sufferers. CCL11 ranges had been additionally discovered to be elevated within the plasma samples of sufferers identified with lengthy COVID. Notably, all of the sufferers with elevated CCL11 plasma ranges had cognitive signs whereas CCL11 ranges weren’t altered amongst lengthy COVID sufferers with no cognitive signs. This prompt that CCL11 performed an instrumental function within the pathology of COVID fog.

The workforce additionally noticed that the variety of novel neurons declined in SARS-CoV-2-infected mice. Furthermore, this discount of neurons was related to the variety of reactive microglia discovered within the hippocampus of those mice. Notably, the systematic administration of CCL11 in uninfected mice additionally replicated the same sample. Moreover, the elevated proportion of reactive microglia and the lowered variety of new neurons within the examined mice indicated a causal affiliation between CCL11 and COVID fog.

Much like CRCI, COVID fog resulted within the discount of oligodendrocytes and the associated precursor cells in addition to a lower in axon myelination within the white matter, a number of weeks after an infection. These alterations may probably have an effect on cognitive perform after COVID-19.


General, the examine findings confirmed that CCL11 was causally associated to COVID fog. The researchers consider that cytokine profiling may function an environment friendly remedy technique towards cognitive syndrome after COVID-19. Furthermore, inhibiting the induction of cytokines may additionally show helpful within the remedy of COVID fog.

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