Thread by @ZdenekVrozina

Tired months after COVID?
A study found that even 11 months later, many people still show impaired mitochondrial function in their immune cells - a possible driver of long COVID symptoms.
And yes, even after mild infections.🧵

Researchers measured mitochondrial membrane potential (ΔΨm) - a key indicator of cellular energy - in blood immune cells (PBMCs) from:
healthy controls
people with active COVID
recovered after 40 days (R1)
recovered after 11 months (R2)

The result?
ΔΨm was significantly reduced in all COVID groups - including R2, 11 months post-infection.
This suggests long-lasting mitochondrial stress, even after "mild" cases with no hospitalization.

So why does ΔΨm matter?
It’s the voltage across the mitochondrial membrane.
If it's lost:
energy (ATP) drops
oxidative stress rises
the cell may trigger apoptosis
In short - the cell is exhausted.

Long COVID symptoms were common in the R2 group:
85% had persistent issues like fatigue, insomnia, brain fog, shortness of breath, or muscle pain.
Their immune cells still showed reduced ΔΨm - even 11 months later.

But - there was a striking sex difference:
ΔΨm recovered in men, but remained low in women
100% of women in R2 had ≥5 long COVID symptoms
Only 58% of men had symptoms (usually just 1-2)

The study suggests that women may experience prolonged mitochondrial stress, possibly due to hormonal or immune factors.
Meanwhile, men’s immune cells showed a partial or full recovery of mitochondrial potential.

Why does this matter?
The authors link sustained ΔΨm loss to:
neurodegenerative risk (eg Alzheimer’s, Parkinson’s)
impaired recovery
chronic inflammation
Mitochondria are central to long-term health - especially in neurons and immune cells.

Sound familiar?
Loss of ΔΨm also happens in:
T cells with exhaustion phenotype
ROS-producing monocytes
HIV-induced immune dysfunction
SARS-CoV-2 may trigger a similar metabolic exhaustion of leukocytes.

And while ΔΨm recovery in men looks good - it's only part of the story.
This study didn’t measure ATP production, ROS levels, or mitochondrial biogenesis.
So even recovered cells may still carry hidden dysfunction.

Takeaway:
ΔΨm loss might be an early biomarker for long COVID risk, a marker of energetic and immunological exhaustion.
SARS-CoV-2 may induce long-term metabolic exhaustion of leukocytes, contributing to chronic inflammation and impaired healing.
Not even a year later.

This was an in vivo human study (n=105), using PBMCs analyzed ex vivo.
Conducted in Mexico before mid-2021 - likely pre-Delta variants (Wuhan/Alpha).
Peer-reviewed, published in Journal of Leukocyte Biology (2022).

Díaz-Resendiz at al., Loss of mitochondrial membrane potential (ΔΨm) in leucocytes as post-COVID-19 sequelae. academic.oup.com/jleukbio/artic…