Patients with Sars Cov
- 2 infection, even after negative swab, may experience persistent symptoms
such as fatigue, weakness and pulmonary impairment, which can last for months
after recovery from the acute phase. In patients recovered from severe forms, a
slow recovery is to be expected. For example, in patients who have been
admitted to the intensive care unit (ICU) the symptoms of "post-ICU
syndrome" cannot be considered exclusive to COVID-19. However, even
non-hospitalized individuals with mild or moderate forms of the disease may
experience post-COVID-19 symptoms, sometimes with disabling characteristics and
inability to resume a normal life [5]. The pathophysiological mechanisms
underlying these manifestations are not clear yet. Persistent endothelial dysfunction,
which plays an important role in the acute phase, could also be at the basis of
post-COVID-19 syndrome or long COVID [11-13]. We know, in fact, that the
SARS-CoV-2 virus can directly damage vascular endothelial cells, causing
systemic endothelial dysfunction. Furthermore, inflammatory cytokines are able
to bind specific receptors on the surface of endothelial cells, promoting the
activation of platelets, the adhesion of circulating leukocytes and altering
the production of nitric oxide [14]. Residual activation of the immune system
after the acute phase could be related to persistent endothelial dysfunction
during convalescence [11]. Despite the prevalence of persistent symptoms in
patients recovered from SARS-COV-2 infection, there are still no specific
therapies approved for this condition. We have planned to treat a small group
of patients suffering from persistent post-COVID-19 symptoms with a natural
amino acid that plays an important role in the regulation of endothelial
function. L-arginine, in fact, is a semi-essential amino acid, substrate of
nitric oxide synthase (NOS), an enzyme responsible for the production of nitric
oxide, which regulates endothelial homeostasis and vascular tone [15,16]. Some
recent studies suggest that amino acid metabolism may play an important role in
the pathophysiology of COVID-19; a reduction in plasma levels of L-arginine
associated with increased arginase activity has been observed in patients with
severe COVID-19 [17-19]. Our data show that oral supplementation of L-Arginine
gave an improvement in fatigue and exercise tolerance in all treated patients,
in a short time and without any side effects. It is also a natural therapy
characterized by low cost, easy availability and the absence of
contraindications.
