Introduction
The new coronavirus (SARS-COV-2) that causes COVID-19 disease was first
detected in Wuhan, China in December 2019 and rapidly spread to more
than 200 countries.1 Although COVID-19 is generally
characterized by respiratory system symptoms such as fever, sore throat,
shortness of breath, and cough, cases presenting with atypical symptoms
such as abdominal pain, headache, diarrhea, smell and taste disorders,
musculoskeletal pain and skin lesions have been widely reported
recently.2
Severe COVİD-19 disease is an uncontrolled response of the immune system
to infection, in which high levels of circulating cytokines lead to
generalized inflammatory response with failure of at least one organ
function and high mortality rates.3 Many COVID-19
related mortality biomarkers such as D-Dimer, C-reactive protein (CRP),
Ferritin, pentraxin-3 and proinflammatory cytokines elevation have been
demonstrated.4-10 However, the search for different
disease-specific biomarkers continues.
Midkine (MK) is a multifunctional cytokine, expressed primarily in
midgestation. It is a heparin-binding growth factor sensitive to
retinoic acid released from various cell types during embryogenesis.
Promotes angiogenesis, cell growth and cell migration. Midkine is also
expressed in various malignancies, suggesting that it may play a role in
tumorigenesis, perhaps through its effects on angiogenesis. Cytokines
and growth factors are classified into structurally related protein
families such as the fibroblast growth factor
family.11 In addition, MK organizes the proliferation,
differentiation, survival, adhesion, migration and gene expression of
immune cells. At the same time, MK is a mitogenic, antiapoptotic,
migrating, chemotactic, angiogenic and fibrinolytic molecule that plays
a role in controlling the inflammatory response.12 MK
can alleviate hypoperfusion and myocardial cell damage due to hypoxia,
as well as promote angiogenesis in myocardial
infarction.13 However, it may accelerate tubular
necrosis in drug or autoimmune kidney damage11 and
pulmonary fibrosis due to acute respiratory distress syndrome (ARDS)
.14 The interesting issue about MK is that it has been
shown in studies that it has bactericidal, antifungal and antiviral
effects in some viruses such as herpes simplex and human
immunodeficiency virus (HIV).15-17
COVID-19 is a new disease and many proinflammatory cytokines and other
acute phase proteins levels have been found to correlate with poor
prognosis in the literature. However, there are no specific biomarkers
in the prognosis and surveillance of COVID-19.18 The
aim of our study was to investigate MK levels in COVID-19 infection and
to explore whether there is a relationship between the prognosis of
patients and midkine levels.