TABLE 2.

Summary of circulating miRNAs associated with neurological dysfunction showing potential dysregulation in COVID-19.

miRNA	Source	Target genes	Status in neurodegenerative diseases	Patients’ information	Status in COVID-19	References
miR-146a	Serum	IRAK1, TRAF6	IS-decreased AD-decreased PD-decreased	1.Different grades of COVID-19 patients (n = 103) 2. 13 COVID-19 patients, characterized by multifocal interstitial pneumonia confirmed by CT-scan and requiring oxygen therapy.	Significantly decreased	Fan et al., 2020; Nakano et al., 2020a,b; Keikha and Jebali, 2021; Keikha et al., 2021; Sabbatinelli et al., 2021
miR-155	Serum	SOCS1, SHIP1, STAT5, IL13Ra1, claudin-1, annexin-2, syntenin-1, DOCK-1	IS-increased AD-increased PD-increased ALS-increased MS-increased	1. 18 patients after diagnosis of Covid-19 and in the recovery period. 2. 20 patients with COVID-19 infection in the acute period and in the recovery period. 3. 150 COVID-19 patients classified into two main groups: moderate patients and severe patients.	Significantly increased	Lopez-Ramirez et al., 2014; Song and Lee, 2015; Donyavi et al., 2021; Zingale et al., 2021; Abbasi-Kolli et al., 2022; Haroun et al., 2022
Let-7b	PBMC	TLR7, HMGA2	AD-increased PD-increased MIC-increased	1. 18 patients after diagnosis of COVID-19 and in the recovery period. 2. 31 COVID-19 positive obese female participants.	Significantly increased	Coleman et al., 2017; Donyavi et al., 2021; Huang et al., 2021b; Qin et al., 2021; Bellae Papannarao et al., 2022
miR-31	Serum	RhoA, APP, BACE1, PARK2, GIGYF2	AD-decreased PD-decreased MSA-decreased	1.Different grades of COVID-19 patients (n = 103) 2. 122 COVID-19 patients with different severity of illness. 3. 10 COVID-19 patients 2–15 days (average 8 days) post symptomatic disease onset.	Significantly decreased	Pearn et al., 2018; Barros-Viegas et al., 2020; Li et al., 2020; Tang et al., 2020; Yan et al., 2020; Bautista-Becerril et al., 2021; Farr et al., 2021; Keikha and Jebali, 2021; Keikha et al., 2021
miR-16	Plasma	APP, BACE1, Tau	AD-decreased	1. 84 COVID-19 patients divided according to the severity of the disease. 2. 94 COVID-19 patients	Significantly decreased	Liu et al., 2012; Parsi et al., 2015; De Gonzalo-Calvo et al., 2021; Li et al., 2022b
miR-21	Plasma/serum	NF-κB, PTEN/AKT,PI3K, GSK-3β, mTOR1, STAT3	AD-decreased PD-decreased IS-decreased	1. 10 COVID-19 patients 2. 13 COVID-19 patients, characterized by multifocal interstitial pneumonia confirmed by CT-scan and requiring oxygen therapy 3. 122 COVID-19 patients with different severity of illness. 4. 6 severe and 6 moderate COVID-19 patients	Significantly decreased	Ma et al., 2011; Feng et al., 2018; Gao et al., 2020; Bai and Bian, 2022; Blount et al., 2022

Ischemia stroke (IS), Alzheimer’s disease (AD), Parkinson’s disease (PD), Amyotrophic lateral sclerosis (ALS), Multiple sclerosis (MS), Multiple system atrophy (MSA), mild cognitive impairment (MIC), Peripheral blood mononuclear cell (PBMC), interleukin-1 receptor-associated kinase 1 (IRAK1), receptor-associated factor 6 (TRAF6), Suppressor of Cytokine Signaling 1 (SOCS1), SH2 Domain-Containing Inositol 5’-Phosphatase1 (SHIP1), Signal Transducers and Activators of Transcription 5 (STAT5) and IL-13 Receptor Alpha 1 (IL13Ra1), Dedicator of cytokinesis 1 (DOCK-1), toll-like receptor 7 (TLR7), High-mobility group AT-hook 2 (HMGA2), amyloid precursor protein (APP), β-secretase (BACE1), parkin E3 ubiquitin-protein ligase (PARK2), interacting GYF protein 2 (GIGYF2), Ras Homolog Family Member A (RhoA), tubulin associated unit protein (TAU protein), Nuclear factor kappaβ (NF-κβ), Phosphatase and tensin homolog (PTEN), Phosphoinositide 3-kinase (PI3K), Mammalian target of rapamycin complex 1 (mTOR1), Glycogen Synthase Kinase 3 Beta (GSK-3β), toll-like receptor 4 (TLR4).