Journal of Current Biomedical Reports jcbior.com Volume 1, Number 1, 2020 1 Editorial Letter A light shining through darkness: probiotic against COVID-19 Meysam Hasannejad-Bibalan1,∗, Hamed Hekmatnezhad2 1Department of Microbiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran 2Department of Basic Sciences, Sari Agricultural Sciences and Natural Resources University, Sari, Iran Keywords: Probiotic, Lactic acid bacteria, COVID-19, SARS-CoV-2 The colonic microbiota play a key role in human gastrointestinal tract physiology include maintaining homeostasis of the large bowel and modulating the host immune response. Lactic acid bacteria (LAB) especially Lactobacillus and Bifidobacterium are the main part of gut microbiota, which are considered as health beneficial probiotic bacteria with valuable effects in humans [1, 2]. Probiotic bacteria are currently used in industrial food production and therapeutically procedures [3]. The lactic acid produced by probiotic bacteria in the fermentation process causes decrease pH to inhibit the growth of putrefactive and pathogenic bacteria. Besides, LAB could have improvement effects on the nutritional value of fermented products through increase the production of the main food components such as vitamins, essential minerals, and amino acids [4]. Probiotics have been shown to be effective in preventing and treating different disorders such as atopic dermatitis, urinary tract- ∗Corresponding author: Dr. Meysam Hasannejad-Bibalan, Ph.D Department of Microbiology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran Tel/Fax: +981333690006 Email: meysam_hasannejad@yahoo.com, hasannejad@gums.ac.ir https://orcid.org/ 0000-0002-9402-098X Received: May 27, 2020 Accepted: May 28, 2020 infections, colorectal cancer, and rheumatoid arthritis [5]. Competition with disease-causing microbes, producing antimicrobial peptides (AMPs), modulate the microenvironment and regulate the host immune system makes probiotics a very interesting field for infectious disease research [6]. Since December 2019, coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affected many people globally, and finding new treatment strategies is crucial [7]. To date, there is not strong practical evidence that showed the use of probiotics has promising effects in patients with COVID-19. However, previous studies suggested that the use of probiotics may reduce or prevent some of the major complications of COVID-19. The most significant cases are reducing antibiotic associated-diarrhea and ventilator-associated pneumonia, and prevention of acute respiratory distress syndrome (ARDS) and upper respiratory tract infections (RTIs) [8, 9]. Regarding the prevention of RTIs, probiotics maybe not directly affect SARS-CoV-2 but can be efficient for reducing the risk of co-infections [9]. Previous indirect evidence gives us hope that probiotics research might eventually deliver therapeutic options for fighting against COVID- 19, but until reaching that goal further in vitro and in vivo researches will be highly needed. Author Contributions All authors contributed equally to this manuscript, and approved the final version of https://jcbior.com/ 2 manuscripts. Conflict of Interests The authors declare that they have no conflicts of interest. Ethical declarations Not applicable. Financial Support None to be declared. References 1. Hasannejad Bibalan M, Eshaghi M, Rohani M, Esghaei M, Darban-Sarokhalil D, Pourshafie MR, et al. Isolates of Lactobacillus plantarum and L. reuteri display greater antiproliferative and antipathogenic activity than other Lactobacillus isolates. J Med Microbiol. 2017; 66(10):1416-20. 2. Hasannejad Bibalan M, Eshaghi M, Rohani M, Pourshafie MR, Talebi M. Determination of Bacteriocin Genes and Antibacterial Activity of Lactobacillus Strains Isolated from Fecal of Healthy Individuals. Int J Mol Cell Med. 2017; 6(1):50- 5. 3. El Hage R, Hernandez-Sanabria E, Van de Wiele T. Emerging Trends in "Smart Probiotics": Functional Consideration for the Development of Novel Health and Industrial Applications. Front Microbiol. 2017; 8:1889. 4. Eshaghi M, Bibalan MH, Rohani M, Esghaei M, Douraghi M, Talebi M, et al. Bifidobacterium obtained from mother's milk and their infant stool; A comparative genotyping and antibacterial analysis. Microb Pathog. 2017; 111:94-8. 5. Bustamante M, Oomah BD, Oliveira WP, Burgos-Díaz C, Rubilar M, Shene C. Probiotics and prebiotics potential for the care of skin, female urogenital tract, and respiratory tract. Folia Microbiol (Praha). 2020; 65(2):245-64. 6. Vieco-Saiz N, Belguesmia Y, Raspoet R, Auclair E, Gancel F, Kempf I, et al. Benefits and Inputs From Lactic Acid Bacteria and Their Bacteriocins as Alternatives to Antibiotic Growth Promoters During Food-Animal Production. Front Microbiol. 2019; 10:57. 7. Li H, Liu SM, Yu XH, Tang SL, Tang CK. Coronavirus disease 2019 (COVID-19): current status and future perspectives. Int J Antimicrob Agents. 2020; 55(5):105951. 8. Mak JWY, Chan FKL, Ng SC. Probiotics and COVID-19: one size does not fit all. Lancet Gastroenterol Hepatol. 2020; S2468-1253(20):30122-9. 9. Baud D, Dimopoulou Agri V, Gibson GR, Reid G, Giannoni E. Using Probiotics to Flatten the Curve of Coronavirus Disease COVID-2019 Pandemic. 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