Quercetin is a naturally occurring polyphenol flavonoid which is rich in antioxidants. It has anti-allergic functions that are known for inhibiting histamine production and pro-inflammatory mediators. Quercetin can regulate the Th1/ Th2 stability, and decrease the antigen-specific IgE antibody releasing by B cells. Quercetin has a main role in antiinflammatory and immunomodulatory function which makes it proper for the management of different diseases. Allergic diseases are a big concern and have high health care costs. In addition, the use of current therapies such as ß2-agonists and corticosteroids has been limited for long term use due to their numerous side effects. Since the effect of quercetin on allergic diseases has been widely studied, in the current article, we review the effect of quercetin on allergic diseases, such as allergic asthma, allergic rhinitis (AR), and atopic dermatitis (AD).

Human papillomavirus (HPV) is the most common sexually transmitted agent worldwide. Early prevention with HPV vaccination is a safe and effective method against this disease. HPV vaccines provided more protection against several oncogenic HPV strains. Three prophylactic HPV vaccines have been approved to target high-risk HPV types and protect against HPV-related disorders. These existing vaccines are based on the recombinant DNA technology and purified L1 protein that is assembled to form HPV empty shells. The prophylactic vaccines are highly immunogenic and can induce production of specific neutralizing antibodies. However, therapeutic vaccines are different from these prophylactic vaccines. They induced cell-mediated immunity against transformed cells, instead of neutralizing antibodies. The second generation of prophylactic HPV vaccines, made from alternative viral components using cost-effective production strategies, is undergoing clinical evaluation. The purpose of this review is to provide a complete and up-to-date review of the types of HPV vaccines and the efficiency of each of them for readers.

Since in cell therapy, there are always concerns about immune rejection, genetic disability, and malignancies, special attention has been paid to extracellular vesicles (EVs) which are secreted by mesenchymal stem cells (MSCs). In the present study, we assessed and compared the therapeutic effects of human adipose‐derived mesenchymal stem cells (hADSC) and hADSC‐EVs from adipose tissue on experimental autoimmune encephalomyelitis (EAE). After induction of EAE in C57Bl/6 mice, they were treated with hADSCs, hADSC‐EVs, or vehicle intravenously. The clinical score of all mice was recorded every other day. Mice were killed at Day 30 and splenocytes were isolated for proliferation assay and determination of the frequency of Treg cells by flow cytometry. Leukocyte infiltration by hematoxylin and eosin, percentages of demyelination areas by luxol fast blue, and mean fluorescence intensity of oligodendrocyte transcription factor 2 (OLIG2) and myelin basic protein (MBP) by immunohistochemistry were assessed in the spinal cord. Our results showed that the maximum mean clinical score and myelin oligodendrocyte glycoprotein‐induced proliferation of splenocytes in hADSC‐ and hADSC‐EV‐treated mice were significantly lower than the control mice (p < .05). We also demonstrated that the frequency of CD4+CD25+Foxp3+ cells was significantly higher in the spleen of hADSC‐treated mice than EAE control mice (p = .023). The inflammation score and the percentages of demyelination areas in hADSC‐ and hADSC‐EV‐treated groups significantly declined compared with the untreated control group (p < .05). We also showed that there was no significant difference in MFI of MBP and OLIG2 in the spinal cord of studied groups. Overall, we suggest that intravenous administration of hADSC‐EVs attenuates the induced EAE through diminishing proliferative potency of T cells, mean clinical score, leukocyte infiltration, and demyelination in a chronic model of multiple sclerosis.

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Coronavirus disease 2019 (COVID-19), an acute respiratory infection, is largely associated with dysregulation and impairment of the immune system. This study investigated how the immune system changes were related to disease severity in COVID-19 patients. The frequencies of different immune cells and levels of pro- and anti-inflammatory cytokines in whole blood of participants were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. The values of other inflammatory agents were also studied. In the late recovery stage, unlike CD56high CD16+/− NK cells and monocytes, CD56low CD16+ NK cell numbers were increased ( P < 0.0001–0.05). Th1, Th2, and Th17 cell percentages were significantly lower in patients than healthy control ( P < 0.0001–0.05), while their frequencies were increased following disease recovery ( P < 0.0001–0.05). The numbers of Tregs, activated CD4+ T cells, and exhausted CD8+ T cells were significantly decreased during a recovery ( P < 0.0001–0.05). No significant change was observed in exhausted CD4+ T cell number during a recovery ( P > 0.05). B cell showed an increased percentage in patients compared to healthy subjects ( P < 0.0001–0.05), whereas its number was reduced following recovery ( P < 0.0001–0.05). IL-1α, IL-1β, IL-6, TNF-α, and IL-10 levels were significantly decreased in the late recovery stage ( P < 0.0001–0.05). However, TGF-β1 level was not significantly changed during the recovery ( P > 0.05). Lymphocyte numbers in patients were significantly decreased ( P < 0.001), unlike ESR value ( P < 0.001). Lymphocyte number was negatively correlated to ESR value and Th2 number ( P < 0.05), while its association with monocyte was significantly positive at the first day of recovery ( P < 0.05). The immune system changes during the disease recovery to improve and regulate immune responses and thereby may associate with the reduction in disease severity.