Almazov National Medical Research Centre, 197341 St. Petersburg, Russia.
H. Turner National Medical Research Center for Children's Orthopedics and Trauma Surgery of the Ministry of Health of the Russian Federation, 196603 St. Petersburg, Russia.
Int J Mol Sci. 2023 Jan 6;24(2):1147. doi: 10.3390/ijms24021147.
In the beginning of COVID-19, the proportion of confirmed cases in the pediatric population was relatively small and there was an opinion that children often had a mild or asymptomatic course of infection. Our understanding of the immune response, diagnosis and treatment of COVID-19 is highly oriented towards the adult population. At the same time, despite the fact that COVID-19 in children usually occurs in a mild form, there is an incomplete understanding of the course as an acute infection and its subsequent manifestations such as Long-COVID-19 or Post-COVID-19, PASC in the pediatric population, correlations with comorbidities and immunological changes. In mild COVID-19 in childhood, some authors explain the absence of population decreasing T and B lymphocytes. Regardless of the patient's condition, they can have the second phase, related to the exacerbation of inflammation in the heart tissue even if the viral infection was completely eliminated-post infectious myocarditis. Mechanism of myocardial dysfunction development in MIS-C are not fully understood. It is known that various immunocompetent cells, including both resident inflammatory cells of peripheral tissues (for example macrophages, dendritic cells, resident memory T-lymphocytes and so on) and also circulating in the peripheral blood immune cells play an important role in the immunopathogenesis of myocarditis. It is expected that hyperproduction of interferons and the enhanced cytokine response of T cells 1 and 2 types contribute to dysfunction of the myocardium. However, the role of Th1 in the pathogenesis of myocarditis remains highly controversial. At the same time, the clinical manifestations and mechanisms of damage, including the heart, both against the background and after COVID-19, in children differ from adults. Further studies are needed to evaluate whether transient or persistent cardiac complications are associated with long-term adverse cardiac events.
在 COVID-19 初期，确诊病例在儿科人群中的比例相对较小，有一种观点认为儿童感染通常呈轻度或无症状。我们对 COVID-19 的免疫反应、诊断和治疗的理解高度偏向于成人人群。与此同时，尽管儿童中的 COVID-19 通常呈轻度形式发生，但对于急性感染的过程及其随后的表现（例如 Long-COVID-19 或 Post-COVID-19、儿科人群中的 PASC）、与合并症的相关性以及免疫学变化，我们的理解并不完整。在儿童轻度 COVID-19 中，一些作者解释了人群中 T 和 B 淋巴细胞减少的现象。无论患者的情况如何，他们都可能出现第二期，与心肌组织炎症加重有关，即使病毒感染已完全消除——感染后心肌炎。MIS-C 中心肌功能障碍发展的机制尚未完全阐明。已知各种免疫活性细胞，包括外周组织的常驻炎症细胞（例如巨噬细胞、树突状细胞、常驻记忆 T 淋巴细胞等）和循环在外周血中的免疫细胞，在心肌炎的免疫发病机制中发挥重要作用。据推测，干扰素的过度产生和 1 型和 2 型 T 细胞的细胞因子反应增强有助于心肌功能障碍。然而，Th1 在心肌炎发病机制中的作用仍存在很大争议。同时，包括心脏在内的损伤的临床表现和机制，无论是在 COVID-19 背景下还是之后，在儿童和成人之间都存在差异。需要进一步的研究来评估心脏的短暂或持续并发症是否与长期不良心脏事件有关。
