Figure 2. Simplified schema summarizing possible role of immunobiotics in immunogical interactions and pathways between gut mucosa and lung epithelium. APC, presenting cells; DC, dendritic cell; TLRs, toll-like receptors; ACE2, angiotensin-converting enzyme 2; SCFAs, short chain fatty acids. (+) Immunobiotics influence positively lung improving immune response (humoral and cell-mediated responses) and controlling inflammatory reactions that generate massive production of proinflammatory cytokines. Mechanisms by which alive virus or viral particles interact with gut cells and immune system are not yet understood.