RESUMEN
The pulmonary epithelial glycocalyx is rich in glycosaminoglycans such as hyaluronan and heparan sulfate. Despite their presence, the importance of these glycosaminoglycans in bacterial lung infections remains elusive. To address this, we intranasally inoculated mice with Streptococcus pneumoniae in the presence or absence of enzymes targeting pulmonary hyaluronan and heparan sulfate, followed by characterization of subsequent disease pathology, pulmonary inflammation, and lung barrier dysfunction. Enzymatic degradation of hyaluronan and heparan sulfate exacerbated pneumonia in mice, as evidenced by increased disease scores and alveolar neutrophil recruitment. However, targeting epithelial hyaluronan in combination with Streptococcus pneumoniae infection further exacerbated systemic disease, indicated by elevated splenic bacterial load and plasma levels of pro-inflammatory cytokines. In contrast, enzymatic cleavage of heparan sulfate resulted in increased bronchoalveolar bacterial burden, lung damage and pulmonary inflammation in mice infected with Streptococcus pneumoniae. Accordingly, heparinase-treated mice also exhibited disrupted lung barrier integrity as evidenced by higher alveolar edema scores and vascular protein leakage into the airways. This finding was corroborated in a human alveolus-on-a-chip platform, confirming that heparinase treatment also disrupts the human lung barrier during Streptococcus pneumoniae infection. Notably, enzymatic pre-treatment with either hyaluronidase or heparinase also rendered human epithelial cells more sensitive to pneumococcal-induced barrier disruption, as determined by transepithelial electrical resistance measurements, consistent with our findings in murine pneumonia. Taken together, these findings demonstrate the importance of intact hyaluronan and heparan sulfate in limiting pneumococci-induced damage, pulmonary inflammation, and epithelial barrier function and integrity.
RESUMEN
BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is driven by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which has led to an enormous burden on patient morbidity and mortality. The renin-angiotensin-aldosterone system (RAAS) plays a significant role in various pulmonary diseases. Since SARS-CoV-2 utilizes the angiotensin-converting enzyme (ACE)2 receptor to exert its virulence and pathogenicity, the RAAS is of particular importance in COVID 19. METHODS: Our preliminary study investigates retrospectively the influence of selected ACE-polymorphisms (I/D location at intron 16 in the B-coding sequence (rs4646994) and A-240T (rs 4291) at the A-promoter) as well as ACE1 and ACE2 serum levels on disease severity and the inflammatory response in inpatients and outpatients with COVID-19. RESULTS: Our study included 96 outpatients and 88 inpatients (65.9% male, mean age 60 years) with COVID-19 from April to December 2020 in four locations in Germany. Of the hospitalized patients, 88.6% participants were moderately ill (n = 78, 64% male, median age 60 years), and 11.4% participants were severely ill or deceased (n = 10, 90% male, median age 71 years). We found no polymorphism-related difference in disease, in age distribution, time to hospitalization and time of hospitalization for the inpatient group. ACE1 serum levels were significantly increased in the DD compared to the II polymorphism and in the TT compared to the AA polymorphism. There was no significant difference in ACE 1 serum levels l between moderately ill and severely ill patients. However, participants requiring oxygen supplementation had significantly elevated ACE1 levels compared to participants not requiring oxygen, with no difference in ACE2 levels whereas females had significantly higher ACE2 levels. CONCLUSIONS: Although there were no differences in the distribution of ACE polymorphisms in disease severity, we found increased proinflammatory regulation of the RAAS in patients with oxygen demand and increased serum ACE2 levels in women, indicating a possible enhanced anti-inflammatory immune response. CLINICAL TRIAL REGISTRATION: PreBiSeCov: German Clinical Trials Register, DRKS-ID: DRKS00021591, Registered on 27th April 2020.