The des-Arg9-bradykinin/B1R axis: Hepatic damage in COVID-19

Abstract

Patients infected by the SARS-CoV-2 virus are commonly diagnosed with threatening liver conditions associated with drug-induced therapies and systemic viral action. RNA-Seq data from cells in bronchoalveolar lavage fluid from COVID-19 patients have pointed out dysregulation of kallikrein-kinin and renin-angiotensin systems as a possible mechanism that triggers multi-organ damage away from the leading site of virus infection. Therefore, we measured the plasma concentration of biologically active peptides from the kallikrein-kinin system, bradykinin and des-Arg⁹-bradykinin, and liver expression of its proinflammatory axis, bradykinin 1 receptor (B1R). We measured the plasma concentration of bradykinin and des-Arg⁹-bradykinin of 20 virologically confirmed COVID-19 patients using a liquid chromatography-tandem mass spectrometry-based methodology. The expression of B1R was evaluated by immunohistochemistry from post-mortem liver specimens of 27 COVID-19 individuals. We found a significantly higher blood level of des-Arg⁹-bradykinin and a lower bradykinin concentration in patients with COVID-19 compared to a healthy, uninfected control group. We also observed increased B1R expression levels in hepatic tissues of patients with COVID-19 under all hepatic injuries analyzed (liver congestion, portal vein dilation, steatosis, and ischemic necrosis). Our data indicate that des-Arg⁹-bradykinin/B1R is associated with the acute hepatic dysfunction induced by the SARS-CoV-2 virus infection in the pathogenesis of COVID-19.

Keywords: COVID-19; SARS-cov-2; bradykinin; bradykinin 1 receptor; contact system; hepatic damage; kinin-kallikrein system; renin-angiotensin system.

FIGURE 1

Bradykinin and des-Arg⁹-BK concentration in plasma of COVID-19 and control patients. (A) 1000 pg ml⁻¹ standard chromatogram for bradykinin (BK), expressed in the graph as relative peak abundance (%) by time. (B) 1000 pg ml⁻¹ standard chromatogram for des-Arg⁹-BK, expressed in the graph as relative peak abundance (%) by time. (C). Calibration curve for Bradykinin and (D). des-Arg⁹-BK showed a good linearity with R ² > 0.99, (E). Bradykinin concentration in human plasma was measured by LC-MS/MS from 15 COVID-19 patients (156.4 ± 129.8 pg ml⁻¹) and compared with 21 control patients (9,929 ± 8,368 pg ml⁻¹). Concentration of bradykinin was lower in the plasma of COVID-19 patients (****p < 0.0001). Y-axis is in logarithmic scale. (F). Des-Arg⁹-BK concentration in human plasma was measured by LC-MS/MS from 18 COVID-19 patients (786.3 ± 658.4 pg ml⁻¹) and compared with 18 control patients (246.0 ± 157.5 pg ml⁻¹). The concentration of des-Arg⁹-BK was higher in the plasma of COVID-19 patients (*p < 0.05). Y-axis is in logarithmic scale.

FIGURE 2

The pattern of liver damage in COVID-19 patients. The pattern of liver damage in hematoxylin and eosin staining images is representative of absent, mild, and moderate/severe. PV–Portal Vein; CV–Central Vein; C–Congestion; S–Steatosis N–Necrosis. Demarcated areas highlighted in some panels indicate congestion, steatosis and ischemic necrosis.

FIGURE 3

Bradykinin 1 receptor (B1R) is expressed in the lung and the liver of SARS-CoV-2 infected patients. (A). Representative images of immunohistochemistry (IHC) staining for B1R in the lung of 3 different COVID-19 patients, as positive control. B1R is observed in alveolar pneumocytes. (B). IHC staining for B1R in the liver of 25 COVID-19 patients (125.9 ± 11.0 a. u.) (on the left) and 5 SARS-CoV-2-uninfected control patients (101.6 ± 5.2 a. u.) (on the right). B1R is observed in hepatocytes. Graphs show quantification of staining intensity in arbitrary units (a.u.). B1R staining was higher in the liver of COVID-19 patients (****p < 0.0001). Scale bar = 50 µm.

FIGURE 4

B1R expression in hepatocytes in COVID-19 patients and its correlation with patterns of liver injuries. (A,B). B1R in the liver of control individuals (n = 5) and COVID-19 patients (n = 25); Comparison between B1R expression level in the liver of 5 control individuals (101.6 ± 5.2 a. u.) and liver of 14 COVID-19 patients with steatosis (123.2 ± 15.5 a. u), 21 with congestion (124.9 ± 11.5 a. u), 19 with PV dilation (123.5 ± 11.3 a. u), and 24 with ischemic necrosis (125.4 ± 11.0 a. u), (p < 0.01). Scale bar = 50 µm.