Id |
Subject |
Object |
Predicate |
Lexical cue |
T8 |
0-2 |
Sentence |
denotes |
1. |
T9 |
3-15 |
Sentence |
denotes |
Introduction |
T10 |
16-312 |
Sentence |
denotes |
About 20% of patients infected with SARS-Cov-2 develop respiratory complications, including pneumonia, that may evolve to severe hypoxemia, acute respiratory distress syndrome (ARDS), pulmonary edema, shock, metabolic acidosis, coagulation dysfunction and multiple organ functional failure [1,2]. |
T11 |
313-497 |
Sentence |
denotes |
Covid-19 patients with severe symptoms exhibit an immune response characterized by elevated serum levels of diverse proinflammatory molecules, including interleukin-6 (IL-6) [3,4,5,6]. |
T12 |
498-832 |
Sentence |
denotes |
Presently, these patients are treated with anti-inflammatory drugs like dexamethasone [7] or cytokine inhibitors, combined with antibiotics to treat secondary infections, sometimes combined with remdesivir, an antiviral originally developed to treat hepatitis C and tested against the Ebola virus disease to reduce the viral load [8]. |
T13 |
833-1066 |
Sentence |
denotes |
Treatment of Covid-19 urges a deeper understanding of the underlying molecular mechanisms involved in disease progression to provide a prompt therapeutical response with an adequate use of available drugs, including drug repurposing. |
T14 |
1067-1188 |
Sentence |
denotes |
Indeed, there is a number of ongoing clinical trials to test the efficacy of diverse FDA-approved drugs against Covid-19. |
T15 |
1189-1335 |
Sentence |
denotes |
Among them, a few involve assessment of the therapeutic efficacy of IL-6 inhibition, unfortunately without reporting conclusive results [9,10,11]. |
T16 |
1336-1505 |
Sentence |
denotes |
Recently, it was proposed that dysregulated bradykinin (BK) signaling could be the trigger of the cytokine storm observed in patients with severe Covid-19 [12,13,14,15]. |
T17 |
1506-1741 |
Sentence |
denotes |
The rational for this hypothesis relies on the increased availability of BK and its metabolite des-Arg9-BK in Covid-19 patients, due to the downregulation of angiotensin converting enzyme 2 (ACE2), the entry protein of SARS-Cov-2 [16]. |
T18 |
1742-1923 |
Sentence |
denotes |
Indeed, ACE2 downregulation increases the amount of angiotensin I processed by the angiotensin-converting enzyme (ACE) with a concomitant decrease of its degradation activity on BK. |
T19 |
1924-2060 |
Sentence |
denotes |
Moreover, levels of des-Arg9-BK are also increased due to the diminished degradative activity of ACE2 caused by its downregulation [12]. |
T20 |
2061-2161 |
Sentence |
denotes |
The BK hypothesis is consistent with the observed elevated levels of IL-6 in Covid-19 patients [17]. |
T21 |
2162-2299 |
Sentence |
denotes |
This new perspective suggests that inhibition of BK signaling may be a suitable therapy to avoid the cytokine storm and its consequences. |
T22 |
2300-2512 |
Sentence |
denotes |
Indeed, as a proof of principle, preliminary results from a limited study suggests that inhibition of the BK signaling is associated with a decrease of the oxygen supplementation needed by Covid-19 patients [18]. |
T23 |
2513-2718 |
Sentence |
denotes |
Nowadays, icatibant is the only BK antagonist approved as therapeutic agent for the treatment of hereditary angioedema [19], in spite of the number of selective BK ligands described in the literature [20]. |
T24 |
2719-2891 |
Sentence |
denotes |
The discovery of the bradykinin hypothesis prompted the launch of an ongoing clinical trial to assess the benefits of icatibant for the treatment of covid-19 patients [21]. |
T25 |
2892-3082 |
Sentence |
denotes |
In other to swiftly test the efficacy of alternative BK antagonists with diverse pharmacological profiles for the treatment of Covid-19, drug repurposing represents a valuable strategy [22]. |
T26 |
3083-3253 |
Sentence |
denotes |
To this aim, we recently carried out a virtual screening study on the DrugBank database [23] aimed at identifying BK ligands among drugs already approved by the FDA [24]. |
T27 |
3254-3444 |
Sentence |
denotes |
The study was carried out using four points common to the pharmacophores derived for the B1 and B2 bradykinin receptors recently reported that were used as queries for the search [25,26,27]. |
T28 |
3445-3569 |
Sentence |
denotes |
Hits identified were subsequently subjected to a docking study using the Molecular Operating Environment (MOE) program [28]. |
T29 |
3570-3721 |
Sentence |
denotes |
The virtual screening process permitted the identification of a small set of drugs as prospective nonselective BK ligands, as described elsewhere [24]. |
T30 |
3722-3890 |
Sentence |
denotes |
Specifically, the DrugBank database, containing a total of 1703 molecules, was screened for compounds that fulfilled a common pharmacophore for the B1 and B2 receptors. |
T31 |
3891-4028 |
Sentence |
denotes |
The study identified eight drugs including raloxifene, sildenafil, cefepime, cefpirome, imatinib, ponatinib, abemaciclib and entrectinib. |
T32 |
4029-4211 |
Sentence |
denotes |
Subsequently, the eight compounds were purchased and tested for their capacity to displace a reference ligand in any of the two bradykinin receptors B1 and B2, respectively at 20 µM. |
T33 |
4212-4390 |
Sentence |
denotes |
Three of the compounds including raloxifene, sildenafil and cefepime displaced the reference ligand from B2, which represents a 40% success rate as found in similar studies [29]. |
T34 |
4391-4483 |
Sentence |
denotes |
However, none of the compounds exhibited affinity for the B1 receptor at this concentration. |
T35 |
4484-4589 |
Sentence |
denotes |
This might be due to the steric hindrance that was not properly included in the virtual screening search. |
T36 |
4590-4726 |
Sentence |
denotes |
Raloxifene, the most potent antagonist identified was further investigated in a functional study in vitro, exhibiting an IC50 of ~16 µM. |
T37 |
4727-4820 |
Sentence |
denotes |
Moreover, the compound showed a weak partial agonist profile with a maximal activity of ~20%. |
T38 |
4821-4986 |
Sentence |
denotes |
Ralixofene is a selective estrogen receptor modulator, exerting estrogen agonist action in some target tissues while acting as an estrogen antagonist in others [30]. |
T39 |
4987-5126 |
Sentence |
denotes |
The compound was approved a few years ago for the treatment of osteoporosis in postmenopausal women, as well as for cancer chemoprotection. |
T40 |
5127-5313 |
Sentence |
denotes |
The discovery of a new pharmacodynamic profile of relixofene as a BK partial agonist opens an opportunity for its repurposing as a therapeutic agent for the treatment of severe Covid-19. |