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LitCovid-PD-FMA-UBERON

LitCovid-PD-UBERON

LitCovid-PubTator

LitCovid-PD-MONDO

{"project":"LitCovid-PD-MONDO","denotations":[{"id":"T311","span":{"begin":592,"end":596},"obj":"Disease"},{"id":"T312","span":{"begin":3710,"end":3718},"obj":"Disease"},{"id":"T313","span":{"begin":3742,"end":3746},"obj":"Disease"},{"id":"T314","span":{"begin":5030,"end":5056},"obj":"Disease"},{"id":"T315","span":{"begin":5875,"end":5881},"obj":"Disease"},{"id":"T316","span":{"begin":6426,"end":6438},"obj":"Disease"},{"id":"T317","span":{"begin":6908,"end":6929},"obj":"Disease"},{"id":"T318","span":{"begin":7356,"end":7377},"obj":"Disease"},{"id":"T319","span":{"begin":7429,"end":7437},"obj":"Disease"},{"id":"T320","span":{"begin":7773,"end":7780},"obj":"Disease"}],"attributes":[{"id":"A311","pred":"mondo_id","subj":"T311","obj":"http://purl.obolibrary.org/obo/MONDO_0011948"},{"id":"A312","pred":"mondo_id","subj":"T312","obj":"http://purl.obolibrary.org/obo/MONDO_0006022"},{"id":"A313","pred":"mondo_id","subj":"T313","obj":"http://purl.obolibrary.org/obo/MONDO_0005091"},{"id":"A314","pred":"mondo_id","subj":"T314","obj":"http://purl.obolibrary.org/obo/MONDO_0005044"},{"id":"A315","pred":"mondo_id","subj":"T315","obj":"http://purl.obolibrary.org/obo/MONDO_0021178"},{"id":"A316","pred":"mondo_id","subj":"T316","obj":"http://purl.obolibrary.org/obo/MONDO_0021166"},{"id":"A317","pred":"mondo_id","subj":"T317","obj":"http://purl.obolibrary.org/obo/MONDO_0005068"},{"id":"A318","pred":"mondo_id","subj":"T318","obj":"http://purl.obolibrary.org/obo/MONDO_0005068"},{"id":"A319","pred":"mondo_id","subj":"T319","obj":"http://purl.obolibrary.org/obo/MONDO_0100096"},{"id":"A320","pred":"mondo_id","subj":"T320","obj":"http://purl.obolibrary.org/obo/MONDO_0005292"}],"text":"5.2. Safety and Efficacy Concerns of MLN4760 and Dx600 ACE2 Inhibitors.\nIt is known that the catalytic cleft of ACE2 consists of two peptidase subdomains: one membrane-distal and the other one membrane-proximal. Their weak interactions are consistent with the ability to transition from open to the closed ACE2 conformation [28,90]. Indeed, the two subdomains undergo a large hinge-bending motion in which membrane-proximal subdomain remains almost unchanged, while membrane-distal subdomain moves to close the distance between the two subdomains, mimicking the opening/closing movement of a clam shell [90]. ACE2 open conformation likely reflects free state of the enzyme available to catch substrates (or inhibitors), then, when the ACE2 receptor binds to a substrate, the membrane-distal subdomain closes around the substrate (or the inhibitor), finally performing the enzymatic activity [24,90]. Interestingly, in cryo–electron microscopy structures of full-length human ACE2, only the closed/substrate-bound conformation of ACE2 was observed in the spike-ACE2 complexes [28]. Since human ACE2 is assembled on cell surface as a homodimer [28], binding of the spike protein trimer onto ACE2 dimer suggests simultaneous binding of two spike protein trimers to substrate-bound conformer of ACE2 homodimer on plasma membrane. The spike binding sites on ACE2 homodimer are localized above the membrane-distal peptidase subdomain of each ACE2 monomer, nevertheless neither ACE2 shedding nor ACE2 binding to spike proteins have been shown to inhibit ACE2 enzymatic activity [16,17,24]. On the other hand, the S-protein-binding region of membrane-distal ACE2 subdomain is not significantly perturbed by the receptor conformational changes and maintains the ability to associate with soluble spike proteins independently on open/closed conformations [24]. Interestingly, an ACE2 specific inhibitor (MLN-4760) has been shown to induce the closed (inhibitor-bound) ACE2 structure [90] and to retain its inhibitory effects on sACE2 bound to spike proteins [24].\nMLN4760 is a potent and selective human ACE2 inhibitor (IC50 = 0.44 nM against soluble human ACE2) whose synthesis produces a racemic mixture of two diastereomers that showed 75:25 ratio for Isomer A: Isomer B [113,114] and the purified isomer B is the isomer commercially available from Merck Millipore [114]. Testing MLN-4760 racemic mixture and its isomers, it was observed a concentration-dependent inhibition of recombinant human (rh)ACE or rhACE2 activities with all three inhibitors [114]. The isomer B was less selective (near minimal-maximal rhACE inhibition range 10−6M-10−4M) than the racemate or the isomer A (near minimal-maximal rhACE inhibition range 10−6M-10−2M) and less effective (near maximal rhACE2 inhibition at 10−7M) than the racemate or the isomer A (near maximal rhACE2 inhibition at 10−8 M) for rhACE2 versus rhACE [114]. Moreover, all three inhibitors exerted a significantly higher inhibitory activity against soluble than membrane-bound forms of (m)ACE2 (near maximal mACE2 inhibition at 10−6M), being the isomer B more selective and effective than the racemate or the isomer A for mACE2 vs. mACE expressed on the surface of mononuclear cells (or CD34 hematopoietic progenitors) [114]. A second ACE2 inhibitor, Dx600, produced similar results to those obtained with the isomer B [114]. Another study evaluated the inhibitory activity of both MLN-4760 and DX600 (either the linear conformational form or the disulfide bridged cyclic variant) inhibitors. In this report, the experiments were performed at pH 6.5 [115], a pH at which rhACE2 proteolysis operates at maximal activity [79] and a condition that resembles hypercapnic acidosis which may occur during SARS. MLN-4760 was still able to strongly and specifically inhibit rhACE2 activity (near maximal inhibition at 10−8 M), preventing rhACE2-driven Ang II degradation into Ang (1–7), whereas DX600 (either linear or cyclic variant) inhibits rhACE2 at relatively higher concentration (near maximal inhibition at 10−6 M–10−7 M, respectively) [115]. Altogether these data indicate that the racemate or the isomer A are more effective in inhibiting soluble forms of ACE2 than isomer B and Dx600. Therefore, these inhibitors at opportune (low) concentrations are expected to preferentially reduce systemic sACE2 activity, while preserving the ACE2 activity of (local) membrane-associated forms of ACE2, knowing that catalytic activity of circulating ACE2 was undetectable in human plasma of healthy subjects due to an endogenous ACE2 inhibitor [116].\nSince MLN-4760 inhibitor promotes the closed ACE2 conformation [90] which is the preferential conformer for virus binding [28], MLN-4760 is expected to not prevent viral entry; nevertheless, its inhibitory function on ACE2 pathway might work on the positive feedback loops (above described) that ultimately favour ACE2 membrane expression and viral entry. A potential risk factor of inhibiting the Ang II metabolization into Ang 1–7 could be the increase of blood pressure. Although ACE2 pathway inhibition might lead to hypertensive effects, treatment with MLN-4760 for 4-5 weeks had no effect on blood pressure when administered 10 mg/kg/day in drinking water in wild type mice [117] nor in male (mRen2)27 transgenic hypertensive rats (administered 30 mg/kg/day subcutaneously via mini-osmotic pumps) [118], suggesting that hypertensive activity mediated by ACE2 inhibition is promptly balanced by compensatory mechanisms either in normal or hypertensive blood pressure conditions. In addition, injections of MLN4760 into the nucleus tractus solitarii has been shown to reduce the baroreceptor reflex in rats, suggesting a role for ACE2 in controlling a reflex bradycardia (see [39,44]). Finally, chronic inhibition of ACE2 with MLN-4760 led to increase of ACE, albuminuria and glomerular injury in streptozotocin-induced diabetic mice, indicating a possible adverse effect of the inhibitor in a diabetic background [119].\nExtensive experiments have been also performed with DX600, a specific peptide ACE2 inhibitor that exhibited a mixed competitive and non-competitive type of inhibition [120]. Actually, several reports describing Dx600 inhibitor administration in mice suggest its safe use. Of interest, a report described its (safe) use alone (1 mg/kg per day) by nasal inhalation for 3 days in a mouse model of endotoxin-induced lung inflammation [121]; however, this inhibitor is less efficacious than MLN-4760 in inhibiting the soluble forms of human rACE2 [114,115]. Altogether these reports on administration of ACE2 inhibitors do not reveal significant adverse impacts or mortality in experimental animals, which suggests their safety in chronic administration. This was also confirmed in human clinical trials with MLN-4760 (clinical name: ORE1001, see later). Of interest, a report showed that on day 28 post-myocardial infarction, adult male Sprague-Dawley rats that had received MLN-4760 (also called C16) 25 mg/mL/day by daily intraperitoneal injection (as a solution of 42 mg/mL in distilled water) tended to have lower left ventricular pulse pressure, mean arterial pressures and left ventricular relaxation time constant-Tau compared to untreated group (see table 2 of the paper) [52], suggesting a possible protective role of ACE2 inhibition in post-myocardial infarction. Therefore, MLN-4760 might be helpful not only for COVID-19 but also in targeted therapies for pathologies correlated with an excessive increase of ACE2 activity that may involve heart, lung, liver, colon or other tissues/organs expressing ACE2 such as blood and endothelial cells. As an example, GL1001 (old name of MLN-4760) showed to produce an anti-inflammatory activity in a mouse model of colitis [122], highlighting the importance of the yin-yang balance of ACE/ACE2 pathways (“in medio stat virtus”)."}

LitCovid-PD-CLO

LitCovid-PD-CHEBI

LitCovid-PD-GO-BP

{"project":"LitCovid-PD-GO-BP","denotations":[{"id":"T119","span":{"begin":2159,"end":2168},"obj":"http://purl.obolibrary.org/obo/GO_0009058"},{"id":"T120","span":{"begin":3621,"end":3632},"obj":"http://purl.obolibrary.org/obo/GO_0006508"},{"id":"T121","span":{"begin":3894,"end":3905},"obj":"http://purl.obolibrary.org/obo/GO_0009056"},{"id":"T122","span":{"begin":5680,"end":5686},"obj":"http://purl.obolibrary.org/obo/GO_0060004"},{"id":"T123","span":{"begin":5740,"end":5746},"obj":"http://purl.obolibrary.org/obo/GO_0060004"},{"id":"T124","span":{"begin":6426,"end":6438},"obj":"http://purl.obolibrary.org/obo/GO_0006954"}],"text":"5.2. Safety and Efficacy Concerns of MLN4760 and Dx600 ACE2 Inhibitors.\nIt is known that the catalytic cleft of ACE2 consists of two peptidase subdomains: one membrane-distal and the other one membrane-proximal. Their weak interactions are consistent with the ability to transition from open to the closed ACE2 conformation [28,90]. Indeed, the two subdomains undergo a large hinge-bending motion in which membrane-proximal subdomain remains almost unchanged, while membrane-distal subdomain moves to close the distance between the two subdomains, mimicking the opening/closing movement of a clam shell [90]. ACE2 open conformation likely reflects free state of the enzyme available to catch substrates (or inhibitors), then, when the ACE2 receptor binds to a substrate, the membrane-distal subdomain closes around the substrate (or the inhibitor), finally performing the enzymatic activity [24,90]. Interestingly, in cryo–electron microscopy structures of full-length human ACE2, only the closed/substrate-bound conformation of ACE2 was observed in the spike-ACE2 complexes [28]. Since human ACE2 is assembled on cell surface as a homodimer [28], binding of the spike protein trimer onto ACE2 dimer suggests simultaneous binding of two spike protein trimers to substrate-bound conformer of ACE2 homodimer on plasma membrane. The spike binding sites on ACE2 homodimer are localized above the membrane-distal peptidase subdomain of each ACE2 monomer, nevertheless neither ACE2 shedding nor ACE2 binding to spike proteins have been shown to inhibit ACE2 enzymatic activity [16,17,24]. On the other hand, the S-protein-binding region of membrane-distal ACE2 subdomain is not significantly perturbed by the receptor conformational changes and maintains the ability to associate with soluble spike proteins independently on open/closed conformations [24]. Interestingly, an ACE2 specific inhibitor (MLN-4760) has been shown to induce the closed (inhibitor-bound) ACE2 structure [90] and to retain its inhibitory effects on sACE2 bound to spike proteins [24].\nMLN4760 is a potent and selective human ACE2 inhibitor (IC50 = 0.44 nM against soluble human ACE2) whose synthesis produces a racemic mixture of two diastereomers that showed 75:25 ratio for Isomer A: Isomer B [113,114] and the purified isomer B is the isomer commercially available from Merck Millipore [114]. Testing MLN-4760 racemic mixture and its isomers, it was observed a concentration-dependent inhibition of recombinant human (rh)ACE or rhACE2 activities with all three inhibitors [114]. The isomer B was less selective (near minimal-maximal rhACE inhibition range 10−6M-10−4M) than the racemate or the isomer A (near minimal-maximal rhACE inhibition range 10−6M-10−2M) and less effective (near maximal rhACE2 inhibition at 10−7M) than the racemate or the isomer A (near maximal rhACE2 inhibition at 10−8 M) for rhACE2 versus rhACE [114]. Moreover, all three inhibitors exerted a significantly higher inhibitory activity against soluble than membrane-bound forms of (m)ACE2 (near maximal mACE2 inhibition at 10−6M), being the isomer B more selective and effective than the racemate or the isomer A for mACE2 vs. mACE expressed on the surface of mononuclear cells (or CD34 hematopoietic progenitors) [114]. A second ACE2 inhibitor, Dx600, produced similar results to those obtained with the isomer B [114]. Another study evaluated the inhibitory activity of both MLN-4760 and DX600 (either the linear conformational form or the disulfide bridged cyclic variant) inhibitors. In this report, the experiments were performed at pH 6.5 [115], a pH at which rhACE2 proteolysis operates at maximal activity [79] and a condition that resembles hypercapnic acidosis which may occur during SARS. MLN-4760 was still able to strongly and specifically inhibit rhACE2 activity (near maximal inhibition at 10−8 M), preventing rhACE2-driven Ang II degradation into Ang (1–7), whereas DX600 (either linear or cyclic variant) inhibits rhACE2 at relatively higher concentration (near maximal inhibition at 10−6 M–10−7 M, respectively) [115]. Altogether these data indicate that the racemate or the isomer A are more effective in inhibiting soluble forms of ACE2 than isomer B and Dx600. Therefore, these inhibitors at opportune (low) concentrations are expected to preferentially reduce systemic sACE2 activity, while preserving the ACE2 activity of (local) membrane-associated forms of ACE2, knowing that catalytic activity of circulating ACE2 was undetectable in human plasma of healthy subjects due to an endogenous ACE2 inhibitor [116].\nSince MLN-4760 inhibitor promotes the closed ACE2 conformation [90] which is the preferential conformer for virus binding [28], MLN-4760 is expected to not prevent viral entry; nevertheless, its inhibitory function on ACE2 pathway might work on the positive feedback loops (above described) that ultimately favour ACE2 membrane expression and viral entry. A potential risk factor of inhibiting the Ang II metabolization into Ang 1–7 could be the increase of blood pressure. Although ACE2 pathway inhibition might lead to hypertensive effects, treatment with MLN-4760 for 4-5 weeks had no effect on blood pressure when administered 10 mg/kg/day in drinking water in wild type mice [117] nor in male (mRen2)27 transgenic hypertensive rats (administered 30 mg/kg/day subcutaneously via mini-osmotic pumps) [118], suggesting that hypertensive activity mediated by ACE2 inhibition is promptly balanced by compensatory mechanisms either in normal or hypertensive blood pressure conditions. In addition, injections of MLN4760 into the nucleus tractus solitarii has been shown to reduce the baroreceptor reflex in rats, suggesting a role for ACE2 in controlling a reflex bradycardia (see [39,44]). Finally, chronic inhibition of ACE2 with MLN-4760 led to increase of ACE, albuminuria and glomerular injury in streptozotocin-induced diabetic mice, indicating a possible adverse effect of the inhibitor in a diabetic background [119].\nExtensive experiments have been also performed with DX600, a specific peptide ACE2 inhibitor that exhibited a mixed competitive and non-competitive type of inhibition [120]. Actually, several reports describing Dx600 inhibitor administration in mice suggest its safe use. Of interest, a report described its (safe) use alone (1 mg/kg per day) by nasal inhalation for 3 days in a mouse model of endotoxin-induced lung inflammation [121]; however, this inhibitor is less efficacious than MLN-4760 in inhibiting the soluble forms of human rACE2 [114,115]. Altogether these reports on administration of ACE2 inhibitors do not reveal significant adverse impacts or mortality in experimental animals, which suggests their safety in chronic administration. This was also confirmed in human clinical trials with MLN-4760 (clinical name: ORE1001, see later). Of interest, a report showed that on day 28 post-myocardial infarction, adult male Sprague-Dawley rats that had received MLN-4760 (also called C16) 25 mg/mL/day by daily intraperitoneal injection (as a solution of 42 mg/mL in distilled water) tended to have lower left ventricular pulse pressure, mean arterial pressures and left ventricular relaxation time constant-Tau compared to untreated group (see table 2 of the paper) [52], suggesting a possible protective role of ACE2 inhibition in post-myocardial infarction. Therefore, MLN-4760 might be helpful not only for COVID-19 but also in targeted therapies for pathologies correlated with an excessive increase of ACE2 activity that may involve heart, lung, liver, colon or other tissues/organs expressing ACE2 such as blood and endothelial cells. As an example, GL1001 (old name of MLN-4760) showed to produce an anti-inflammatory activity in a mouse model of colitis [122], highlighting the importance of the yin-yang balance of ACE/ACE2 pathways (“in medio stat virtus”)."}

LitCovid-sentences

LitCovid-PD-HP

{"project":"LitCovid-PD-HP","denotations":[{"id":"T93","span":{"begin":3710,"end":3718},"obj":"Phenotype"},{"id":"T94","span":{"begin":5030,"end":5056},"obj":"Phenotype"},{"id":"T95","span":{"begin":5747,"end":5758},"obj":"Phenotype"},{"id":"T96","span":{"begin":5848,"end":5859},"obj":"Phenotype"},{"id":"T97","span":{"begin":6908,"end":6929},"obj":"Phenotype"},{"id":"T98","span":{"begin":7356,"end":7377},"obj":"Phenotype"},{"id":"T99","span":{"begin":7773,"end":7780},"obj":"Phenotype"}],"attributes":[{"id":"A93","pred":"hp_id","subj":"T93","obj":"http://purl.obolibrary.org/obo/HP_0001941"},{"id":"A94","pred":"hp_id","subj":"T94","obj":"http://purl.obolibrary.org/obo/HP_0032263"},{"id":"A95","pred":"hp_id","subj":"T95","obj":"http://purl.obolibrary.org/obo/HP_0001662"},{"id":"A96","pred":"hp_id","subj":"T96","obj":"http://purl.obolibrary.org/obo/HP_0012592"},{"id":"A97","pred":"hp_id","subj":"T97","obj":"http://purl.obolibrary.org/obo/HP_0001658"},{"id":"A98","pred":"hp_id","subj":"T98","obj":"http://purl.obolibrary.org/obo/HP_0001658"},{"id":"A99","pred":"hp_id","subj":"T99","obj":"http://purl.obolibrary.org/obo/HP_0002583"}],"text":"5.2. Safety and Efficacy Concerns of MLN4760 and Dx600 ACE2 Inhibitors.\nIt is known that the catalytic cleft of ACE2 consists of two peptidase subdomains: one membrane-distal and the other one membrane-proximal. Their weak interactions are consistent with the ability to transition from open to the closed ACE2 conformation [28,90]. Indeed, the two subdomains undergo a large hinge-bending motion in which membrane-proximal subdomain remains almost unchanged, while membrane-distal subdomain moves to close the distance between the two subdomains, mimicking the opening/closing movement of a clam shell [90]. ACE2 open conformation likely reflects free state of the enzyme available to catch substrates (or inhibitors), then, when the ACE2 receptor binds to a substrate, the membrane-distal subdomain closes around the substrate (or the inhibitor), finally performing the enzymatic activity [24,90]. Interestingly, in cryo–electron microscopy structures of full-length human ACE2, only the closed/substrate-bound conformation of ACE2 was observed in the spike-ACE2 complexes [28]. Since human ACE2 is assembled on cell surface as a homodimer [28], binding of the spike protein trimer onto ACE2 dimer suggests simultaneous binding of two spike protein trimers to substrate-bound conformer of ACE2 homodimer on plasma membrane. The spike binding sites on ACE2 homodimer are localized above the membrane-distal peptidase subdomain of each ACE2 monomer, nevertheless neither ACE2 shedding nor ACE2 binding to spike proteins have been shown to inhibit ACE2 enzymatic activity [16,17,24]. On the other hand, the S-protein-binding region of membrane-distal ACE2 subdomain is not significantly perturbed by the receptor conformational changes and maintains the ability to associate with soluble spike proteins independently on open/closed conformations [24]. Interestingly, an ACE2 specific inhibitor (MLN-4760) has been shown to induce the closed (inhibitor-bound) ACE2 structure [90] and to retain its inhibitory effects on sACE2 bound to spike proteins [24].\nMLN4760 is a potent and selective human ACE2 inhibitor (IC50 = 0.44 nM against soluble human ACE2) whose synthesis produces a racemic mixture of two diastereomers that showed 75:25 ratio for Isomer A: Isomer B [113,114] and the purified isomer B is the isomer commercially available from Merck Millipore [114]. Testing MLN-4760 racemic mixture and its isomers, it was observed a concentration-dependent inhibition of recombinant human (rh)ACE or rhACE2 activities with all three inhibitors [114]. The isomer B was less selective (near minimal-maximal rhACE inhibition range 10−6M-10−4M) than the racemate or the isomer A (near minimal-maximal rhACE inhibition range 10−6M-10−2M) and less effective (near maximal rhACE2 inhibition at 10−7M) than the racemate or the isomer A (near maximal rhACE2 inhibition at 10−8 M) for rhACE2 versus rhACE [114]. Moreover, all three inhibitors exerted a significantly higher inhibitory activity against soluble than membrane-bound forms of (m)ACE2 (near maximal mACE2 inhibition at 10−6M), being the isomer B more selective and effective than the racemate or the isomer A for mACE2 vs. mACE expressed on the surface of mononuclear cells (or CD34 hematopoietic progenitors) [114]. A second ACE2 inhibitor, Dx600, produced similar results to those obtained with the isomer B [114]. Another study evaluated the inhibitory activity of both MLN-4760 and DX600 (either the linear conformational form or the disulfide bridged cyclic variant) inhibitors. In this report, the experiments were performed at pH 6.5 [115], a pH at which rhACE2 proteolysis operates at maximal activity [79] and a condition that resembles hypercapnic acidosis which may occur during SARS. MLN-4760 was still able to strongly and specifically inhibit rhACE2 activity (near maximal inhibition at 10−8 M), preventing rhACE2-driven Ang II degradation into Ang (1–7), whereas DX600 (either linear or cyclic variant) inhibits rhACE2 at relatively higher concentration (near maximal inhibition at 10−6 M–10−7 M, respectively) [115]. Altogether these data indicate that the racemate or the isomer A are more effective in inhibiting soluble forms of ACE2 than isomer B and Dx600. Therefore, these inhibitors at opportune (low) concentrations are expected to preferentially reduce systemic sACE2 activity, while preserving the ACE2 activity of (local) membrane-associated forms of ACE2, knowing that catalytic activity of circulating ACE2 was undetectable in human plasma of healthy subjects due to an endogenous ACE2 inhibitor [116].\nSince MLN-4760 inhibitor promotes the closed ACE2 conformation [90] which is the preferential conformer for virus binding [28], MLN-4760 is expected to not prevent viral entry; nevertheless, its inhibitory function on ACE2 pathway might work on the positive feedback loops (above described) that ultimately favour ACE2 membrane expression and viral entry. A potential risk factor of inhibiting the Ang II metabolization into Ang 1–7 could be the increase of blood pressure. Although ACE2 pathway inhibition might lead to hypertensive effects, treatment with MLN-4760 for 4-5 weeks had no effect on blood pressure when administered 10 mg/kg/day in drinking water in wild type mice [117] nor in male (mRen2)27 transgenic hypertensive rats (administered 30 mg/kg/day subcutaneously via mini-osmotic pumps) [118], suggesting that hypertensive activity mediated by ACE2 inhibition is promptly balanced by compensatory mechanisms either in normal or hypertensive blood pressure conditions. In addition, injections of MLN4760 into the nucleus tractus solitarii has been shown to reduce the baroreceptor reflex in rats, suggesting a role for ACE2 in controlling a reflex bradycardia (see [39,44]). Finally, chronic inhibition of ACE2 with MLN-4760 led to increase of ACE, albuminuria and glomerular injury in streptozotocin-induced diabetic mice, indicating a possible adverse effect of the inhibitor in a diabetic background [119].\nExtensive experiments have been also performed with DX600, a specific peptide ACE2 inhibitor that exhibited a mixed competitive and non-competitive type of inhibition [120]. Actually, several reports describing Dx600 inhibitor administration in mice suggest its safe use. Of interest, a report described its (safe) use alone (1 mg/kg per day) by nasal inhalation for 3 days in a mouse model of endotoxin-induced lung inflammation [121]; however, this inhibitor is less efficacious than MLN-4760 in inhibiting the soluble forms of human rACE2 [114,115]. Altogether these reports on administration of ACE2 inhibitors do not reveal significant adverse impacts or mortality in experimental animals, which suggests their safety in chronic administration. This was also confirmed in human clinical trials with MLN-4760 (clinical name: ORE1001, see later). Of interest, a report showed that on day 28 post-myocardial infarction, adult male Sprague-Dawley rats that had received MLN-4760 (also called C16) 25 mg/mL/day by daily intraperitoneal injection (as a solution of 42 mg/mL in distilled water) tended to have lower left ventricular pulse pressure, mean arterial pressures and left ventricular relaxation time constant-Tau compared to untreated group (see table 2 of the paper) [52], suggesting a possible protective role of ACE2 inhibition in post-myocardial infarction. Therefore, MLN-4760 might be helpful not only for COVID-19 but also in targeted therapies for pathologies correlated with an excessive increase of ACE2 activity that may involve heart, lung, liver, colon or other tissues/organs expressing ACE2 such as blood and endothelial cells. As an example, GL1001 (old name of MLN-4760) showed to produce an anti-inflammatory activity in a mouse model of colitis [122], highlighting the importance of the yin-yang balance of ACE/ACE2 pathways (“in medio stat virtus”)."}

2_test

PMC:7408073 / 53765-61651 JSONTXT

Annnotations TAB JSON ListView MergeView

PMC:7408073 / 53765-61651 JSON TXT