Аутоантитела к ангиотензину 2
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chuka_lisПолезная работа для понимания механизмов патологии при ковиде и после.
При попадании вируса в организм и дальше чем в слизистые, что обычно хараткеризуется ковидом средней тяжести и хуже, в людей начинают вырабатываться антитела к вирусу, чаще всего к его шипику, который- один из самых иммуногенных компонентов вируса, расположен на поверхности, и служит "ключиком" для проникновения в клетку через АСЕ2.
Однако, АСЕ2 на клетках тела вовсе не предназначен для того, чтобы в них проникал вирус, а вообще, имеет основную функцию (одну из), связанную с регуляций артериального давления- это рецептор-фермент клетки для связывания с секреторными ангиотензинами 1 или 2, которые этот мембранный рецептор АСЕ2 (ангиотензин-превращающий фермент-2) конвертирует в ангиотензины 1-9 (1й) и 1-7 (2й). А дальше уже эти превращенные ангиотензины выполняют свои функции (для1-7- сосудорасширяющую, вто время как ангиотензин 2 сам по себе- работает как сосудосуживающий фактор).
Авторы предположили, что если антитела вырабатываются на шипик, которых подходит к АСЕ2 как "ключик к замочку", то есть вероятность, что часть из этих антител может связываться и с ангиотензином 2 (который тоже подходит к АСЕ2 как "ключик к замочку"). И они могут выступать в роли аутоантител, которые будут вносить разлад в работу организма. Ведь антитела с перекрестной активностью будут связываться не только с коронавирусными шипиками, но и с собственным ангиотензином 2, мешая его регуляторной функции. К тому же, выработка этих аутоантител может и "закрепиться", вызвав иммунопатологию- ведь мы регулярно производим этот ангиотензин 2 для своих регуляторных нужд..
Потому они решили поискать эти аутоантитела у больных ковидом.
Разумеется, они их нашли.
Более чем у половины (53%) госпитализированных с ковидом обнаружены антитела к ангиотензину 2 во время болезни. При этом, среди "контроля" таких было менее 2%. С учетом того, что гипертензия может играть роль в тяжести болезни, проверили: сколько может быть людей с аутоантителами (выработанными в силу разных причн) среди тех, у кого диагностирована гипертензия до пандемии. Таких оказалось 15%.
То есть, ковид определенно способствует тому, чтобы вырабатывались аутоантитела к ангиотензину 2.
Далее ученые провели эксперимент на мышах, вакцинировав их шипиковым белком в присутствии адьюванта. Вакцинация тоже привела к тому, что у части животных появились антитела не только к шипику, но и к ангиотензину 2.
Уровни и наличие антител к РСЧ и ангиотензину не особо коррелировали между собой, т.е. при том что могли быть проинициированы одним и тем же процессом, друг от друга не особо зависели.
Связав эти 2 явления ( аутоантитела у ковидных, и аутоантитела у мышей после вацинации), исследователи решили проверить наличие корреляции между присутствием антител к ангиотензину в крови, и тяжестью ковида.
И обнаружили, что ассоциация есть. У тех, у кого была аутоантитела к ангиотензину2, было больше проблем со скачками давления (+-70 мм рт ст в течении дня) и необходимости в медикаментозных вазопрессорах, и было хуже насыщение крови кислородом. Была ли у них гипертензия до ковида или нет, особой роли не играло.
Поскольку тяжесть ковида почти напрямую связана с уровнем оксигенации (маркер респираторного дистресс-синдрома)- анализ показал что есть корреляция между наличием аутоантител и тяжестью течения болезни. Хотя это не причинно следственная связь, и работа не показывает механизмов патологии, но рекомендует дальнейшие исследования в этом направлении.
Потому что кросс-реактивность между эпитопами шипика и его РСЧ и ангиотензина 2 у моноклональных антител, выделенных от больных и вакцинирваонных мышей была, хоть и не очень высокая (те стимулируется их выработка "отдельно"). Авторы определили регионы этих антигенных эпитопов и для шипика короны, и для ангиотензина 2, которые "садятся" на АСЕ2 в слегка разных местах.
У примерно 5% из выборки ковидных аутоантитела в крови были и спустя полтора месяца после болезни.
Вообще ковид характеризуется тем, что привносит нарушения в работу иммунитета, и, в частности, способствует появлени. разных аутоантител.
Аутоантитела к ангиотензину-2, как к регулятору АД, могут нарушать работу сердечно-сосудистой системы, и пр..
Here, we sought to explore whether SARS-CoV-2infectionmight induce auto-antibodies againstthe peptide AngII. We hypothesized thatthe simultaneous binding of SARS-CoV-2 and AngII to ACE-2 might lead totheir co-phagocytosisby antigen-presenting cells, thus providing a strongimmune adjuvant (the virusmolecules)to the self-peptide AngII, leading to an anti-AngII autoimmune response(6, 7). Moreover, we askedwhether some epitopemimicry might exist between a domain on the Spike protein and AngII, based on their shared binding to ACE-2. Importantly, the induction of anti-AngII antibodies in COVID-19 patients, if it occurs,could interfere with AngII processing by ACE2 and signalingto its receptors, potentially contributingto thedysregulation of vascular tension and worsening acute respiratory distress syndrome
We conducted observational studies using serum of hospitalized COVID-19 patients and determinedthatsuch autoantibodies are indeed induced,independently ofanti-RBDlevels.Instead, their presence and levels were strongly correlatedwith blood pressure dysregulationandpooroxygenation. We finally demonstrated cross-reactivityof some antibodies between AngII and the Spike protein, suggesting immune epitopehomology between these molecules.
We began by assessing thepresence of IgG antibodies against AngIIin the plasmaof 221subjects, among which 115were hospitalized COVID-19 patients convalescentfroma SARS-CoV-2 infection, 58 were controldonors (i.e. non-SARS-CoV-2 infectedand non-hypertensive), and 48 were hypertensive non-SARS-CoV-2 infected donors. Surprisingly, we found that a substantial proportion,63% (73/115),of the COVID-19 patientshad positive levels of anti-AngII autoantibodies, as determined by an ELISA absorbance greater than 3 standard deviations above the mean ofthe controldonorgroup
Of these, 53%(39/73)hadhigh levels, defined asgreater than twice the positive threshold. In contrast, only one controldonor(1.7%) wasanti-AngII positive,with a leveljust above the positive limit.Patient age, sex, andbody mass index(BMI)were not significantly correlated with anti-AngII positivity, although older patients trendedtowardsincreasedlevels of anti-AngII(p=0.064by Spearman correlation,). Additional trends suggested thatfemale COVID-19 patientswere more likely to develop high anti-AngII levels (42% vs. 25% of males, Fig.S1B) as well as patients with BMI≥25 (38% vs. 20%of patients with normal BMI,)
Since a majority of the hospitalized COVID-19patients in this cohort had pre-existinghypertension(COVID HTN, 64%), we measured anti-AngII levels in plasmafrom hypertensive donorstaken prior to the pandemic(non-COVID HTN)to determine whether autoantibodies against AngII could have been pre-existing in HTNpatients. Interestingly, we detected anti-AngII antibodies in 15%of these hypertensive donors, which was far less thaninCOVID-19patients.
These results indicate that infection with SARS-CoV-2 promotes the development of anti-AngII IgG antibodies in a majority of patientsthat developed severe disease (i.e., requiredhospitalization), regardless of whether they had pre-existing hypertension.
..data suggest that antibodies levels generated against AngII are not necessarily correlated with those against RBD.
Wenext studied the developmentof anti-AngII IgG in miceupon exposure to SARS-CoV-2 antigens(notethat murine and human AngII are 100% homologous). Wevaccinatedmice at 0 and 21 days with10 μg Spike orRBD
We furtheranalyzed the time course of the immune responsesin mice, measuring anti-AngII levels at weeks1, 2, 3 and 4forthe mice vaccinated with RBD+ MPLA/alumor Spike + MPLA/Alumthat were positive for anti-AngII. Thisanalysis highlightedan increase in anti-AngII levels over time, specificallybetweenweeks1-2 and week 4 post-vaccination (Fig.2B). Of note,theincreaseinanti-AngII IgG titerswasmore substantialafter the vaccination boost at week 3.These results demonstrate that anti-AngII autoantibodies can be inducedin mice by vaccination against Spike orRBD,in the absence of SARS-CoV-2 infection, at least with MPLA/Alum-containing adjuvants.
Having determined that anti-AngII antibodies could develop both in hospitalized COVID-19 patients and in mice aftervaccination with MPLA/alum-adjuvanted SARS-CoV-2 antigens, we further examinedhospitalized COVID-19 patients for potential correlative effects of anti-AngII antibodies on blood pressure dysregulation, blood oxygenation,and disease severity.First, we observed thatthe levels of anti-AngIIwere significantly higher inpatients with dysregulated blood pressure(BP), as definedby (i)episodes of hypotension that required administration of vasopressors, (ii) large daily fluctuations in blood pressure (daily mean arterial pressure range(ΔMAP)≥70mmHg), or (iii) at least 2 consecutive days of hypotension(MAP<65mmHg) inpatientswith pre-existing HTN
Of note, these 3 subgroups of patients with dysregulated PB are not exclusive, with52% of patients belonging tomultiplecategories. Consistent with these observations, a majority of patients with blood pressure dysregulation were positive for anti-AngII (81%vs. 53% in patients with normal blood pressure, Fig.3C), among which45% had high levelsof anti-AngII.And finally, patients needing vasopressors were the most likely to have positive or high levels ofanti-AngII, although among each of the groups with dysregulated blood pressure, >80% wereanti-AngII(+)
Foreach patient, we selected thelowest daily mean SF ratio value obtained within a two-day window of the measurement ofanti-AngII. The lowest daily mean SF ratio was compared between the COVID-19 patients whodeveloped auto-antibodies against AngII (73patients) and those whodid not (42patients). We found that the SF ratio was stronglyreduced in anti-AngII(+)patients (Fig.3F), demonstrating a correlation between anti-AngIIantibodies and reducedblood oxygenation in these patients.
Since the clinical severity of COVIDdirectly depends on thepatient's blood oxygenation, patients with SF ratio ≥314 are considered as having a disease of low severity, while patientswith SF ratio < 235suffer from a highly severe form of COVID.Based on this, we thencompared anti-AngII levels withdisease severity and found thatpatients with severe vs.mild disease had increasedanti-AngII antibodies(p=0.053, Fig.3G).Similarly, we found a significant increase in the proportion of anti-AngII(+) patients along with disease severity (p=0.035byχ2test, Fig. 3H). Indeed, 77% of patients with severe disease were anti-AngII(+), including41% withhigh levels, as comparedto 50% and 29%,respectively,in patients with mild disease. Together, these results demonstrate a correlation between the presence and levels of anti-AngII in COVID-19patients anddysregulatedbloodpressure, lower blood oxygenation,and increaseddisease severity.
Because anti-AngII antibodies developedin response to SARS-CoV-2 infection in hospitalized patients or vaccinationwith some adjuvantsin mice, we hypothesized that anti-AngII antibodies may result from molecular structuralmimicrybetween the AngII peptide and certain epitopes present in Spike or RBD. In thatcase, anti-AngII and anti-RBD could potentially cross-bind to both antigens. To test this hypothesis, weassessed the binding of two murineIgGmonoclonal anti-AngII antibodies(clone E7 and clone B938M) to recombinant SARS-CoV-2 Spike or RBD.We found that both monoclonal anti-AngII antibodies bound to Spike and RBD, although with a lower affinity to RBD than to Spike
We further demonstratedthat themonoclonal anti-AngII antibodies mayinterfere with AngII binding to itscognate receptorAT1, suggestingthat AngII-AT1 signaling couldbe modulated bythe presence of anti-AngII
We then soughtto identifythe epitopes of Spike or RBDthat lead to cross-reactivity to AngII
Of note, although both Spike and AngII share the same receptor,ACE-2, their binding on ACE-2 occurs at 2 distinct locations
Importantly, most regions targeted by clones E7 and/orB938M have been characterized as being the main B cells epitopes in COVID patients
These regions, which are likely to containtheepitopes generatinganti-AngII autoantibodies, are(1) aa21-aa40, (2)aa447-aa468, (3)aa551-aa585, (4)aa786-aa804, (5) aa1131-1160 of Spike.
Taken together, using monoclonal anti-AngII and anti-RBD antibodies, we demonstrate that antibody cross-binding between AngII and Spike/RBD can occur, even if weakly, which may suggest some structural homology between AngII and certainepitopes of Spike/RBD.
SARS-CoV-2infection has been shownto induce broad immune dysregulation(15, 16), including generation of wide-ranging autoantibodyresponses(17).For example, generation of autoantibodies against phospholipids hasbeen shown to contribute to coagulation disorders (18, 19),and against Type I interferons to reduced immune response to infection(20). Here, we show that autoantibodies can be generated against AngII, a key regulator of vascular tension.We further showthat generation of anti-AngII autoantibodies correlated with disease severity as reflected in dysregulation of vascular tensionand lower blood oxygenation.
This, along with our in vitrosignaling data, suggests that the anti-AngII autoantibodies, even if low affinity, may be able to interfere with signaling between AngII and its receptors AT1 andACE-2. Interestingly, some COVID-19 patients had also been shown to develop autoantibodies against AT1 and ACE-2, which similarly correlated with enhanced pro-inflammatory responsesand increased disease severity (21, 22). Such autoantibodies against AT1 and ACE-2 have been also observed in patients suffering from other vascular pathologies, particularly in malignant hypertension (8)or constrictive vasculopathy (9).Therefore, systematic quantification of autoantibodies against key molecules of the renin-angiotensin pathway(i.e. AngII, AT1, and ACE-2),in diseases characterized by vasculardysregulation, including COVID-19,might reveal a common underlying autoimmune etiology. Lastly, we highlighted the immune epitopes of Spike that could share structural homology with AngII, providingmolecular insights in the immune mechanisms that could lead to the generationof anti-AngII autoantibodies upon infection by SARS-CoV-2.
При попадании вируса в организм и дальше чем в слизистые, что обычно хараткеризуется ковидом средней тяжести и хуже, в людей начинают вырабатываться антитела к вирусу, чаще всего к его шипику, который- один из самых иммуногенных компонентов вируса, расположен на поверхности, и служит "ключиком" для проникновения в клетку через АСЕ2.
Однако, АСЕ2 на клетках тела вовсе не предназначен для того, чтобы в них проникал вирус, а вообще, имеет основную функцию (одну из), связанную с регуляций артериального давления- это рецептор-фермент клетки для связывания с секреторными ангиотензинами 1 или 2, которые этот мембранный рецептор АСЕ2 (ангиотензин-превращающий фермент-2) конвертирует в ангиотензины 1-9 (1й) и 1-7 (2й). А дальше уже эти превращенные ангиотензины выполняют свои функции (для1-7- сосудорасширяющую, вто время как ангиотензин 2 сам по себе- работает как сосудосуживающий фактор).
Авторы предположили, что если антитела вырабатываются на шипик, которых подходит к АСЕ2 как "ключик к замочку", то есть вероятность, что часть из этих антител может связываться и с ангиотензином 2 (который тоже подходит к АСЕ2 как "ключик к замочку"). И они могут выступать в роли аутоантител, которые будут вносить разлад в работу организма. Ведь антитела с перекрестной активностью будут связываться не только с коронавирусными шипиками, но и с собственным ангиотензином 2, мешая его регуляторной функции. К тому же, выработка этих аутоантител может и "закрепиться", вызвав иммунопатологию- ведь мы регулярно производим этот ангиотензин 2 для своих регуляторных нужд..
Потому они решили поискать эти аутоантитела у больных ковидом.
Разумеется, они их нашли.
Более чем у половины (53%) госпитализированных с ковидом обнаружены антитела к ангиотензину 2 во время болезни. При этом, среди "контроля" таких было менее 2%. С учетом того, что гипертензия может играть роль в тяжести болезни, проверили: сколько может быть людей с аутоантителами (выработанными в силу разных причн) среди тех, у кого диагностирована гипертензия до пандемии. Таких оказалось 15%.
То есть, ковид определенно способствует тому, чтобы вырабатывались аутоантитела к ангиотензину 2.
Далее ученые провели эксперимент на мышах, вакцинировав их шипиковым белком в присутствии адьюванта. Вакцинация тоже привела к тому, что у части животных появились антитела не только к шипику, но и к ангиотензину 2.
Уровни и наличие антител к РСЧ и ангиотензину не особо коррелировали между собой, т.е. при том что могли быть проинициированы одним и тем же процессом, друг от друга не особо зависели.
Связав эти 2 явления ( аутоантитела у ковидных, и аутоантитела у мышей после вацинации), исследователи решили проверить наличие корреляции между присутствием антител к ангиотензину в крови, и тяжестью ковида.
И обнаружили, что ассоциация есть. У тех, у кого была аутоантитела к ангиотензину2, было больше проблем со скачками давления (+-70 мм рт ст в течении дня) и необходимости в медикаментозных вазопрессорах, и было хуже насыщение крови кислородом. Была ли у них гипертензия до ковида или нет, особой роли не играло.
Поскольку тяжесть ковида почти напрямую связана с уровнем оксигенации (маркер респираторного дистресс-синдрома)- анализ показал что есть корреляция между наличием аутоантител и тяжестью течения болезни. Хотя это не причинно следственная связь, и работа не показывает механизмов патологии, но рекомендует дальнейшие исследования в этом направлении.
Потому что кросс-реактивность между эпитопами шипика и его РСЧ и ангиотензина 2 у моноклональных антител, выделенных от больных и вакцинирваонных мышей была, хоть и не очень высокая (те стимулируется их выработка "отдельно"). Авторы определили регионы этих антигенных эпитопов и для шипика короны, и для ангиотензина 2, которые "садятся" на АСЕ2 в слегка разных местах.
У примерно 5% из выборки ковидных аутоантитела в крови были и спустя полтора месяца после болезни.
Вообще ковид характеризуется тем, что привносит нарушения в работу иммунитета, и, в частности, способствует появлени. разных аутоантител.
Аутоантитела к ангиотензину-2, как к регулятору АД, могут нарушать работу сердечно-сосудистой системы, и пр..
Here, we sought to explore whether SARS-CoV-2infectionmight induce auto-antibodies againstthe peptide AngII. We hypothesized thatthe simultaneous binding of SARS-CoV-2 and AngII to ACE-2 might lead totheir co-phagocytosisby antigen-presenting cells, thus providing a strongimmune adjuvant (the virusmolecules)to the self-peptide AngII, leading to an anti-AngII autoimmune response(6, 7). Moreover, we askedwhether some epitopemimicry might exist between a domain on the Spike protein and AngII, based on their shared binding to ACE-2. Importantly, the induction of anti-AngII antibodies in COVID-19 patients, if it occurs,could interfere with AngII processing by ACE2 and signalingto its receptors, potentially contributingto thedysregulation of vascular tension and worsening acute respiratory distress syndrome
We conducted observational studies using serum of hospitalized COVID-19 patients and determinedthatsuch autoantibodies are indeed induced,independently ofanti-RBDlevels.Instead, their presence and levels were strongly correlatedwith blood pressure dysregulationandpooroxygenation. We finally demonstrated cross-reactivityof some antibodies between AngII and the Spike protein, suggesting immune epitopehomology between these molecules.
We began by assessing thepresence of IgG antibodies against AngIIin the plasmaof 221subjects, among which 115were hospitalized COVID-19 patients convalescentfroma SARS-CoV-2 infection, 58 were controldonors (i.e. non-SARS-CoV-2 infectedand non-hypertensive), and 48 were hypertensive non-SARS-CoV-2 infected donors. Surprisingly, we found that a substantial proportion,63% (73/115),of the COVID-19 patientshad positive levels of anti-AngII autoantibodies, as determined by an ELISA absorbance greater than 3 standard deviations above the mean ofthe controldonorgroup
Of these, 53%(39/73)hadhigh levels, defined asgreater than twice the positive threshold. In contrast, only one controldonor(1.7%) wasanti-AngII positive,with a leveljust above the positive limit.Patient age, sex, andbody mass index(BMI)were not significantly correlated with anti-AngII positivity, although older patients trendedtowardsincreasedlevels of anti-AngII(p=0.064by Spearman correlation,). Additional trends suggested thatfemale COVID-19 patientswere more likely to develop high anti-AngII levels (42% vs. 25% of males, Fig.S1B) as well as patients with BMI≥25 (38% vs. 20%of patients with normal BMI,)
Since a majority of the hospitalized COVID-19patients in this cohort had pre-existinghypertension(COVID HTN, 64%), we measured anti-AngII levels in plasmafrom hypertensive donorstaken prior to the pandemic(non-COVID HTN)to determine whether autoantibodies against AngII could have been pre-existing in HTNpatients. Interestingly, we detected anti-AngII antibodies in 15%of these hypertensive donors, which was far less thaninCOVID-19patients.
These results indicate that infection with SARS-CoV-2 promotes the development of anti-AngII IgG antibodies in a majority of patientsthat developed severe disease (i.e., requiredhospitalization), regardless of whether they had pre-existing hypertension.
..data suggest that antibodies levels generated against AngII are not necessarily correlated with those against RBD.
Wenext studied the developmentof anti-AngII IgG in miceupon exposure to SARS-CoV-2 antigens(notethat murine and human AngII are 100% homologous). Wevaccinatedmice at 0 and 21 days with10 μg Spike orRBD
We furtheranalyzed the time course of the immune responsesin mice, measuring anti-AngII levels at weeks1, 2, 3 and 4forthe mice vaccinated with RBD+ MPLA/alumor Spike + MPLA/Alumthat were positive for anti-AngII. Thisanalysis highlightedan increase in anti-AngII levels over time, specificallybetweenweeks1-2 and week 4 post-vaccination (Fig.2B). Of note,theincreaseinanti-AngII IgG titerswasmore substantialafter the vaccination boost at week 3.These results demonstrate that anti-AngII autoantibodies can be inducedin mice by vaccination against Spike orRBD,in the absence of SARS-CoV-2 infection, at least with MPLA/Alum-containing adjuvants.
Having determined that anti-AngII antibodies could develop both in hospitalized COVID-19 patients and in mice aftervaccination with MPLA/alum-adjuvanted SARS-CoV-2 antigens, we further examinedhospitalized COVID-19 patients for potential correlative effects of anti-AngII antibodies on blood pressure dysregulation, blood oxygenation,and disease severity.First, we observed thatthe levels of anti-AngIIwere significantly higher inpatients with dysregulated blood pressure(BP), as definedby (i)episodes of hypotension that required administration of vasopressors, (ii) large daily fluctuations in blood pressure (daily mean arterial pressure range(ΔMAP)≥70mmHg), or (iii) at least 2 consecutive days of hypotension(MAP<65mmHg) inpatientswith pre-existing HTN
Of note, these 3 subgroups of patients with dysregulated PB are not exclusive, with52% of patients belonging tomultiplecategories. Consistent with these observations, a majority of patients with blood pressure dysregulation were positive for anti-AngII (81%vs. 53% in patients with normal blood pressure, Fig.3C), among which45% had high levelsof anti-AngII.And finally, patients needing vasopressors were the most likely to have positive or high levels ofanti-AngII, although among each of the groups with dysregulated blood pressure, >80% wereanti-AngII(+)
Foreach patient, we selected thelowest daily mean SF ratio value obtained within a two-day window of the measurement ofanti-AngII. The lowest daily mean SF ratio was compared between the COVID-19 patients whodeveloped auto-antibodies against AngII (73patients) and those whodid not (42patients). We found that the SF ratio was stronglyreduced in anti-AngII(+)patients (Fig.3F), demonstrating a correlation between anti-AngIIantibodies and reducedblood oxygenation in these patients.
Since the clinical severity of COVIDdirectly depends on thepatient's blood oxygenation, patients with SF ratio ≥314 are considered as having a disease of low severity, while patientswith SF ratio < 235suffer from a highly severe form of COVID.Based on this, we thencompared anti-AngII levels withdisease severity and found thatpatients with severe vs.mild disease had increasedanti-AngII antibodies(p=0.053, Fig.3G).Similarly, we found a significant increase in the proportion of anti-AngII(+) patients along with disease severity (p=0.035byχ2test, Fig. 3H). Indeed, 77% of patients with severe disease were anti-AngII(+), including41% withhigh levels, as comparedto 50% and 29%,respectively,in patients with mild disease. Together, these results demonstrate a correlation between the presence and levels of anti-AngII in COVID-19patients anddysregulatedbloodpressure, lower blood oxygenation,and increaseddisease severity.
Because anti-AngII antibodies developedin response to SARS-CoV-2 infection in hospitalized patients or vaccinationwith some adjuvantsin mice, we hypothesized that anti-AngII antibodies may result from molecular structuralmimicrybetween the AngII peptide and certain epitopes present in Spike or RBD. In thatcase, anti-AngII and anti-RBD could potentially cross-bind to both antigens. To test this hypothesis, weassessed the binding of two murineIgGmonoclonal anti-AngII antibodies(clone E7 and clone B938M) to recombinant SARS-CoV-2 Spike or RBD.We found that both monoclonal anti-AngII antibodies bound to Spike and RBD, although with a lower affinity to RBD than to Spike
We further demonstratedthat themonoclonal anti-AngII antibodies mayinterfere with AngII binding to itscognate receptorAT1, suggestingthat AngII-AT1 signaling couldbe modulated bythe presence of anti-AngII
We then soughtto identifythe epitopes of Spike or RBDthat lead to cross-reactivity to AngII
Of note, although both Spike and AngII share the same receptor,ACE-2, their binding on ACE-2 occurs at 2 distinct locations
Importantly, most regions targeted by clones E7 and/orB938M have been characterized as being the main B cells epitopes in COVID patients
These regions, which are likely to containtheepitopes generatinganti-AngII autoantibodies, are(1) aa21-aa40, (2)aa447-aa468, (3)aa551-aa585, (4)aa786-aa804, (5) aa1131-1160 of Spike.
Taken together, using monoclonal anti-AngII and anti-RBD antibodies, we demonstrate that antibody cross-binding between AngII and Spike/RBD can occur, even if weakly, which may suggest some structural homology between AngII and certainepitopes of Spike/RBD.
SARS-CoV-2infection has been shownto induce broad immune dysregulation(15, 16), including generation of wide-ranging autoantibodyresponses(17).For example, generation of autoantibodies against phospholipids hasbeen shown to contribute to coagulation disorders (18, 19),and against Type I interferons to reduced immune response to infection(20). Here, we show that autoantibodies can be generated against AngII, a key regulator of vascular tension.We further showthat generation of anti-AngII autoantibodies correlated with disease severity as reflected in dysregulation of vascular tensionand lower blood oxygenation.
This, along with our in vitrosignaling data, suggests that the anti-AngII autoantibodies, even if low affinity, may be able to interfere with signaling between AngII and its receptors AT1 andACE-2. Interestingly, some COVID-19 patients had also been shown to develop autoantibodies against AT1 and ACE-2, which similarly correlated with enhanced pro-inflammatory responsesand increased disease severity (21, 22). Such autoantibodies against AT1 and ACE-2 have been also observed in patients suffering from other vascular pathologies, particularly in malignant hypertension (8)or constrictive vasculopathy (9).Therefore, systematic quantification of autoantibodies against key molecules of the renin-angiotensin pathway(i.e. AngII, AT1, and ACE-2),in diseases characterized by vasculardysregulation, including COVID-19,might reveal a common underlying autoimmune etiology. Lastly, we highlighted the immune epitopes of Spike that could share structural homology with AngII, providingmolecular insights in the immune mechanisms that could lead to the generationof anti-AngII autoantibodies upon infection by SARS-CoV-2.
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