Involvement of the Bradykinin B1 Receptor in Microglial Activation: In Vitro and In Vivo Studies

The importance of brain inflammation to Alzheimer’s disease (AD) pathogenesis has been accepted of late, with it currently being held that brain inflammation aggravates AD pathology. One important aspect of brain inflammation is the recruitment and activation of microglia, a process termed microgliosis. Kinins and bradykinin (BK), in particular, are major pro-inflammatory mediators in the periphery, although all of the factors comprising the kinin system have also been described in the brain. Moreover, it was shown that the amyloid β (Aβ) peptide (a component of AD plaques) enhances kinin secretion and activates BK receptors that can, in turn, stimulate Aβ production. Still, the role of bradykinin in modulating brain inflammation and AD is not completely understood. In this study, we aimed to investigate the roles of the bradykinin B1 receptor (B1R) and bradykinin B2 receptor (B2R) in regulating microglial secretion of pro-inflammatory factors in vitro. Furthermore, the effects of intranasal administration of specific B1R and B2R antagonists on Aβ burden and microglial accumulation in the brains of transgenic AD mice were studied. The data obtained show that neither R-715 (a B1R antagonist) nor HOE 140 (a B2R antagonist) altered microglial cell viability. However, R-715, but not HOE 140, markedly increased lipopolysaccharide-induced nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) release, as well as inducible nitric oxide synthase expression in BV2 microglial cells. Neither antagonist altered NO nor TNF-α production in non-stimulated cells. We also showed that intranasal administration of R-715 but not HOE 140 to 8-week-old 5X familial AD mice enhanced amyloid burden and microglia/macrophage accumulation in the cortex. To conclude, we provide evidence supporting a role of B1R in brain inflammation and in the regulation of amyloid deposition in AD mice, possibly with microglial/macrophage involvement. Further studies are required to test whether modulation of this receptor can serve as a novel therapeutic strategy for AD

Microglial Activation Is Modulated by Captopril: in Vitro and in Vivo Studies

The renin-angiotensin system (RAS) is an important peripheral system involved in homeostasis modulation, with angiotensin II (Ang II) serving as the main effector hormone. The main enzyme involved in Ang II formation is angiotensin-converting enzyme (ACE). ACE inhibitors (ACEIs) such as captopril (Cap) are predominantly used for the management of hypertension. All of the components of the RAS have also been identified in brain. Centrally located hormones such as Ang II can induce glial inflammation. Moreover, in Alzheimer’s disease (AD) models, where glial inflammation occurs and is thought to contribute to the propagation of the disease, increased levels of Ang II and ACE have been detected. Interestingly, ACE overexpression in monocytes, migrating to the brain was shown to prevent AD cognitive decline. However, the specific effects of captopril on glial inflammation and AD remain obscure. In the present study, we investigated the effect of captopril, given at a wide concentration range, on inflammatory mediators released by lipopolysaccharide (LPS)-treated glia. In the current study, both primary glial cells and the BV2 microglial cell line were used. Captopril decreased LPS-induced nitric oxide (NO) release from primary mixed glial cells as well as regulating inducible NO synthase (iNOS) expression, NO, tumor necrosis factor-α (TNF-α) and induced interleukin-10 (IL-10) production by BV2 microglia. We further obtained data regarding intranasal effects of captopril on cortical amyloid β (Aβ) and CD11b expression in 5XFAD cortex over three different time periods. Interestingly, we noted decreases in Aβ burden in captopril-treated mice over time which was paralleled by increased microglial activation. These results thus shed light on the neuroprotective role of captopril in AD which might be related to modulation of microglial activation

miR-155: A Potential Biomarker for Predicting Mortality in COVID-19 Patients

COVID-19, a pandemic of severe acute respiratory syndrome caused by Coronavirus 2 (SARS-CoV-2), continues to pose diagnostic and therapeutic challenges due to its unpredictable clinical course. Prognostic biomarkers may improve care by enabling quick identification of patients who can be safely discharged home versus those who may need careful respiratory monitoring and support. MicroRNAs (miRNAs) have risen to prominence as biomarkers for many disease states and as tools to assist in medical decisions. In the present study, we aimed to examine circulating miRNAs in hospitalized COVID-19 patients and to explore their potential as biomarkers for disease severity. We studied, by quantitative PCR, the expressions of miR-21, miR-146a, miR-146b, miR-155, and miR-499 in peripheral blood. We found that mild COVID-19 patients had 2.5-fold less circulating miR-155 than healthy people, and patients with a severe COVID-19 disease had 5-fold less circulating miR-155 than healthy people. In addition, we found that miR-155 is a good predictor of COVID-19 mortality. We suggest that examining miR-155 levels in patients’ blood, upon admission to hospital, will ameliorate the care given to COVID-19 patients

Telmisartan Modulates Glial Activation: In Vitro and In Vivo Studies.

The circulating renin-angiotensin system (RAS), including the biologically active angiotensin II, is a fundamental regulatory mechanism of blood pressure conserved through evolution. Angiotensin II components of the RAS have also been identified in the brain. In addition to pro-inflammatory cytokines, neuromodulators, such as angiotensin II can induce (through angiotensin type 1 receptor (AT1R)) some of the inflammatory actions of brain glial cells and influence brain inflammation. Moreover, in Alzheimer's disease (AD) models, where neuroinflammation occurs, increased levels of cortical AT1Rs have been shown. Still, the precise role of RAS in neuroinflammation is not completely clear. The overall aim of the present study was to elucidate the role of RAS in the modulation of glial functions and AD pathology. To reach this goal, the specific aims of the present study were a. to investigate the long term effect of telmisartan (AT1R blocker) on tumor necrosis factor-α (TNF-α), interleukin 1-β (IL1-β) and nitric oxide (NO) release from glial cells. b. to examine the effect of intranasally administered telmisartan on amyloid burden and microglial activation in 5X familial AD (5XFAD) mice. Telmisartan effects in vivo were compared to those of perindopril (angiotensin converting enzyme inhibitor). Long-term-exposure of BV2 microglia to telmisartan significantly decreased lipopolysaccharide (LPS) -induced NO, inducible NO synthase, TNF-α and IL1-β synthesis. The effect of Telmisartan on NO production in BV2 cells was confirmed also in primary neonatal rat glial cells. Intranasal administration of telmisartan (1 mg/kg/day) for up to two months significantly reduced amyloid burden and CD11b expression (a marker for microglia) both in the cortex and hipoccampus of 5XFAD. Based on the current view of RAS and our data, showing reduced amyloid burden and glial activation in the brains of 5XFAD transgenic mice, one may envision potential intervention with the progression of glial activation and AD by using AT1R blockers

Intranasal administration of telmisartan decreases amyloid plaques and CD11b staining in the cortex and hippocampus of 4-month old 5XFAD mice.

<p>Mice were treated with telmisartan (Tel) or vehicle (N,N-dimethylformamide/polyethylene glycol 400/saline (2:6:2) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0155823#pone.0155823.ref047" target="_blank">47</a>]) for 8 weeks. The brains of 4-month-old mice were sectioned and immunolabeled with anti-Aβ (red) and anti-CD11b (green) antibodies and countersained with DAPI (blue). (<b>a, c</b>) Representative cortical sections from WT or 5XFAD mice treated with 1 mg/kg/day telmisartan or with vehicle. (<b>e, g</b>) Representative hippocampal sections of WT or 5XFAD mice treated with 1 mg/kg/day telmisartan or with vehicle. Each experiment included 6 mice per group (n = 18 in total). (<b>b, d, f, h</b>) Quantification of the average sum of Aβ-stained area <b>(b, f)</b> or of CD11b-stained area <b>(d, h)</b>, represented as the mean ± SEM percentage of stained area in the corresponding vehicle-treated group in at least 3 determinants. Statistical significance was determined using one-way ANOVA, followed by a Tukey—Kramer Multiple Comparison Test. ***P<0.001 vs. WT+Tel; ^^P<0.01 vs. 5XFAD+vehicle; ^^^P<0.001 vs. 5XFAD+vehicle. Scale bar is 200 μm.</p

Intranasal administration of telmisartan decreases amyloid plaques and CD11b staining in the cortex of 3-month-old 5XFAD mice.

<p>Mice were treated with telmisartan (Tel) or with vehicle (N,N-dimethylformamide/polyethylene glycol 400/saline (2:6:2) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0155823#pone.0155823.ref047" target="_blank">47</a>]) for 3.5 weeks, and their brains were sectioned and immunolabeled with anti-Aβ (red) and anti-CD11b (green) antibodies and countersained with DAPI (blue). <b>(a, c)</b> Representative cortex brain section of WT or 5XFAD mice treated with 1 mg/kg/day telmisartan or with vehicle. Each experiment included 5 mice per group (n = 15 in total). (<b>b, d</b>) Quantification of the average sum of Aβ-stained area <b>(b)</b> and of CD11b-stained area <b>(d)</b>, represented as the mean ± SEM percentage of stained area in the corresponding vehicle-treated group, in at least 3 determinaions. Statistical significance was determined using one-way ANOVA, followed by a Tukey—Kramer Multiple Comparison Test. **P<0.01 vs. WT+Tel; ***P<0.001 vs. WT+Tel, ^^P<0.01 vs. 5XFAD+ vehicle; ^^^P<0.001 vs. 5XFAD + vehicle. <b>(e, f)</b> Representative hippocampal section of 5XFAD mice treated with vehicle. Scale bar is 200 μm.</p

Telmisartan attenuated LPS-induced TNF-α and IL1-β release from BV2 microglia cells.

<p>Cells were incubated with LPS (7 ng/ml) in the presence or absence of telmisartan (Tel), at 1 μM or 5 μM, for 24h. Media were collected and analyzed for TNF-α and IL1-β levels and cells were counted. <i>Insets</i>: TNF-α and IL1-β levels measured in non-stimulated cells treated with Tel at 1 μM or 5 μM. Data presented as means ± SEM and are representatives of 2–3 independent experiments (overall n = 8–12). Statistical significance was determined using one-way ANOVA, followed by a Tukey—Kramer Multiple Comparison Test. ***P < 0.001 vs. control (non-stimulated cells); ^^^P < 0.001 vs. LPS; ^###P < 0.001 vs. LPS+Telmisartan 1μM; NS (non-significant) vs. control.</p

Telmisartan decreased iNOS expression in LPS-induced BV2 microglia.

<p>Cells were incubated with LPS (7 ng/ml) in the presence or absence of telmisartan (Tel), at 1 μM or 5 μM, for 24h. 40 μg protein of whole cell lysate was loaded on 7.5% polyacrylamide-SDS gels. Analysis of iNOS was performed using antibodies against iNOS (130 kDa) and β-actin (40 kDa). Results are representative of two independent experiments and are presented as means ± SEM (overall n = 4–6). ***P<0.001 vs. control; ^^^P<0.001 vs. LPS.</p

Intranasal administration of perindopril decreases amyloid plaques and CD11b staining in the cortex of 3-month old 5XFAD mice.

<p>Mice were treated with perindopril or vehicle (saline) for 3.5 weeks. The brains of 3-month-old mice were sectioned and immunolabeled with anti-Aβ (red) and anti-CD11b (green) antibodies and countersained with DAPI (blue). <b>(a, c)</b> Representative brain section of WT or 5XFAD mice treated with 1 mg/kg/day perindopril or with vehicle. Each experiment included 5 mice per group (n = 15 in total). (<b>b, d)</b> Quantification of the average sum of Aβ-stained area <b>(b)</b> or of CD11b-stained area <b>(d)</b>, are represented as the mean ± SEM percentage of stained area in the corresponding vehicle-treated group in at least 3 determinants. Statistical significance was determined using one-way ANOVA, followed by a Tukey—Kramer Multiple Comparison Test. **P<0.01 vs. WT+perindopril; ***P<0.001 vs. WT+perindopril; ^^^P<0.001 vs. 5XFAD+vehicle. Scale bar is 200 μm.</p

Maternal and Neonatal Immune Responses Following COVID-19 Infection and Vaccinations in Pregnancy

The objective of the study was to compare the maternal and neonatal humoral immune responses among different groups of women, namely those vaccinated by the BNT162b2 vaccine, not vaccinated, and COVID-19-recovered parturient women at the time of delivery. This is a prospective cohort study of pregnant women, divided into four groups: Group A &ldquo;Recovered&rdquo;&mdash;recovered and not vaccinated. Group B &ldquo;Second Vaccination&rdquo;&mdash;first and second doses only. Group C &ldquo;Third Vaccination&rdquo;&mdash;third dose. Group D &ldquo;No Third Vaccination&rdquo;&mdash;women eligible for the third dose of the vaccine but did not receive it. Maternal and umbilical cord blood were sampled and tested for SARS-CoV-2 IgG antibodies on admittance to labor and immediately postpartum, respectively. Maternal serum SARS-CoV-2 IgG levels were significantly higher among Group C compared to Group B (741.6 (514.5&ndash;1069) vs. 333.5 (327&ndash;340.2), respectively). Both groups had higher antibody levels compared to Groups A and D (113.5 (61.62&ndash;209.1) and 57.99 (32.93&ndash;102.1), respectively). Similarly, umbilical cord blood SARS-CoV-2 IgG levels were also highest among Group C compared to the other three groups (1269 (953.4&ndash;1690) vs. Group B, 322.6 (305.6&ndash;340.5), Group A, 109 (49.01&ndash;242.6), and Group D, 103.9 (48.59&ndash;222), respectively). In conclusion, pregnant women who were fully vaccinated with three dosages before delivery generated the highest levels of maternal and neonatal SARS-CoV-2 IgG antibodies