2-Methoxyestradiol Ameliorates Angiotensin II–Induced Hypertension by Inhibiting Cytosolic Phospholipase A 2 α Activity in Female Mice

We tested the hypothesis that CYP1B1 (cytochrome P450 1B1)-17β-estradiol metabolite 2-methoxyestradiol protects against Ang II (angiotensin II)–induced hypertension by inhibiting group IV cPLA 2 α (cytosolic phospholipase A 2 α) activity and production of prohypertensive eicosanoids in female mice. Ang II (700 ng/kg per minute, SC) increased mean arterial blood pressure (BP), systolic and diastolic BP measured by radiotelemetry, renal fibrosis, and reactive oxygen species production in wild-type mice ( cPLA 2 α +/+ /Cyp1b1 +/+ ) that were enhanced by ovariectomy and abolished in intact and ovariectomized -cPLA 2 α −/− /Cyp1b1 +/+ mice. Ang II–induced increase in SBP measured by tail-cuff, renal fibrosis, reactive oxygen species production, and cPLA 2 α activity measured by its phosphorylation in the kidney, and urinary excretion of prostaglandin E 2 and thromboxane A 2 metabolites were enhanced in ovariectomized- cPLA 2 α +/+ /Cyp1b1 +/+ and intact cPLA 2 α +/+ /Cyp1b1 −/− mice. 2-Methoxyestradiol and arachidonic acid metabolism inhibitor 5,8,11,14-eicosatetraynoic acid attenuated the Ang II–induced increase in SBP, renal fibrosis, reactive oxygen species production, and urinary excretion of prostaglandin E 2 , and thromboxane A 2 metabolites in ovariectomized- cPLA 2 α +/+ /Cyp1b1 +/+ and intact cPLA 2 α +/+ /Cyp1b1 −/− mice. Antagonists of prostaglandin E 2 and thromboxane A 2 receptors EP1 and EP3 and TP, respectively, inhibited Ang II–induced increases in SBP and reactive oxygen species production and renal fibrosis in ovariectomized- cPLA 2 α +/+ /Cyp1b1 +/+ and intact cPLA 2 α +/+ /Cyp1b1 −/− mice. These data suggest that CYP1B1-generated metabolite 2-methoxyestradiol mitigates Ang II–induced hypertension and renal fibrosis by inhibiting cPLA 2 α activity, reducing prostaglandin E 2 , and thromboxane A 2 production and stimulating EP1 and EP3 and TP receptors, respectively. Thus, 2-methoxyestradiol and the drugs that selectively block EP1 and EP3 and TP receptors could be useful in treating hypertension and its pathogenesis in females.

Abstract MP63: Cytochrome P450 1B1 Mediated Inhibition Of Group IV Cytosolic Phospholipase A 2 α In Paraventricular Nucleus Protects Female Mice From Angiotensin II-Induced Hypertension, Increased Renal Sympathetic Activity And Proteinuria

Recently we showed that 2-methoxyestradiol (2-ME), an estrogen (E2) metabolite generated by CYP1B1 (cytochrome P450 1B1) in the paraventricular nucleus (PVN), protects female mice from Ang (angiotensin) II-induced hypertension and increased renal sympathetic activity. We also demonstrated that group IV cPLA 2 α (cytosolic phospholipase A 2 α) in the brain contributes to Ang II-induced hypertension in male mice. This study was conducted to determine the contribution of central cPLA 2 α and its relationship to CYP1B1 in Ang II-induced hypertension in female mice. cPLA 2 α knockdown in the PVN by transduction with adenovirus (Ad)-cPLA 2 α-short hairpin (sh)RNA (200 nL, bilaterally, 1.0х10 12 pfu/mL) but not its control Ad-scrambled (Scr)-shRNA (2.5х10 11 pfu/mL) in ovariectomized (OVX) wild-type ( cPLA 2 α +/+ / Cyp1b1 +/+ , n=8/group) and intact cPLA 2 α +/+ / Cyp1b1 -/- (n=12/group) female mice attenuated the effect of Ang II (700 ng/kg/min, subcutaneous, osmotic pump, 2 weeks) to increase the systolic blood pressure (SBP, mmHg) as measured by tail-cuff (Day 12: 129±3 vs 168±7 and 119±3 vs 172±5, respectively, P<0.05). Moreover, reconstitution of cPLA 2 α in the PVN by transduction with Ad-cPLA 2 α-DNA (1.1х10 12 pfu/mL) but not its control Ad-GFP-DNA (1.0х10 11 pfu/mL) in OVX- cPLA 2 α -/- / Cyp1b1 +/+ mice (n=4/group) restored the effect of Ang II to increase SBP (Day 12: 163±7 vs 124±4, P<0.05). Furthermore, Ad-cPLA 2 α-shRNA but not Ad-Scr-shRNA transduction in the PVN in OVX- cPLA 2 α +/+ / Cyp1b1 +/+ and intact cPLA 2 α +/+ / Cyp1b1 -/- mice reduced and Ad-cPLA 2 α-DNA but not Ad-GFP-DNA transduction in the PVN in OVX- cPLA 2 α -/- / Cyp1b1 +/+ mice restored the effect of Ang II to increase the renal sympathetic activity as indicated by urinary norepinephrine level (ng/mL, 324±36 vs 707±94, 359±49 vs 979±70, 690±44 vs 421±43, respectively, n=4/group, P<0.05) and proteinuria (mg/24 hour, 4±1 vs 10±0.4, 3±0.4 vs 7±1, 9±0.8 vs 3±0.7, respectively, n=4/group, P<0.05). These data suggest that E2-CYP1B1 derived metabolite 2-ME protects against Ang II-induced hypertension, renal sympathetic activity, and proteinuria by inhibiting cPLA 2 α activity in the PVN. Thus, 2-ME and/or agents inhibiting cPLA 2 α activity could be useful for treating hypertension and its pathogenesis in females.

Microglia TREM2R47H Alzheimer-linked variant enhances excitatory transmission and reduces LTP via increased TNF-α levels

To study the mechanisms by which the p.R47H variant of the microglia gene and Alzheimer’s disease (AD) risk factor TREM2 increases dementia risk, we created Trem2R47H KI rats. Trem2R47H rats were engineered to produce human Aβ to define human-Aβ-dependent and -independent pathogenic mechanisms triggered by this variant. Interestingly, pre- and peri-adolescent Trem2R47H rats present increased brain concentrations of TNF-α, augmented glutamatergic transmission, suppression of Long-term-Potentiation (LTP), an electrophysiological surrogate of learning and memory, but normal Aβ levels. Acute reduction of TNF-α activity with a neutralizing anti-TNF-α antibody occludes the boost in amplitude of glutamatergic transmission and LTP suppression observed in young Trem2R47H/R47H rats. Thus, the microglia-specific pathogenic Trem2 variant boosts glutamatergic neuronal transmission and suppresses LTP by increasing brain TNF-α concentrations, directly linking microglia to neuronal dysfunction. Future studies will determine whether this phenomenon represents an early, Aβ-independent pathway that facilitates dementia pathogenesis in humans.

Distinct single cell gene expression in peripheral blood monocytes correlates with tumor necrosis factor inhibitor treatment response groups defined by type I interferon in rheumatoid arthritis

Previously, we demonstrated that type I IFN (IFNβ/α) activity can predict non-response to tumor necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA). In this study, we examine the biology of TNFi non-response in monocytes from RA patients. We compared single cell gene expression in purified classical (CL, n=342) and non-classical (NC, n=359) monocytes. RA patients were grouped according to their pre-TNFi IFNβ/α activity: those likely to have EULAR no response (non-response group, IFNβ/α 0 or >1.3, n=9) and those likely to have EULAR moderate or good response (response group, IFNβ/α > 0 and ≤1.3, n=6). Major differences in gene expression were apparent in principal component and unsupervised cluster analyses. CL monocytes from the non-response group were unlikely to express JAK1 and IFI27 (p <0.0001 and p 0.0005, respectively). In NC monocytes from the same group, expression of IFNAR1, IRF1, TNFA, TLR4 (p ≤0.0001 for each) and others was enriched. Interestingly, JAK1 expression was absent in CL and NC monocytes from 9 patients. This pattern strongly associated with the non-response IFNβ/α group, suggesting a major biological difference between JAK1 expressors and non-expressors. The type I IFN activity that was previously found to predict TNFi response associated with changes in gene expression in monocytes that suggest differential IFN pathway activation in RA patients who are either likely to respond or to have no response to TNFi. This work could suggest mechanisms for TNFi non-response, and potential therapeutic strategies for those patients unlikely to respond to TNFi.

3521 Distinct single cell gene expression in peripheral blood monocytes correlates with treatment response groups to TNF-alpha inhibition in rheumatoid arthritis

OBJECTIVES/SPECIFIC AIMS: The cellular mechanisms that underlie the IFNβ/α ratio that predicts response are not known. Effects of IFN on single immune cells may be masked in whole blood or mixed cell populations. By studying the effect of IFNβ/α activity ratio on individual monocytes, we can determine the functional impact of the IFN ratio and suggest the cellular mechanisms that underlie response/non-response to TNFi therapy in RA. METHODS/STUDY POPULATION: We used single cell analysis to investigate whether monocyte gene expression differs significantly between RA patients according to their pre-TNFi serum IFN-β/α ratio. Single classical (CL) and non-classical (NC) blood-derived monocytes were isolated from 15 seropositive RA subjects prior to biologic therapy. Subjects were grouped by pre-TNFi serum IFN-β/α ratio into two groups, those with a high IFN-β/α ratio (≥1.3, n = 6) and those with a low IFN-β/α ratio (<1.3, n = 9). 87 target genes were analyzed. Genes that varied significantly between the groups by categorical analyses were tested in multivariate logistic regression models. RESULTS/ANTICIPATED RESULTS: Every participant was seropositive for rheumatoid factor and antibodies to cyclic citrullinated peptide. Among the participants in the groups, there were no significant differences in age or DAS scores (P>0.05). The treatments were comparable and none were being treated with biologic therapy. There were striking differences in monocyte gene expression between patients with pre-treatment blood IFNβ/α activity <1.3 and ≥1.3. Expression of (1) key type I IFN pathway genes (JAK1, STAT2, IFIT2, IFIH1, PRDM1); (2) IL12; (3) CD36; and (4) CTLA4 were the strongest differentiators between groups (p<0.0001 for each, corrected for multiple comparisons). DISCUSSION/SIGNIFICANCE OF IMPACT: In this study we were able to measure gene expression in single monocytes from seropositive RA patients prior to biologic treatment. Within-cell co-expression patterns demonstrate biological differences in monocytes of RA patients with an IFNβ/α ≥1.3, the ratio of type I IFNs which predicts non-response to TNFi. The data suggest that there may be differential IFN production and pathway activation in patients who do not respond to TNFi. The increased expression of CD36 in monocytes from RA patients with high IFN β/α activity may be a reflection of increased “foam cells” in the inflamed tissue of patients who do not respond to TNFi. Enrichment of CTLA4 in those with high serum IFNβ/α suggests that CTLA4-Ig may be less likely to be an effective alternative for someone who is not likely to respond to TNFi. Current work includes determining whether the peripheral blood findings reflect altered cellular composition, type I IFN production and signaling in the synovium. Significance: This work will help to develop a more individualized approach to therapy in RA and determine an immunological basis of response/non-response to TNFi.