Targeting Impaired Antimicrobial Immunity in the Brain for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and aging is the most common risk factor for developing the disease. The etiology of AD is not known but AD may be considered as a clinical syndrome with multiple causal pathways contributing to it. The amyloid cascade hypothesis, claiming that excess production or reduced clearance of amyloid-beta (Aβ) and its aggregation into amyloid plaques, was accepted for a long time as the main cause of AD. However, many studies showed that Aβ is a frequent consequence of many challenges/pathologic processes occurring in the brain for decades. A key factor, sustained by experimental data, is that low-grade infection leading to production and deposition of Aβ, which has antimicrobial activity, precedes the development of clinically apparent AD. This infection is chronic, low grade, largely clinically silent for decades because of a nearly efficient antimicrobial immune response in the brain. A chronic inflammatory state is induced that results in neurodegeneration. Interventions that appear to prevent, retard or mitigate the development of AD also appear to modify the disease. In this review, we conceptualize further that the changes in the brain antimicrobial immune response during aging and especially in AD sufferers serve as a foundation that could lead to improved treatment strategies for preventing or decreasing the progression of AD in a disease-modifying treatment.

Expression and Cellular Distribution of P-Glycoprotein and Breast Cancer Resistance Protein in Amyotrophic Lateral Sclerosis Patients

For amyotrophic lateral sclerosis (ALS), achieving and maintaining effective drug levels in the brain is challenging due to the activity of ATP-binding cassette (ABC) transporters which efflux drugs that affect drug exposure and response in the brain. We investigated the expression and cellular distribution of the ABC transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) using immunohistochemistry in spinal cord (SC), motor cortex, and cerebellum from a large cohort of genetically well characterized ALS patients (n = 25) and controls (n = 14). The ALS group included 17 sporadic (sALS) and 8 familial (fALS) patients. Strong P-gp expression was observed in endothelial cells in both control and ALS specimens. Immunohistochemical analysis showed higher P-gp expression in reactive astroglial cells in both gray (ventral horn) and white matter of the SC, as well as in the motor cortex of all ALS patients, as compared with controls. BCRP expression was higher in glia in the SC and in blood vessels and glia in the motor cortex of ALS patients, as compared with controls. P-gp and BCRP immunoreactivity did not differ between sALS and fALS cases. The upregulation of both ABC transporters in the brain may explain multidrug resistance in ALS patients and has implications for the use of both approved and experimental therapeutics.

?Facilitation of primary coronary angioplasty by early start of a glycoprotein 2b/3a inhibitor: results of the ongoing tirofiban in myocardial infarction evaluation (On-TIME) trial

AIM

Although primary angioplasty is effective despite additional transportation delay, improved patency before PCI might be obtained by starting pharmacological pre-treatment before transportation.

METHODS AND RESULTS

From June 2001 to November 2002, 507 patients with acute myocardial infarction, who were transferred to a PCI centre, were randomised to early, pre-hospital initiation of Tirofiban (Early) or to initiation in the catheterisation laboratory (Late). The primary end-point was TIMI flow grade 3 of the infarct-related vessel (IRV) at initial angiography, as assessed by an independent core-lab. The effect of Tirofiban on each TIMI flow component, the presence of thrombus at initial angiography and pre-PCI myocardial blush grade were secondary end-points. A large proportion of patients (41%) was diagnosed and randomised in the ambulance, without intervention of a physician. In the Early group, Tirofiban was administered a median of 59 min (range 11-178 min) earlier than in the Late group. At initial angiography, TIMI 3 flow was present in 19% the Early group and in 15% in the Late group (P = 0.22). The combined incidence of TIMI 2 or 3 flow was present in 43% in the Early group and in 34% in the Late group, respectively (P = 0.04). Thrombus or a fresh occlusion was present in 60% and 73% in the Early and Late group, respectively (P = 0.002). A pre-PCI myocardial blush grades 2 or 3 was more often present in the Early group (30% vs. 22%, P = 0.04). However, no difference in TIMI 3 flow or myocardial blush grade was found between the groups, post-PCI. At one-year follow-up, the combined incidence of death or recurrent MI was not different between the groups (7.0% vs. 7.0%, P = 0.99).

CONCLUSION

Early initiation of Tirofiban did not improve initial TIMI 3 flow of the IRV significantly. Despite a better patency (TIMI 2 or 3 flow), a lower prevalence of thrombus or fresh occlusion and a better myocardial perfusion in the infarct-related region pre-PCI, no beneficial effect on post-PCI angiographic or clinical outcome was found, as compared to initiation of Tirofiban in the catheterisation laboratory.

A multicenter study of the tolerability of tirofiban versus placebo in patients undergoing planned intracoronary stent placement

BACKGROUND

The use of intravenous glycoprotein IIb/IIIa-receptor antagonists has been shown to improve outcomes in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Tirofiban has shown benefit in a wide range of patients presenting with acute coronary syndromes. Although this agent has been used in patients undergoing percutaneous coronary intervention, a literature search identified no prospective data comparing tirofiban with placebo in patients undergoing planned intracoronary stent placement.

OBJECTIVE

This study examined the tolerability of tirofiban in patients undergoing percutaneous intervention with planned intracoronary stent placement.

METHODS

This was a multinational, multicenter, prospective, randomized, double-blind, placebo-controlled trial in patients scheduled to undergo PTCA with planned intracoronary stent placement. Patients were randomized in a 3:2 ratio to receive tirofiban as an intravenous bolus (10 microg/kg over 3 minutes) and maintenance infusion (0.10 microg/kg per minute for 36 hours) or a bolus and infusion of placebo. All patients received periprocedural aspirin and heparin and an optional postprocedural thienopyridine (ticlopidine or clopidogrel). Laboratory and safety monitoring were performed throughout the 36 hours after the procedure and at hour 40 or hospital discharge. The primary end point was the proportion of patients with bleeding, defined according to Thrombolysis in Myocardial Infarction (TIMI) trial criteria. The number of patients with cardiac events (death, myo- cardial infarction, urgent revascularization) during the first 30 days after stent placement was also assessed.

RESULTS

Eight hundred ninety-four patients (536 tirofiban, 358 placebo) were enrolled, all of whom received aspirin and heparin periprocedurally and optional ticlopidine or clopidogrel after the procedure. No significant between-group differences were observed in the incidence of TIMI major bleeding (0.2% tirofiban, 0.6% placebo) or any TIMI bleeding (3.2% and 1.7%, respectively). The incidence of TIMI minor bleeding was higher with tirofiban than with placebo (2.8% vs 0.6%). The 30-day incidence of the composite end point of any cardiac event was 3.9% in both groups.

CONCLUSIONS

On a background of concomitant aspirin, heparin, and a thienopyridine, tirofiban was generally well tolerated in patients undergoing PTCA with planned intracoronary stent placement. Further investigation is needed to ascertain the optimal dosing of tirofiban and heparin to achieve reductions in ischemic complications of intracoronary stenting with an acceptable incidence of bleeding complications.

Effects of losartan and candesartan monotherapy and losartan/hydrochlorothiazide combination therapy in patients with mild to moderate hypertension. Losartan Trial Investigators

OBJECTIVE

The goal of this multicenter, double-blind, randomized, parallel-group study was to compare the effects of losartan potassium (hereafter referred to as losartan), candesartan cilexitil (hereafter referred to as candesartan), and losartan/hydrochlorothiazide (HCTZ) in patients with mild to moderate hypertension (sitting diastolic blood pressure [SiDBP] 95-115 mm Hg).

METHODS

A total of 1161 patients were randomized in a 2:2:1 ratio to 12 weeks of treatment with losartan 50 mg QD, possibly titrated to 100 mg QD (n = 461); candesartan 8 mg QD, possibly titrated to 16 mg QD (n = 468); or losartan 50 mg QD, possibly titrated to losartan 50 mg plus HCTZ 12.5 mg QD (n = 232). At 6 weeks, the regimens of patients not reaching a goal SiDBP <90 mm Hg were titrated as described, whereas patients achieving this goal continued with low-dose monotherapy. The single primary end point at 12 weeks tested the equivalence of the 2 monotherapy regimens, predefined as a maximum between-treatment difference in the mean change from baseline trough SiDBP of 2.5 mm Hg.

RESULTS

At 12 weeks, changes in SiDBP/sitting systolic blood pressure (SiSBP) of -12.4/-14.4 mm Hg with losartan 50 mg/100 mg and -13.1/-15.8 mm Hg with candesartan 8 mg/16 mg demonstrated equivalence between the 2 monotherapy regimens (95% CI for difference in SiDBP, -1.6 to 0.2). At 12 weeks, the losartan 50 mg/50 mg plus HCTZ 12.5 mg regimen had reduced SiDBP/SiSBP significantly more (-14.3/-18.0 mm Hg) than either the candesartan 8 mg/16 mg (SiDBP, P = 0.045; SiSBP, P = 0.017) or losartan 50 mg/100 mg regimen (SiDBP and SiSBP, P = 0.001). During the last 6 weeks, patients whose regimen had been titrated to losartan 50 mg plus HCTZ 12.5 mg (n = 114) showed a greater reduction in SiDBP/SiSBP (-14.5/ -18.7 mm Hg) than did those whose regimen had been titrated to either losartan 100 mg (-10.5/-12.3 mm Hg; n = 211) or candesartan 16 mg (-11.5/-13.2 mm Hg; n = 206), representing a clinically meaningful > or = 2.5-mm Hg) difference. All 3 treatments were well tolerated, with few patients experiencing drug-related adverse events (6.9% losartan 50 mg/100 mg, 7.5% candesartan 8 mg/16 mg, 3.0% losartan 50 mg/ 50 mg plus HCTZ 12.5 mg). Candesartan 8 mg/16 mg increased serum uric acid levels (0.13 mg/dL; 95% CI, 0.04 to 0.23), whereas losartan 50 mg/100 mg decreased them (-0.14 mg/dL; 95% CI, -0.24 to -0.04), and losartan 50 mg/50 mg plus HCTZ 12.5 mg left them unchanged (0.06 mg/dL; 95% CI, -0.07 to 0.20).

CONCLUSIONS

Losartan 50 mg/100 mg and candesartan 8 mg/16 mg were comparable treatments in terms of blood pressure reduction. After titration, losartan 50 mg plus HCTZ 12.5 mg was superior to either candesartan 16 mg or losartan 100 mg in reducing hypertension. Losartan, but not candesartan, lowered serum uric acid levels and attenuated the expected increase in uric acid levels with HCTZ 12.5 mg.