Endothelial dysfunction after repeated Chlamydia pneumoniae infection in apolipoprotein E-knockout mice

BACKGROUND

Arterial relaxation is largely regulated by endothelial nitric oxide (NO). Its diminished activity has been associated with incipient atherosclerosis. We investigated the endothelium-dependent relaxation of aorta in apolipoprotein E-knockout (apoE-KO) mice exposed to single or repeated Chlamydia pneumoniae inoculation.

METHODS AND RESULTS

Forty-eight apoE-KO mice, 8 weeks old, were inoculated intranasally with C pneumoniae (n=24) or saline (n=24) every 2 weeks over a 6-week period. Twenty mice (10 infected and 10 controls) were killed at 2 weeks and 6 weeks, respectively, after the first inoculation. The smooth muscle tone of aortic rings was measured in vitro at both time points. The norepinephrine-precontracted thoracic aortic rings were successively exposed to methacholine in the absence and presence of N:(G)-nitro-L-arginine methyl ester (L-NAME) and diclofenac. The methacholine-induced relaxation was attenuated in the infected mice at 6 weeks in both the absence and presence of L-NAME (P:<0.05 and P:<0.01, respectively). When administered together with L-NAME, diclofenac enhanced the relaxation of the L-NAME-pretreated aortas in infected mice at 2 weeks (P:<0.05) but not in noninfected mice. The relaxation response from infected mice tended to differ in the same manner at 6 weeks (P:<0.1). No intimal thickening was detected at either time point.

CONCLUSIONS

C pneumoniae impairs arterial endothelial function, and the NO pathway is principally involved. Cyclooxygenase-dependent vasoconstricting products may also account for the infection-induced impaired relaxation. These findings further support the role of C pneumoniae infection in atherosclerosis development.

Modulation of antibody kinetics by the cell membrane active agent tween 80 in vivo

The modulation of antibody uptake by the tumour has been crucial in many radioantibody applications for delivering optimal dose for therapy. Our approach was to modulate the monoclonal antibody (MAb) uptake by using a surface detergent (Tween 80). Our Mab was raised against the tyrosine kinase receptor recombinant protein tie. Mice bearing Lewis lung carcinoma xenografts were studied after injecting I-125 labeled IgG1 subclass monoclonal antibody 3c4c7g6 tie protein. The biodistribution was studied at 4, 24, 48, 72, 96 and 120 hours after intravenous injection. Tween 80 was administered intratumourally, 0.04% of tumour volume. Without Tween 80 the antibody half-lives in tumour were 90 hours, in blood 39 hours, in liver 22 hours, and in kidney 52 hours, whereas using intratumoural Tween 80 half-lives were in tumour 66 hours, in blood 26 hours, in liver 27.5 hours and in kidney 27.5 hours. Although the Tween manipulation did not increase uptakes by organs, it did enhance clearance rate from the blood. This data indicates that antibody dose can be optimized by surface detergent, enhancing clearance without any burden to critical organs. This might be crucial in adjusting delivered radioimmunotherapy dose by changing the mean residence time of an antibody.

In vivo modulators of antibody kinetics

The aim of the present study was to summarize the effect of in vivo modulation of antibody kinetics and to present new data on the in vivo effect of the cell membrane active detergent Tween 80 and the cytokine interleukin-2 (IL-2) on the accumulation and clearance of a radioactive antibody. Mice bearing Lewis lung carcinoma xenografts and rats bearing DMBA-induced mammary carcinomas were studied after injecting I-125 labeled IgG1 monoclonal antibody (3c4c7g6) raised against a tyrosine kinase receptor protein Tie. Expression of Tie is known to be abundant in vascular endothelia and possibly related to malignant angiogenesis. Tween 80 was administered intratumorally (0.04% of tumor volume), whereas IL-2 was administered intraperitoneally. In the Lewis lung tumor model, the absolute tumor uptake varied between 2 and 5% ID/g, and maximum uptake was achieved after 24 h with Tween, and after 48 h without Tween. Tween manipulation did not increase the uptake in any normal organ, but it enhanced antibody clearance from the blood. In the DMBA rat model, IL-2 had no effect on blood clearance, but enhanced the uptake of Tie antibody into the tumor from 2.5-0.9 to 4.5-0.4% ID/g at 48 h. These data indicate that antibody biodistribution and pharmacokinetics can be modulated by a surface detergent and a cytokine, giving decreased exposure to critical organs, and increased uptake into the tumor. This type of manipulation provides an opportunity to optimize radioimmunotherapy.

The subrenal capsule assay in selecting chemotherapy for ovarian cancer: a prospective randomized trial

In order to find out whether the response rate and survival in epithelial ovarian cancer can be improved by aid of sensitivity testing with the subrenal capsule assay (SRCA), 196 patients with FIGO Stage II-IV epithelial ovarian cancer were randomized to be treated with either cyclophosphamide-doxorubicin-cisplatin (CAP) or SRCA-guided chemotherapy. The drug combinations tested with the SRCA were (1) cyclophosphamide-doxorubicin-carboplatin (CACAR), (2) CAP, (3) carboquone-methotrexate-tegafur (CQ-MTX-TEG), (4) cisplatin-etoposide-hexamethyl-melamine (P-VP-HXM), and (5) bleomycin-epirubicin-cisplatin (BEP). A total of 132 patients (CAP, 69; SRCA, 63) were eligible for efficacy analysis based on relaparotomy findings. The overall response rate was 59% in the CAP arm and 62% in the SRCA arm. In the SRCA arm, 16 patients were treated with CACAR, 24 with CAP, 10 with CQ-MTX-TEG, 11 with P-VP-HXM, and 2 with BEP. The response rate to CACAR was 63% and to SRCA-CAP was 75%. The number of complete responses was higher when CAP was given as guided by the assay than when given at random (14/24 vs 23/69; P = 0.03, Pearson chi 2). Survival curves as estimated by Kaplan-Meier method gave a median survival of 24 (SE = 4) months to the SRCA arm and 28 (SE = 5) for the CAP arm (P = 0.7; log-rank test). Because no survival benefit was achieved, the SRCA obviously needs further development before it can be routinely recommended in the choice of first-line chemotherapy for patients with ovarian cancer.

Radioimmunodetection of prostate cancer by 111In-labeled monoclonal antibody against prostatic acid phosphatase

Purified human prostate acid phosphatase (PAP) was used to generate a specific monoclonal antibody (FC 3001) for detection of PAP expressed by some prostatic carcinomas. DTPA derivatives of MoAb-F(ab')2-fragments were labeled with indium-111 chloride. This labeled antibody was tested in 15 prostate cancer patients who underwent staging pelvic lymphadenectomy; 9 of them received labeled antibody alone whereas 6 received simultaneous injections of labeled and unlabeled antibody with two dose levels (40 or 80 mg). Biodistribution data obtained by direct blood measurements and imaging procedures indicated that simultaneous injection of unlabeled antibody reduced both the blood elimination rate and the accumulation in the liver. Accumulation of the radionuclide in pelvic lymph node metastases was observed in some patients but in a couple of patients accumulation was noted also in normal lymph nodes. The method cannot in its present design replace staging pelvic lymphadenectomy and further studies are needed for elaboration of clinically useful radioimmunodetection methods.

Chemosensitizing effect of an antiestrogen, toremifene, on ovarian cancer

The chemosensitizing effect of an antiestrogen, toremifene, was studied on 2 human ovarian cancer cell lines in vitro and on 3 fresh surgical ovarian tumor explants with the aid of the subrenal capsule assay (SRCA). Also, 11 patients with secondarily drug resistant, recurrent gynecologic cancer (8 ovarian and 3 uterine cancers) were treated with 240 mg toremifene daily for 1 week before each course of cytostatics. Toremifene potentiated the effect of doxorubicin on both cell lines. This was also the case on 1 cell line that was not completely resistant to doxorubicin. The SRCA showed a clear potentiating effect of toremifene only on the tumor overtly resistant to the combination of cisplatin, doxorubicin, and cyclophosphamide. Of the 11 patients treated with toremifene and cytostatics, the response of 8 patients was evaluable: 3 had partial response, 3 no change, and 2 progressive disease. Toremifene seems to have a chemopotentiating effect on gynecologic drug-resistant tumors.