Targeting ryanodine receptor type 2 to mitigate chemotherapy-induced neurocognitive impairments in mice.

Chemotherapy-induced cognitive dysfunction (chemobrain) is an important adverse sequela of chemotherapy. Chemobrain has been identified by the National Cancer Institute as a poorly understood problem for which current management or treatment strategies are limited or ineffective. Here, we show that chemotherapy treatment with doxorubicin (DOX) in a breast cancer mouse model induced protein kinase A (PKA) phosphorylation of the neuronal ryanodine receptor/calcium (Ca2+) channel type 2 (RyR2), RyR2 oxidation, RyR2 nitrosylation, RyR2 calstabin2 depletion, and subsequent RyR2 Ca2+ leakiness. Chemotherapy was furthermore associated with abnormalities in brain glucose metabolism and neurocognitive dysfunction in breast cancer mice. RyR2 leakiness and cognitive dysfunction could be ameliorated by treatment with a small molecule Rycal drug (S107). Chemobrain was also found in noncancer mice treated with DOX or methotrexate and 5-fluorouracil and could be prevented by treatment with S107. Genetic ablation of the RyR2 PKA phosphorylation site (RyR2-S2808A) also prevented the development of chemobrain. Chemotherapy increased brain concentrations of the tumor necrosis factor-α and transforming growth factor-ß signaling, suggesting that increased inflammatory signaling might contribute to oxidation-driven biochemical remodeling of RyR2. Proteomics and Gene Ontology analysis indicated that the signaling downstream of chemotherapy-induced leaky RyR2 was linked to the dysregulation of synaptic structure-associated proteins that are involved in neurotransmission. Together, our study points to neuronal Ca2+ dyshomeostasis via leaky RyR2 channels as a potential mechanism contributing to chemobrain, warranting further translational studies.

Synthesis and preliminary biological evaluation of radiolabeled 5-BDBD analogs as new candidate PET radioligands for P2X4 receptor.

P2X4 receptor has become an interesting molecular target for treatment and PET imaging of neuroinflammation and associated brain diseases such as Alzheimer's disease. This study reports the first design, synthesis, radiolabeling and biological evaluation of new candidate PET P2X4 receptor radioligands using 5-BDBD, a specific P2X4 receptor antagonist, as a scaffold. 5-(3-Hydroxyphenyl)-1-[11C]methyl-1,3-dihydro-2H-benzofuro[3,2-e][1,4]diazepin-2-one (N-[11C]Me-5-BDBD analog, [11C]9) and 5-(3-Bromophenyl)-1-[11C]methyl-1,3-dihydro-2H-benzofuro[3,2-e][1,4]diazepin-2-one (N-[11C]Me-5-BDBD, [11C]8c) were prepared from their corresponding desmethylated precursors with [11C]CH3OTf through N-[11C]methylation and isolated by HPLC combined with SPE in 30-50% decay corrected radiochemical yields with 370-1110GBq/µmol specific activity at EOB. 5-(3-[18F]Fluorophenyl)-1,3-dihydro-2H-benzofuro[3,2-e][1,4]diazepin-2-one ([18F]F-5-BDBD, [18F]5a) and 5-(3-(2-[18F]fluoroethoxy)phenyl)-1,3-dihydro-2H-benzofuro[3,2-e][1,4]diazepin-2-one ([18F]FE-5-BDBD, [18F]11) were prepared from their corresponding nitro- and tosylated precursors by nucleophilic substitution with K[18F]F/Kryptofix 2.2.2 and isolated by HPLC-SPE in 5-25% decay corrected radiochemical yields with 111-740GBq/µmol specific activity at EOB. The preliminary biological evaluation of radiolabeled 5-BDBD analogs indicated these new radioligands have similar biological activity with their parent compound 5-BDBD.

Use of a multiantigen detection algorithm for diagnosis of Kaposi's sarcoma-associated herpesvirus infection.

The ability to readily and accurately diagnose Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8) infection in individuals remains a demanding task. Among the available diagnostic methods, sensitivities and specificities range widely, and many are inadequate for large-scale screening studies. We examined a serological algorithm for detecting KSHV in human sera having high sensitivity and specificity. This method uses previously described open reading frame (ORF) K8.1 and ORF65 peptide-based enzyme-linked immunosorbent assays and a novel purified recombinant full-length LANA1 protein. We generated two multiantigen algorithms: one that maximized sensitivity and one that maximized specificity. These serological algorithms were then used to evaluate seroprevalence rates among populations of clinical and epidemiological importance. The serological algorithms yielded sensitivities of 96% and 93% and specificities of 94% and 98% for the more sensitive and specific algorithms, respectively. Among kidney donors, seroprevalence was low, 4.0% (2/50), and similar to that of blood donors (P = 0.46; odds ratio [OR], 1.4; confidence interval [CI], 0.14 to 7.9) using the highly specific algorithm. Using the sensitive algorithm, 8.0% (4/50) were infected compared to 6.4% (16/250) observed among blood donors (OR, 1.3; CI, 0.41 to 4.0; P = 0.43). Among subjects requiring bone marrow transplantation, seroprevalence rates were not elevated compared to those of blood donors (OR, 2.0; 95% CI, 0.10 to 122.9; P = 0.50). Because the need for high-quality KSHV detection methods are warranted and because questions remain about the optimal methods for assessing KSHV infection in individuals, we propose a systematic approach to standardize and optimize the assessment of KSHV infection rates using a combination of established and novel serological assays and methods.

Kaposi sarcoma-associated herpesvirus and primary and secondary pulmonary hypertension.

BACKGROUND: Kaposi sarcoma-associated herpesvirus (KSHV) has been implicated as a factor in the pathogenesis of primary pulmonary hypertension (PPH). We conducted a case-control study of patients with PPH and pulmonary hypertension (PH) associated with other disorders (secondary PH) to look for evidence of KSHV infection. MATERIALS AND METHODS: The study population was composed of patients with a diagnosis of PH at the University of California San Francisco Medical Center Department of Cardiology between July and November 2003. Serologic testing for KSHV was performed using enzyme-linked immunosorbent assays based on peptides from open reading frame-65 and K8.1, using sera from 19 patients with PPH, 29 patients with secondary PH, and 150 control subjects RESULTS: The overall seroprevalence of KSHV among all study participants was 2.0%. The rate among control subjects was 0.7% (1 of 150 subjects); among the study participants with PPH, we found no evidence of KSHV infection (0 of 19 patients). There was no significant difference between the observed seroprevalence of KSHV among patients with PPH compared to control subjects (p = 0.89). Of the 29 patients with a diagnosis of secondary PH, 3 patients (10.3%) were KSHV seropositive. Significantly, two of the three KSHV-infected secondary PH patients were also HIV positive, a known independent risk factor for KSHV infection and secondary PH. CONCLUSION: Our data do not support KSHV infection having a significant role in PPH or non-HIV-associated secondary PH compared to age- and gender-matched control subjects.