Boffito, M. | bioRxiv Science

bioRxiv2023

Role of the NO-GC/cGMP signaling pathway in platelet biomechanics

Cyclic guanosine monophosphate (cGMP) is a second messenger produced by the NO-sensitive guanylyl cyclase (NO-GC) enzyme. In platelets, the NO-GC/cGMP pathway inhibits aggregation. One aspect of the inhibitory mechanism involves changes in the cytoskeleton; however, the molecular mechanisms underlying platelet inhibition and its correlation with cytoskeletal cellular stiffness are poorly understood. We measured the cellular stiffness of individual platelets after treatment with the NO-GC stimulator riociguat or the NO-GC activator cinaciguat, using scanning ion conductance microscopy (SICM). We quantified changes in platelet shape using deep learning-based platelet morphometry. Cytoskeletal actin polymerization and platelet activation were measured by co-immunostaining F-actin and P-selectin, respectively. To test for clinical applicability of NO-GC stimulators in the context of increased thrombogenicity risk, we investigated the effect of riociguat on platelets from human immunodeficiency virus (HIV)-positive patients taking abacavir sulphate (ABC)-containing regimens, compared with HIV-negative volunteers. Stimulation of human and murine platelets with the NO-GC stimulator riociguat or with the NO-GC activator cinaciguat downregulated P-selectin expression, decreased F-actin polymerization, and decreased cellular stiffness by {approx}50%, compared to vehicle control. In addition, platelets became more circular, indicating decreased activation. Riociguat did not cause any change in platelet aggregation or circularity in HIV-positive patients taking ABC-containing regimens. These results corroborate a functional role of the NO-GC enzyme in platelet biomechanics (cellular stiffness) in correlation with the inhibition of platelet activation and morphological changes. The observed changes in stiffness and platelet shape therefore demonstrate the possibility of pharmacologically targeting the NO-GC/cGMP pathway.

biochemistry↗

bioRxiv2019

Evaluation of the psychometric properties of the HIV Disability Questionnaire among adults living with HIV in the United Kingdom

ObjectiveTo evaluate the psychometric properties of the HIV Disability Questionnaire (HDQ) among adults living with HIV in London, United Kingdom (UK). MethodsThis is a cross-sectional measurement study. We recruited and administered the self-reported HDQ, seven criterion measures, and a demographic questionnaire with adults living with HIV accessing HIV care. We determined median and interquartile ranges (IQR) for disability presence, severity and episodic scores (range 0-100). We calculated Cronbachs alpha () Kuder-Richardson-20 (KR-20) statistics for disability and episodic scores respectively (internal consistency reliability), smallest detectable change (SDC) for each HDQ severity item and domain (precision), and tested 36 a priori hypotheses assessing correlations between HDQ and criterion scores (construct validity). ResultsOf N=243 participants, all were male, median age 40 years, 94% currently taking antiretroviral therapy, and 22% living with [≥]2 concurrent health conditions. Median HDQ domain scores ranged from 0 (IQR: 0,7) (difficulties with day-to-day activities domain) to 27 (IQR: 14, 41) (uncertainty domain). Cronbachs alpha for the HDQ severity scale ranged from 0.85 (95% Confidence Interval (CI): 0.80-0.90) in the cognitive domain to 0.93 (95%CI: 0.91-0.94) in the mental-emotional domain. The KR-20 statistic for the HDQ episodic scale ranged from 0.74 (95%CI: 0.66-0.83) in the cognitive domain to 0.91 (95%CI: 0.89-0.94) in the uncertainty domain. SDC ranged from 7.3-15.0 points on the HDQ severity scale for difficulties with day-to-day activities and cognitive symptoms domains, respectively. The majority of the construct validity hypotheses (n=30/36, 83%) were confirmed. ConclusionsThe HDQ possesses internal consistency reliability and construct validity with varied precision when administered to males living with HIV in London, UK. Clinicians and researchers may use the HDQ to measure the nature and extent of disability experienced by PLHIV in the UK, and to inform HIV service provision to address the health-related challenges among PLHIV.

epidemiology↗