NF-κB: a new player in angiostatic therapy

Angiogenesis is considered a promising target in the treatment of cancer. Most of the angiogenesis inhibitors in late-stage clinical testing or approved for the treatment of cancer act indirectly on endothelial cells. They either neutralize angiogenic growth factors from the circulation or block the signaling pathways activated by these growth factors. Another group of angiogenesis inhibitors are the direct angiostatic compounds. These agents have a direct effect on the endothelium, affecting cellular regulatory pathways, independently of the tumor cells. The reason that this category of agents is lagging behind regarding their translation to the clinic may be the lack of sufficient knowledge on the mechanism of action of these compounds. The transcription factor NF-κB has been recently connected with multiple aspects of angiogenesis. In addition, several recent studies report that angiogenesis inhibition is associated to NF-κB activation. This is of special interest since in tumor cells NF-κB activation has been associated to inhibition of apoptosis and currently novel treatment strategies are being developed based on inhibition of NF-κB. The paradigm that systemic NF-κB inhibition can serve as an anti-cancer strategy, therefore, might need to be re-evaluated. Based on recent data, it might be speculated that NF-κB activation, when performed specifically in endothelial cells, could be an efficient strategy for the treatment of cancer

Persistent central nervous system immune activation following more than 10 years of effective HIV antiretroviral treatment

OBJECTIVE: Low-grade immune activation is common in people living with HIV (PLHIV), despite long-term viral suppression by antiretroviral therapy (ART). The clinical significance of this activation remains unclear. The aim of this study was to examine residual intrathecal immune activation in relation to signs of neuronal injury and neurocognitive impairment in PLHIV who had been virally suppressed on ART for more than 10 years. DESIGN/METHOD: Twenty neuroasymptomatic PLHIV on suppressive ART for a median of 13.2 years were retrospectively identified from the longitudinal prospective Gothenburg HIV cerebrospinal fluid (CSF) study. HIV-RNA, neopterin, and neurofilament light protein (NFL) levels were measured in paired plasma and CSF samples. Pretreatment samples were available for 14 patients. Cognitive function was assessed by CogState at follow-up. RESULTS:: CSF neopterin decreased from a median (IQR) of 17.8 (10.6–29.7) to 6.1 (4.6–8.0) nmol/l during treatment (P < 0.001). In 11 out of 20 participants (55%), CSF neopterin levels were above the upper normal reference limit (5.8 nmol/l) at follow-up. Age-adjusted CSF NFL decreased to within-normal levels from a median of (IQR) 1179 (557–2707) to 415 (292–610) ng/l (P < 0.001). No significant correlations were found between CSF neopterin and CSF NFL or neurocognitive performance. CONCLUSION: Although CSF neopterin decreased significantly, more than 50% of the patients had CSF concentrations above the upper normal reference value despite more than 10 years of suppressive ART. We found no correlation between CSF neopterin, CSF NFL or neurocognitive performance at follow-up, indicating that low-grade immune activation during suppressive ART may be clinically benign

Development of a New Biomechanical ex vivo Perfusion System - Studies on effects of biomechanical and inflammatory stress on hemostatic genes in human vascular endothelium

The vascular endothelium is a multifunctional interface constantly exposed to biomechanical forces such as shear and tensile stress. Biomechanical stress is involved in the pathophysiological process of the vessel wall and thus affects vascular remodeling, atherosclerosis and thrombogenesis. Many different systems have been designed to subject endothelial cells to mechanical stress. However, previous systems have had large limitations in creating physiologically relevant biomechanical stress protocols. Therefore, there is a need for more refined biological perfusion systems that as accurately as possible mimics the in vivo conditions. In the present work, a new biomechanical ex vivo perfusion system for integrative physiological and molecular biology studies of intact vessels of different sizes as well as artificial vessels was developed. This model was constructed for advanced perfusion protocols under strictly controlled biomechanical (shear stress, tensile stress) as well as metabolic (temperature, pH, oxygen tension) conditions. The system enables monitoring and regulation of vessel lumen diameter, shear stress, mean pressure, variable pulsatile pressure and flow profiles, and diastolic reversed flow. The vessel lumen measuring technique is based on detection of the amount of flourescein over a vessel segment. A combination of flow resistances, on/off switches and capacitances creates a wide range of possible combinations of pulsatile pressures and flow profiles. The perfusion platform was extensively evaluated technically as well as biologically by perfusion of high precision made glass capillaries, human umbilical arteries as well as endothelialized artificial vessels. Artificial vessels with a confluent human umbilical vein endothelial cell layer were exposed to different levels of shear stress or different levels of static or pulsatile pressure. Shear stress was a more powerful stimulus than static or pulsatile tensile stress. While shear stress affected mRNA expression of all six studied genes (t-PA, PAI-1, u-PA, thrombomodulin, eNOS and VCAM-1), neither gene was found to be regulated by tensile stress. Shear stress suppressed t-PA and VCAM-1 in a dose response dependent way. The expression of thrombomodulin was also reduced by shear stress. u-PA, eNOS and PAI-1 were induced by shear stress, but showed no obvious dose response effect for these genes. Further, the unexpected suppression of t-PA by shear stress was studied by using mechanistic experiments with pharmacologic inhibitors. Our data indicate that the suppressive effect of shear stress on t-PA was mediated by suppression of JNK and not by p38 MAPK and ERK1/2. The interplay between inflammatory stress and different combination of tensile as well as shear stress was studied on six key anti- and pro-thrombotic genes in HUVEC. The endothelial cell response to TNF-α was not modulated by tensile stress. Again, shear stress was a more potent stimulus. Shear stress counteracted the cytokine-induced expression of VCAM-1, and the cytokine-suppressed expression of thrombomodulin and eNOS. Shear stress and TNF-α additively induced PAI-1, whereas shear stress blocked the cytokine effect on t-PA and u-PA. In conclusion, these findings illustrate that biomechanical forces, particularly shear stress, have important regulatory effects on endothelial gene function. A possible pathophysiological scenario is that an unfavourable hemodynamic milieu leads to a lower threshold for the induction of genes related to endothelial dysfunction in lesion-prone areas upon negative stress, such as inflammation