Candidates For Pharmacological Intervention Research Articles

Effect of Ultraviolet Radiation and Benzo[a]pyrene Co-Exposure on Skin Biology: Autophagy as a Potential Target.

The skin is the outermost protective barrier of the human body. Its role is to protect against different physical, chemical, biological and environmental stressors. The vast majority of studies have focused on investigating the effects of single environmental stressors on skin homeostasis and the induction of several skin disorders, such as cancer or ageing. On the other hand, much fewer studies have explored the consequences of the co-exposure of skin cells to two or more stressors simultaneously, which is much more realistic. In the present study, we investigated, using mass-spectrometry-based proteomic analysis, the dysregulated biological functions in skin explants after their co-exposure to ultraviolet radiation (UV) and benzo[a]pyrene (BaP). We observed that several biological processes were dysregulated, among which autophagy appeared to be significantly downregulated. Furthermore, immunohistochemistry analysis was carried out to validate the downregulation of the autophagy process further. Altogether, the output of this study provides an insight into the biological responses of skin to combined exposure to UV + BaP and highlights autophagy as a potential target that might be considered in the future as a novel candidate for pharmacological intervention under such stress conditions.

P-hydroxy benzaldehyde revitalizes the microenvironment of peri-infarct cortex in rats after cerebral ischemia-reperfusion

BackgroundThe formation of glial scar around the ischemic core following cerebral blood interruption exerts a protective effect in the subacute phase but impedes neurorepair in the chronic phase. Therefore, the present study aimed to explore whether p-hydroxy benzaldehyde (p-HBA), a phenolic compound isolated from Gastrodia elata Blume, can cut the Gordian knot of glial scar and promote brain repair after cerebral ischemia. MethodsThe effects of p-HBA on neurorepair were evaluated using a rat model of transient middle cerebral artery occlusion (tMCAO). The motor functions were evaluated by neurobehavioral tests, the pathophysiological processes in the peri-infarct cortex (PIC) were detected by viral-based lineage tracking or immunofluorescence staining, and the putative signaling pathway was analyzed by western blot. ResultsAdministration of p-HBA in the acute stage after stroke onset alleviated the motor impairment in tMCAO rats in a time-dependent manner. The corresponding cellular events were inhibition of astrogliosis, facilitating the conversion of reactive astrocytes (RAs) into neurons, and prompting angiogenesis in PIC, thereby protecting the structure of the neurovascular unit (NVU). One of the underlying molecular mechanisms is the activation of the neurogenic switch of the Wnt/β-catenin signaling pathway. Notably, p-HBA only promotes astrocyte-to-neuron conversion in the PIC, and only partial RAs were converted to neurons. This pattern of conversion ensures that the brain structure remains unaltered, and the beneficial role of glial scarring is preserved during the subacute phase after ischemia. ConclusionsThese results provided a potential approach to address the dilemma of glial scarring after brain injury, i.e., the pharmacological promotion of astrocyte-to-neuron conversion in the PIC without interfering with normal brain tissue, which mitigates but does not eliminate the glial scar. Subsequently, the neuron rescue-unfriendly environment is switched to a beneficial reconstruction milieu in PIC, which is conducive to neurorepair. Moreover, p-HBA could be a candidate for pharmacological intervention.

Identification of differentially expressed subpathways via a bilevel consensus scoring of network topology and gene expression.

Identifying differentially expressed subpathways connected to the emergence of a disease that can be considered as candidates for pharmacological intervention, with minimal off-target effects, is a daunting task. In this direction, we present a bilevel subpathway analysis method to identify differentially expressed subpathways that are connected with an experimental condition, while taking into account potential crosstalks between subpathways which arise due to their connectivity in a combined multi-pathway network. The efficacy of the method is demonstrated on a hematopoietic stem cell aging dataset, with findings corroborated using recent literature.

Cellular fatty acid synthase is required for late stages of HIV-1 replication

BackgroundLike all viruses, HIV-1 relies on host systems to replicate. The human purinome consists of approximately two thousand proteins that bind and use purines such as ATP, NADH, and NADPH. By virtue of their purine binding pockets, purinome proteins are highly druggable, and many existing drugs target purine-using enzymes. Leveraging a protein affinity media that uses the purine-binding pocket to capture the entire purinome, we sought to define purine-binding proteins regulated by HIV-1 infection.ResultsUsing purinome capture media, we observed that HIV-1 infection increases intracellular levels of fatty acid synthase (FASN), a NADPH-using enzyme critical to the synthesis of de novo fatty acids. siRNA mediated knockdown of FASN reduced HIV-1 particle production by 80%, and treatment of tissue culture cells or primary PBMCs with Fasnall, a newly described selective FASN inhibitor, reduced HIV-1 virion production by 90% (EC50 = 213 nM). Despite the requirement of FASN for nascent virion production, FASN activity was not required for intracellular Gag protein production, indicating that FASN dependent de novo fatty acid biosynthesis contributes to a late step of HIV-1 replication.ConclusionsHere we show that HIV-1 replication both increases FASN levels and requires host FASN activity. We also report that Fasnall, a novel FASN inhibitor that demonstrates anti-tumor activity in vivo, is a potent and efficacious antiviral, blocking HIV-1 replication in both tissue culture and primary cell models of HIV-1 replication. In adults, most fatty acids are obtained exogenously from the diet, thus making FASN a plausible candidate for pharmacological intervention. In conclusion, we hypothesize that FASN is a novel host dependency factor and that inhibition of FASN activity has the potential to be exploited as an antiretroviral strategy.

Conformational heterogeneity of the calmodulin binding interface.

Calmodulin (CaM) is a ubiquitous Ca2+ sensor and a crucial signalling hub in many pathways aberrantly activated in disease. However, the mechanistic basis of its ability to bind diverse signalling molecules including G-protein-coupled receptors, ion channels and kinases remains poorly understood. Here we harness the high resolution of molecular dynamics simulations and the analytical power of Markov state models to dissect the molecular underpinnings of CaM binding diversity. Our computational model indicates that in the absence of Ca2+, sub-states in the folded ensemble of CaM's C-terminal domain present chemically and sterically distinct topologies that may facilitate conformational selection. Furthermore, we find that local unfolding is off-pathway for the exchange process relevant for peptide binding, in contrast to prior hypotheses that unfolding might account for binding diversity. Finally, our model predicts a novel binding interface that is well-populated in the Ca2+-bound regime and, thus, a candidate for pharmacological intervention.

Restoring polyamines protects from age-induced memory impairment in an autophagy-dependent manner.

Age-dependent memory impairment is known to occur in several organisms, including Drosophila, mouse and human. However, the fundamental cellular mechanisms that underlie these impairments are still poorly understood, effectively hampering the development of pharmacological strategies to treat the condition. Polyamines are among the substances found to decrease with age in the human brain. We found that levels of polyamines (spermidine, putrescine) decreased in aging fruit flies, concomitant with declining memory abilities. Simple spermidine feeding not only restored juvenile polyamine levels, but also suppressed age-induced memory impairment. Ornithine decarboxylase-1, the rate-limiting enzyme for de novo polyamine synthesis, also protected olfactory memories in aged flies when expressed specifically in Kenyon cells, which are crucial for olfactory memory formation. Spermidine-fed flies showed enhanced autophagy (a form of cellular self-digestion), and genetic deficits in the autophagic machinery prevented spermidine-mediated rescue of memory impairments. Our findings indicate that autophagy is critical for suppression of memory impairments by spermidine and that polyamines, which are endogenously present, are candidates for pharmacological intervention.

Optic Neuropathy in McCune-Albright Syndrome: Effects of Early Diagnosis and Treatment of Growth Hormone Excess

GH excess is a serious complication of McCune-Albright syndrome (MAS) and has been associated with craniofacial morbidity. The aim of the study was to determine whether early diagnosis and treatment of MAS-associated GH excess prevents optic neuropathy and hearing impairment, the major morbidities associated with GH excess. A retrospective cross-sectional analysis was conducted at a clinical research center. Twenty-two subjects with MAS-associated GH excess and 21 control MAS subjects without GH excess were included in the study. Biochemical testing included random GH, nadir GH after glucose load, nadir GH on frequent sampling, and IGF-I Z-score. Subjects underwent imaging, ophthalmological, audiological, and otolaryngological assessment. Treatment included octreotide, pegvisomant, transphenoidal surgery, and/or radiotherapy as indicated. Association of optic neuropathy and hearing impairment to age at GH excess diagnosis/treatment was measured. Of 129 MAS subjects, 26 (20%) were diagnosed with GH excess based on elevation of two measures of GH function. Of these, 22 subjects were candidates for pharmacological intervention. Optic neuropathy was significantly correlated with intervention status, with no cases in the early intervention group (diagnosed/treated before age 18) or the control group, and four of seven (57%) in the late intervention group (diagnosed/treated after age 18) (Fisher's exact test; odds ratio, 0.027; P = 0.0058). Early diagnosis/intervention was not associated with reduction in hearing deficits (odds ratio, 1.25; P = 1.00). Mean head circumference SD score was significantly higher in the late (6.08; range, 2.70 to 22.56) than the early intervention (2.67; range, -0.65 to 6.72) or control groups (2.13; range, -2.06 to 7.79) (P = 0.003). Early diagnosis/treatment of GH excess in MAS is important to prevent optic neuropathy and craniofacial expansion. The relationship between hearing deficits and GH excess remains less clear and requires further study.

Epigenetic Therapeutics in Autoimmune Disease

Several lines of evidence suggest the involvement of disturbance in epigenetic processes in autoimmune disease. Most noteworthy is the global DNA hypomethylation seen in lupus. Epigenetic states in difference from genetic lesions are potentially reversible and hence candidates for pharmacological intervention. Potential targets for drug development are histone modification and DNA methylating and demethylating enzymes. The most advanced set of drugs in clinical development are histone deacetylase (HDAC) inhibitors. However, the prevalence of DNA hypomethylation in lupus suggests that we should shift our attention from HDAC inhibitors to DNA demethylation inhibitors. MBD2 was recently proposed to be involved in demethylation in T cells in lupus and is, therefore, a candidate target. Although this field is at its infancy, it carries great promise.

Response to therapy with interferon alpha-2b and prednisolone in aggressive systemic mastocytosis: report of five cases and review of the literature

Aggressive systemic mastocytosis (ASM) is a hematopoietic neoplasm characterized by infiltration of visceral organs by neoplastic mast cells (MCs) with consecutive organopathy and respective clinical and laboratory findings (so called C-Findings). Whereas, it is generally appreciated that patients with ASM are candidates for pharmacological intervention, no ideal drug or drug combination have been identified yet. One drug proposed to work in ASM is interferon alpha-2b (IFN-α2b). However, little is known so far about the quality of responses to IFN-α2b and actual response rates. We here report on five ASM patients treated with either a combination of IFN-α2b (3×3 million units per week) and prednisolone ( n=4), or IFN-α2b alone ( n=1). During therapy, two of the five patients showed a major response defined by complete resolution of C-Finding(s), one a partial response (partial regression of C-Findings), and one a stable disease (no changes in C-Findings). In one patient, progression to mast cell leukemia was seen after 3 months. In contrast to the other patients, this patient exhibited >10% MCs in his bone marrow (bm) smear at first presentation. In summary, our data confirm beneficial effects of IFN-α2b (plus prednisolone) for a group of patients with ASM, whereas patients with mast cell leukemia may require more aggressive therapy. Prospective trials with more patients are now required to further document these drug effects and to better define subgroups of patients with ASM who show good and long-lasting responses to IFN-α2b.

Focus on the Senses

Sensory nerves in the periphery respond to noxious stimuli that produce pain, thermal stimuli sensed as heat or cold, and mechanical stimuli perceived as touch. Two groups (Cockayne et al . and Souslova et al .) studied how sensory perception was altered in mice when the gene for the P2X 3 adenosine triphosphate (ATP) receptor was knocked out. A third group (Price et al .) focused on sensory deficits in mice lacking the gene for the sodium channel BNC1, which is not a voltage-gated channel. The BNC1 -/- mice exhibited decreased responsiveness to mechanical stimuli sensed by the class of rapidly adapting mechanoreceptors. The BNC1 channel is normally expressed by nerves found at the base of hair follicles consistent with its having an essential role in touch perception. The P2X 3 knockout mice demonstrated decreased pain-related behavior. Furthermore, the P2X 3 -/- mice lost a rapidly desensitizing ATP-induced current in dorsal root ganglia and had altered ATP-induced currents in nodose ganglia consistent with a role for the P2X 3 receptor in nociception. Additional phenotypes were also noted in the P2X 3 -/- mice. Cockayne et al . reported that the mice urinated less frequently and provided evidence for the P2X 3 receptor in bladder volume reflexes; Souslova et al. reported a defect in neuronal responsiveness to nonnoxious thermal stimuli (temperatures below 45°C but greater than 37°C). Although these results suggest that the P2X 3 receptor may be a candidate for pharmacological intervention in treating urinary incontinence and pain management, Souslova et al . found that the mice were hyperalgesic under conditions of chronic inflammation. The accompanying commentary by Cook and McCleskey highlights these caveats. Cockayne, D.A., Hamilton, S.G., Zhu, Q.-M., Dunn, P.M., Zhong, Y., Novakovic, S., Malmberg, A.B., Cain, G., Berson, A., Kassotakis, L., Hedley, L., Lachnit, W.G., Burnstock, G., McMahon, S.B., and Ford, A.P.D.W. (2000) Urinary bladder hyporeflexia and reduced pain-related behaviour in P2X 3 -deficient mice. Nature 407 : 1011-1015. [Online Journal] Souslova, V., Cesare, P., Ding, Y., Akopian, A.N., Stanfa, L., Suzuki, R., Carpenter, K., Dickenson, A., Boyce, S., Hill, R., Nebenius-Oosthuizen, D., Smith, A.J.H., Kidd, E.J., and Wood, J.N. (2000) Warm-coding deficits and aberrant inflammatory pain in mice lacking P2X 3 receptors. Nature 407 : 1015-1017. [Online Journal] Price, M.P., Lewin, G.R., McIlwrath, S.L., Cheng, C., Xie, J., Heppenstall, P.A., Stucky, C.L., Mannsfeldt, A.G., Brennan, T.J., Drummond, H.A., Qiao, J., Benson, C.J., Tarr, D.E., Hrstka, R.F., Yang, B., Williamson, R.A., and Welsh, M.J. (2000) The mammalian sodium channel BNC1 is required for normal touch sensation. Nature 407 : 1007-1011. [Online Journal] Cook, S.P., and McCleskey, E.W. (2000) ATP, pain and a full bladder. Nature 407 : 951-952. [Online Journal]

The vulnerable atherosclerotic plaque

Several major clinical trials reported over the past three years have shown that lowering of plasma cholesterol with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, has led to a substantial reduction in clinical events such as heart attack, stroke or death. These striking and encouraging observations were not predicted from the morphological changes in atherosclerotic lesions measured in a number of trials reported a few years earlier. Concurrent with these experiences with drugs, pathologists were describing those atherosclerotic plaques from post-mortem examination that seemed to be responsible for the acute coronary events. These plaques were usually eccentric in cross-section and contained a fluid lipid core with a thinned fibrous cap. Such vulnerable plaques were believed to be particularly prone to rupture which led to thrombosis and to the acute coronary events. A combination of these concurrent paths of clinical and pathological research has led to the proposition that the statins, and some other drugs, may stabilise the vulnerable atherosclerotic plaques, perhaps as a downstream consequence of their primary mechanism of action. An explosion of interest in the biology of the vulnerable atherosclerotic plaque has resulted. Numerous factors have been identified that may contribute to stabilisation or destabilisation of plaques and many of these may be candidates for pharmacological intervention. However, the difficulty in assessing plaque stability non-invasively is a major technical barrier which must be overcome before these targets can be exploited.