The effect of 5,8,11,14-eicosatetraynoic acid on endothelial cell gene expression

In vitro and in silico cholinesterase inhibitory potential of metabolites from Laurencia snackeyi (Weber-van Bosse) M. Masuda

Alzheimer's disease (AD) is a neurodegenerative disease that causes deterioration in intelligence and psychological activities. Yet, till today, no cure is available for AD. The marine environment is an important sink of bioactive compounds with neuroprotective potential with reduced adverse effects. Recently, we collected the red algae Laurencia snackeyi from Terumbu Island, Malaysia which is known to be rich in halogenated metabolites making it the most sought-after red algae for pharmaceutical studies. The red alga was identified based on basic morphological characteristics, microscopic observation and chemical data from literature. The purplish-brown algae was confirmed a new record. In Malaysia, this species is poorly documented in Peninsular Malaysia as compared to its eastern continent Borneo. Thus, this study intended to investigate the diversity of secondary metabolites present in the alga and its cholinesterase inhibiting potential for AD. The extract inhibited both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with IC50 values of  14.45 ± 0.34 μ g mL-1 and 39.59 ± 0.24 μ g mL-1, respectively. Subsequently, we isolated the synderanes, palisadin A (1), aplysistatin (2) and 5-acetoxypalisadin B (3) that was not exhibit potential. Mass spectrometry analysis detected at total of 33 additional metabolites. The computational aided molecular docking using the AChE and BChE receptors on all metabolites shortlisted 5,8,11,14-eicosatetraynoic acid (31) and 15-hydroxy-1-[2-(hydroxymethyl)-1-piperidinyl]prost-13-ene-1,9-dione (42) with best inhibitory properties, respectively with the lowest optimal combination of S-score and RMSD values. This study shows the unexplored potential of marine natural resources, however, obtaining sufficient biomass for detailed investigation is an uphill task. Regardless, there is a lot of potential for future prospects with a wide range of marine natural resources to study and the incorporation of synthetic chemistry, in vivo studies in experimental design.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03725-6.

Virus-Derived Chemokine Modulating Protein Pre-Treatment Blocks Chemokine–Glycosaminoglycan Interactions and Significantly Reduces Transplant Immune Damage

Immune cell invasion after the transplantation of solid organs is directed by chemokines binding to glycosaminoglycans (GAGs), creating gradients that guide immune cell infiltration. Renal transplant is the preferred treatment for end stage renal failure, but organ supply is limited and allografts are often injured during transport, surgery or by cytokine storm in deceased donors. While treatment for adaptive immune responses during rejection is excellent, treatment for early inflammatory damage is less effective. Viruses have developed highly active chemokine inhibitors as a means to evade host responses. The myxoma virus-derived M-T7 protein blocks chemokine: GAG binding. We have investigated M-T7 and also antisense (ASO) as pre-treatments to modify chemokine: GAG interactions to reduce donor organ damage. Immediate pre-treatment of donor kidneys with M-T7 to block chemokine: GAG binding significantly reduced the inflammation and scarring in subcapsular and subcutaneous allografts. Antisense to N-deacetylase N-sulfotransferase1 (ASONdst1) that modifies heparan sulfate, was less effective with immediate pre-treatment, but reduced scarring and C4d staining with donor pre-treatment for 7 days before transplantation. Grafts with conditional Ndst1 deficiency had reduced inflammation. Local inhibition of chemokine: GAG binding in donor organs immediately prior to transplant provides a new approach to reduce transplant damage and graft loss.

Arachidonic acid cascade in endothelial pathobiology

Arachidonic acid (AA) and its metabolites (eicosanoids) represent powerful mediators, used by organisms to induce and suppress inflammation as a part of the innate response to disturbances. Several cell types participate in the synthesis and release of AA metabolites, while many cell types represent the targets for eicosanoid action. Endothelial cells (EC), forming a semi-permeable barrier between the interior space of blood vessels and underlying tissues, are of particular importance for the development of inflammation, since endothelium controls such diverse processes as vascular tone, homeostasis, adhesion of platelets and leukocytes to the vascular wall, and permeability of the vascular wall for cells and fluids. Proliferation and migration of endothelial cells contribute significantly to new vessel development (angiogenesis). This review discusses endothelial-specific synthesis and action of arachidonic acid derivatives with a particular focus on the mechanisms of signal transduction and associated intracellular protein targets.

Activation and regulation of Hsp32 and Hsp70

Endothelial cells (EC) play a key role in the propagation of inflammatory responses. Better understanding of inflammatory processes in EC might provide new ways of controlling inflammation. We report here that the known antioxidant pyrrolidinedithiocarbamate (PDTC) leads to time and dose dependent activation of heat-shock protein 70 (Hsp70) as well as Hsp32 in EC. We further demonstrate that PDTC activates heat-shock factor 1 (HSF1), one of several transcription factor involved in the upregulation of heat-shock proteins. And more importantly, we demonstrate that Hsp32 as well as Hsp70 can be upregulated independently of the transcription factor nuclear factor kappaB (NF-kappaB). The presented data provide further insight into the mechanism of Hsp32 and Hsp70 regulation, as well as further distinguishing these genes from other so called 'protective genes' whose upregulation depends on the activation of NF-kappaB. These findings indicate that Hsp32 and Hsp70 might be ideal candidates among protective genes. Hsp32 and Hsp70 provide many desirable protective effects but, being independent of NF-kappaB, would leave open the option to interfere with the upregulation of proinflammatory genes by modulating the activation of NF-kappaB.

Camouflaging endothelial cells: does it prolong graft survival?

Camouflaging antigens on the surface of cells seems an appealing way to prevent activation of the immune system. We explored the possibility of preventing hyperacute rejection by chemically camouflaging endothelial cells (EC). In vitro as well as in vivo experiments were performed. First, the ability of mPEG coating to prevent antibody-antigen interactions was evaluated. Second, we tested the degree to which mPEG coating prevents activation of EC by stimuli such as TNF-alpha and LPS. Third, in vivo experiments were performed to test the ability of mPEG coating to prolong xenograft survival. We demonstrate that binding of several antibodies to EC or serum proteins can be inhibited by mPEG. Furthermore, binding of TNF-alpha as well as LPS to EC is blocked since mPEG treatment of EC inhibits the subsequent up-regulation of E-selectin by these stimuli. However, in vivo experiments revealed that currently this method alone is not sufficient to prevent hyperacute rejection.

Ibuprofen: new explanation for an old phenomenon

Nuclear factor-kappaB (NF-kappaB) translocation from the cytoplasm into the nucleus and the subsequent DNA binding is an essential prerequisite in the up-regulation of many pro-inflammatory genes, e.g. tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta). The anti-inflammatory drug ibuprofen, thought to exert its beneficial effects mainly by suppressing the production of eicosanoids, inhibited the up-regulation of the pro-inflammatory cytokines IL-1beta and TNF-alpha. This effect was independent of the described potential of ibuprofen as a cyclooxygenase inhibitor. Ibuprofen inhibited the activation and translocation of the key transcription factor NF-kappaB by blocking the degradation of inhibitor-kappaBalpha, a protein that forms a complex with NF-kappaB, thereby preventing the release and subsequent translocation of NF-kappaB into the nucleus and the expression of inflammatory cytokines. The presented data offer a new explanation for the anti-inflammatory effect of ibuprofen.