Investigation of LPA₁ receptor antagonism / ATX inhibition by a scaffold hopping aproach and SAR analysis

The Autotaxin-Lysophosphatidic acid (ATX-LPA) signalling pathway has been implicated in a variety of human disease states including angiogenesis, autoimmune diseases, cancer, fibrotic disease, inflammation, neurodegeneration, and neuropathic pain, amongst others. Two methods have been pursued in attempts to develop novel targets for this disease state which include: Route A - the development of novel LPA1 receptor antagonist, and Route B - the inhibition of the enzyme ATX required for the production of LPA (Scheme 1). Both of these routes will be pursued within this study with a view to developing novel targets for the inhibition of the LPA-ATX signalling pathway. Scheme 1: Proposed routes for the development of novel LPA-ATX inhibitors. A small compound library was constructed to target Route A, where of the compounds analysed none exhibited LPA1 receptor antagonism. Pleasingly, cross screening against ATX inhibition revealed several hit compounds, indicating the ability of cross-talk between these two signalling pathways. In regards to the second route, an extensive compound library was built based on the development of SAR surrounding a known potent ATX inhibitor by Amira Pharmaceuticals. The designed compounds were screened using a dual assay procedure (LPC and (bis-p-nitrophenyl)phosphate assay) which indicated a range of active compounds, as well as indicating the complexity associated with the binding mode of this particular motif.The Autotaxin-Lysophosphatidic acid (ATX-LPA) signalling pathway has been implicated in a variety of human disease states including angiogenesis, autoimmune diseases, cancer, fibrotic disease, inflammation, neurodegeneration, and neuropathic pain, amongst others. Two methods have been pursued in attempts to develop novel targets for this disease state which include: Route A - the development of novel LPA1 receptor antagonist, and Route B - the inhibition of the enzyme ATX required for the production of LPA (Scheme 1). Both of these routes will be pursued within this study with a view to developing novel targets for the inhibition of the LPA-ATX signalling pathway. Scheme 1: Proposed routes for the development of novel LPA-ATX inhibitors. A small compound library was constructed to target Route A, where of the compounds analysed none exhibited LPA1 receptor antagonism. Pleasingly, cross screening against ATX inhibition revealed several hit compounds, indicating the ability of cross-talk between these two signalling pathways. In regards to the second route, an extensive compound library was built based on the development of SAR surrounding a known potent ATX inhibitor by Amira Pharmaceuticals. The designed compounds were screened using a dual assay procedure (LPC and (bis-p-nitrophenyl)phosphate assay) which indicated a range of active compounds, as well as indicating the complexity associated with the binding mode of this particular motif

Identification of a novel class of autotaxin inhibitors through cross-screening

Three novel series were generated in order to mimic the pharmacophoric features displayed by lead compound AM095, a Lysophosphatidic acid (LPA1) receptor antagonist. Biological evaluation of this array of putative LPA1 antagonists led us to the discovery of three novel series of inhibitors of the ecto-enzyme Autotaxin (ATX), responsible for LPA production in blood, with potencies in the range 1 – 4 μM accompanied with good (> 100 μg/mL) solubility

Structure-activity relationships of small molecule autotaxin inhibitors with a discrete binding mode

Autotaxin (ATX) is a secreted enzyme responsible for the hydrolysis of lysophosphatidylcholine (LPC) to the bioactive lysophosphatidic acid (LPA) and choline. The ATX-LPA signalling pathway is implicated in cell survival, migration, and proliferation; thus, the inhibition of ATX is a recognized therapeutic target for a number of diseases including fibrotic diseases, cancer, and inflammation, amongst others. Many of the developed synthetic inhibitors for ATX have resembled the lipid chemotype of the native ligand; however, a small number of inhibitors have been described that deviate from this common scaffold. Herein, we report the structure-activity relationships (SAR) of a previously reported small molecule ATX inhibitor. We show through enzyme kinetics studies that analogues of this chemotype are noncompetitive inhibitors, and using a crystal structure with ATX we confirm the discrete binding mode

Impact of CD4 and CD8 dynamics and viral rebounds on loss of virological control in HIV controllers

Objective: HIV controllers (HICs) spontaneously maintain HIV viral replication at low level without antiretroviral therapy (ART), a small number of whom will eventually lose this ability to control HIV viremia. The objective was to identify factors associated with loss of virological control. Methods: HICs were identified in COHERE on the basis of \ue2\u89\ua55 consecutive viral loads (VL) \ue2\u89\ua4500 copies/mL over \ue2\u89\ua51 year whilst ART-naive, with the last VL \ue2\u89\ua4500 copies/mL measured \ue2\u89\ua55 years after HIV diagnosis. Loss of virological control was defined as 2 consecutive VL >2000 copies/mL. Duration of HIV control was described using cumulative incidence method, considering loss of virological control, ART initiation and death during virological control as competing outcomes. Factors associated with loss of virological control were identified using Cox models. CD4 and CD8 dynamics were described using mixed-effect linear models. Results: We identified 1067 HICs; 86 lost virological control, 293 initiated ART, and 13 died during virological control. Six years after confirmation of HIC status, the probability of losing virological control, initiating ART and dying were 13%, 37%, and 2%. Current lower CD4/CD8 ratio and a history of transient viral rebounds were associated with an increased risk of losing virological control. CD4 declined and CD8 increased before loss of virological control, and before viral rebounds. Discussion: Expansion of CD8 and decline of CD4 during HIV control may result from repeated low-level viremia. Our findings suggest that in addition to superinfection, other mechanisms, such as low grade viral replication, can lead to loss of virological control in HICs

Long-term Mortality in HIV-Positive Individuals Virally Suppressed for >3 Years With Incomplete CD4 Recovery

Virally suppressed HIV-positive individuals on combination antiretroviral therapy who do not achieve a CD4 count >200 cells/µL have substantially increased long-term mortality. The increased mortality was seen across different patient groups and for all causes of deat

High Risk of Secondary Infections Following Thrombotic Complications in Patients With COVID-19

Background. This study’s primary aim was to evaluate the impact of thrombotic complications on the development of secondary infections. The secondary aim was to compare the etiology of secondary infections in patients with and without thrombotic complications. Methods. This was a cohort study (NCT04318366) of coronavirus disease 2019 (COVID-19) patients hospitalized at IRCCS San Raffaele Hospital between February 25 and June 30, 2020. Incidence rates (IRs) were calculated by univariable Poisson regression as the number of cases per 1000 person-days of follow-up (PDFU) with 95% confidence intervals. The cumulative incidence functions of secondary infections according to thrombotic complications were compared with Gray’s method accounting for competing risk of death. A multivariable Fine-Gray model was applied to assess factors associated with risk of secondary infections. Results. Overall, 109/904 patients had 176 secondary infections (IR, 10.0; 95% CI, 8.8–11.5; per 1000-PDFU). The IRs of secondary infections among patients with or without thrombotic complications were 15.0 (95% CI, 10.7–21.0) and 9.3 (95% CI, 7.9–11.0) per 1000-PDFU, respectively (P = .017). At multivariable analysis, thrombotic complications were associated with the development of secondary infections (subdistribution hazard ratio, 1.788; 95% CI, 1.018–3.140; P = .043). The etiology of secondary infections was similar in patients with and without thrombotic complications. Conclusions. In patients with COVID-19, thrombotic complications were associated with a high risk of secondary infections

Ascorbic acid and intestinal metaplasia in the stomach: a prospective, randomized study

Intestinal type metaplasia plays a role in intestinal type gastric carcinoma development. Ascorbic acid demonstrates a protective effect against gastric carcinogenesis, due to its ability to inactivate oxygen free-radicals as well as its nitrite-scavenging effects