JLK 6

JLK 6, an isocoumarin, is a selective inhibitor of γ-secretase, with an IC50 value between 10 μM-1 mM [1, 2].

The enzyme γ-secretase catalyzes the cleavage of β-Amyloid precursor protein (βAPP) to produce Amyloid β-peptide (Aβ). Aβ is a part of the plaque present in the brain of patients with Alzheimer’s disease. γ-secretase also targets other substrates like Notch. Notch is a transmembrane protein which is involved in important functions during different stages in development, both embryonic and adulthood [1].

HEK293 cells were used. In these cells, wild-type βAPP was overexpressed (962 fmol/mL in 35-mm wells). JLK6 markedly reduced Aβ secreted from these cells. Interestingly, JLK6 potentiated the recovery of two fragments. Immunological characterization indicated that one fragment was labelled with a specific antibody against the Asp1 residue of Aβ. JLK6 also inhibited the Aβ recovery from cells overexpressing Swedish-mutant βAPP to a similar extent [2].

In the zebrafish embryo, JLK isocoumarin inhibitors did not change the Notch pathway responsible for somitogenesis. Unlike other γ-secretase inhibitors, these agents did not affect E-cadherin processing. JLKs did not inhibit α-secretase, β-site APP cleaving enzymes (BACE) 1 and BACE2, GSK3β kinase and proteasome. JLK inhibitors prevented Aβ production without inducing unwanted cleavages of other proteins [1].

References:
[1].  Petit A, Pasini A, Alves Da Costa C, et al. JLK isocoumarin inhibitors: Selective γ-secretase inhibitors that do not interfere with notch pathway in vitro or in vivo. Journal of neuroscience research, 2003, 74(3): 370-377.
[2].  Petit A, Bihel F, da Costa CA, et al. New protease inhibitors prevent γ-secretase-mediated production of Aβ40/42 without affecting Notch cleavage. Nature cell biology, 2001, 3(5): 507-511.

Cognitive and psychosocial function in retired professional hockey players.[Pubmed:28396361]

J Neurol Neurosurg Psychiatry. 2017 Jun;88(6):512-519.

BACKGROUND AND OBJECTIVE: The relationship between repeated concussions and neurodegenerative disease has received significant attention, particularly research in postmortem samples. Our objective was to characterise retired professional ice hockey players' cognitive and psychosocial functioning in relation to concussion exposure and apolipoprotein epsilon4 status. METHODS: Alumni athletes (N=33, aged 34-71 years) and an age-matched sample of comparison participants (N=18) were administered measures of cognitive function and questionnaires concerning psychosocial and psychiatric functioning. RESULTS: No significant group differences were found on neuropsychological measures of speeded attention, verbal memory or visuospatial functions, nor were significant differences observed on computerised measures of response speed, inhibitory control and visuospatial problem solving. Reliable group differences in cognitive performance were observed on tests of executive and intellectual function; performance on these measures was associated with concussion exposure. Group differences were observed for cognitive, affective and behavioural impairment on psychosocial questionnaires and psychiatric diagnoses. There was no evidence of differential effects associated with age in the alumni athletes. Possession of an apolipoprotein epsilon4 allele was associated with increased endorsement of psychiatric complaints, but not with objective cognitive performance. CONCLUSIONS: We found only subtle objective cognitive impairment in alumni athletes in the context of high subjective complaints and psychiatric impairment. Apolipoprotein epsilon4 status related to psychiatric, but not cognitive status. These findings provide benchmarks for the degree of cognitive and behavioural impairment in retired professional athletes and a point of comparison for future neuroimaging and longitudinal studies.

Identification of asthma phenotypes in a tertiary care medical center.[Pubmed:25319436]

Am J Med Sci. 2014 Dec;348(6):480-5.

BACKGROUND: Asthma affects 5% to 10% of the population and its severity is assessed using 4 parameters: lung function, symptom frequency, rescue inhaler use, and number of asthma exacerbations. Asthma is increasingly recognized as a clinical syndrome rather than a single disease. However, the current classification system fails to reflect the heterogeneous characteristics of the disease. METHODS: A retrospective chart review of 139 patients with mild, moderate, and severe persistent asthma was performed. Variables including baseline and maximal forced expiratory volume over first second (percent predicted), and age of asthma onset were used to classify patients. RESULTS: This yielded 5 clusters similar to Severe Asthma Research Program (SARP). Subjects in cluster 1 (n = 32) and cluster 2 (n = 47) had early-onset atopic asthma and reduced lung function but differed in medication requirement and health care utilization. Cluster 3 (n = 32) consisted of older obese women with late-onset asthma, less atopy, and mildly reduced forced expiratory volume over first second. Members of cluster 4 (n = 20) and cluster 5 (n = 8) had atopic asthma with severe obstruction but differed in bronchodilator response, age of onset, and oral corticosteroid use. Compared with SARP, our subjects were older, had a higher percentage of African Americans and obesity, and less severe asthma (P < 0.05). The observed clusters differed from SARP clusters in the following: (1) more frequent asthma exacerbations and medication use among cluster 1 and cluster 2; (2) lower medication use in cluster 3 and cluster 4; (3) although total health care utilization was similar, there were fewer emergency department visits in cluster 3 (P < 0.05). CONCLUSIONS: The SARP algorithm may be used to classify diverse asthmatic populations into a clinically reproducible phenotypic cluster.

What is the impact of chronic kidney disease stage and cardiovascular disease on the annual cost of hospital care in moderate-to-severe kidney disease?[Pubmed:25924679]

BMC Nephrol. 2015 Apr 29;16:65.

BACKGROUND: Reliable estimates of the impacts of chronic kidney disease (CKD) stage, with and without cardiovascular disease, on hospital costs are needed to inform health policy. METHODS: The Study of Heart and Renal Protection (SHARP) randomized trial prospectively collected information on kidney disease progression, serious adverse events and hospital care use in a cohort of patients with moderate-to-severe CKD. In a secondary analysis of SHARP data, the impact of participants' CKD stage, non-fatal cardiovascular events and deaths on annual hospital costs (i.e. all hospital admissions, routine dialysis treatments and recorded outpatient/day-case attendances in United Kingdom 2011 prices) were estimated using linear regression. RESULTS: 7,246 SHARP patients (2,498 on dialysis at baseline) from Europe, North America, and Australasia contributed 28,261 years of data. CKD patients without diabetes or vascular disease incurred annual hospital care costs ranging from pound403 (95% confidence interval: 345-462) in CKD stages 1-3B to pound525 (449-602) in CKD stage 5 (not on dialysis). Patients in receipt of maintenance dialysis incurred annual hospital costs of pound18,986 (18,620-19,352) in the year of initiation and pound23,326 (23,231-23,421) annually thereafter. Patients with a functioning kidney transplant incurred pound24,602 (24,027-25,178) in hospital care costs in the year of transplantation and pound1,148 (978-1,318) annually thereafter. Non-fatal major vascular events increased annual costs in the year of the event by pound6,133 (5,608-6,658) for patients on dialysis and by pound4,350 (3,819-4,880) for patients not on dialysis, and were associated with increased costs, though to a lesser extent, in subsequent years. CONCLUSIONS: Renal replacement therapy and major vascular events are the main contributors to the high hospital care costs in moderate-to-severe CKD. These estimates of hospital costs can be used to inform health policy in moderate-to-severe CKD.

Factors Affecting Visual Field Outcomes in the Idiopathic Intracranial Hypertension Treatment Trial.[Pubmed:26618282]

J Neuroophthalmol. 2016 Mar;36(1):6-12.

BACKGROUND: To determine the prevalence of visual field (VF) performance failures (PF) and treatment failures (TFs), and identify factors associated with PFs in the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT). METHODS: A total of 165 participants from 38 sites with idiopathic intracranial hypertension (IIH) and mild visual loss were randomized to either acetazolamide-plus diet or placebo-plus diet. The IIHTT Visual Field Reading Center evaluated 2950 Swedish Interactive Threshold Algorithm Standard 24-2 VFs from the enrolled participants. A TF was defined when the participant's VF mean deviation (MD) worsened >/=2 to 3 dB from the average baseline MD (range of -2 to -7 dB) with a second retest confirming the visual deterioration. A PF was determined when the participant's: 1) VF results met TF criteria but were not confirmed on retest, 2) deterioration was confirmed on retest but the IIHTT Adjudication Committee concluded a TF was clinically unlikely. RESULTS: TF was detected in 7/165 (4%) of the participants and PF was detected in 35/165 (21%) of the participants on at least 1 examination. Four of the 35 PFs were adjudicated for TF, however based on clinical review by the adjudication committee and a third retest, they were judged as PFs. Of the 2,950 total IIHTT VF examinations, 2.7% met PF criteria. CONCLUSIONS: PF was confirmed in 21% of subjects and in 2.7% of the total number of VF examinations and was reversible on repeat testing. We recommend retesting when perimetric worsening occurs in otherwise clinically stable or improving IIH patients.

Maternal Dietary Patterns during Pregnancy Are Associated with Newborn Body Composition.[Pubmed:28539412]

J Nutr. 2017 Jul;147(7):1334-1339.

Background: Maternal dietary intake during pregnancy may influence offspring growth and adiposity. Specific dietary patterns associated with newborn adiposity have not been identified.Objective: We aimed to identify patterns of maternal dietary intake associated with gestational weight gain (GWG) and fasting glucose during pregnancy and to evaluate whether adherence to these patterns is associated with newborn adiposity.Methods: In the Healthy Start prospective cohort, dietary intake during pregnancy was assessed via 24-h recalls. Reduced-rank regression identified dietary patterns predictive of GWG and fasting glucose. Associations between dietary patterns and newborn fat mass, fat-free mass, and adiposity were estimated by using linear regression models among 764 ethnically diverse mother-infant pairs.Results: Two dietary patterns were identified. Pattern 1, correlated with greater GWG (r = 0.22, P < 0.01), was characterized by a higher consumption of poultry, nuts, cheese, fruits, whole grains, added sugars, and solid fats. Greater adherence to pattern 1 (upper compared with lower tertile) predicted a greater newborn fat-free mass (61 g; 95% CI: 12, 110 g) but no difference in fat mass or adiposity. Pattern 2, correlated with greater maternal fasting glucose (r = 0.16, P < 0.01), was characterized by a higher consumption of eggs, starchy vegetables, solid fats, fruits, and nonwhole grains and a lower consumption of dairy foods, dark-green vegetables, and whole grains. Greater adherence to pattern 2 was associated with a greater newborn birth weight (80 g; 95% CI: 15, 145 g), fat mass (33 g; 95% CI: 8, 59 g), and adiposity (0.9%; 95% CI: 0.3%, 1.6%).Conclusions: Among pregnant women, adherence to a dietary pattern characterized by an intake of poultry, nuts, cheese, and whole grains was associated with greater GWG but not maternal fasting glucose or newborn adiposity. Adherence to a pattern characterized by an intake of eggs, starchy vegetables, and nonwhole grains was associated with higher maternal fasting glucose and greater newborn adiposity. Maternal dietary patterns during pregnancy may influence newborn body composition.

Dll4 signalling through Notch1 regulates formation of tip cells during angiogenesis.[Pubmed:17259973]

Nature. 2007 Feb 15;445(7129):776-80.

In sprouting angiogenesis, specialized endothelial tip cells lead the outgrowth of blood-vessel sprouts towards gradients of vascular endothelial growth factor (VEGF)-A. VEGF-A is also essential for the induction of endothelial tip cells, but it is not known how single tip cells are selected to lead each vessel sprout, and how tip-cell numbers are determined. Here we present evidence that delta-like 4 (Dll4)-Notch1 signalling regulates the formation of appropriate numbers of tip cells to control vessel sprouting and branching in the mouse retina. We show that inhibition of Notch signalling using gamma-secretase inhibitors, genetic inactivation of one allele of the endothelial Notch ligand Dll4, or endothelial-specific genetic deletion of Notch1, all promote increased numbers of tip cells. Conversely, activation of Notch by a soluble jagged1 peptide leads to fewer tip cells and vessel branches. Dll4 and reporters of Notch signalling are distributed in a mosaic pattern among endothelial cells of actively sprouting retinal vessels. At this location, Notch1-deleted endothelial cells preferentially assume tip-cell characteristics. Together, our results suggest that Dll4-Notch1 signalling between the endothelial cells within the angiogenic sprout serves to restrict tip-cell formation in response to VEGF, thereby establishing the adequate ratio between tip and stalk cells required for correct sprouting and branching patterns. This model offers an explanation for the dose-dependency and haploinsufficiency of the Dll4 gene, and indicates that modulators of Dll4 or Notch signalling, such as gamma-secretase inhibitors developed for Alzheimer's disease, might find usage as pharmacological regulators of angiogenesis.

JLK isocoumarin inhibitors: selective gamma-secretase inhibitors that do not interfere with notch pathway in vitro or in vivo.[Pubmed:14598313]

J Neurosci Res. 2003 Nov 1;74(3):370-7.

gamma-Secretase activity is involved in the generation of Abeta and therefore likely contributes to the pathology of Alzheimer's disease. Blocking this activity was seen as a major therapeutic target to slow down or arrest Abeta-related AD progression. This strategy seemed more doubtful when it was established that gamma-secretase also targets other substrates including Notch, a particularly important transmembrane protein involved in vital functions, at both embryonic and adulthood stages. We have described previously new non-peptidic inhibitors able to selectively inhibit Abeta cellular production in vitro without altering Notch pathway. We show here that in vivo, these inhibitors do not alter the Notch pathway responsible for somitogenesis in the zebrafish embryo. In addition, we document further the selectivity of JLK inhibitors by showing that, unlike other described gamma-secretase inhibitors, these agents do not affect E-cadherin processing. Finally, we establish that JLKs do not inhibit beta-site APP cleaving enzymes (BACE) 1 and BACE2, alpha-secretase, the proteasome, and GSK3beta kinase. Altogether, JLK inhibitors are the sole agents to date that are able to prevent Abeta production without triggering unwanted cleavages of other proteins.

New protease inhibitors prevent gamma-secretase-mediated production of Abeta40/42 without affecting Notch cleavage.[Pubmed:11331880]

Nat Cell Biol. 2001 May;3(5):507-11.

We have designed new non-peptidic potential inhibitors of gamma-secretase and examined their ability to prevent production of amyloid-beta 40 (Abeta40) and Abeta42 by human cells expressing wild-type and Swedish-mutant beta-amyloid precursor protein (betaAPP). Here we identify three such agents that markedly reduce recovery of both Abeta40 and Abeta42 produced by both cell lines, and increase that of C99 and C83, the carboxy-terminal fragments of betaAPP that are derived from beta-and alpha-secretase, respectively. Furthermore, we show that these inhibitors do not affect endoproteolysis of endogenous or overexpressed presenilins. These inhibitors are totally unable to affect the mDeltaEnotch-1 cleavage that leads to generation of the Notch intracellular domain (NICD). These represent the first non-peptidic inhibitors that are able to prevent gamma-secretase cleavage of betaAPP without affecting processing of mDeltaEnotch-1 or endoproteolysis of presenilins. The distinction between these two proteolytic events, which are both prevented by disruption of presenilin genes, indicates that although they are intimately linked with betaAPP and Notch maturation, presenilins are probably involved in the control of maturation processes upstream of enzymes that cleave gamma-secretase and Notch.