👤 Marie-Ève Tremblay

Pain is one of the leading causes of disability worldwide. Despite the various pharmacological treatments available, patients with chronic pain often remain with significant disabilities and unsatisfactory pain control. Cannabis and cannabinoids are sometimes used in the treatment of chronic pain as they have been shown to be useful in a subset of patients. Some of the adverse effects associated with cannabis use, such as cannabis use disorder (CUD) and cannabis-induced psychosis, have been associated with several genetic variants. Despite this, the paucity of the data or the contradictory results for reported variants limits our ability to use them as genetic markers to personalize cannabis treatment tailored to patients’ genetic background. The aim of this genetic association study was to investigate the link between previously reported genes and cannabinoid response in terms of pain response, CUD and risk of psychotic adverse events in patients with chronic pain. Phone or in person interviews were conducted to document participants’ characteristics, cannabis use and effects, concurrent pharmacotherapy and comorbid conditions. Screening for CUD was performed using the Cannabis Use Disorders Identification Test – Revised. Blood or saliva samples were collected for the genotyping of 18 variants in 11 genes ( One hundred participants were recruited, with blood or saliva samples collected from 77 of them. Two single-nucleotide polymorphisms (SNP) in cannabinoid receptor 1 ( These results suggest alternative allele carriers of rs1049353 and rs2023239 could be at an increased risk of psychotic adverse events related to cannabis use, although additional investigation is required to replicate and confirm these findings. The online version contains supplementary material available at 10.1186/s42238-026-00408-w. Show less

The importance of any enhanced atherogenicity of triglyceride (TG)-rich lipoproteins (TRLs) will depend on the relative abundance of these particles compared with low-density lipoprotein (LDL) or total apolipoprotein (apo)B. Accordingly, we determined the contribution that TRLs make to total apoB as TG or apoB concentrations increase. We also describe compositional changes in TRLs as TG or apoB increases to assess whether very low-density lipoprotein (VLDL-[C]) is a valid proxy for VLDL-apoB. We used sequential ultracentrifugation to separate lipoprotein fractions in plasma samples from 1940 dyslipidemic patients not on lipid-lowering medication, and measured apoB, cholesterol and TG in the plasma and in each subfraction. We analyzed these data in quartiles of TG or apoB. There was wide variance in all parameters in all quartiles of both TG and apoB. Although VLDL-apoB accounted for almost all the increase in total apoB across TG quartiles, LDL-apoB still accounted for 80% of the total in TG quartile 4. In contrast, LDL-apoB accounted for 90% of the increase in apoB across apoB quartiles. As TG increases, the increase in VLDL-C is explained more by increased VLDL-C/apoB when TG is moderately elevated, and more by increased VLDL-apoB when TG is very high. In conclusion, VLDL-apoB only becomes a substantial component of total apoB with extreme hypertriglyceridemia and VLDL-C is not an appropriate proxy for VLDL-apoB. Show less

The apolipoprotein E4 (APOE4) allele is the strongest genetic risk factor for Alzheimer's disease (AD) and is linked to poorer cerebrovascular health. Cerebrovascular reactivity (CVR), an indicator of vascular reserve, and cerebral pulsatility (CP), a marker of vascular stiffness, are sensitive biomarkers of early vascular dysfunction associated with aging and AD. However, the relationship between APOE4 status and these cerebrovascular metrics remains unclear. This study investigated whether the APOE genotype influences longitudinal changes in CVR and CP, and their association with cognitive performance in cognitively unimpaired individuals. We utilized the PREVENT-AD cohort, including 101 APOE4 carriers (30 males and 71 females) and 152 non-APOE4 carriers (48 males and 104 females) aged 55 and older. Relative CVR and CP were derived from resting state functional magnetic resonance imaging data, with regional values extracted from cerebral arterial territories. Results indicated significant interactions between APOE4 status and relative CVR in the left middle cerebral artery and left posterior cerebral artery (PCA) territories. APOE4 status disaggregated analyses revealed that APOE4 carriers uniquely presented a significant decline in relative CVR within the left PCA. Furthermore, sex-specific effects were identified, with female APOE4 carriers having lower relative CVR in the right anterior cerebral artery territory compared to female non-carriers. Importantly, higher relative CVR was positively associated with better cognitive performance in APOE4 carriers. No significant effects of APOE4 status on CP were found. Together, these findings suggest that relative CVR may be an important early measure of cerebrovascular health and cognition in cognitively intact APOE4 carriers. Show less

Food allergy (FA) is a great public health concern with an increased prevalence in the last decades. The underlying development mechanisms of FA and food sensitization (FS), which represents the first stage of development of FA, are influenced by environmental, epigenetic, and genetic factors. DNA methylation is an important epigenetic mediator of gene-environment interactions and key to understanding these mechanisms. Studies have linked whole-genome DNA methylation profile to FA and FS, but they all use methylation arrays. Methylation sequencing captures target regions of methylome with an extensive coverage. Thus, our objective was to identify CpG sites in genome-wide immune regulatory regions associated with FS and test their association with genetic variants using methylation quantitative trait loci (mQTL) analysis in French-Canadian individuals. In 114 individuals from the Saguenay-Lac-Saint-Jean asthma family cohort, a total of 10 CpG sites out of 5,233,004 CpG sites were associated with the FS status (P < 1 × 10 To our knowledge, this is a unique association study between FS and DNA methylation using targeted bisulfite sequencing across the genome. This approach provides high-resolution assessment of genome-wide functional methylome that yields valuable understandings to this field of research. The results reveal potential relationships between FS, CpG sites, and genetic variants located in genes involved in allergic diseases. This provides potential insights on the underlying effects of DNA methylation and genetic variants on FS and possibly the pathogenesis of FA. Further epigenome-wide studies on larger samples combined with genome-wide genotyping are needed to validate the results and verify the biological potential of these CpG sites. Show less

This study examined dark microglia-a state linked to central nervous system pathology and neurodegeneration-during postnatal development in the mouse ventral hippocampus, finding that dark microglia interact with blood vessels and synapses and perform trogocytosis of pre-synaptic axon terminals. Furthermore, we found that dark microglia in development notably expressed C-type lectin domain family 7 member A (CLEC7a), lipoprotein lipase (LPL) and triggering receptor expressed on myeloid cells 2 (TREM2) and required TREM2, differently from other microglia, suggesting a link between their role in remodeling during development and central nervous system pathology. Together, these results point towards a previously under-appreciated role for dark microglia in synaptic pruning and plasticity during normal postnatal development. Show less

A better understanding of adipose tissue (AT) dysfunction, which includes morphological and functional changes such as adipocyte hypertrophy as well as impaired adipogenesis, lipid storage/mobilization, endocrine and inflammatory responses, is needed in the context of obesity. One dimension of AT dysfunction, secretory adiposopathy, often assessed as a low plasma adiponectin (A)/leptin (L) ratio, is commonly observed in obesity. The aim of this study was to examine markers of AT development and metabolism in 67 women of varying age and adiposity (age: 40-62 years; body mass index, BMI: 17-41 kg/m Body composition, regional AT distribution and circulating adipokines were determined. Lipolysis was measured from glycerol release in subcutaneous abdominal (SCABD) and omental (OME) adipocytes under basal, isoproterenol-, forskolin (FSK)- and dibutyryl-cyclic AMP (DcAMP)-stimulated conditions. Adipogenesis (C/EBP-α/β/δ, PPAR-γ2 and SREBP-1c) and lipid metabolism (β2-ARs, HSL, FABP4, LPL and GLUT4) gene expression (RT-qPCR) was assessed in both fat depots. Participants in the upper versus lower tertile of adiponectin, leptin or the A/L ratio were compared. Basal lipolysis was similar between groups. Women with a low plasma A/L ratio were characterized by higher adiposity and larger SCABD and OME adipocytes (p<0.01) compared to those with a high ratio. In OME adipocytes, women in the low adiponectinemia tertile showed higher isoproterenol-stimulated lipolysis (0.01Show less

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spinal deformity. The incidence of AIS in females is 8.4 times higher than in males. Several hypotheses on the role of estrogen have been postulated for the progression of AIS. Recently, Centriolar protein gene POC5 ( Show less

Metabolic syndrome (MetS) comprises a cluster of risk factors including central obesity, hypertension, dyslipidemia, and impaired glucose homeostasis. Lifestyle interventions that promote improvements in diet quality and physical activity represent a first line of therapy for MetS. However, varying responses to lifestyle interventions are well documented and may be partially explained by underlying genetic differences. The aim of this study was to investigate if variants in genes previously associated with MetS influence the magnitude of change in MetS risk during a 1-year lifestyle intervention. The present study used data collected from the Canadian Health Advanced by Nutrition and Graded Exercise study cohort (n = 159 men and women) to investigate the effect of 17 candidate single nucleotide polymorphisms (SNPs) on response to a 1-year lifestyle intervention. Associations between SNPs and the continuous MetS (cMetS) score, as well as individual MetS components, were examined. Reductions in cMetS score at both 3 months and 1 year were significantly associated with 2 variants: rs662799 (A/G) in apolipoprotein A5 (APOA5) and rs1501299 (G/T) in adiponectin (ADIPOQ). Individuals carrying a minor T allele in rs1501299 experienced a greater reduction in cMetS score at both 3 months and 1 year, whereas major allele AA homozygotes in rs662799 experienced greater reductions in cMetS score during the intervention. No associations were identified between the aforementioned SNPs and individual components of MetS. Both un-weighted and weighted genetic risk scores (GRS) using these 2 SNPs revealed that individuals carrying none of the risk alleles experienced significantly greater reductions in cMetS score after 1 year. The findings from the current study suggest that individuals with certain genotypes may benefit more from a lifestyle intervention for MetS and that specific variants, either independently or as part of a GRS, could be used as a nutrigenomic tool to tailor the intervention to reduce the risk of MetS. Show less

Apolipoprotein C-III (APOC3) is a key regulator of plasma triglyceride levels. Elevated triglyceride levels are associated with a risk of adverse cardiovascular events and pancreatitis. ISIS 304801 is a second-generation antisense inhibitor of APOC3 synthesis. We conducted a randomized, double-blind, placebo-controlled, dose-ranging, phase 2 study to evaluate ISIS 304801 in untreated patients with fasting triglyceride levels between 350 mg per deciliter (4.0 mmol per liter) and 2000 mg per deciliter (22.6 mmol per liter) (ISIS 304801 monotherapy cohort), as well as in patients receiving stable fibrate therapy who had fasting triglyceride levels between 225 mg per deciliter (2.5 mmol per liter) and 2000 mg per deciliter (ISIS 304801-fibrate cohort). Eligible patients were randomly assigned to receive either ISIS 304801, at doses ranging from 100 to 300 mg, or placebo, once weekly for 13 weeks. The primary outcome was the percentage change in APOC3 level from baseline. A total of 57 patients were treated in the ISIS 304801 monotherapy cohort (41 received active agent, and 16 received placebo), and 28 patients were treated in the ISIS 304801-fibrate cohort (20 received active agent, and 8 received placebo). The mean (±SD) baseline triglyceride levels in the two cohorts were 581±291 mg per deciliter (6.6±3.3 mmol per liter) and 376±188 mg per deciliter (4.2±2.1 mmol per liter), respectively. Treatment with ISIS 304801 resulted in dose-dependent and prolonged decreases in plasma APOC3 levels when the drug was administered as a single agent (decreases of 40.0±32.0% in the 100-mg group, 63.8±22.3% in the 200-mg group, and 79.6±9.3% in the 300-mg group, vs. an increase of 4.2±41.7% in the placebo group) and when it was administered as an add-on to fibrates (decreases of 60.2±12.5% in the 200-mg group and 70.9±13.0% in the 300-mg group, vs. a decrease of 2.2±25.2% in the placebo group). Concordant reductions of 31.3 to 70.9% were observed in triglyceride levels. No safety concerns were identified in this short-term study. We found that treatment with ISIS 304801 was associated with significant lowering of triglyceride levels, among patients with a broad range of baseline levels, through selective antisense inhibition of APOC3 synthesis. (Funded by Isis Pharmaceuticals; ClinicalTrials.gov number, NCT01529424.). Show less

The accumulation of insoluble amyloid-beta (Aβ) peptides is associated with neurodegenerative disorders, such as Alzheimer's disease (AD). As essential tremor (ET) could involve neurodegenerative processes in the cerebellum, we quantified soluble and insoluble Aβ in cerebellar cortices from patients diagnosed with ET (n=9), compared to Controls (n=16) or individuals with Parkinson's disease (n=10). Although ante-mortem cognitive performance was not documented, all individuals included had the diagnosis of AD ruled out by a neuropathologist. ELISA-determined concentrations of insoluble Aβ42 in ET patients displayed a bimodal distribution, with a median 246-fold higher than in Controls (P<0.01, Kruskal-Wallis). Higher Aβ42 concentrations were measured in the parietal cortex of the same ET patients, compared to Controls (107-fold median increase, P<0.01, Kruskal-Wallis), but similar phosphorylated tau levels were detected. The rise in cerebellar insoluble Aβ42 concentrations is not associated to APP expression and processing or the ApoE4 status. However, Aβ42 levels in ET individuals were correlated with cerebellar insoluble phosphorylated tau (r(2)=0.71, P=0.005), unphosphorylated neurofilament heavy chain (NF-H; r(2)=0.50, P=0.030) and Lingo-1 (r(2)=0.73, P=0.007), indicative of a generalized neurodegenerative process involving the cerebellum. Our results suggest prevalent accumulations of insoluble Aβ42 in the cerebellum of ET, but not in age-matched PD. Whether this anomaly plays a role in ET symptoms warrants further investigations. Show less

The familial chylomicronemia syndrome is a genetic disorder characterized by severe hypertriglyceridemia and recurrent pancreatitis due to a deficiency in lipoprotein lipase (LPL). Currently, there are no effective therapies except for extreme restriction in the consumption of dietary fat. Apolipoprotein C-III (APOC3) is known to inhibit LPL, although there is also evidence that APOC3 increases the level of plasma triglycerides through an LPL-independent mechanism. We administered an inhibitor of APOC3 messenger RNA (mRNA), called ISIS 304801, to treat three patients with the familial chylomicronemia syndrome and triglyceride levels ranging from 1406 to 2083 mg per deciliter (15.9 to 23.5 mmol per liter). After 13 weeks of study-drug administration, plasma APOC3 levels were reduced by 71 to 90% and triglyceride levels by 56 to 86%. During the study, all patients had a triglyceride level of less than 500 mg per deciliter (5.7 mmol per liter) with treatment. These data support the role of APOC3 as a key regulator of LPL-independent pathways of triglyceride metabolism. Show less

Essential tremor (ET) is the most prevalent adult-onset movement disorder. Despite its health burden, no clear pathognomonic sign has been identified to date because of the rarity of clinicopathological studies. Moreover, treatment options are still scarce and have not significantly changed in the last 30 years, underscoring the urgent need to develop new treatment avenues. In the recent years, leucine-rich repeat (LRR) and immunoglobulin (Ig) domain-containing Nogo receptor-interacting proteins 1 and 2 (LINGO1 and LINGO2, respectively) have been increasingly regarded as possible ET modulators due to emerging genetic association studies linking LINGO with ET. We have investigated LINGO protein and messenger RNA (mRNA) expression in the cerebellum of patients with ET, patients with Parkinson's disease (PD), and a control group using Western immunoblotting and in situ hybridization. Protein levels of LINGO1, but not LINGO2, were significantly increased in the cerebellar cortex of ET patients compared with controls, particularly in individuals with longer disease duration. Compared with controls, LINGO1 protein levels were increased in the cerebellar white matter of PD and ET patients but, for the latter, only when disease duration exceeded 20 years. However, no alteration in LINGO1 mRNA was observed between groups in either the cerebellar cortex or the white matter. We observed alterations in LINGO expression in diseased brain that seemed to progress along with the disease, being initiated in the cerebellar cortex before reaching the white matter. Because LINGO up-regulation has been identified as a potential pathological response to ongoing neurodegenerative processes, the present data suggest that LINGO1 is a potential drug target for ET. Show less

Links between substance use habits, obesity, stress and the related cardiovascular outcomes can be, in part, because of loci with pleiotropic effects. To investigate this hypothesis, we performed genome-wide mapping in 119 multigenerational families from a population in the Saguenay-Lac-St-Jean region with a known founder effect using 58,000 single-nucleotide polymorphisms and 437 microsatellite markers to identify genetic components of the following factors: habitual alcohol, tobacco and coffee use; response to mental and physical stress; obesity-related traits; and heart rate (HR) and blood pressure (BP) measures. Habitual alcohol and/or tobacco users had attenuated HR responses to mental stress compared with non-users, whereas hypertensive individuals had stronger HR and systolic BP responses to mental stress and a higher obesity index than normotensives. Genetic mappings uncovered numerous shared genes among substance use, stress response, obesity and hemodynamic traits, including CAMK4, CNTN4, DLG2, FHIT, GRID2, ITPR2, NOVA1 and PRKCE, forming network of interacting proteins, sharing synaptic function and display higher and patterned expression profiles in brain-related tissues; moreover, pathway analysis of shared genes pointed to long-term potentiation. Subgroup genetic mappings uncovered additional shared synaptic genes, including CAMK4, CNTN5 and DNM3 (hypertension-specific); CNTN4, DNM3, FHIT and ITPR1 (sex-specific), having protein interactions with genes driven from general analysis. In summary, consistent with the observed phenotypic correlations, we found substantial overlap among genomic determinants of these traits in synapse, which supports the notion that the neural synapse may be a shared interface behind substance use, stress, obesity, HR, BP as well as the observed sex- and hypertension-specific genetic differences. Show less

The mechanisms responsible for the ectopic adrenal expression of glucose-dependent insulinotropic peptide (GIP) receptor (GIPR) in GIP-dependent Cushing's syndrome (CS) are unknown. Chronic adrenal stimulation by ACTH in Cushing's disease or GIP in GIP-dependent ACTH-independent macronodular adrenal hyperplasia both lead to the induction of genes implicated in adrenal proliferation and steroidogenesis. The objective of the study was to identify genes differentially expressed specifically in GIP-dependent CS that could be implicated in the ectopic expression of GIPR. We used the Affymetrix U133 plus 2.0 microarray oligochips to compare the whole genome expression profile of adrenal tissues from five cases of GIP-dependent bilateral ACTH-independent macronodular adrenal hyperplasia with CS, one case of GIP-dependent unilateral adenoma with CS, five cases of ACTH-dependent hyperplasias, and a pool of adrenals from 62 normal individuals. After data normalization and statistical filtering, 723 genes with differential expression were identified, including 461 genes or sequences with a known functional implication, classified in eight dominant functional classes. Specific findings include repression of perilipin, the overexpression of 13 G protein-coupled receptors, and the potential involvement of Rho-GTPases. We also isolated 94 probe sets potentially linked to the formation of GIP-dependent nodules adjacent to the diffuse hyperplasia. These included probe sets related to the linker histone H1 and repression of RXRa and CCND2. The expression profiles for eight genes were confirmed by real-time RT-PCR. This study identified an extensive series of potentially novel target candidate genes that could be implicated in the molecular mechanisms of ectopic expression of the GIPR as well as in the multistep progression of GIP-dependent CS. Show less

The molecular mechanisms responsible for glucose-dependent insulinotrophic peptide receptor or gastric inhibitory polypeptide receptor (GIPR) ectopic expression and function in GIP-dependent Cushing's syndrome (CS) are still unknown. GIPR presumably acts, like the ACTH receptor (ACTHR), through the Gs protein/cyclic AMP/protein kinase A (PKA) pathway to stimulate steroidogenesis. We studied the expression of several genes involved in this pathway in the adrenal tissues of patients with GIP-dependent CS. RNA was extracted from adrenal tissues from nine patients with GIP-dependent CS [seven ACTH-independent bilateral macronodular adrenal hyperplasia (AIMAH), two adenomas], two control whole adult adrenals, two fasciculata cell-enriched preparations from normal adrenals, seven patients with Cushing's disease (CD) and two normal pancreas. Multiplex reverse transcriptase polymerase chain reaction (RT-PCR) evaluated the expression of GIPR, ACTHR, SF-1, Nur77, DAX-1, CYP11A, 3beta-HSD, CYP21, CREB and CREM genes. GIPR mRNA was overexpressed in all GIP-dependent cases. In normal adrenals and in the adrenal tissues from patients with CD, minimal amounts of GIPR mRNA were detected. ACTHR mRNA expression was observed in all GIP-dependent adrenal tissues. The expression of steroidogenic enzymes and some specific and ubiquitous transcription factors (TFs) involved in the ACTHR cascade was significantly reduced. Our results indicate that the expression of ACTHR and other genes located downstream in the ACTHR cascade, including steroidogenic enzymes genes and some transcription factors, are relatively suppressed in GIP-dependent CS. Although the expression of aberrant receptors plays an important role in steroidogenesis and initiation of cell proliferation, additional genetic events might occur, altering the activity of the ACTHR pathway. Show less

A novel 17beta-hydroxysteroid dehydrogenase (17beta-HSD) chronologically named type 12 17beta-HSD (17beta-HSD12), that transforms estrone (E1) into estradiol (E2) was identified by sequence similarity with type 3 17beta-HSD (17beta-HSD3) that catalyzes the formation of testosterone from androstenedione in the testis. Both are encoded by large genes spanning 11 exons, most of them showing identical size. Using human embryonic kidney-293 cells stably expressing 17beta-HSD12, we have found that the enzyme catalyzes selectively and efficiently the transformation of E1 into E2, thus identifying its role in estrogen formation, in contrast with 17beta-HSD3, the enzyme involved in the biosynthesis of the androgen testosterone in the testis. Using real-time PCR to quantify mRNA in a series of human tissues, the expression levels of 17beta-HSD12 as well as two other enzymes that perform the same transformation of E1 into E2, namely type 1 17beta-HSD and type 7 17beta-HSD, it was found that 17beta-HSD12 mRNA is the most highly expressed in the ovary and mammary gland. To obtain a better understanding of the structural basis of the difference in substrate specificity between 17beta-HSD3 and 17beta-HSD12, we have performed tridimensional structure modelization using the coordinates of type 1 17beta-HSD and site-directed mutagenesis. The results show the potential role of bulky amino acid F234 in 17beta-HSD12 that blocks the entrance of androstenedione. Overall, our results strongly suggest that 17beta-HSD12 is the major estrogenic 17beta-HSD responsible for the conversion of E1 to E2 in women, especially in the ovary, the predominant source of estrogens before menopause. Show less

The best characterized effect of glucose-dependent insulinotropic polypeptide (GIP) is its stimulatory effect on insulin secretion by pancreatic beta-cells. Recently, it was demonstrated that some cases of primary adrenal Cushing's syndrome were secondary to the ectopic expression of non-mutated GIP receptor (GIP-R) in bilateral adrenal hyperplasias or unilateral adrenal adenomas, resulting in food-dependent steroidogenesis. Using a human multiple-expression tissue array, GIP-R was found to be expressed in a large number of human adult and fetal tissues, but not in the adrenal gland. The analysis of the promoter region of human (h) GIP-R gene revealed six consensus sequences important in regulating the reporter gene activity and capable of binding to Sp1 and Sp3 transcription factors. Data obtained by gene array and semi-quantitative RT-PCR showed an increase in the expression of Sp3 and CRSP9 (co-regulator of Sp1 transcription factor, subunit 9) in the adrenal adenomas or bilateral macronodular hyperplasias of patients with GIP-dependent Cushing's syndrome; they were, however, also increased in some patients with non-GIP-dependent cortisol-secreting adenomas or with ACTH-dependent Cushing's disease. This study represents the first step in our understanding of the mechanisms involved in the regulation of the expression of the hGIP-R gene. Show less

Gastric inhibitory polypeptide (GIP)-dependent Cushing's syndrome (CS) results from the ectopic expression of non-mutated GIP receptor (hGIPR) in the adrenal cortex. We evaluated whether mutations or polymorphisms in the regulatory region of the GIPR gene could lead to this aberrant expression. We studied 9.0kb upstream and 1.3kb downstream of the GIPR gene putative promoter (pProm) by sequencing leukocyte DNA from controls and from adrenal tissues of GIP- and non-GIP-dependent CS patients. The putative proximal promoter region (800 bp) and the first exon and intron of the hGIPR gene were sequenced on adrenal DNA from nine GIP-dependent CS, as well as on leukocyte DNA of nine normal controls. Three variations found in this region were found in all patients and controls; at position -4/-5, an insertion of a T was seen in four out of nine patients and in five out of nine controls. Transient transfection studies conducted in rat GC and mouse Y1 cells showed that the TT allele confers loss of 40% in the promoter activity. The analysis of the 8-kb distal pProm region revealed eight distal single nucleotide polymorphisms (SNPs) without probable association with the disease, since frequencies in patients and controls were very similar. In conclusion, mutations or SNPs in the regulatory region of the GIPR gene are unlikely to underlie GIP-dependent CS. Show less

Gastric inhibitory polypeptide (GIP)-dependent Cushing's syndrome has been reported to occur either in unilateral adrenal adenoma or in bilateral macronodular adrenal hyperplasia. A 33-yr-old woman with Cushing's syndrome was found to have two 2.5- to 3-cm nodules in the right adrenal on computed tomography scan; the left adrenal appeared normal except for the presence of a small 0.8 x 0.6-cm nodule. Uptake of iodocholesterol was limited to the right adrenal. Plasma morning cortisol was 279 nmol/L fasting and 991 nmol/L postprandially, and ACTH remained suppressed. Plasma cortisol increased after oral glucose (202%) or a lipid-rich meal (183%), but not after a protein-rich meal (95%) or iv glucose (93%); the response to oral glucose was blunted by pretreatment with 100 microg octreotide, sc. Plasma cortisol and GIP levels were positively correlated (r = 0.95; P = 0.0001); cortisol was stimulated by the administration of human GIP iv (225%), but not by GLP-1, insulin, TRH, GnRH, glucagon, arginine vasopressin, upright posture, or cisapride orally. A right adrenalectomy was performed; GIP receptor messenger ribonucleic acid was overexpressed in both adrenal nodules and in the adjacent cortex. Histopathology revealed diffuse macronodular adrenal hyperplasia without internodular atrophy. Three months after surgery, fasting plasma ACTH and cortisol were suppressed, but cortisol increased 3.6-fold after oral glucose, whereas ACTH remained suppressed; this was inhibited by octreotide pretreatment, suggesting that cortisol secretion by the left adrenal is also GIP dependent. We conclude that GIP-dependent nodular hyperplasia can progress in an asynchronous manner and that GIPR overexpression is an early event in this syndrome. Show less

Abnormal responsiveness of adrenocortical cells to gastric inhibitory polypeptide (GIP) in food-dependent Cushing's syndrome suggested that adrenal expression of ectopic, overexpressed, or mutated GIP receptor (GIPR) underlies this syndrome. The expression of GIPR was studied by RT-PCR in human adrenal tissues from two patients with GIP-dependent Cushing's syndrome (adenoma, bilateral hyperplasia), five fetal or adult controls, one patient with Cushing's disease, and four patients with non-food-dependent cortisol-secreting adenomas or bilateral hyperplasias and compared to that in normal pancreas. Hybridization of the RT-PCR-amplified ribonucleic acids with the human GIPR complementary DNA showed an overexpression of GIPR in the adrenals of the two GIP-dependent Cushing's syndrome patients compared to that in normal adrenal tissues (2-3 orders of magnitude) or pancreas (10-fold); no signal could be seen in adrenal adenomas or macronodular hyperplasia from cases of non-food-dependent Cushing's syndrome. No mutation of the GIPR was identified by sequencing the full-length receptor in GIP-dependent adrenal tissue. New alternative spliced isoforms of the GIPR were found, but are identical in GIP-dependent and normal adrenal tissues. Incubation of adrenal cells with GIP stimulates cortisol secretion in GIP-dependent, but not in normal fetal, adult, or non-food-dependent Cushing's syndrome, adrenals. We conclude that the GIPR overexpression and its coupling to steroidogenesis underlie GIP-dependent Cushing's syndrome. Show less