Glibenclamide reverses cardiovascular abnormalities of Cantu Syndrome driven by K_ATP channel overactivity

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Abstract

Cantu Syndrome (CS) is a complex disorder caused by gain-of-function (GoF) mutations in ABCC9 and KCNJ8, which encode the SUR2 and Kir6.1 subunits, respectively, of vascular smooth muscle (VSM) KATP channels. CS includes dilated vasculature, marked cardiac hypertrophy, and other cardiovascular abnormalities. There is currently no targeted therapy, and it is unknown whether cardiovascular features can be reversed once manifest. Using combined transgenic and pharmacological approaches in a knock-in mouse model of CS, we have shown that reversal of vascular and cardiac phenotypes can be achieved (1) by genetic downregulation of KATP channel activity specifically in VSM, and (2) by chronic administration of the clinically-used KATP channel inhibitor, glibenclamide. These findings demonstrate (i) that VSM KATP channel GoF underlies CS cardiac enlargement, (ii) reversibility of CS-associated abnormalities and (iii) evidence of in vivo efficacy of glibenclamide as a therapeutic agent in CS.

Authors

Conor McClenaghan, Yan Huang, Zihan Yan, Theresa Harter, Carmen M. Halabi, Rod Chalk, Attila Kovacs, Gijs van Haaften, Maria S. Remedi, Colin G. Nichols

CD8⁺ T cells target cerebrovasculature in children with cerebral malaria

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Abstract

BACKGROUND. Cerebral malaria (CM) accounts for nearly 400,000 deaths annually in African children. Current dogma suggests that CM results from infected RBC (iRBC) sequestration in the brain microvasculature and resulting sequelae. Therapies targeting these events have been unsuccessful; findings in experimental models suggest that CD8+ T cells drive disease pathogenesis. However, these data have largely been ignored because corroborating evidence in humans is lacking. This work fills a critical gap in our understanding of CM pathogenesis that is impeding development of therapeutics. METHODS. Using multiplex immunohistochemistry, we characterized cerebrovascular immune cells in brain sections from 34 children who died from CM or other causes. Children were grouped by clinical diagnosis (CM+ or –), iRBC sequestration (Seqhi, lo, or 0) and HIV status (HIV+ or –). RESULTS. We identified effector CD3+CD8+ T cells engaged on the cerebrovasculature in 69% of CM+ HIV– children. The number of intravascular CD3+CD8+ T cells was influenced by CM status (CM+ vs –, P = 0.004) and sequestration level (Seqhi > lo, P = 0.010). HIV co-infection significantly increased T cell numbers and shifted cells from an intravascular (P = 0.004) to perivascular (P < 0.0001) distribution. CONCLUSION. Within the studied cohort, CM is associated with cerebrovascular engagement of CD3+CD8+ T cells, which is exacerbated by HIV coinfection. Thus, CD3+CD8+ T cells are highly promising targets for CM adjunctive therapy, opening new avenues for the treatment of this deadly disease. FUNDING. This research was supported by the Intramural Research Program of the National Institutes of Health.

Authors

Brittany A. Riggle, Monica Manglani, Dragan Maric, Kory R. Johnson, Myoung-Hwa Lee, Osorio Lopes Abath Neto, Terrie E. Taylor, Karl B. Seydel, Avindra Nath, Louis H. Miller, Dorian B. McGavern, Susan K. Pierce

DGCR8 microprocessor defect characterizes familial multinodular goiter with schwannomatosis

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Abstract

Background: DICER1 is the only miRNA biogenesis component associated with an inherited tumor syndrome, featuring multinodular goiter (MNG) and rare pediatric-onset lesions. Other susceptibility genes for familial forms of MNG likely exist. Methods: Whole exome sequencing of a kindred with early-onset MNG and schwannomatosis was followed by investigation of germline pathogenic variants that fully segregated with the disease. Genome wide analyses were performed on 13 tissue samples from familial and non-familial DGCR8-E518K positive tumors, including MNG, schwannomas, papillary thyroid cancers (PTC) and Wilms Tumors. MiRNA profiles of four tissue types were compared, and sequencing of miRNA, pre-miRNA and mRNA was performed in a subset of 9 schwannomas, four of which harbor DGCR8-E518K. Results: We identified c.1552G>A;p.E518K in DGCR8, a microprocessor located in 22q, in the kindred. The variant identified is a somatic hotspot in Wilms Tumors and has been identified in two PTCs. Copy number loss of chromosome 22q, leading to loss of heterozygosity at the DGCR8 locus, was found in all 13 samples harboring c.1552G>A;p.E518K. miRNA profiling of PTC, MNG, schwannomas and Wilms Tumors revealed a common profile among E518K hemizygous tumors. In vitro cleavage demonstrated improper processing of pre-miRNA by DGCR8-E518K. MicroRNA and RNA profiling show that this variant disrupts precursor microRNA production, impacting populations of canonical microRNAs and mirtrons. Conclusions: We identified DGCR8 as the cause of an unreported autosomal dominant mendelian tumor susceptibility syndrome: familial multinodular goiter with schwannomatosis. Funded by CIHR, Compute Canada, Alex’s Lemonade Stand Foundation, and the Mia Neri Foundation for Childhood Cancer.

Authors

Barbara Rivera, Javad Nadaf, Somayyeh Fahiminiya, Maria Apellaniz-Ruiz, Avi Saskin, Anne-Sophie Chong, Sahil Sharma, Rabea Wagener, Timothée Revil, Vincenzo Condello, Zineb Harra, Nancy Hamel, Nelly Sabbaghian, Karl Muchantef, Christian Thomas, Leanne de Kock, Marie-Noëlle Hébert-Blouin, Angelia V. Bassenden, Hannah Rabenstein, Ozgur Mete, Ralf Paschke, Marc P. Pusztaszeri, Werner Paulus, Albert Berghuis, Jiannis Ragoussis, Yuri E. Nikiforov, Reiner Siebert, Steffen Albrecht, Robert Turcotte, Martin Hasselblatt, Marc R. Fabian, William D. Foulkes

Insulin resistance drives hepatic de novo lipogenesis in nonalcoholic fatty liver disease

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Abstract

Background. An increase in intrahepatic triglyceride (IHTG) is the hallmark feature of nonalcoholic fatty liver disease (NAFLD) and is decreased by weight loss. Hepatic de novo lipogenesis (DNL) contributes to steatosis in people with NAFLD. The physiological factors that stimulate hepatic DNL and the effect of weight loss on hepatic DNL are not clear.Methods. Hepatic DNL, 24-h integrated plasma insulin and glucose concentrations, and both liver and whole-body insulin sensitivity were determined in people who were lean (n = 14), obese with normal IHTG content (Obese, n = 26) and obese with NAFLD (Obese-NAFLD, n = 27). Hepatic DNL was assessed by using the deuterated water method corrected for the potential confounding contribution of adipose tissue DNL. Liver and whole-body insulin sensitivity were assessed by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with glucose tracer infusion. Six subjects in the Obese-NAFLD group were also evaluated before and after 10% diet-induced weight loss.Results. The contribution of hepatic DNL to IHTG-palmitate was 11%, 19% and 38% in the Lean, Obese and Obese-NAFLD groups, respectively. Hepatic DNL was inversely correlated with hepatic and whole-body insulin sensitivity, but directly correlated with 24-h plasma glucose and insulin concentrations. Weight loss decreased IHTG content, in conjunction with a decrease in hepatic DNL and 24-h plasma glucose and insulin concentrations. Conclusions. These data suggest hepatic DNL is an important regulator of IHTG content, and that increases in circulating glucose and insulin stimulate hepatic DNL in people with NAFLD. Weight loss decreases IHTG content, at least in part, by decreasing hepatic DNL.

Authors

Gordon I. Smith, Mahalakshmi Shankaran, Mihoko Yoshino, George G. Schweitzer, Maria Chondronikola, Joseph W. Beals, Adewole L. Okunade, Bruce W. Patterson, Edna Nyangau, Tyler Field, Claude B. Sirlin, Saswata Talukdar, Marc K. Hellerstein, Samuel Klein

IL-36γ drives skin toxicity induced by EGFR/MEK inhibition and commensal Cutibacterium acnes

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Abstract

Epidermal growth factor receptor (EGFR) and MEK inhibitors (EGFR/MEKi) are beneficial for the treatment of solid cancers but are frequently associated with severe therapy-limiting acneiform skin toxicities. The underlying molecular mechanisms are poorly understood. Using gene expression profiling we identified IL-36γ and IL-8 as candidate drivers of EGFR/MEKi skin toxicity. We provide molecular and translational evidence that EGFR/MEKi in concert with the skin commensal bacterium Cutibacterium acnes act synergistically to induce IL-36γ in keratinocytes and subsequently IL-8, leading to cutaneous neutrophilia. IL-36γ expression was the combined result of C. acnes-induced NF-κB activation and EGFR/MEKi-mediated expression of the transcription factor Krüppel-like factor 4 (KLF4), due to the presence of both NF-κB- and KLF4-binding sites in the human IL-36γ gene promoter. EGFR/MEKi increased KLF4 expression by blockade of the EGFR-MEK-ERK pathway. These results provide an insight into understanding the pathological mechanism of the acneiform skin toxicities induced by EGFR/MEKi and identify IL-36γ and the transcription factor KLF4 as potential therapeutic targets.

Authors

Takashi K. Satoh, Mark Mellett, Barbara Meier-Schiesser, Gabriele Fenini, Atsushi Otsuka, Hans-Dietmar Beer, Tamara Rordorf, Julia-Tatjana Maul, Jürg Hafner, Alexander A. Navarini, Emmanuel Contassot, Lars E. French

Oral N-acetylcysteine improves cone function in retinitis pigmentosa patients in phase 1 trial

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Background: In retinitis pigmentosa (RP) rod photoreceptors degenerate from one of many mutations after which cones are compromised by oxidative stress. N-acetylcysteine (NAC) reduces oxidative damage and increases cone function/survival in RP models. We tested the safety, tolerability, and visual function effects of oral NAC in RP patients. Methods: Subjects (n = 10 per cohort) received 600 mg (cohort 1), 1200 mg (cohort 2), or 1800 mg (cohort 3) NAC BID for 12 weeks and then TID for 12 weeks. Best-corrected visual acuity (BCVA), macular sensitivity, ellipsoid zone (EZ) width, and aqueous NAC were measured. Linear mixed effects models were used to estimate the rates of changes during the treatment period. Results: There were 9 drug-related gastrointestinal adverse events which resolved spontaneously or with dose reduction (MTD 1800 mg bid). During the 24 week treatment period, mean BCVA significantly improved at 0.4 (95% CI 0.2–0.6, P < 0.001), 0.5 (95% CI 0.3–0.7, P < 0.001) and 0.2 (95% CI 0.02–0.4, P = 0.03) letters/month in cohorts 1, 2 and 3, respectively. There was no significant improvement in mean sensitivity (MS) over time in cohorts 1 and 2, but there was in cohort 3 (0.15 dB/month, 95%CI 0.04–0.26). There was no significant change in mean EZ width in any cohort. Conclusion: Oral NAC is safe and well-tolerated in patients with moderately advanced RP and may improve suboptimally functioning macular cones. A randomized, placebo-controlled trial is needed to determine if oral NAC can provide long term stabilization and/or improvement in visual function in patients with RP.

Authors

Peter A. Campochiaro, Mustafa Iftikhar, Gulnar Hafiz, Anam Akhlaq, Grace Tsai, Dagmar Wehling, Lili Lu, G. Michael Wall, Mandeep S. Singh, Xiangrong Kong

Neuromuscular junctions are stable in patients with cancer cachexia

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Abstract

Cancer cachexia is a major cause of patient morbidity and mortality, with no efficacious treatment or management strategy. Despite sharing pathophysiological features with a number of neuromuscular wasting conditions, including age-related sarcopenia, the mechanisms underlying cachexia remain poorly understood. Studies of related conditions suggest that pathological targeting of the neuromuscular junction (NMJ) may play a key role in cachexia, but this has yet to be investigated in human patients. Here, high-resolution morphological analyses were undertaken on NMJs of rectus abdominis obtained from patients undergoing upper GI cancer surgery compared with controls (N=30; n=1,165 NMJs). Cancer patients included those with cachexia and weight-stable disease. Despite the low skeletal muscle index and significant muscle fibre atrophy in patients with cachexia, NMJ morphology was fully conserved. No significant differences were observed in any of the pre- and post-synaptic variables measured. We conclude that NMJs remain structurally intact in rectus abdominis in both cancer and cachexia, suggesting that denervation of skeletal muscle is not a major driver of pathogenesis. The absence of NMJ pathology is in stark contrast to related conditions, such as age-related sarcopenia, and supports the hypothesis that intrinsic changes within skeletal muscle, independent of any changes in motor neurons, represent the primary locus of neuromuscular pathology in cancer cachexia.

Authors

Ines Boehm, Janice Miller, Thomas M. Wishart, Stephen J. Wigmore, Richard J.E. Skipworth, Ross A. Jones, Thomas H. Gillingwater

Chikungunya virus replication in skeletal muscle cells is required for disease development

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Abstract

Chikungunya virus (CHIKV) is an arbovirus capable of causing a severe and often debilitating rheumatic syndrome in humans. CHIKV replicates in a wide variety of cell types in mammals, which has made attributing pathologic outcomes to replication at specific sites difficult. To assess the contribution of CHIKV replication in skeletal muscle cells to pathogenesis, we engineered a CHIKV strain exhibiting restricted replication in these cells via incorporation of target sequences for skeletal muscle cell-specific miR-206. This virus, which we term SKE, displayed diminished replication in skeletal muscle cells in a mouse model of CHIKV disease. Mice infected with SKE developed less severe disease signs, including diminished swelling in the inoculated foot and less necrosis and inflammation in the interosseous muscles. SKE infection was associated with diminished infiltration of T cells into the interosseous muscle as well as decreased production of IL-1b, IL-6, IP-10, and TNFa. Importantly, blockade of the IL-6 receptor led to diminished swelling of a control CHIKV strain capable of replication in skeletal muscle, reducing swelling to levels observed in mice infected with SKE. These data implicate replication in skeletal muscle cells and release of IL-6 as important mediators of CHIKV disease.

Authors

Anthony J. Lentscher, Mary K. McCarthy, Nicholas A. May, Bennett J. Davenport, Stephanie A. Montgomery, Krishnan Raghunathan, Nicole McAllister, Laurie A. Silva, Thomas E. Morrison, Terence S. Dermody

Impaired folate one-carbon metabolism causes formate-preventable hydrocephalus in glycine decarboxylase-deficient mice

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Abstract

Ventriculomegaly and hydrocephalus are associated with loss of function of glycine decarboxylase (Gldc) in mice and in humans suffering from Non-Ketotic Hyperglycinemia (NKH), a neurometabolic disorder characterised by accumulation of excess glycine. Here, we showed that ventriculomegaly in Gldc-deficient mice is preceded by stenosis of the Sylvian aqueduct and malformation or absence of the sub-commissural organ and pineal gland. Gldc functions in the glycine cleavage system, a mitochondrial component of folate metabolism, whose malfunction results in accumulation of glycine and diminished supply of glycine-derived one-carbon units to the folate cycle. We showed that inadequate one-carbon supply, as opposed to excess glycine is the cause of hydrocephalus associated with loss of function of the glycine cleavage system. Maternal supplementation with formate prevented both ventriculomegaly, as assessed at pre-natal stages, and post-natal development of hydrocephalus in Gldc-deficient mice. Furthermore, ventriculomegaly was rescued by genetic ablation of 5,10-methylene tetrahydrofolate reductase (Mthfr), which results in retention of one-carbon groups in the folate cycle at the expense of transfer to the methylation cycle. In conclusion, a defect in folate metabolism can lead to pre-natal aqueduct stenosis and resultant hydrocephalus. These defects are preventable by maternal supplementation with formate, which acts as a one-carbon donor.

Authors

Chloe Santos, Yun Jin Pai, M. Raasib Mahmood, Kit-Yi Leung, Dawn Savery, Simon N. Waddington, Andrew J. Copp, Nicholas D.E. Greene

Lysine acetyltransferase 8 is involved in cerebral development and syndromic intellectual disability

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Abstract

Epigenetic integrity is critical for many eukaryotic cellular processes. An important question is how different epigenetic regulators control development and impact disease. Lysine acetyltransferase 8 (KAT8) is critical for acetylation of histone H4 at lysine 16 (H4K16), an evolutionarily conserved epigenetic mark. It is unclear what roles KAT8 plays in cerebral development and human disease. Here, we report that cerebrum-specific knockout mice displayed cerebral hypoplasia in the neocortex and hippocampus, along with improper neural stem and progenitor cell (NSPC) development. Mutant cerebrocortical neuroepithelia exhibited faulty proliferation, aberrant neurogenesis, massive apoptosis and scant H4K16 propionylation. Mutant NSPCs formed poor neurospheres, and pharmacological KAT8 inhibition abolished neurosphere formation. Moreover, we describe KAT8 variants in nine patients with intellectual disability, seizures, autism, dysmorphisms and other anomalies. The variants altered chromobarrel and catalytic domains of KAT8, thereby impairing nucleosomal H4K16 acetylation. Valproate was effective for treating epilepsy in at least two of the individuals. This study uncovers a critical role of KAT8 in cerebral and NSPC development, identifies nine individuals with KAT8 variants, and links deficient H4K16 acylation directly to intellectual disability, epilepsy and other developmental anomalies.

Authors

Lin Li, Mohammad Ghorbani, Monika Weisz-Hubshman, Justine Rousseau, Isabelle Thiffault, Rhonda E. Schnur, Catherine Breen, Renske Oegema, Marjan M.M. Weiss, Quinten Waisfisz, Sara Welner, Helen Kingston, Jordan A. Hills, Elles M.J. Boon, Lina Basel-Salmon, Osnat Konen, Hadassa Goldberg-Stern, Lily Bazak, Shay Tzur, Jianliang Jin, Xiuli Bi, Michael Bruccoleri, Kirsty McWalter, Megan T. Cho, Maria Scarano, G. Bradley Schaefer, Susan S. Brooks, Susan Starling Hughes, K.L.I. van Gassen, Johanna M. van Hagen, Tej K. Pandita, Pankaj B. Agrawal, Philippe M. Campeau, Xiang-Jiao Yang