Neonatal-Onset Chronic Diarrhea Caused by Homozygous Nonsense WNT2B Mutations.

Homozygous nonsense mutations in WNT2B were identified in three individuals from two unrelated families with severe, neonatal-onset osmotic diarrhea after whole-exome sequencing was performed on trios from the two families. Intestinal biopsy samples from affected individuals were used for histology and immunofluorescence and to generate enteroids ex vivo. Histopathologic evaluation demonstrated chronic inflammatory changes in the stomach, duodenum, and colon. Immunofluorescence demonstrated diminished staining for OLFM4, a marker for intestinal stem cells (ISCs). The enteroids generated from WNT2B-deficient intestinal epithelium could not be expanded and did not survive passage. Addition of CHIR-99021 (a GSK3A and GSK3B inhibitor and activator of canonical WNT/ß-CATENIN signaling) could not rescue WNT2B-deficient enteroids. Addition of supplemental recombinant murine WNT2B was able to perpetuate small enteroids for multiple passages but failed to expand their number. Enteroids showed a 10-fold increase in the expression of LEF1 mRNA and a 100-fold reduction in TLR4 expression, compared with controls by quantitative RT-PCR, indicating alterations in canonical WNT and microbial pattern-recognition signaling. In summary, individuals with homozygous nonsense mutations in WNT2B demonstrate severe intestinal dysregulation associated with decreased ISC number and function, likely explaining their diarrheal phenotype. WNT2B deficiency should be considered for individuals with neonatal-onset diarrhea.

Brown Syndrome Following Upper Eyelid Ptosis Repair.

Brown syndrome is characterised by impaired supraduction worse in adduction due to a restricted superior oblique tendon passing through the trochlea. A few reports have previously described Brown syndrome after upper eyelid surgery, including blepharoplasty and ptosis repair. The authors describe two additional cases of Brown syndrome following ptosis repair. The first case is a 65-year-old woman with new-onset vertical binocular diplopia following bilateral levator advancement surgery. Ocular motility examination demonstrated moderate impairment of elevation in adduction. The second case is a 35-year-old woman who presented with new-onset intermittent binocular diplopia following right upper lid ptosis repair. Examination revealed large vertical fusional amplitudes and a large left intermittent hyperphoria in an alignment pattern consistent with Brown syndrome. Despite presenting after surgery, these cases differ in mechanism. The first case likely occurred due to intraoperative impairment of the superior oblique tendon sheath or trochlea, whereas the second case represented an unmasking of a long-standing, previous vertical strabismus that was consistent with a Brown syndrome pattern.

Targeting collagen strands by photo-triggered triple-helix hybridization.

Collagen remodeling is an integral part of tissue development, maintenance, and regeneration, but excessive remodeling is associated with various pathologic conditions. The ability to target collagens undergoing remodeling could lead to new diagnostics and therapeutics as well as applications in regenerative medicine; however, such collagens are often degraded and denatured, making them difficult to target with conventional approaches. Here, we present caged collagen mimetic peptides (CMPs) that can be photo-triggered to fold into triple helix and bind to collagens denatured by heat or by matrix metalloproteinase (MMP) digestion. Peptide-binding assays indicate that the binding is primarily driven by stereo-selective triple-helical hybridization between monomeric CMPs of high triple-helical propensity and denatured collagen strands. Photo-triggered hybridization allows specific staining of collagen chains in protein gels as well as photo-patterning of collagen and gelatin substrates. In vivo experiments demonstrate that systemically delivered CMPs can bind to collagens in bones, as well as prominently in articular cartilages and tumors characterized by high MMP activity. We further show that CMP-based probes can detect abnormal bone growth activity in a mouse model of Marfan syndrome. This is an entirely new way to target the microenvironment of abnormal tissues and could lead to new opportunities for management of numerous pathologic conditions associated with collagen remodeling and high MMP activity.

Altered tissue behavior of a non-aneurysmal descending thoracic aorta in the mouse model of Marfan syndrome.

Aortic aneurysm is predominantly found in the ascending aorta in patients with Marfan syndrome (MFS). However, descending aortic disease has emerged as a problem since people are living longer because of improved medical and surgical management of the ascending aorta. Diagnostic procedures before disease onset and the mechanisms involved in the transition of normal aortic tissue to aneurysm remain unclear. We determined signs of descending aortic disease before disease onset in mice with a mutation in the fibrillin 1 gene (Fbn1(+/C1039G)), a validated mouse model of disease susceptibility and progression of aortic aneurysm of MFS. We analyzed a tubular unfixed non-aneurysmal descending thoracic aorta from 8-month-old wild-type and Fbn1(+/C1039G) mice by a tubular biaxial tester that works in conjunction with a two-photon nonlinear microscope. Fbn1(+/C1039G) mouse aorta was more compliant in the circumferential direction. Two-photon imaging showed defective organization of adventitial collagen fibers in the pressurized aortas of Fbn1(+/C1039G) mice. Moreover, disruption in the elastic lamina was noted in the absence of aneurysms in pressurized aortas but not unpressurized aortas of Fbn1(+/C1039G) mice. At the molecular level, this altered tissue behavior in non-aneurysmal descending aortas of Fbn1(+/C1039G) mice was accompanied by an increasing trend of canonical but not noncanonical, transforming growth factor-ß (TGFß) signaling. Finally, assays of in vitro collagen lattice formation in mouse wild-type and TGFß1-deficient embryonic fibroblasts indicate that TGFß1 can regulate collagen organization. The ability to reveal the presence of altered biomechanics and microstructure coupled with subtle changes in TGFß signaling provides a novel surrogate measure of tissue susceptibility to aneurysm before disease onset.

Accessory iris membranes: Removing the veil.

PURPOSE: To report a case of a young adult with dense bilateral accessory iris membranes (AIMs). OBSERVATIONS: AIMs can influence vision by multiple mechanisms. We discuss clinical examination and imaging considerations that can help parse optical and refractive complications to better guide intervention discussions. We also describe our surgical approach and perioperative management to help minimize trauma to the eye and maximize favorable surgical outcomes in these cases. CONCLUSIONS AND IMPORTANCE: This case highlights the excellent symptomatic, visual acuity and stereopsis gains that can be achieved following surgical intervention for this clinical entity, even in older patients.

Survey of Ehlers-Danlos Patients' ophthalmic surgery experiences.

BACKGROUND: Ehlers-Danlos Syndrome (EDS) is a rare disease affecting approximately 1 in 5,000 people. Although ophthalmic conditions associated with EDS have been described, little data exist concerning ophthalmic surgical outcomes experienced by EDS patients. METHODS: Patients with EDS were surveyed via the EDS Society and asked about their ophthalmic surgical experiences including procedure, complications, and the timing with respect to receiving the EDS diagnosis. Complications were confirmed as such by subspecialists. RESULTS: Of 579 respondents, 467 reported confirmed EDS, and 112 of those had an ophthalmic procedure, including refractive surgery, cataract/lens surgery, retinal surgery, strabismus surgery, oculoplastic surgery, corneal surgery, and laser surgery for glaucoma. The rate of confirmed complications was: 23%-refractive, 33%-lens/cataract, 33%-retina, 59%-strabismus, 23%- oculoplastics, 0%-cornea, and 25%-glaucoma laser. In addition, 76% of patients underwent surgery prior to the EDS diagnosis. CONCLUSIONS: Patients with EDS may have elevated risk of postoperative ophthalmic surgical complications. It would seem reasonable to systemically and prospectively explore how patients with EDS respond to ophthalmic surgery. Furthermore, it would seem circumspect to ask surgical candidates patients about whether they carry a diagnosis of EDS or have signs and symptoms of EDS prior to surgery.

Transposition procedures in Duane retraction syndrome.

Duane retraction syndrome, or Duane syndrome (DS), is one of several congenital cranial dysinnervation disorders. Patients present with limited horizontal eye movement(s) and globe retraction with eyelid fissure narrowing on attempted adduction due to co-contraction of the lateral and medial rectus muscles in one or both eyes. Various surgical approaches have been proposed to improve binocular alignment, reduce head turn, and minimize undesirable up- or downshoots in DS. Transposition procedures are one such approach, and a number of techniques have been described. These may involve one or both vertical rectus muscles and may or may not include full or partial disinsertion of the rectus muscle(s) from the insertion. Options involving both vertical rectus muscles include full vertical rectus transposition (VRT), partial VRT, rectus muscle union, and other modifications to be discussed. Options involving one vertical rectus muscle include superior rectus transposition (SRT) and inferior rectus transposition (IRT). The effectiveness of any transposition procedure may be enhanced with augmentation (posterior fixation) sutures, resection of the transposed muscle(s), and/or simultaneous weakening of the ipsilateral medial rectus muscle. This review discusses the indications, strengths, weaknesses, and other considerations of these approaches within the context of DS. Since the majority of DS cases are unilateral and most have the esotropic form, this will be the main focus of the review, although other forms will also be discussed.

Acquired reversible Brown syndrome caused by focal abscess of the superior oblique muscle.

A 16-year-old boy with a history of relapsed acute myeloid leukemia and a right lower lobe lung abscess confirmed to be Aspergillus presented for a baseline eye examination prior to consideration of bone marrow transplantation. He noted double vision in up-and-left gaze, and his examination was consistent with an acquired right-sided Brown syndrome. Magnetic resonance imaging revealed a 4 mm rim-enhancing inflammatory focus in the right superior oblique muscle. His Brown syndrome resolved after treatment with systemic antimicrobials.

A deleterious gene-by-environment interaction imposed by calcium channel blockers in Marfan syndrome.

Calcium channel blockers (CCBs) are prescribed to patients with Marfan syndrome for prophylaxis against aortic aneurysm progression, despite limited evidence for their efficacy and safety in the disorder. Unexpectedly, Marfan mice treated with CCBs show accelerated aneurysm expansion, rupture, and premature lethality. This effect is both extracellular signal-regulated kinase (ERK1/2) dependent and angiotensin-II type 1 receptor (AT1R) dependent. We have identified protein kinase C beta (PKCß) as a critical mediator of this pathway and demonstrate that the PKCß inhibitor enzastaurin, and the clinically available anti-hypertensive agent hydralazine, both normalize aortic growth in Marfan mice, in association with reduced PKCß and ERK1/2 activation. Furthermore, patients with Marfan syndrome and other forms of inherited thoracic aortic aneurysm taking CCBs display increased risk of aortic dissection and need for aortic surgery, compared to patients on other antihypertensive agents.

Matrix-dependent perturbation of TGFß signaling and disease.

Transforming growth factor beta (TGFß) is a multipotent cytokine that is sequestered in the extracellular matrix (ECM) through interactions with a number of ECM proteins. The ECM serves to concentrate latent TGFß at sites of intended function, to influence the bioavailability and/or function of TGFß activators, and perhaps to regulate the intrinsic performance of cell surface effectors of TGFß signal propagation. The downstream consequences of TGFß signaling cascades in turn provide feedback modulation of the ECM. This review covers recent examples of how genetic mutations in constituents of the ECM or TGFß signaling cascade result in altered ECM homeostasis, cellular performance and ultimately disease, with an emphasis on emerging therapeutic strategies that seek to capitalize on this refined mechanistic understanding.

Mutations in the TGF-ß repressor SKI cause Shprintzen-Goldberg syndrome with aortic aneurysm.

Elevated transforming growth factor (TGF)-ß signaling has been implicated in the pathogenesis of syndromic presentations of aortic aneurysm, including Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS). However, the location and character of many of the causal mutations in LDS intuitively imply diminished TGF-ß signaling. Taken together, these data have engendered controversy regarding the specific role of TGF-ß in disease pathogenesis. Shprintzen-Goldberg syndrome (SGS) has considerable phenotypic overlap with MFS and LDS, including aortic aneurysm. We identified causative variation in ten individuals with SGS in the proto-oncogene SKI, a known repressor of TGF-ß activity. Cultured dermal fibroblasts from affected individuals showed enhanced activation of TGF-ß signaling cascades and higher expression of TGF-ß-responsive genes relative to control cells. Morpholino-induced silencing of SKI paralogs in zebrafish recapitulated abnormalities seen in humans with SGS. These data support the conclusions that increased TGF-ß signaling is the mechanism underlying SGS and that high signaling contributes to multiple syndromic presentations of aortic aneurysm.

Loss-of-function mutations in TGFB2 cause a syndromic presentation of thoracic aortic aneurysm.

Loeys-Dietz syndrome (LDS) associates with a tissue signature for high transforming growth factor (TGF)-ß signaling but is often caused by heterozygous mutations in genes encoding positive effectors of TGF-ß signaling, including either subunit of the TGF-ß receptor or SMAD3, thereby engendering controversy regarding the mechanism of disease. Here, we report heterozygous mutations or deletions in the gene encoding the TGF-ß2 ligand for a phenotype within the LDS spectrum and show upregulation of TGF-ß signaling in aortic tissue from affected individuals. Furthermore, haploinsufficient Tgfb2(+/-) mice have aortic root aneurysm and biochemical evidence of increased canonical and noncanonical TGF-ß signaling. Mice that harbor both a mutant Marfan syndrome (MFS) allele (Fbn1(C1039G/+)) and Tgfb2 haploinsufficiency show increased TGF-ß signaling and phenotypic worsening in association with normalization of TGF-ß2 expression and high expression of TGF-ß1. Taken together, these data support the hypothesis that compensatory autocrine and/or paracrine events contribute to the pathogenesis of TGF-ß-mediated vasculopathies.

Angiotensin II type 2 receptor signaling attenuates aortic aneurysm in mice through ERK antagonism.

Angiotensin II (AngII) mediates progression of aortic aneurysm, but the relative contribution of its type 1 (AT1) and type 2 (AT2) receptors remains unknown. We show that loss of AT2 expression accelerates the aberrant growth and rupture of the aorta in a mouse model of Marfan syndrome (MFS). The selective AT1 receptor blocker (ARB) losartan abrogated aneurysm progression in the mice; full protection required intact AT2 signaling. The angiotensin-converting enzyme inhibitor (ACEi) enalapril, which limits signaling through both receptors, was less effective. Both drugs attenuated canonical transforming growth factor-ß (TGFß) signaling in the aorta, but losartan uniquely inhibited TGFß-mediated activation of extracellular signal-regulated kinase (ERK), by allowing continued signaling through AT2. These data highlight the protective nature of AT2 signaling and potentially inform the choice of therapies in MFS and related disorders.

Noncanonical TGFß signaling contributes to aortic aneurysm progression in Marfan syndrome mice.

Transforming growth factor-ß (TGFß) signaling drives aneurysm progression in multiple disorders, including Marfan syndrome (MFS), and therapies that inhibit this signaling cascade are in clinical trials. TGFß can stimulate multiple intracellular signaling pathways, but it is unclear which of these pathways drives aortic disease and, when inhibited, which result in disease amelioration. Here we show that extracellular signal-regulated kinase (ERK) 1 and 2 and Smad2 are activated in a mouse model of MFS, and both are inhibited by therapies directed against TGFß. Whereas selective inhibition of ERK1/2 activation ameliorated aortic growth, Smad4 deficiency exacerbated aortic disease and caused premature death in MFS mice. Smad4-deficient MFS mice uniquely showed activation of Jun N-terminal kinase-1 (JNK1), and a JNK antagonist ameliorated aortic growth in MFS mice that lacked or retained full Smad4 expression. Thus, noncanonical (Smad-independent) TGFß signaling is a prominent driver of aortic disease in MFS mice, and inhibition of the ERK1/2 or JNK1 pathways is a potential therapeutic strategy for the disease.