NOX1 Regulates Collective and Planktonic Cell Migration: Insights From Patients With Pediatric-Onset IBD and NOX1 Deficiency

BACKGROUND

Genetic defects of pediatric-onset inflammatory bowel disease (IBD) provide critical insights into molecular factors controlling intestinal homeostasis. NOX1 has been recently recognized as a major source of reactive oxygen species (ROS) in human colonic epithelial cells. Here we assessed the functional consequences of human NOX1 deficiency with respect to wound healing and epithelial migration by studying pediatric IBD patients presenting with a stop-gain mutation in NOX1.

METHODS

Functional characterization of the NOX1 variant included ROS generation, wound healing, 2-dimensional collective chemotactic migration, single-cell planktonic migration in heterologous cell lines, and RNA scope and immunohistochemistry of paraffin-embedded patient tissue samples.

RESULTS

Using exome sequencing, we identified a stop-gain mutation in NOX1 (c.160C>T, p.54R>*) in patients with pediatric-onset IBD. Our studies confirmed that loss-of-function of NOX1 causes abrogated ROS activity, but they also provided novel mechanistic insights into human NOX1 deficiency. Cells that were NOX1-mutant showed impaired wound healing and attenuated 2-dimensional collective chemotactic migration. High-resolution microscopy of the migrating cell edge revealed a reduced density of filopodial protrusions with altered focal adhesions in NOX1-deficient cells, accompanied by reduced phosphorylation of p190A. Assessment of single-cell planktonic migration toward an epidermal growth factor gradient showed that NOX1 deficiency is associated with altered migration dynamics with loss of directionality and altered cell-cell interactions.

CONCLUSIONS

Our studies on pediatric-onset IBD patients with a rare sequence variant in NOX1 highlight that human NOX1 is involved in regulating wound healing by altering epithelial cytoskeletal dynamics at the leading edge and directing cell migration.

Drug Screen Identifies Leflunomide for Treatment of Inflammatory Bowel Disease Caused by TTC7A Deficiency

BACKGROUND & AIMS

Mutations in the tetratricopeptide repeat domain 7A gene (TTC7A) cause intestinal epithelial and immune defects. Patients can become immune deficient and develop apoptotic enterocolitis, multiple intestinal atresia, and recurrent intestinal stenosis. The intestinal disease in patients with TTC7A deficiency is severe and untreatable, and it recurs despite resection or allogeneic hematopoietic stem cell transplant. We screened drugs for those that prevent apoptosis of in cells with TTC7A deficiency and tested their effects in an animal model of the disease.

METHODS

We developed a high-throughput screen to identify compounds approved by the US Food and Drug Administration that reduce activity of caspases 3 and 7 in TTC7A-knockout (TTC7A-KO) HAP1 (human haploid) cells and reduce the susceptibility to apoptosis. We validated the effects of identified agents in HeLa cells that stably express TTC7A with point mutations found in patients. Signaling pathways in cells were analyzed by immunoblots. We tested the effects of identified agents in zebrafish with disruption of ttc7a, which develop intestinal defects, and colonoids derived from biopsy samples of patients with and without mutations in TTC7A. We performed real-time imaging of intestinal peristalsis in zebrafish and histologic analyses of intestinal tissues from patients and zebrafish. Colonoids were analyzed by immunofluorescence and for ion transport.

RESULTS

TTC7A-KO HAP1 cells have abnormal morphology and undergo apoptosis, due to increased levels of active caspases 3 and 7. We identified drugs that increased cell viability; leflunomide (used to treat patients with inflammatory conditions) reduced caspase 3 and 7 activity in cells by 96%. TTC7A-KO cells contained cleaved caspase 3 and had reduced levels of phosphorylated AKT and X-linked inhibitor of apoptosis (XIAP); incubation of these cells with leflunomide increased levels of phosphorylated AKT and XIAP and reduced levels of cleaved caspase 3. Administration of leflunomide to ttc7a^-/- zebrafish increased gut motility, reduced intestinal tract narrowing, increased intestinal cell survival, increased sizes of intestinal luminal spaces, and restored villi and goblet cell morphology. Exposure of patient-derived colonoids to leflunomide increased cell survival, polarity, and transport function.

CONCLUSIONS

In a drug screen, we identified leflunomide as an agent that reduces apoptosis and activates AKT signaling in TTC7A-KO cells. In zebrafish with disruption of ttc7a, leflunomide restores gut motility, reduces intestinal tract narrowing, and increases intestinal cell survival. This drug might be repurposed for treatment of TTC7A deficiency.

Awareness and knowledge of developmental co-ordination disorder among physicians, teachers and parents

BACKGROUND

Obtaining a diagnosis of developmental co-ordination disorder (DCD) is a long, inconsistent and frustrating journey for families, with apparently little awareness of DCD in schools or the medical community.

METHODS

An online survey was completed by 1297 participants: parents (n = 501), teachers (n = 202), family/general physicians (n = 339) and paediatricians (n = 255).

RESULTS

Only 20% of the sample had knowledge of DCD, with 41% of the paediatricians and 23% of family/general physicians familiar. Of participants who have awareness, only 11-59% have knowledge of the impact of DCD on social, emotional and physical health. Less than 30% of physicians have awareness of the secondary consequences. Few physicians diagnose DCD and less than one-third believe it is easy to make a diagnosis; this is in contrast to the fact that most parents report confidence in their physician's ability to make a timely diagnosis.

CONCLUSIONS

If less than one-half of physicians have knowledge of DCD and even fewer are knowledgeable of the secondary consequences of the condition, it is not surprising that DCD is infrequently diagnosed and that families need to search for support. This survey confirms observations that the condition is not well known and there is a need for greater awareness of DCD.

Animal welfare and international trade

Globalisation is becoming a force that is revolutionising international trade, particularly that of animals and animal products. There is increasing interest in animal welfare worldwide, and as part of its 2001-2005 Strategic Plan the World Organisation for Animal Health (OIE) identified the development of international standards on animal welfare as a priority. The OIE's scientific approach to standard-setting provides the foundation for the development, and acceptance by all OIE Member Countries, of these animal welfare guidelines. The paper discusses how these guidelines on animal welfare can be implemented, both within the provisions of World Trade Organization (WTO) agreements and within the framework of voluntary codes of conduct. Even if animal welfare guidelines are not covered by any WTO agreements in the future, bi- and multilateral agreements, voluntary corporate codes, and transparent labelling of products should result in a progressive acceptance of OIE guidelines. Ultimately, consumer demands and demonstrable gains in animal production will result in an incremental evolution in animal welfare consciousness and adherence to international standards.

The efficacy of fluoxetine in improving physical symptoms associated with premenstrual dysphoric disorder

OBJECTIVE

To determine the effectiveness of fluoxetine in alleviating physical symptoms of premenstrual dysphoric disorder.

DESIGN

Randomised, double-blind, placebo controlled, parallel study.

SETTING

Canadian University based outpatient clinics. Participants Four hundred and five subjects, of whom 320 with prospectively determined premenstrual dysphoric disorder were randomised.

METHODS

Randomised women were assigned to fluoxetine 20 or 60 mg/day or placebo. Common physical symptoms associated with premenstrual dysphoric disorder including breast tenderness, bloating, and headache were evaluated by visual analog scales and the self-rated and observer premenstrual tension syndrome scales.

OUTCOME MEASURES

Luteal phase change from mean baseline scores to mean treatment scores for all scales.

RESULTS

Fluoxetine treatment was statistically superior to placebo, with no significant differences between the two fluoxetine dosages in their effects on physical symptoms.

CONCLUSION

Daily fluoxetine treatment is superior to placebo in improving the most common physical symptoms associated with premenstrual dysphoric disorder.

Hemodialysis urea rebound: the effect of increasing dialysis efficiency

Urea rebound has been documented to occur after hemodialysis, but the magnitude and causes are not clearly defined. In this study we evaluated the effect of high-flux hemodialysis on urea rebound and Kt/V. Blood urea nitrogen samples were obtained before, immediately after, and 30 minutes after hemodialysis in 49 patients. Rebound was evaluated with respect to dialysis efficiency, dialysis treatment time, the occurrence of hypotension, and hematocrit. Urea rebound was significant and resulted in an overall decrease in Kt/V from 1.2 +/- 0.3 to 1.0 +/- 0.2 (P < 0.001). Of the 45 patients with a measured Kt/V of greater than 1.0, 40% had an actual delivered Kt/V of less than 1.0 once rebound was taken into account. Urea rebound correlated strongly with dialysis efficiency but not with hypotension, suggesting that rebound resulted primarily from delayed urea mass transfer across cell membranes. We conclude that increasing dialysis efficiency increases urea rebound and increases the error in Kt/V determinations from single pool urea kinetics.

The effect of calcium channel blockers on the cyclosporine dose requirement in renal transplant recipients

Thirteen patients found to be hypertensive following renal transplantation were treated with either a calcium channel blocker or other antihypertensive therapy for control of blood pressure. Immunosuppression was either with cyclosporine and prednisone alone or with cyclosporine, azathioprine, and prednisone. Patients had weekly or biweekly cyclosporine whole-blood levels measured by radioimmunoassay drawn approximately 12 h after their last dose. Patients treated with cyclosporine and prednisone alone had their cyclosporine dosage adjusted to maintain their cyclosporine level between 400 and 900 ng/mL between 1 and 6 months following transplantation. Patients treated with cyclosporine, azathioprine, and prednisone had their cyclosporine level adjusted to be between 100 and 400 ng/mL during this same time period. Cyclosporine levels were significantly higher in verapamil-treated patients and significantly lower in nifedipine-treated patients as compared to controls. The dose of cyclosporine administered was significantly lower in the verapamil-treated patients and higher in the nifedipine-treated patients than controls. Normalizing the whole-blood cyclosporine level for the dose of cyclosporine, and verapamil-treated patients had a significantly greater, and the nifedipine-treated patients a significantly lower value than control patients. These data suggest the verapamil treatment results in significantly higher levels of cyclosporine whereas nifedipine therapy may actually result in lower cyclosporine levels for a given dose of cyclosporine than seen in patients not exposed to these drugs.

The allograft response

The allograft response is a response by host T lymphocytes reacting to transplantation antigens that are carried on allogeneic lymphoreticuler cells. In vivo this response usually leads to graft rejection. It is possible to circumvent this response by the elimination of the lymphoreticular cells from the grafts prior to transplantation. The paradox of the strong response to transplantation antigen on lymphoreticular cells and the weak response to the same antigen on graft parenchymal cells can be explained by the signaling requirements for T lymphocyte activation.