In Silico and In Vitro Analysis of IL36RN Alterations Reveals Critical Residues for the Function of the Interleukin-36 Receptor Complex

Generalized pustular psoriasis is a potentially life-threatening skin disease, associated with IL36RN disease alleles. IL36RN encodes the IL-36 receptor antagonist (IL-36Ra), a protein that downregulates the activity of IL-36 cytokines by blocking their receptor (IL-36R). Although generalized pustular psoriasis can be treated with IL-36R inhibitors, the structural underpinnings of the IL-36Ra/IL-36R interaction remain poorly understood. In this study, we sought to address this question by systematically investigating the effects of IL36RN sequence changes. We experimentally characterized the effects of 30 IL36RN variants on protein stability. In parallel, we used a machinelearning tool (Rhapsody) to analyze the IL-36Ra three-dimensional structure and predict the impact of all possible amino acid substitutions. This integrated approach identified 21 amino acids that are essential for IL-36Ra stability. We next investigated the effects of IL36RN changes on IL-36Ra/IL-36R binding and IL-36R signaling. Combining invitro assays and machine learning with a second program (mCSM), we identified 13 amino acids that are critical for IL-36Ra/IL36R engagement. Finally, we experimentally validated three representative predictions, further confirming the reliability of Rhapsody and mCSM. These findings shed light on the structural determinants of IL-36Ra activity, with potential to facilitate the design of new IL-36 inhibitors and aid the interpretation of IL36RN variants in diagnostic settings.

The prescribing of acid suppressants prior to the endoscopic diagnosis of Barrett's oesophagus and oesophagitis

BACKGROUND

There has been a dramatic rise in incidences of Barrett's oesophagus and oesophageal adenocarcinoma. It has been suggested that the introduction and use of acid suppression therapy may be a factor in the rising incidences of Barrett's oesophagus and oesophageal adenocarcinoma.

METHODS

This was a record linkage study, using a prescribing database and an endoscopy database. Patients who had undergone their first endoscopy during the period 1992-1995 and received the diagnosis of Barrett's oesophagus or oesophagitis were identified. The prescribing of acid suppressants was compared for the 3 years prior to endoscopy, between those with Barrett's oesophagus and those with oesophagitis.

RESULTS

There was no significant difference between the Barrett's patients and the oesophagitis patients in the proportion that had been exposed to acid suppression therapy (53.4% vs. 51.7%, P=0.704). The mean number of days of prescribing among those who had been exposed to acid suppression therapy was higher in the Barrett's group (340.5 vs. 237.0 days, P=0.001).

CONCLUSIONS

Patients with Barrett's oesophagus have received more acid suppressant therapy prior to diagnosis. The reasons for this are not clear. However, 46.6% of Barrett's patients have not been exposed to acid suppressant therapy.

The variability of goniometric measurements in ambulatory children with spastic cerebral palsy

This study assessed the variability of six goniometric measurements commonly used in the assessment of children with cerebral palsy (CP). Three experienced paediatric physiotherapists recorded three consecutive measurements of six joint ranges from 12 children with spastic CP. A fourth measurement was recorded 1 week later. The order of measurement with regards to both joint measurement and tester, was randomised to ensure a balanced experimental design. A blinded procedure was adopted with masked goniometers and a second assessor present to record the measurement. Results, analysed using generalizability theory, showed same day and different day measurement error of +/-10-14 degrees (95% confidence limits) for the foot/thigh angle, abduction and internal rotation of the hip. The source of this was child-assessor and residual error. For ankle dorsiflexion and the popliteal angles, same day measurement error was similar. However, for joint ranges recorded on different days, error ranged from +/-18-28 degrees. The major source of this was systematic differences in measurements recorded on different days. Results show a need for caution when using goniometric measurements in clinical decision making, particularly in the more tone dependent biarticular muscles after an initial assessment.