Intestinal Epithelial Cell-Intrinsic Deletion of Setd7 Identifies Role for Developmental Pathways in Immunity to Helminth Infection

The intestine is a common site for a variety of pathogenic infections. Helminth infections continue to be major causes of disease worldwide, and are a significant burden on health care systems. Lysine methyltransferases are part of a family of novel attractive targets for drug discovery. SETD7 is a member of the Suppressor of variegation 3-9-Enhancer of zeste-Trithorax (SET) domain-containing family of lysine methyltransferases, and has been shown to methylate and alter the function of a wide variety of proteins in vitro. A few of these putative methylation targets have been shown to be important in resistance against pathogens. We therefore sought to study the role of SETD7 during parasitic infections. We find that Setd7-/- mice display increased resistance to infection with the helminth Trichuris muris but not Heligmosomoides polygyrus bakeri. Resistance to T. muris relies on an appropriate type 2 immune response that in turn prompts intestinal epithelial cells (IECs) to alter differentiation and proliferation kinetics. Here we show that SETD7 does not affect immune cell responses during infection. Instead, we found that IEC-specific deletion of Setd7 renders mice resistant to T. muris by controlling IEC turnover, an important aspect of anti-helminth immune responses. We further show that SETD7 controls IEC turnover by modulating developmental signaling pathways such as Hippo/YAP and Wnt/β-Catenin. We show that the Hippo pathway specifically is relevant during T. muris infection as verteporfin (a YAP inhibitor) treated mice became susceptible to T. muris. We conclude that SETD7 plays an important role in IEC biology during infection.

Arterial thrombosis enhanced by an acute phase response

Induction of an acute phase response causes changes in the levels of specific plasma proteins. Fibrinogen is elevated to approximately twice its normal concentration by trauma, inflammation, or infection. In this study, an acute phase response was induced by subcutaneous turpentine injection in rats. Twenty-four hours later, an arterial model of thrombosis was created bilaterally in the femoral arteries. Patency at 1 and 7 days postoperatively was 24% (9/38) in comparison to 56% (20/36) in control (saline-injected) rats undergoing the same thrombosis model. Fibrinogen levels were elevated in the turpentine group to 5.3 +/- 0.8 mg/ml at the time of the surgery and 7.2 +/- 0.3 mg/ml 24 hours after surgery. In contrast, the control group had plasma fibrinogen levels of 2.5 +/- 0.2 mg/ml at the time of surgery and 5.4 +/- 0.5 mg/ml 24 hours postoperatively. These findings suggest that when an acute phase reaction has been induced several hours prior to a microvascular procedure, there may be an increased risk for development of arterial thrombosis.

Topical heparin enhances patency in a rat model of arterial thrombosis

Heparin added to irrigation solutions and used in microvascular surgery may have activity as a topical antithrombotic agent. A rat model of arterial thrombosis was used to evaluate topical heparin for preventing thrombosis. A crush injury was applied to both femoral arteries, and then they were transected and anastomosed. The vessel on one side of each rat was washed out and the wound irrigated with physiological saline containing one of three concentrations of heparin: 0, 100, or 500 U/ml. The vessel on the contralateral side was irrigated with unheparinized saline throughout. Patency rates at 24 hours were 63% (10 of 16) for vessels irrigated with either 100 or 500 U/ml of heparin. The contralateral vessels had 24-hour patencies of 19% (3 of 16) for each group (p < 0.05). The group receiving bilateral, unheparinized irrigation had a 24-hour patency of 29% (8 of 28). Activated partial thromboplastin times were significantly prolonged (p < 0.05) 20 minutes into the recirculation for the groups receiving 100 or 500 U/ml of heparin: 44 +/- 3 and 62 +/- 6 seconds (mean +/- standard error of the mean), respectively, in comparison to averages of 33 to 35 seconds at 24 hours in all groups and at 20 minutes after reflow in the control group. This study indicates that heparin added to the irrigation solution significantly enhances patency in compromised arterial anastomoses. The results also indicate a pitfall with studying topical heparin for microvascular surgery in rat models: acute elevation of activated partial thromboplastin time values.

Survey of analgesia regimens in burns centres in the UK

A survey of the analgesia regimens used in burns units throughout the UK was performed. Continuous intravenous opiate infusions remain the mainstay for providing pain relief in patients in severe pain as a result of burn injuries. Other methods include: patient-controlled analgesia in appropriate patients, bolus doses of opiates combined with Entonox for control of peaks of pain and a wide variety of oral analgesics for less painful burn injuries.

Axonal regeneration rate through cross-face nerve grafts

The disfigurement of irreversible unilateral facial paralysis can be corrected by cross-face nerve grafting in conjunction with muscle transplantation. A total of 33 patients underwent cross-face nerve grafting using the sural nerve prior to undergoing the second stage of the procedure. Before a muscle transplant can be successfully connected to the distal end of the cross-face nerve graft, the regenerating axons need to have grown from the contralateral facial nerve to the distal end of the nerve graft. This can be tested by the Tinel sign. A retrospective study was performed to determine the rate of growth of regenerating axons through the cross-face nerve graft. A rate of axon growth of 1.8 mm/day was found, and also an inverse relationship between the age of the patient and the regeneration rate. These results can be used as a guide in planning patients' treatment.