Commentary: Perspectives on diverticulitis and the art of clinical science - treat the man not the scan

MLL1 is regulated by KSHV LANA and is important for virus latency

Mixed lineage leukemia 1 (MLL1) is a histone methyltransferase. Kaposi's sarcoma-associated herpesvirus (KSHV) is a leading cause of malignancy in AIDS. KSHV latently infects tumor cells and its genome is decorated with epigenetic marks. Here, we show that KSHV latency-associated nuclear antigen (LANA) recruits MLL1 to viral DNA where it establishes H3K4me3 modifications at the extensive KSHV terminal repeat elements during primary infection. LANA interacts with MLL1 complex members, including WDR5, integrates into the MLL1 complex, and regulates MLL1 activity. We describe the 1.5-Å crystal structure of N-terminal LANA peptide complexed with MLL1 complex member WDR5, which reveals a potential regulatory mechanism. Disruption of MLL1 expression rendered KSHV latency establishment highly deficient. This deficiency was rescued by MLL1 but not by catalytically inactive MLL1. Therefore, MLL1 is LANA regulable and exerts a central role in virus infection. These results suggest broad potential for MLL1 regulation, including by non-host factors.

The gastroenterologist's view

The traditional view that recurrent episodes of diverticulitis lead to progressively complicated disease resulting in a disadvantageous course, more difficult, complicated operations and lethal outcomes did not stand the test of evidence. Only a minority of patients with acute diverticulitis will ever require surgery, and if so, this occurs during or early after the first episode. Complications and recurrence of disease after surgery are enumerable. Strong indicators favoring sigmoid colectomy are major abscess, free air, and fistula, i.e. perforating disease. This occurs predominantly at the initial presentation, frequently in younger or immunosuppressed patients. Important differential diagnoses must be considered both for initial diagnosis of diverticulitis and for recurrent episodes. Conservative management of recurrent diverticulitis is safe and best guided by gastroenterological expertise. Sophisticated ultrasound experience as a part of this competence allows detailed evaluation of the local status and the best evidence in the literature for diagnosing diverticulitis is on US. In practice, however, the question of perforating diverticulitis is adequately answered by subtle CT scan. Medical therapy is usually the treatment of choice for recurrent diverticulitis. Avoidance of drugs bearing the hazard of perforation (e.g. NSAIDs) is emphasized, and smoking is strongly discouraged. A mathematical model based on published data shows that patients with recurrent diverticulitis overall (only) profit from surgery if they are hit by four episodes during the course of disease. This is where theory and reality (should) meet.