Regulation of TGFβ and BMP signalling in human B cells by latent Epstein-Barr virus

Most individuals are infected with EBV, which establishes latent infection in B cells. Although usually asymptomatic, EBV persistence is associated with several types of lymphoma. TGFβ signals via TGFβ receptors (TGFβR) 1 and 2 and is generally pro-apoptotic and anti-proliferative, but EBV infection renders cells resistant to these effects. The aim of this thesis was to investigate further the mechanism by which this occurs. Using the EBV-negative Burkitt lymphoma cell line BL31 infected with a panel of BAC-derived wild-type and recombinant EBVs, this study has confirmed by qRT-PCR that EBV down-regulates TGFβR2 transcription, leading to suppression of TGFβ signalling as detected by western blot for phosphorylated SMAD2. Use of recombinant viruses with deletions of individual latent proteins has shown that LMP1, LMP2A, EBNA3B and EBNA3C cooperate in this repression of TGFβR2 and suppression of signalling. Chromatin immunoprecipitation analysis has shown that the repression of TGFβR2 is accompanied by deposition of the repressive epigenetic mark histone H3 lysine 27 trimethylation and concomitant binding of SUZ12, a subunit of polycomb-repressive complex 2, to the TGFβR2 promoter. Infection of primary B cells with EBV also leads to repression of TGFβR2 and suppression of TGFβ signalling. Additionally, EBV up-regulates TGFβR3, a co-receptor for signalling by both TGFβ and bone morphogenetic proteins (BMPs), a related group of ligands which signal via SMADs 1, 5 and 8. This led to an investigation into the effects of EBV on BMP signalling. Although EBV increases signalling in response to BMP2, BMP4 and BMP6 in BL31 cells, this is not via the up-regulation of TGFβR3. BMP2 and BMP4 induce G1 arrest in BL31 cells, but EBV does not alter this. EBV also up-regulates SMAD1 and down-regulates SMAD5. The polycomb-mediated repression of TGFβR2 is a mechanism by which EBV might promote lymphomagenesis. In addition, the finding that EBV alters several components of BMP signalling suggests that BMP signalling may be important in B-cell biology.Open Acces

Systematic review and meta-analysis of the management of acute uncomplicated diverticulitis:time to change traditional practice

Background: To evaluate comparative outcomes of outpatient (OP) versus inpatient (IP) treatment and antibiotics (ABX) versus no antibiotics (NABX) approach in the treatment of uncomplicated (Hinchey grade 1a) acute diverticulitis. Methods: A systematic online search was conducted using electronic databases. Comparative studies of OP versus IP treatment and ABX versus NABX approach in the treatment of Hinchey grade 1a acute diverticulitis were included. Primary outcome was recurrence of diverticulitis. Emergency and elective surgical resections, development of complicated diverticulitis, mortality rate, and length of hospital stay were the other evaluated secondary outcome parameters. Results: The literature search identified twelve studies (n = 3,875) comparing NABX (n = 2,008) versus ABX (n = 1,867). The NABX group showed a lower disease recurrence rate and shorter length of hospital stay compared with the ABX group (P = 0.01) and (P = 0.004). No significant difference was observed in emergency resections (P = 0.33), elective resections (P = 0.73), development of complicated diverticulitis (P = 0.65), hospital re-admissions (P = 0.65) and 30-day mortality rate (P = 0.91). Twelve studies (n = 2,286) compared OP (n = 1,021) versus IP (n = 1,265) management of uncomplicated acute diverticulitis. The two groups were comparable for the following outcomes: treatment failure (P = 0.10), emergency surgical resection (P = 0.40), elective resection (P = 0.30), disease recurrence (P = 0.22), and mortality rate (P = 0.61). Conclusion: Observation-only treatment is feasible and safe in selected clinically stable patients with uncomplicated acute diverticulitis (Hinchey 1a classification). It may provide better outcomes including decreased length of hospital stay. Moreover, the OP approach in treating patients with Hinchey 1a acute diverticulitis is comparable to IP management. Future high-quality randomised controlled studies are needed to understand the outcomes of the NABX approach used in an OP setting in managing patients with uncomplicated acute diverticulitis

Thrombotic microangiopathy in untreated myeloma patients receiving carfilzomib, cyclophosphamide and dexamethasone on the CARDAMON study

Proteasome inhibitors have been associated with thrombotic microangiopathy (TMA) — a group of disorders characterised by occlusive microvascular thrombosis causing microangiopathic haemolytic anaemia, thrombocytopenia and end‐organ damage. To date, carfilzomib‐associated TMA has predominantly been described in relapsed/refractory myeloma patients. We report eight patients with newly diagnosed myeloma who experienced TMA events while receiving carfilzomib on the phase II CARDAMON trial. The first three occurred during maintenance single‐agent carfilzomib, two occurred at induction with carfilzomib given with cyclophosphamide and dexamethasone (KCd) and three occurred during KCd consolidation. At TMA presentation 6/8 were hypertensive; 7/8 had acute kidney injury and in three, renal impairment persisted after resolution of TMA in other respects. The mechanism of carfilzomib‐associated TMA remains unclear, though patients with known hypertension seem particularly susceptible. Given the first three cases occurred during maintenance after a longer than five‐week treatment break, a protocol amendment was instituted with: aggressive hypertension management, carfilzomib step‐up dosing (20 mg/m2 on day 1) at start of maintenance before dose escalation to 56 mg/m2 maximum, and adding 10 mg dexamethasone as premedication to maintenance carfilzomib infusions. No further TMA events occurred during maintenance following this amendment and the TMA incidence reduced from 4·2 to 1·6 per 1 000 patient cycles

Dasatinib crosses the blood-brain barrier and is an efficient therapy for central nervous system philadelphia chromosome positive leukemia

Although imatinib, a BCR-ABL tyrosine kinase inhibitor, is used to treat acute Philadelphia chromosome-positive (Ph+) leukemia, it does not prevent central nervous system (CNS) relapses resulting from poor drug penetration through the blood-brain barrier. Imatinib and dasatinib (a dual-specific SRC/BCR-ABL kinase inhibitor) were compared in a pre-clinical mouse model of intracranial Ph+ leukemia. Clinical dasatinib treatment in patients with CNS Ph+ leukemia was assessed. In preclinical studies, dasatinib increased survival, whereas imatinib failed to inhibit intracranial tumor growth. Stabilization and regression of CNS disease were achieved with continued dasatinib administration. The drug also demonstrated substantial activity in 11 adult and pediatric patients with CNS Ph+ leukemia. Eleven evaluable patients had clinically significant, long-lasting responses, which were complete in 7 patients. In 3 additional patients, isolated CNS relapse occurred during dasatinib therapy; and in 2 of them, it was caused by expansion of a BCR-ABL-mutated dasatinib-resistant clone, implying selection pressure exerted by the compound in the CNS. Dasatinib has promising therapeutic potential in managing intracranial leukemic disease and substantial clinical activity in patients who experience CNS relapse while on imatinib therapy. This study is registered at ClinicalTrials. gov as CA180006 (#NCT00108719) and CA180015 (#NCT00110097)

Influences on pre-hospital delay in the diagnosis of colorectal cancer: a systematic review

Colorectal cancer is a major global health problem, with survival varying according to stage at diagnosis. Delayed diagnosis can result from patient, practitioner or hospital delay. This paper reports the results of a review of the factors influencing pre-hospital delay – the time between a patient first noticing a cancer symptom and presenting to primary care or between first presentation and referral to secondary care. A systematic methodology was applied, including extensive searches of the literature published from 1970 to 2003, systematic data extraction, quality assessment and narrative data synthesis. Fifty-four studies were included. Patients' non-recognition of symptom seriousness increased delay, as did symptom denial. Patient delay was greater for rectal than colon cancers and the presence of more serious symptoms, such as pain, reduced delay. There appears to be no relationship between delay and patients' age, sex or socioeconomic status. Initial misdiagnosis, inadequate examination and inaccurate investigations increased practitioner delay. Use of referral guidelines may reduce delay, although evidence is currently limited. No intervention studies were identified. If delayed diagnosis is to be reduced, there must be increased recognition of the significance of symptoms among patients, and development and evaluation of interventions that are designed to ensure appropriate diagnosis and examination by practitioners