Transplant renal artery stenosis in a child with BK nephropathy.

TRAS and BK nephropathy are known complications of RT, but the association between both has not been reported. A 2-year-old girl underwent a deceased donor renal transplant from a 20-year-old donor, along with bilateral native nephrectomies. She had a DGF due to a renal artery thrombus and required thrombectomy with re-anastomosis. Heparin and aspirin were used. Immunosuppressive agents included thymoglobulin, steroid, tacrolimus, and MMF. CMV and EBV DNA PCRs were negative, but she developed BK viremia at 2 months with stable allograft function. Immunosuppression was reduced, and leflunomide was initiated. Blood pressures were well controlled on low-dose amlodipine. Five months after RT, she presented with hypertensive emergency, following a respiratory infection, and required dialysis for oliguric acute kidney injury. Allograft biopsy showed evidence of BK nephropathy. Immunosuppression was further minimized. Doppler renal US and renal artery duplex studies were both suggestive of TRAS. Angiogram showed severe proximal anastomotic TRAS (>95% occlusion). PTA with stenting was done with immediate improvement in the blood flow and reduction in the pressure gradient. BPs and renal function normalized. Ten months post-RT, she remains normotensive with stable renal function and resolution of BK viremia. Although ureteral stenosis and nephropathy are known to occur with BK infection, TRAS is an interesting association and possibly suggest the tropism of BK virus to the vascular endothelial cells. Timely recognition and management of both is important to prevent uncontrolled hypertension and allograft dysfunction.

Novel replisome-associated proteins at cellular replication forks in EBV-transformed B lymphocytes.

Epstein-Barr virus (EBV) is an oncogenic herpesvirus and WHO class 1 carcinogen that resides in B lymphocytes of nearly all humans. While silent in most, EBV can cause endemic Burkitt lymphoma in children and post-transplant lymphoproliferative disorders/lymphomas in immunocompromised hosts. The pathogenesis of such lymphomas is multifactorial but to a large extent depends on EBV's ability to aggressively drive cellular DNA replication and B cell proliferation despite cell-intrinsic barriers to replication. One such barrier is oncogenic replication stress which hinders the progression of DNA replication forks. To understand how EBV successfully overcomes replication stress, we examined cellular replication forks in EBV-transformed B cells using iPOND (isolation of Proteins on Nascent DNA)-mass spectrometry and identified several cellular proteins that had not previously been linked to DNA replication. Of eight candidate replisome-associated proteins that we validated at forks in EBV-transformed cells and Burkitt lymphoma-derived cells, three zinc finger proteins (ZFPs) were upregulated early in B cells newly-infected with EBV in culture as well as expressed at high levels in EBV-infected B blasts in the blood of immunocompromised transplant recipients. Expressed highly in S- and G2-phase cells, knockdown of each ZFP resulted in stalling of proliferating cells in the S-phase, cleavage of caspase 3, and cell death. These proteins, newly-identified at replication forks of EBV-transformed and Burkitt lymphoma cells therefore contribute to cell survival and cell cycle progression, and represent novel targets for intervention of EBV-lymphomas while simultaneously offering a window into how the replication machinery may be similarly modified in other cancers.

Isolated abdominal nocardiosis in a pediatric renal transplant recipient.

Nocardia infection after RT is uncommon. The most common modes of exposure are inhalation of dust containing nocardia or contaminated soil/water and surgical instruments. Isolated abdominal nocardiosis following RT has not been reported. We report an 11-year-old female who developed nocardia abscesses of the abdomen post-RT. ESRD was secondary to FSGS and she had received multiple immunosuppressive agents prior to transplant. Induction immunosuppression consisted of thymoglobulin and maintenance was with tacrolimus, mycophenolate, and prednisone. There were construction activities in the hospital ward during her hospital stay. Due to immediate recurrence of FSGS in the allograft, she received plasma exchange, rituximab, and IVIG. Anti-infective prophylaxis consisted of TMP-SMX, valganciclovir, and nystatin. She developed multiple loculated fluid collections in the abdomen 6 weeks later. Histology of lesions demonstrated suppurative caseating granulomatous inflammation and the AFB culture showed Nocardia farcinica. With the reduction of immunosuppressive agents along with usage of TMP-SMX, imipenem-cilastatin, and linezolid, she had a partial recovery after 9 months with persistent small abscesses but remained asymptomatic clinically. There was no evidence of nocardia infection in lungs and brain. Repeat AFB culture from the lesions was negative. Allograft function remained stable throughout. She remains on oral TMP-SMX therapy. We postulated that she could have acquired nocardia either from the contaminated air particles in the hospital from the construction activities or reactivation of nocardia from prior colonization. Nocardia infection should be suspected in immunocompromised patients with unexplained fever and abdominal pain.