The immunoproteasome: An old player with a novel and emerging role in alloimmunity

Modern treatment strategies for the maintenance of allograft acceptance frequently target ubiquitously-expressed pathways, leading to significant side-effects and poor long-term allograft outcomes. Constitutive proteasome inhibitors, which have recently been introduced for the treatment of antibody-mediated rejection, target the ubiquitously-expressed proteasome. To limit off-target effects and serious mechanism-based toxicity, however, these inhibitors are administered intermittently and suboptimally. Immunoproteasomes, which are an inducible subset of proteasomes enriched in immune cells, replace constitutive proteasomes after cell exposure to proinflammatory cytokines such as interferon-γ. While immunoproteasomes were first described as processors of antigen for presentation by major histocompatibility complex molecules, recent findings point to its broader biological roles. These vary from activating different subsets of the immune system, by controlling transcriptional activators and downstream cytokines, to affecting their differentiation and survival. These emerging roles of the immunoproteasome in activated immune cells have made it a rational candidate for the targeted treatment of immune-mediated diseases. Preclinical studies have established its role in maintaining allograft acceptance without significant short- or long-term toxicity. This review provides a brief background of the immunoproteasome and outlines its role in immunological pathways and its potential in alloimmunity.

Canine GM2-Gangliosidosis Sandhoff Disease Associated with a 3-Base Pair Deletion in the HEXB Gene

BACKGROUND

GM2-gangliosidosis is a fatal neurodegenerative lysosomal storage disease (LSD) caused by deficiency of either β-hexosaminidase A (Hex-A) and β-hexosaminidase B (Hex-B) together, or the GM2 activator protein. Clinical signs can be variable and are not pathognomonic for the specific, causal deficiency.

OBJECTIVES

To characterize the phenotype and genotype of GM2-gangliosidosis disease in an affected dog.

ANIMALS

One affected Shiba Inu and a clinically healthy dog.

METHODS

Clinical and neurologic evaluation, brain magnetic resonance imaging (MRI), assays of lysosomal enzyme activities, and sequencing of all coding regions of HEXA, HEXB, and GM2A genes.

RESULTS

A 14-month-old, female Shiba Inu presented with clinical signs resembling GM2-gangliosidosis in humans and GM1-gangliosidosis in the Shiba Inu. Magnetic resonance imaging (MRI) of the dog's brain indicated neurodegenerative disease, and evaluation of cerebrospinal fluid (CSF) identified storage granules in leukocytes. Lysosomal enzyme assays of plasma and leukocytes showed deficiencies of Hex-A and Hex-B activities in both tissues. Genetic analysis identified a homozygous, 3-base pair deletion in the HEXB gene (c.618-620delCCT).

CONCLUSIONS AND CLINICAL IMPORTANCE

Clinical, biochemical, and molecular features are characterized in a Shiba Inu with GM2-gangliosidosis. The deletion of 3 adjacent base pairs in HEXB predicts the loss of a leucine residue at amino acid position 207 (p.Leu207del) supporting the hypothesis that GM2-gangliosidosis seen in this dog is the Sandhoff type. Because GM1-gangliosidosis also exists in this breed with almost identical clinical signs, genetic testing for both GM1- and GM2-gangliosidosis should be considered to make a definitive diagnosis.

Whole-exome sequencing identifies a homozygous donor splice-site mutation in STAG3 that causes primary ovarian insufficiency

Primary ovarian insufficiency (POI) is the depletion or loss of normal ovarian function, which cause infertility in women before the age of 40 years. Two homozygous germline truncation mutations in STAG3 gene had been reported to causes POI in consanguineous families. Here, we aimed to identify the genetic cause of POI in 2 affected sisters manifested with primary amenorrhea and partial development of secondary sexual characters with normal range of height of a consanguineous Han Chinese family. Whole-exome and Sanger sequencing identified a homozygous donor splice-site mutation (NM_012447.2: c.1573+5G>A) in the STAG3 gene. RT-PCR revealed that the mutation causes loss of wild-type donor splice-site which leads to aberrant splicing of STAG3 mRNA and consecutive formation of STAG3 alternative transcript (p.Leu490Thrfs*10) . This is the first report of splice-site mutation of STAG3 gene causes POI in 2 Han Chinese patients.

Prognostic significance of tumour regression grade after neoadjuvant chemoradiotherapy for a cohort of patients with locally advanced rectal cancer: an 8-year retrospective single-institutional study

AIM

Locally advanced rectal cancer (LARC) is frequently treated with neoadjuvant chemoradiotherapy (NACRT) to reduce the risk of local recurrence and improve survival. Tumour response to NACRT is variable and may influence the prognosis after subsequent surgery. This study compared the prognostic values of tumour regression grade (TRG) and neoadjuvant pathological (ypTNM) downstaging in patients with Stage II and III rectal cancer treated with NACRT followed by curative surgery.

METHOD

This study included 185 patients with LARC treated with long-course radiotherapy (45 Gy in 25 fractions) plus 5-fluorouracil over 5 weeks between 2005 and 2013. We used multivariate analysis to assess the relationship of Dworak's five-tier TRG, ypTNM stage and ypTNM downstaging with clinicopathological factors, 5-year disease-free survival (DFS) and 5-year overall survival (OS).

RESULTS

Total regression (TRG4), good regression (TRG3), moderate regression (TRG2), minor regression (TRG1) and no regression (TRG0) were seen in 38 (20.6%), 65 (35.2%), 43 (23.2%), 28 (15.1%) and 11 (5.9%) patients, respectively. TNM downstaging following NACRT occurred in 109 (58.9%) patients. The 5-year DFS rates after NACRT for TRG0, TRG1, TRG2, TRG3 and TRG4 were 0%, 58.5%, 66.4%, 80.4% and 82.6%, respectively (P < 0.001). The ypTNM stage correlated with 5-year DFS (P = 0.004) but not 5-year OS (P = 0.075). Multivariate analysis demonstrated that TRG was related to both DFS and OS (P < 0.001).

CONCLUSION

TRG measured on a five-tier system was better than ypTNM stage for predicting outcome in patients with LARC treated with NACRT and surgery.

Increasing the interval between neoadjuvant chemoradiotherapy and surgery in esophageal cancer: a meta-analysis of published studies

The aim of this meta-analysis was to clarify whether a longer interval between the end of neoadjuvant chemoradiotherapy (nCRT) and surgery is associated with better outcomes in esophageal cancer. nCRT followed by surgery is the most common approach for patients with resectable esophageal cancer. Operations are performed within 2-8 weeks after nCRT; however, the optimal interval between nCRT and surgery for esophageal cancer is unknown. We performed a systematic literature search in MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and the Clinical Trials database for studies published between January 2000 and December 2014. Eligible studies were prospective or retrospective studies of esophageal cancer that assessed the effects of intervals longer or shorter than 7-8 weeks between the end of nCRT and surgery. The primary end-points were the overall survival (OS) and pathologic complete response (pCR). Secondary end-points were anastomotic leak, R0 resection, and postoperative mortality rate. A meta-analysis was performed to estimate odds ratios (ORs) using fixed-effect and random-effect models, with Review Manager 5.2. The five studies that met the eligibility requirements included 1,016 patients: 520 in the shorter interval group (≤7-8 weeks) and 496 in the longer interval group (>7-8 weeks). The results of our meta-analysis indicate that a longer interval between nCRT and surgery may be disadvantageous for 2-year OS (OR = 1.40, 95% confidence interval [CI]: 1.09-1.80, P = 0.010) and R0 resection rate (OR = 1.71, 95% CI: 1.14-2.22, P = 0.009). The pCR, anastomotic leak rate, and postoperative morbidity were similar in the two groups. A longer interval (more than the standard 7-8 weeks) from the end of preoperative nCRT to surgery did not increase the rate of pCR in esophageal cancer, and the different intervals had similar effects on anastomotic leak rate and postoperative mortality rates. However, the longer interval between nCRT and surgery may be disadvantageous for long-term OS. These results should be validated prospectively in a randomized trial.

Yttrium-90 Glass Microspheres Injected VIA the Portal Vein

Nondegradable glass microspheres (35 μ) were injected into the portal vein for toxicity test in 15 rabbits. In 10 animals the microspheres were loaded with 90Y, giving liver absorbed doses between 24.6 and 437.4 Gy, and in 5 with 89Y (control group). The total amount of microspheres injected in each animal varied between 35 and 140 mg. The rabbits in the experimental group tolerated the effect of radioembolization in a dose 4 times higher than the upper limit of the clinical dose (100 Gy). After injection of 90Y glass microspheres into the portal vein of rats with diethylnitrosamine (DEN)-induced hepatic carcinoma, the microspheres, in addition to the liver parenchyma, accumulated in central and peripheral parts of the cancer nodules, causing necrosis. The internal radiation therapy of 90Y glass microspheres delivered via the portal vein may be an effective nonsurgical method for the treatment of liver cancer, especially in small nodules.

Transluminal Catheter Angioplasty of Abdominal Aorta in Takayasu's Arteritis

Nine patients with Takayasu's arteritis and a long stenotic segment of the abdominal aorta were treated by percutaneous transluminal angioplasty (PTA). Intermittent claudication dissappeared in six of seven cases, the femoral pulse reappeared in all five; ankle/arm indices increased in seven cases; elevated blood pressure normalized in seven of eight cases. Seven patients were followed for 3 to 28 months. They were all free of symptoms from the lower extremities. In three patients with or without renal artery stenosis and with hypertension, the blood pressure decreased after PTA of the abdominal aorta only. PTA may be a valuable treatment in Takayasu's arteritis and stenosis of the abdominal aorta.