JAK Inhibition Prevents DNA Damage and Apoptosis in Testicular Ischemia-Reperfusion Injury via Modulation of the ATM/ATR/Chk Pathway

Testicular ischemia reperfusion injury (tIRI) causes oxidative stress-induced DNA damage leading to germ cell apoptosis (GCA). The aim of the study is to establish a direct link between JAK2 activation and the DNA damage response (DDR) signaling pathways and their role in tIRI-induced GCA using AG490, a JAK2 specific inhibitor. Male Sprague Dawley rats (n = 36) were divided into three groups: sham, unilateral tIRI and tIRI + AG490 (40 mg/kg). During tIRI, augmentation in the phosphorylation levels of the JAK2/STAT1/STAT3 was measured by immunohistochemistry. Observed spermatogenic arrest was explained by the presence of considerable levels of DSB, AP sites and 8OHdG and activation of caspase 9, caspase 3 and PARP, which were measured by colorimetric assays and TUNEL. The ATM/Chk2/H2AX and ATR/Chk1 pathways were also activated as judged by their increased phosphorylation using Western blot. These observations were all prevented by AG490 inhibition of JAK2 activity. Our findings demonstrate that JAK2 regulates tIRI-induced GCA, oxidative DNA damage and activation of the ATM/Chk2/H2AX and ATR/Chk1 DDR pathways, but the cell made the apoptosis decision despite DDR efforts.

JNK inhibition alleviates oxidative DNA damage, germ cell apoptosis, and mitochondrial dysfunction in testicular ischemia reperfusion injury

The aim of this study is to determine whether the c-Jun N-terminal kinase (JNK) signaling is a regulator of oxidative DNA damage, germ cell apoptosis (GCA), and mitochondrial dysfunction during testicular ischemia reperfusion injury (tIRI) using the JNK inhibitor SP600125. Male Sprague Dawley rats (n = 36) were equally divided into three groups: sham, tIRI only, and tIRI + SP600125 (15 mg/kg). Testicular ischemia was induced for 1 h followed by 4 h of reperfusion prior to animal sacrifice. Spermatogenesis was evaluated by light microscopy, while expression of oxidative stress and GCA-related mRNAs and proteins were evaluated by real-time polymerase chain reaction and colorimetric assays, respectively. Expressions of JNK, p53, and survivin were detected by immunofluorescence (IF) staining. Indicators of mitochondrial dysfunction were examined by western blot analysis and colorimetric assay. In comparison to sham, the tIRI testes showed a significant increase in lipid and protein oxidation products. Oxidative DNA damage was reflected by a significant increase in the number of DNA strand breaks, increased concentration of 8-OHdG, and elevated poly (ADP-ribose) polymerase activity. Spermatogenic damage was associated with the activation of caspase 3 and elevated Bax to Bcl2 ratio. This was also accompanied by a significantly heightened IF expression of the phosphorylated forms of JNK and p53 paralled with the suppression of survivin. Mitochondrial dysfunction was reflected by NAD+ depletion, overexpression of uncoupling protein 2, and increased level of cytochrome c. Such tIRI-induced modulations were all attenuated by SP600125 treatment prior to reperfusion. In conclusion, JNK signaling regulates oxidative DNA damage, GCA, and mitochondrial dysfunction through activation of p53 and suppression of survivin during tIRI.

Inhibition of NADPH oxidase alleviates germ cell apoptosis and ER stress during testicular ischemia reperfusion injury

Testicular torsion and detorsion (TTD) is a serious urological condition affecting young males that is underlined by an ischemia reperfusion injury (tIRI) to the testis as the pathophysiological mechanism. During tIRI, uncontrolled production of oxygen reactive species (ROS) causes DNA damage leading to germ cell apoptosis (GCA). The aim of the study is to explore whether inhibition of NADPH oxidase (NOX), a major source of intracellular ROS, will prevent tIRI-induced GCA and its association with endoplasmic reticulum (ER) stress. Sprague-Dawley rats (n = 36) were divided into three groups: sham, tIRI only and tIRI treated with apocynin (a NOX inhibitor). Rats undergoing tIRI endured an ischemic injury for 1 h followed by 4 h of reperfusion. Spermatogenic damage was evaluated histologically, while cellular damages were assessed using real time PCR, immunofluorescence staining, Western blot and biochemical assays. Disrupted spermatogenesis was associated with increased lipid and protein peroxidation and decreased antioxidant activity of the enzyme superoxide dismutase (SOD) as a result of tIRI. In addition, increased DNA double strand breaks and formation of 8-OHdG adducts associated with increased phosphorylation of the DNA damage response (DDR) protein H2AX. The ASK1/JNK apoptosis signaling pathway was also activated in response to tIRI. Finally, increased immuno-expression of the unfolded protein response (UPR) downstream targets: GRP78, eIF2-α1, CHOP and caspase 12 supported the presence of ER stress. Inhibition of NOX by apocynin protected against tIRI-induced GCA and ER stress. In conclusion, NOX inhibition minimized tIRI-induced intracellular oxidative damages leading to GCA and ER stress.

Lymphedema: an unusual complication of sirolimus therapy

INTRODUCTION

Lymphedema is an increasingly observed complication of sirolimus (SIR) therapy. In this report, we describe four renal recipients with SIR-induced lymphedema of varying severity.

CASES REPORTS

Patient 1, a 38-year-old man developed lymphedema of the left upper limb after being exposed to SIR for 30 months (mean daily Rapamune dose, 3 mg; trough level, 10-18 ng/mL). Venography and duplex ultrasound were normal. Lymphangiography was showed delayed lymphatic drainage. SIR was replaced with Prograf with significant improvement in the lymphedema over the next 6 months. Patient 2, a 26-year-old woman, developed lymphedema of the left lower limb at 24 months after starting SIR (mean daily dose, 3 mg; trough level, 10-15 ng/mL). Lymphangiography showed delayed drainage of lymphatics in the left lower limb. The patient was shifted to Prograf and there was some improvement over the next 4 months. Patient 3, a 28-year-old man, developed lymphedema of the left upper limb at 24 months after the start of SIR (mean daily dose, 2 mg, trough level, 6-15 ng/mL). Lymphangiography showed evidence of lymphatic obstruction. SIR was changed to cyclosporine with only mild improvement in lymphedema over the next 6 months. Patient 4, a 46-year-old man, developed lymphedema of the right upper limb at 7 months after starting SIR (mean daily dose, 6 mg; trough level, 10-16 ng/mL). Lymphangiography showed complete blockage of the lymphatic channels. SIR was changed to cyclosporine and there was mild improvement in lymphedema over the next 8 to 10 months.

CONCLUSION

The exact mechanism of SIR-induced lymphedema is unknown. The absence of other demonstrable etiologies and spontaneous improvement after discontinuation of SIR suggest that this drug was the responsible factor in these four patients. It occurred 7 to 30 months after transplantation. This is the fourth such report in the literature to the best of our knowledge.

Renal Transplantation in Children

OBJECTIVE

Renal transplantation is the preferred method for the treatment of children in end-stage renal disease (ESRD). In this retrospective study, we analyzed the results at our center.

PATIENTS AND METHODS

Between November 1993 and June 2006, 86 children (50 boys and 36 girls) received organs from 50 living donors (LDTx) and 36 cadaveric donors (CDTx). Twenty children were <10 years. In addition to ESRD, some patients had one or more other high-risk factors, eg, abnormal lower urinary tract in 36 recipients (42%). The procedure was a preemptive transplantation in 28, and a retransplantation in 9 recipients. Induction immunosuppression used either antithymocyte globulin (43 cases) or anti-interleukin-2 receptor antibodies (20 cases).

RESULTS

Patients were followed for 6 to 150 months. There were 24 surgical complications (28%), 26 acute rejection episodes (33%), and 17 of systemic bacterial or viral infections. Two recipients died at 1 and 21 months. The 14 grafts were lost at 1 day to 87 months. The 1- and 10-year actuarial survival rates were 99% and 98%, respectively, for the recipients, and 88% and 84%, respectively, for the grafts. The 10-year actuarial graft survival rates were 98% in LDTx and 64% in CDTx; 86% in recipients >10 years old and 75% in recipients <10 years old. Abnormal urinary tract, pretransplantation dialysis, and transplant number showed no effect on graft survival. All pediatric recipients with functioning grafts are fully rehabilitated.

CONCLUSION

Renal transplantation is the preferred method of treatment for children in ESRD. Higher graft survival rates were achieved in older children and following LDTx.