The DNA damage response pathway regulates the expression of the immune checkpoint CD47.

CD47 is a cell surface ligand expressed on all nucleated cells. It is a unique immune checkpoint protein acting as "don't eat me" signal to prevent phagocytosis and is constitutively overexpressed in many tumors. However, the underlying mechanism(s) for CD47 overexpression is not clear. Here, we show that irradiation (IR) as well as various other genotoxic agents induce elevated expression of CD47. This upregulation correlates with the extent of residual double-strand breaks (DSBs) as determined by γH2AX staining. Interestingly, cells lacking mre-11, a component of the MRE11-RAD50-NBS1 (MRN) complex that plays a central role in DSB repair, or cells treated with the mre-11 inhibitor, mirin, fail to elevate the expression of CD47 upon DNA damage. On the other hand, both p53 and NF-κB pathways or cell-cycle arrest do not play a role in CD47 upregualtion upon DNA damage. We further show that CD47 expression is upregulated in livers harvested from mice treated with the DNA-damage inducing agent Diethylnitrosamine (DEN) and in cisplatin-treated mesothelioma tumors. Hence, our results indicate that CD47 is upregulated following DNA damage in a mre-11-dependent manner. Chronic DNA damage response in cancer cells might contribute to constitutive elevated expression of CD47 and promote immune evasion.

The Effect of a 26-Hour Fast in Living Kidney Donors.

BACKGROUND: Living kidney donation is widely practiced, and short- and long-term outcomes are acceptable. Within the living kidney donor population there are unique ethnic groups who practice customs that affect kidney function. In Judaism, Yom Kippur (Day of Atonement) is a 25- to 26-hour fast practiced yearly. There are no studies describing the effect of this fast on LKDs. METHODS: Living kidney donors were approached via e-mail. Exclusion criteria were conditions considered prohibitive of fasting. Control participants were potential living kidney donors approved by the standard medical evaluation but that had not yet donated. Blood and urine samples were obtained at 3 time points: baseline: 3 months before fast; fasting: 1 hour after fast; and follow-up: 14 days after fast. RESULTS: In total, 85 living kidney donors and 27 control participants were included. Donors were older (42.8 vs 38.8 years) and had a higher baseline creatinine (103 vs 72 umol/L). All other parameters were the same. The percent change between fasting and nonfasting creatinine was smaller in living kidney donors than in control participants (0.12% vs 0.21% change, P = .04). Values of sodium, albumin, and osmolarity were not different between groups. Time from donation did not influence results. CONCLUSIONS: Living kidney donors practicing a day fast showed a different pattern regarding the change in creatinine levels. This pattern cannot be considered hazardous for living kidney donors. The emotional wellbeing of living kidney donors is of utmost importance, and this first report of the safety of a 24-hour fast is reassuring. These findings may be of interest to other religious groups, for example, the Muslim community which observes Ramadan.

Practical recommendations for kidney transplantation in the COVID-19 pandemic.

Kidney transplantation at the time of a global viral pandemic has become challenging in many aspects. Firstly, we must reassess deceased donor safety (for the recipient) especially in communities with a relatively high incidence of coronavirus disease 19 (COVID-19). With respect to elective live donors, if one decides to do them at all, similar considerations must be made that may impose undue hardship on the donor. Recipient selection is also problematic since there is clear evidence of a much higher morbidity and mortality from COVID-19 for patients older than 60 and those with comorbidities such as hypertension, diabetes, obesity and lung disease. Unfortunately, many, if not most of dialysis patients fit that mold. We may and indeed must reassess our allocation policies, but this must be done based on data rather than conjecture. Follow-up routines must be re-engineered to minimize patient travel and exposure. Reliance on technology and telemedicine is paramount. Making this technology available to patients is extremely important. Modifying or changing immunosuppression protocols is controversial and not based on clinical studies. Nevertheless, we should reassess the need for induction therapy across the board for ordinary patients and the more liberal use of mammalian target of rapamycin inhibitors in transplant patients with proven infection.

Access-related infections in two haemodialysis units: results of a nine-year intervention and surveillance program.

Background: Access-related infections are a major cause of morbidity and mortality in haemodialysis patients. Our goal was to decrease the rate of these infections by implementing an intervention and surveillance program. Methods: This intervention took place in two haemodialysis units (Units A and B) and was a joint effort by the haemodialysis staff and the unit for infection prevention and control. It included reviewing the work methods and work space, observations on compliance with standard precautions and handling of the vascular access, creating a checklist and a designated kit for handling the vascular access and prospective surveillance of access-related infections. Results: During a nine-year period, the haemodialysis units A and B treated 4471 and 7547 patients (mean number of patients per year: 497 (range 435-556) and 839 (range 777-1055), respectively). For most patients, the procedure was done through an arteriovenous fistula (66.7%, range 50.3-81.5%). The access-related infection rate decreased significantly in both haemodialysis units: from 3 to 0.9% (trend: p < 0.05, linear regression: p < 0.001) in Unit A and from 0.9 to 0.2% (trend: p < 0.05, linear regression: p = 0.01) in Unit B. Conclusions: An intervention which included introduction of a checklist and designated kit, together with ongoing surveillance and feedback, resulted in a significant decrease in the access-related infection rates in both haemodialysis units.

Age limitation for organ transplantation: the Israeli example.

In 2013 the Israeli Ministry of Health appointed a public committee to examine the policy of placing an age limitation on candidates listed for organ transplantation. The committee rejected the use of an age limit criterion for listing candidates for transplantation and recommended to abolish it. However, opinions differed regarding the use of recipients' age in shaping a fair organ allocation policy. The committee's recommendations were adopted and put into force as of April 2014. This article unfolds the committee deliberations on accommodating values of formal equality for optimising the use of organ transplantation.

Implementation of guidelines for metabolic syndrome control in kidney transplant recipients: results at a single center.

BACKGROUND: Cardiovascular disease is a leading cause of death among kidney transplant recipients. Metabolic syndrome increases the risk for cardiovascular events and decreases graft survival. Lately, guidelines for management of the metabolic syndrome, primarily hypertension, diabetes mellitus (DM) and hypercholesterolemia have dramatically changed in an attempt to decrease cardiovascular risks among kidney transplant recipients. In the present study we examined whether these guideline changes had impact on our management of post-transplantation patients and the subsequent treatment outcomes for these diseases. METHODS: Data were obtained from kidney transplant clinic files from two follow-up (FU) periods-between 1994-1997 and between 2008-2011. Demographic data, monitoring and screening frequency for cardiovascular risk factors, immunosuppression regimen, treatment for hypertension, diabetes and hyperlipidemia, treatment outcomes and graft function changes were compared between the two follow-up periods. RESULTS: There was a significant increase in the percentage of patients undergoing transplantation due to renal failure secondary to diabetes and/or hypertension. Patient monitoring and screening during the second FU period were less frequent, but more targeted, reflecting changes in clinic routines. Blood pressure was better controlled in the second FU period (p < 0.01), as was hypercholesterolemia (p < 0.001). High fasting glucose levels were more prevalent among patients in the second group (p < 0.005), although more patients received treatment for DM (p < 0.001). Significantly, fewer patients experienced deterioration of kidney functions during the second FU period (p < 0.001). CONCLUSIONS: We found that guideline changes had impact on clinical practice, which translated to better control of the metabolic syndrome. DM control is challenging. Overall, stability of kidney function improved.

Highly efficient, in-vivo Fas-mediated apoptosis of B-cell lymphoma by hexameric CTLA4-FasL.

Non-Hodgkin lymphomas (NHLs) account for 4% of all malignancies. 5-year survival rate increased to 50% with new treatment modalities, however there is need for new effective treatment for the more aggressive, relapsing forms. Recently, CTLA4-FasL, that can bind to B7 and Fas receptor (Fas), was shown to induce robust apoptosis of cell lines originating from B cell lymphomas expressing both B7 and Fas, by activating pro-apoptotic signals in parallel to abrogating anti-apoptotic ones. The present study focuses on the unique properties of CTLA4-FasL as a potent apoptosis inducer of malignant cells in-vitro and in a xenograft model. CTLA4-FasL was found to naturally form a stable homo-hexamer. CTLA4-FasL induces robust apoptosis of a large variety of malignant cells while relatively sparing non-malignant ones, being more efficient when both receptors (B7 and Fas) are expressed on target cells. Even in non-B7 expressing cells, CTLA4-FasL exhibited better apoptotic activity than its parts, alone or in combination, however, only in B7 expressing cells apoptosis occurs at low concentrations and CTLA4-FasL induces activation of apoptotic signals and reduces anti-apoptotic ones. Importantly, CTLA4-FasL efficiently inhibited the growth of human B cell lineage tumors in a xenograft model, by provoking tumor cells' apoptosis. Thus, CTLA4-FasL, a natural homo-hexamer protein, induces robust apoptosis of malignant cells, in-vitro and in-vivo. In B-cell lymphoma, its potency stems from the combination of its synergistic effect of activating the caspases while abrogating the anti-apoptotic signaling, with its unique hexameric structure, making CTLA4-FasL a promising candidate for aggressive B cell lymphomas treatment.

Serum vitamin D levels in kidney transplant recipients: the importance of an immunosuppression regimen and sun exposure.

BACKGROUND: Vitamin D deficiency was shown to be prevalent among renal transplant recipients in northern countries, but little is known regarding risk factors. OBJECTIVES: To test vitamin D levels in kidney transplant recipients residing closer to the equator, compare them to levels in liver transplant recipients and hemodialysis patients, and identify possible risk factors. METHODS: In a cross-sectional study 103 kidney transplant recipients, 27 liver transplant recipients and 50 hemodialysis patients followed at our institute were tested for vitamin D levels. Demographic data, medical history and current treatment were recorded from the medical files. RESULTS: Inadequate vitamin D levels (< 30 ng/ml) were found in 75% of all patients and 75% of all kidney transplant recipients. Vitamin D levels were higher among dialysis patients than transplant recipients, though deficiency rates were similar. No association was found between kidney function and vitamin deficiency. Deficiency was associated with higher prednisone doses, use of mycophenolate sodium, tacrolimus, and iron supplements, or lower doses of vitamin D supplementation. CONCLUSIONS: Despite potential higher ultraviolet B exposure, inadequate vitamin D levels were prevalent in our study group. Importantly, some immunosuppressive medications were associated with vitamin D deficiency and high doses of vitamin D were associated with less deficiency.

Regulation of NaPi-IIa mRNA and transporter protein in chronic renal failure: role of parathyroid hormone (PTH) and dietary phosphate (Pi).

Chronic renal failure (CRF) is associated with a high fractional phosphate excretion (FEPi), secondary hyperparathyroidism, and resistance to parathyroid hormone (PTH). This study was undertaken to characterize the role of PTH and dietary Pi in the regulation of PTH/PTH-related peptide receptor (PTHrP-R) mRNA and NaPi-IIa mRNA and protein in CRF. The following groups of rats were studied: (1) sham-operated (control); (2) CRF: 6 weeks after 5/6 nephrectomy (NPX); (3) NPX and parathyroidectomy (NPX + PTX); (4) NPX rats fed a low-Pi diet (NPX + LP); (5) sham-operated rats fed a low-Pi diet (control + LP); (6) sham-operated after PTX (control + PTX). Expression of NaPi-IIa mRNA and PTH/PTHrP-R mRNA was determined in the renal cortex by Northern hybridization. NaPi-IIa protein abundance was determined in cortical brush border membranes by immunoblotting. In NPX rats creatinine clearance decreased to 40 +/- 4%, PTH/PTHrP-R mRNA to 52.1 +/- 2% and NaPi-IIa mRNA to 41.2 +/- 5.5% of control. The PTH/PTHrP-R and NaPi-IIa mRNA in the NPX + PTX and NPX + LP group was similar to that in NPX. NaPi-IIa protein abundance was reduced in NPX compared with control, but was increased dramatically in NPX + PTX and NPX + LP compared to NPX, paralleled by a decrease in FEPi. These findings suggest that the elevated FEPi in CRF is maintained by decreased NaPi-IIa mRNA and NaPi-IIa protein abundance. In contrast, the observed decrease in FEPi with PTX or LP diet in CRF is mediated, at least partly, by increased NaPi-IIa protein abundance with no change in NaPi-IIa mRNA, suggesting post-transcriptional regulation of the NaPi-IIa transporter.

CTLA-4. FasL induces alloantigen-specific hyporesponsiveness.

The APC:T cell interface can be effectively targeted with immunotherapeutic proteins. We previously described a unique trans signal converter protein, CTLA-4. Fas ligand (FasL), that has the inherent capacities to tether the T cell inhibitor FasL (CD95 ligand) to the surfaces of B7 (CD80 and CD86)-positive APC (via CTLA-4:B7 interaction), and in so doing, to simultaneously interfere with B7-to-CD28 T cell activation signals. Given the continuing need for agents capable of inducing allograft tolerance without generalized immunosuppression, we have explored in depth the functional activity of CTLA-4. FasL in human allogeneic MLR. CTLA-4. FasL inhibits 1 degrees MLR and induces specific hyporesponsiveness in 2 degrees MLR, with both effects only partially reversible with exogenous IL-2. Moreover, the presence of exogenous IL-2 during the 1 degrees MLR does not affect the induction of hyporesponsiveness upon restimulation. Furthermore, CTLA-4. FasL enables partial activation of allostimulated T cells, reduces the fraction of actively dividing cells, and increases the percentage of dead cells among dividing T cells. Taken together, these findings suggest that CTLA-4. FasL-mediated inhibition of secondary alloantigenic responses involves both anergy induction and clonal deletion. Thus, CTLA-4. FasL, a paradigmatic trans signal converter protein, manifests unique functional properties and emerges as a potentially useful immunotherapeutic for modulating alloresponsiveness.