Acute diabetic foot in post kidney transplantation patients receiving chronic immunosuppression-clinical presentation and outcomes.

AIMS: Data regarding diabetic foot ulcers in patients after solid organ transplantation, particularly kidney transplantation, are limited. Chronic immunosuppression may be associated with impaired wound healing and a higher risk of amputations. In this study, we characterised the clinical presentation and outcomes of patients after kidney transplantation admitted to the diabetic foot unit, compared to non-kidney-transplant patients. MATERIALS AND METHODS: Data on the baseline characteristics, clinical presentation, and outcomes of all patients admitted to the diabetic foot unit of a large tertiary centre between the years 2014 and 2019 were collected. The most recent admission of each patient was considered. Primary outcomes were major amputations and 1 year mortality rate. RESULTS: During the study period, 537 patients were hospitalised, 18 of them were receiving immunosuppressive therapy due to kidney transplantation. Baseline characteristics of the patients were broadly similar, except that smoking was reported by 22.0% of the non-transplant patients and by none of the post-transplant patients (p = 0.01). Post-transplant patients tended to be younger (59.4 ± 11.1 vs. 65.3 ± 12.2; p = 0.07), were more likely to have type-1 diabetes (16.7% vs. 5.2%; p = 0.07) and had lower glucose levels upon admission (9.4 ± 4.3 vs. 12.0 ± 6.4 mmol/L; p = 0.07). Overall, 30% of the patients underwent major amputation, in-patient mortality rate was 9.3%, and 1 year mortality rate was 27.2%. Rates were similar in the post-transplant versus the non-post-transplant patients (p = 0.83, 1.00, 0.59, respectively). CONCLUSIONS: Post-transplant patients did not incur worse outcomes in spite of immunosuppressive therapy. Limb salvage efforts should be pursued in these patients similar to the overall population.

Impact of tozinameran (BNT162b2) mRNA vaccine on kidney transplant and chronic dialysis patients: 3-5 months follow-up.

BACKGROUND: Determining the humoral immunogenicity of tozinameran (BNT162b2) in patients requiring chronic renal replacement therapy, and its impact on COVID-19 morbidity several months after vaccination, may guide risk assessment and changes in vaccination policy. METHODS: In a prospective post-vaccination cohort study with up to 5 months follow-up we studied outpatient dialysis and kidney transplant patients and respective healthcare teams. Outcomes were anti S1/S2 antibody responses to vaccine or infection, and infection rate during follow-up. RESULTS: One hundred seventy-five dialysis patients (40% women, 65 ± 15 years), 252 kidney transplant patients (33% women, 54 ± 14 years) and 71 controls (65% women, 44 ± 14 years) were followed. Three months or longer after vaccination we detected anti S1/S2 IgG antibodies in 79% of dialysis patients, 42% of transplant recipients and 100% of controls, whereas respective rates after infection were 94%, 69% and 100%. Predictors of non-response were older age, diabetes, history of cancer, lower lymphocyte count and lower vitamin-D levels. Factors associated with lower antibody levels in dialysis patients were modality (hemodialysis vs peritoneal) and high serum ferritin levels. In transplant patients, hypertension and higher calcineurin or mTOR inhibitor drug levels were linked with lower antibody response. Vaccination was associated with fewer subsequent infections (HR 0.23, p < 0.05). Moreover, higher antibody levels (particularly above 59 AU/ml) were associated with fewer events, with a HR 0.41 for each unit increased in log10titer (p < 0.05). CONCLUSIONS: Dialysis patients, and more strikingly kidney transplant recipients, mounted reduced antibody response to COVID-19 mRNA vaccination. Lesser humoral response was associated with more infections. Measures to identify and protect non-responsive patients are required.

Repeat Kidney Transplant in a Patient With a Double Inferior Vena Cava and Difficult Venous Access: A Case Report.

Many obstacles may complicate renal transplant, the preferred treatment for end-stage renal disease. Anatomic anomalies are of special importance during surgery. Double inferior vena cava is a rare anomaly reported in 0.2% to 3% of the population and may complicate renal transplant in certain cases. We present a case of a 29-year-old man with end-stage renal disease who was scheduled for repeat kidney renal transplant from a living related donor. His transplant posed many challenges to the transplant team. These included (1) difficult access for dialysis, which required transhepatic insertion of a dialysis catheter, (2) anomalous inferior vena cava anatomy with a double inferior vena cava, (3) a blocked right inferior vena cava, and (4) a small blocked bridging vein connecting the right inferior vena cava to an additional left inferior vena cava. A stent was inserted into the bridging vein to allow venous drainage from the graft. During the transplant procedure, the donated kidney was transplanted into the left iliac fossa and anastomosed to the left external iliac vein. The surgery was successful, without major operative or postoperative complications. The patient was discharged with normal renal function and enjoys normal renal function 6 months after surgery. This case emphasizes the importance of pretransplant evaluation and preparation and the need for high index of suspicion for anatomic variants in donors and recipients.

An in-vitro tumour microenvironment model using adhesion to type I collagen reveals Akt-dependent radiation resistance in renal cancer cells.

BACKGROUND: Renal cell carcinoma (RCC) is considered resistant to ionizing radiation. Recently, the extracellular matrix (ECM) has been shown to play a role in both drug resistance and radiation resistance (RR). While fibronectin has been extensively investigated in the context of RR, the role of type I collagen [col(I)], a principal constituent of the ECM in tumour metastases, in RR of RCC is unknown. METHODS: RCC cell adhesion to matrix was studied via pre-coating a variety of ECM glycoproteins onto plates. Cancer cell apoptosis and cell cycle were evaluated with flow cytometry using annexin V and propidium iodide stains, respectively. Activation of cellular survival signalling was analysed with western blots, and specific molecular inhibitors were correspondingly employed to block signalling. Hypoxia (<1%) was induced via N(2)/CO(2) gas flow in a specialized chamber. RESULTS: While adherence to col(I) enhanced RCC cell proliferation in general, col(I) and fibronectin, but not fibrinogen, could confer specific anti-apoptotic RR to RCC cells. The radioprotective effect of col(I) was maintained during both hypoxia/reoxygenation and normoxia conditions. In contrast to intact col(I), micronized col(I), lacking the natural fibrillar structure, was not radioprotective. The effect of col(I) in RCC cells is mediated via attenuation of apoptosis rather than cell cycle redistribution, involving the PI3 kinase/Akt pathway but not the MAP kinase pathway. CONCLUSIONS: Adherence to col(I) appears to be a relevant environmental cue enhancing RR in RCC cells, Akt dependently. Our results support inhibition of the PI3-kinase/Akt pathway as a radiosensitizing approach.

A novel dynamic matrix detachment model reveals a shift from apoptosis to necrosis in melanoma cells.

Anchorage-independence is a hallmark of invasive cancer. The setback of the classical poly-HEMA static matrix detachment (SMD) anoikis model is the absence of dynamic fluid circulation, resulting in cell aggregates. We addressed this problem by developing a novel 3D cell culture dynamic matrix detachment (DMD) model with a turbulent-free laminar flow, yielding a very low shear stress. In this study, we focused on melanoma cells where apoptosis was evaluated both via annexin V flow cytometry and caspase cleavage. The DMD model was superior to SMD in the induction of melanoma cell death and in revealing a shift from apoptosis to necrotic cell death, as evident by failure to activate caspase 9 and a decrease in annexin V stain. Combination of DMD with cisplatin could further accentuate necrotic cell death in cisplatin-resistant melanoma cells. Thus, the DMD model may be a useful matrix deprivation model to identify necrotic vs. apoptotic cell death pathways.

A 3D rotary renal and mesenchymal stem cell culture model unveils cell death mechanisms induced by matrix deficiency and low shear stress.

BACKGROUND: In epithelial and endothelial cells, detachment from the matrix results in anoikis, a form of apoptosis, whereas stromal and cancer cells are often anchorage independent. The classical anoikis model is based on static 3D epithelial cell culture conditions (STCK). METHODS: We characterized a new model of renal, stromal and mesenchymal stem cell (MSC) matrix deprivation, based on slow rotation cell culture conditions (ROCK). This model induces anoikis using a low shear stress, laminar flow. The mechanism of cell death was determined via FACS (fluorescence-activated cell sorting) analysis for annexin V and propidium iodide uptake and via DNA laddering. RESULTS: While only renal epithelial cells progressively died in STCK, the ROCK model could induce apoptosis in stromal and transformed cells; cell survival decreased in ROCK versus STCK to 40%, 52%, 62% and 7% in human fibroblast, rat MSC, renal cell carcinoma (RCC) and human melanoma cell lines, respectively. Furthermore, while ROCK induced primarily apoptosis in renal epithelial cells, necrosis was more prevalent in transformed and cancer cells [necrosis/apoptosis ratio of 72.7% in CaKi-1 RCC cells versus 4.3% in MDCK (Madin-Darby canine kidney) cells]. The ROCK-mediated shift to necrosis in RCC cells was further accentuated 3.4-fold by H(2)O(2)-mediated oxidative stress while in adherent HK-2 renal epithelial cells, oxidative stress enhanced apoptosis. ROCK conditions could also unveil a similar pattern in the LZ100 rat MSC line where in ROCK 44% less apoptosis was observed versus STCK and 45% less apoptosis versus monolayer conditions. Apoptosis in response to oxidative stress was also attenuated in the rat MSC line in ROCK, thereby highlighting rat MSC transformation. CONCLUSIONS: The ROCK matrix-deficiency cell culture model may provide a valuable insight into the mechanism of renal and MSC cell death in response to matrix deprivation.