Donor genetic variants in interleukin-6 and interleukin-6 receptor associate with biopsy-proven rejection following kidney transplantation

Donor genetic burden for cerebrovascular risk and kidney transplant outcome

BACKGROUND AND HYPOTHESIS

Kidney grafts from donors who died of stroke and related traits have worse outcomes relative to grafts from both living donors and those who died of other causes. We hypothesise that deceased donors, particularly those who died of stroke, have elevated polygenic burden for cerebrovascular traits. We further hypothesise that this donor polygenic burden is associated with inferior graft outcomes in the recipient.

METHODS

Using a dataset of 6666 deceased and living kidney donors from seven different European ancestry transplant cohorts, we investigated the role of polygenic burden for cerebrovascular traits (hypertension, stroke, and intracranial aneurysm (IA)) on donor age of death and recipient graft outcomes.

RESULTS

We found that kidney donors who died of stroke had elevated intracranial aneurysm and hypertension polygenic risk scores, compared to healthy controls and living donors. This burden was associated with age of death among donors who died of stroke. Increased donor polygenic risk for hypertension was associated with reduced long term graft survival (HR: 1.44, 95% CI [1.07, 1.93]) and increased burden for hypertension, and intracranial aneurysm was associated with reduced recipient estimated glomerular filtration rate (eGFR) at 1 year.

CONCLUSIONS

Collectively, the results presented here demonstrate the impact of inherited factors associated with donors' death on long-term graft function.

Crosstalk mechanisms between glomerular endothelial cells and podocytes in renal diseases and kidney transplantation

The glomerular filtration barrier (GFB), composed of endothelial cells, glomerular basement membrane, and podocytes, is a unique structure for filtering blood while detaining plasma proteins according to size and charge selectivity. Structurally, the fenestrated endothelial cells, which align the capillary loops, are in close proximity to mesangial cells. Podocytes are connected by specialized intercellular junctions known as slit diaphragms and are separated from the endothelial compartment by the glomerular basement membrane. Podocyte-endothelial cell communication or crosstalk is required for the development and maintenance of an efficient filtration process in physiological conditions. In pathological situations, communication also has an essential role in promoting or delaying disease progression. Podocytes and endothelial cells can secrete signaling molecules, which act as crosstalk effectors and, through binding to their target receptors, can trigger bidirectional paracrine or autocrine signal transduction. Moreover, the emerging evidence of extracellular vesicles derived from various cell types engaging in cell communication has also been reported. In this review, we summarize the principal pathways involved in the development and maintenance of the GFB and the progression of kidney disease, particularly in kidney transplantation.

Association Between Pre-Transplant Oral Health and Post-Liver Transplant Complications

Oral disease is linked with systemic inflammation and various systemic conditions, including chronic liver disease. Liver transplantation (LT) candidates often need dental infection focus eradication, and after LT, there is high risk of many inflammation-related complications. We studied whether pre-LT dental status is associated with the occurrence of post-LT complications. This study included 225 adult LT recipients whose teeth were examined and treated before LT, and 40 adult LT recipients who did not have pre-LT dental data available. Data on post-LT complications were collected from the national liver transplant registry and followed up until the end of July 2020. Worse pre-LT dental status was associated with a higher risk of acute rejection post-LT compared to patients with good dental status. Worse dental status was also associated with higher 1-year-post-LT ALT levels and lower albumin levels. In conclusion, poor pre-LT oral health seems to associate with an increased risk of post-LT acute rejection and with elevated ALT levels and decreased albumin levels, suggesting an effect on post-LT liver health. Therefore, prevention and treatment of oral and dental diseases should be promoted early in the course of liver disease.

An interleukin 6-based genetic risk score strengthened with interleukin 10 polymorphisms associated with long-term kidney allograft outcomes

Of all kidney transplants, half are still lost in the first decade after transplantation. Here, using genetics, we probed whether interleukin 6 (IL-6) could be a target in kidney transplantation to improve graft survival. Additionally, we investigated if a genetic risk score (GRS) based on IL6 and IL10 variants could improve prognostication of graft loss. In a prospective cohort study, DNA of 1271 donor-recipient kidney transplant pairs was analyzed for the presence of IL6, IL6R, IL10, IL10RA, and IL10RB variants. These polymorphisms and their GRS were then associated with 15-year death-censored allograft survival. The C|C-genotype of the IL6 polymorphism in donor kidneys and the combined C|C-genotype in donor-recipient pairs were both associated with a reduced risk of graft loss (p = .043 and p = .042, respectively). Additionally, the GRS based on IL6, IL6R, IL10, IL10RA, and IL10RB variants was independently associated with the risk of graft loss (HR 1.53, 95%-CI [1.32-1.84]; p < .001). Notably, the GRS improved risk stratification and prediction of graft loss beyond the level of contemporary clinical markers. Our findings reveal the merits of a polygenic IL-6-based risk score strengthened with IL-10- polymorphisms for the prognostication and risk stratification of late graft failure in kidney transplantation.

A functional TGFB1 polymorphism in the donor associates with long-term graft survival after kidney transplantation

Background

Improvement of long-term outcomes in kidney transplantation remains one of the most pressing challenges, yet drug development is stagnating. Human genetics offers an opportunity for much-needed target validation in transplantation. Conflicting data exist about the effect of transforming growth factor-beta 1 (TGF-β1) on kidney transplant survival, since TGF-β1 has pro-fibrotic and protective effects. We investigated the impact of a recently discovered functional TGFB1 polymorphism on kidney graft survival.

Methods

We performed an observational cohort study analysing recipient and donor DNA in 1271 kidney transplant pairs from the University Medical Centre Groningen in The Netherlands, and associated a low-producing TGFB1 polymorphism (rs1800472-C > T) with 5-, 10- and 15-year death-censored kidney graft survival.

Results

Donor genotype frequencies of rs1800472 in TGFB1 differed significantly between patients with and without graft loss (P = 0.014). Additionally, the low-producing TGFB1 polymorphism in the donor was associated with an increased risk of graft loss following kidney transplantation (hazard ratio = 2.12 for the T-allele; 95% confidence interval 1.18–3.79; P = 0.012). The incidence of graft loss within 15 years of follow-up was 16.4% in the CC-genotype group and 31.6% in the CT-genotype group. After adjustment for transplant-related covariates, the association between the TGFB1 polymorphism in the donor and graft loss remained significant. In contrast, there was no association between the TGFB1 polymorphism in the recipient and graft loss.

Conclusions

Kidney allografts possessing a low-producing TGFB1 polymorphism have a higher risk of late graft loss. Our study adds to a growing body of evidence that TGF-β1 is beneficial, rather than harmful, for kidney transplant survival.