Significance of IL-2, IL-2R, IL-6, and TNF-alpha as a diagnostic test of acute rejection after renal transplantation

Chronic Kidney Disease-Mineral Bone Disease biomarkers in kidney transplant patients

Background:

Chronic Kidney Disease associated with Mineral Bone Disease (CKD-MBD) is frequent in kidney transplant patients. Post-transplantation bone disease is complex, especially in patients with pre-existing metabolic bone disorders that are further affected by immunosuppressive medications and changes in renal allograft function. Main biochemical abnormalities of mineral metabolism in kidney transplantation (KTx) include hypophosphatemia, hyperparathyroidism (HPTH), insufficiency or deficiency of vitamin D, and hypercalcemia.

Objective:

This review aimed to summarize the pathophysiology and main biomarkers of CKD-MBD in KTx.

Methods:

A comprehensive and non-systematic search in PubMed was independently made with an emphasis on biomarkers in mineral bone disease in KTx.

Results:

CKD-MBD can be associated with numerous factors including secondary HPTH, metabolic dysregulations before KTx, and glucocorticoids therapy in post-transplant subjects. Fibroblast growth factor 23 (FGF23) reaches normal levels after KTx with good allograft function, while calcium, vitamin D and phosphorus, ultimately, result in hypercalcemia, persistent vitamin D insufficiency, and hypophosphatemia respectively. As for PTH levels, there is an initial tendency of a significant decrease, followed by a raise due to secondary or tertiary HPTH. In regard to sclerostin levels, there is no consensus in the literature.

Conclusion:

KTx patients should be continuously evaluated for mineral homeostasis and bone status, both cases with successful kidney transplantation and those with reduced functionality. Additional research on CKD-MBD pathophysiology, diagnosis, and management is essential to guarantee long-term graft function, better prognosis, good quality of life, and reduced mortality for KTx patients.

The Impact of Inflammation on the Immune Responses to Transplantation: Tolerance or Rejection?

Transplantation (Tx) remains the optimal therapy for end-stage disease (ESD) of various solid organs. Although alloimmune events remain the leading cause of long-term allograft loss, many patients develop innate and adaptive immune responses leading to graft tolerance. The focus of this review is to provide an overview of selected aspects of the effects of inflammation on this delicate balance following solid organ transplantation. Initially, we discuss the inflammatory mediators detectable in an ESD patient. Then, the specific inflammatory mediators found post-Tx are elucidated. We examine the reciprocal relationship between donor-derived passenger leukocytes (PLs) and those of the recipient, with additional emphasis on extracellular vesicles, specifically exosomes, and we examine their role in determining the balance between tolerance and rejection. The concept of recipient antigen-presenting cell "cross-dressing" by donor exosomes is detailed. Immunological consequences of the changes undergone by cell surface antigens, including HLA molecules in donor and host immune cells activated by proinflammatory cytokines, are examined. Inflammation-mediated donor endothelial cell (EC) activation is discussed along with the effect of donor-recipient EC chimerism. Finally, as an example of a specific inflammatory mediator, a detailed analysis is provided on the dynamic role of Interleukin-6 (IL-6) and its receptor post-Tx, especially given the potential for therapeutic interdiction of this axis with monoclonal antibodies. We aim to provide a holistic as well as a reductionist perspective of the inflammation-impacted immune events that precede and follow Tx. The objective is to differentiate tolerogenic inflammation from that enhancing rejection, for potential therapeutic modifications. (Words 247).

The 82-plex plasma protein signature that predicts increasing inflammation

The objective of the study was to define the specific plasma protein signature that predicts the increase of the inflammation marker C-reactive protein from index day to next-day using proteome analysis and novel bioinformatics tools. We performed a prospective study of 91 incident kidney transplant recipients and quantified 359 plasma proteins simultaneously using nano-Liquid-Chromatography-Tandem Mass-Spectrometry in individual samples and plasma C-reactive protein on the index day and the next day. Next-day C-reactive protein increased in 59 patients whereas it decreased in 32 patients. The prediction model selected and validated 82 plasma proteins which determined increased next-day C-reactive protein (area under receiver-operator-characteristics curve, 0.772; 95% confidence interval, 0.669 to 0.876; P < 0.0001). Multivariable logistic regression showed that 82-plex protein signature (P < 0.001) was associated with observed increased next-day C-reactive protein. The 82-plex protein signature outperformed routine clinical procedures. The category-free net reclassification index improved with 82-plex plasma protein signature (total net reclassification index, 88.3%). Using the 82-plex plasma protein signature increased net reclassification index with a clinical meaningful 10% increase of risk mainly by the improvement of reclassification of subjects in the event group. An 82-plex plasma protein signature predicts an increase of the inflammatory marker C-reactive protein.

Association between IL-6 -174G/C polymorphism and acute rejection of renal allograft: evidence from a meta-analysis

BACKGROUND

Results from published studies on the association of donor or recipient IL-6 -174G/C (rs1800795) polymorphism with acute rejection (AR) of renal allograft are conflicting. We performed a meta-analysis to estimate the possible association.

METHODS

Studies were identified by searching PUBMED and EMBASE until July 1, 2011. Meta-analysis was performed in a fixed/random effects model using Revman 5.0.25 and STATA10.0.

RESULTS

Seven studies addressing the association between donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism and acute rejection of renal allograft were identified. Pooled OR based on 341 cases (whose recipient developed acute rejection) and 702 controls (whose recipient did not develop acute rejection) was 0.59 (95% CI, 0.26-1.33; p=0.20), with a strong between-study heterogeneity. No association was observed in the subgroup analysis based on ethnicity. 13 studies evaluating the association between recipient IL-6 -174G/C polymorphism and acute rejection were identified. Pooled OR based on 451 cases (patients did not develop acute rejection) and 848 controls was 1.00 (95% CI=0.72-1.37; p=0.98), with a weak between-study heterogeneity.

CONCLUSIONS

Donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism had a tendency of decreased risk for acute rejection, although it was not statistically significant. Recipient high producer genotype was not associated with acute rejection of renal allograft. Additional well designed studies with larger sample size are needed to support our findings, especially for the association between donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism and acute renal allograft rejection.

Inhibition of allogeneic inflammatory responses by the Ribonucleotide Reductase Inhibitors, Didox and Trimidox

Background

Graft-versus-host disease is the single most important obstacle facing successful allogeneic stem cell transplantation (SCT). Even with current immunosuppressive therapies, morbidity and mortality rates are high. Current therapies including cyclosporine A (CyA) and related compounds target IL-2 signaling. However, although these compounds offer great benefit, they are also associated with multiple toxicities. Therefore, new compounds with a greater efficacy and reduced toxicity are needed to enable us to overcome this hurdle.

Methods

The allogeneic mixed lymphocyte reaction (MLR) is a unique ex vivo method to study a drug's action on the initial events resulting in T-cell activation and proliferation, synonymous to the initial stages of tissue and organ destruction by T-cell responses in organ rejection and Graft-versus-host disease. Using this approach, we examined the effectiveness of two ribonucleotide reductase inhibitors (RRI), Didox and Trimidox, to inhibit T-cell activation and proliferation.

Results

The compounds caused a marked reduction in the proliferative responses of T-cells, which is also accompanied by decreased secretion of cytokines IL-6, IFN-γ, TNF-α, IL-2, IL-13, IL-10 and IL-4.

Conclusions

In conclusion, these data provide critical information to justify further investigation into the potential use of these compounds post allogeneic bone marrow transplantation to alleviate graft-versus-host disease thereby achieving better outcomes.

Inflammation and endothelial activation are linked to renal function in long-term kidney transplantation

The aim of this study was to investigate the relationships between inflammation and adhesion molecules in long-term kidney transplantation. We measured serum concentrations of tumor necrosis factor-alpha (TNFalpha) and intercellular and vascular cell adhesion molecules (ICAM-1 and VCAM-1) in 35 renal transplant recipients (mean age of transplantation 5 +/- 3 years) and in 35 chronic renal insufficiency (CRI) patients; twenty-six healthy subjects were enrolled as controls. Transplanted showed higher values than controls of TNFalpha (P < 0.0001), ICAM-1 (P < 0.0001), and VCAM-1 (P < 0.0001). CRI group as well exhibited higher concentrations than controls of TNFalpha (P < 0.0001), ICAM-1 (P < 0.0001), and VCAM-1 (P < 0.0001). Transplanted and CRI patients had similar blood pressure and renal function levels, and TNFalpha, ICAM-1, and VCAM-1 were not significantly different in the two groups. In transplanted group ICAM-1, VCAM-1, and TNFalpha correlated negatively and independently with glomerular filtration rate (GFR) -P < 0.00001 for all. TNFalpha as well correlated with ICAM-1 and VCAM-1 (P < 0.001, respectively). In CRI group, TNFalpha correlated with serum creatinine, ICAM-1, and VCAM-1 (P = 0.01 for all). In conclusion, in long-term renal transplantation, the level of kidney function and both inflammation and endothelial activation are closely related. In fact, the multiple regression analysis demonstrated that the level of kidney insufficiency and the levels of the studied molecules were independently associated.

In Renal Transplanted Patients Inflammation and Oxidative Stress Are Interrelated

INTRODUCTION

The inflammatory state plays a well-documented role to cause oxidative stress, especially in end-stage renal disease (ESRD) patients, wherein several cardiovascular risk factors are amplified by the coexistence of a microinflammatory state with increased oxidative stress.

METHODS

We measured serum concentrations of high sensitivity C-reactive protein (CRP), tumor necrosis factor alpha (TNFalpha), 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha-in vivo oxidative stress marker) in 15 chronic renal failure (CRF) and 15 transplant patients versus 15 healthy controls. Exclusion criteria were: age <30 or >65 years as well as a diagnosis of diabetes or cardiovascular diseases. We evaluated systolic (SBP) and diastolic blood pressure (DBP), serum creatinine (sCr), and glomerular filtration rate (GFR).

RESULTS

Both the transplanted and the CRF group showed significantly higher values of CRP, TNFalpha, and 8-iso-PGF2alpha than the controls (P < .05 for all). SBP, DBP, and sCr were not different between transplanted and CRF patients. CRP was higher in transplant recipients than in CRF patients (P < .05). No difference in TNFalpha levels was observed between the two groups. 8-iso-PGF2alpha was significantly higher in the CRF than in the transplanted group (P < .05), although the latter cohort showed a positive correlation between 8-iso-PGF2alpha and TNFalpha (P < .001), sCr (P < .001), SBP (P < .05), and DBP (P < .05). In the same group both 8-iso-PGF2alpha and TNFalpha were negatively correlated with GFR (r -.824 and -.866, respectively; P < .001 for both).

CONCLUSION

We observed the coexistence of increased oxidative stress and an inflammatory state among renal graft recipients.

TH1/TH2 cytokine analysis in Iranian renal transplant recipients

The pretransplant cytokine profile of donor and recipient blood and tissues may be associated with transplant outcome. A Th1 response is generally associated with transplant rejection, while a Th2 response may lead to tolerance and stable graft survival. A total of 56 (37 male and 19 female) patients of mean 36 +/- 5 years were candidates for living unrelated kidney transplantation. Serum samples were collected 24 hours pretransplantation as well as at 1 and 2 weeks posttransplantation. Immunosuppression consisted of cyclosporine, prednisolone, and mycophenolate mofetil. Among the transplanted patients, 19 (33.9%) individuals experienced an acute rejection episode, as proven by biopsy, as well as an increased serum creatinine and blood urea nitrogen, within 14 days after transplantation. We determined serum concentrations of interleukin (IL) 2 and interferon (IFN)-gamma for Th1 and IL4 and IL10 for Th2 by an enzyme-linked immunosorbent assay method (Bender med system kits, Germany). Among Th1 cytokines, the mean concentration levels for groups with versus without acute rejection were: IL-2 pretransplant 15 pg/mL vs 6.8 pg/mL, respectively (P = .005); IL-2 at 1 week, 19 pg/mL vs 4.85 pg/mL, respectively (P = .001); IL-2 at 2 weeks, 21.1 pg/mL vs 4.65 pg/mL, respectively (P = .0001); IFN-gamma pretransplant 161.1 pg/mL vs 65.2 pg/mL, respectively (P = .001); IFN-gamma at 1 week, 175.6 pg/mL vs 66.5 pg/mL, respectively (P = .001); and IFN-gamma at 2 weeks, 173.7 pg/mL vs 77.1 pg/mL (P = .001). IL-2 and IFN-gamma levels were significantly higher in the group with acute rejection versus those without acute rejection. In conclusion, these data suggest that cytokine analysis, especially of Th1 cytokines, might be a valuable prognotic index of kidney transplant outcome.

Value of Pretransplantation Cytokine Profiles for Predicting Acute Rejection in Renal Transplant Recipients

Episodes of acute rejection may represent an important risk factor for the development of chronic allograft nephropathy. Various studies have shown that pretransplant cytokine profiles in recipient blood are associated with transplant outcome. Serum samples were collected 24 hours before transplantation from 57 patients (38 men and 19 women of age 36 +/- 5 years) receiving kidneys from unrelated living donors. Additional samples were collected at 1 and 2 weeks after transplantation, as well as during every rejection episode. The immunosuppression consisted of a cyclosporine, prednisolone, and mycophenolate mofetil. Among the transplanted patients, 19 (33.3%) individuals experienced an acute rejection episode based on an increased level of serum creatinine and blood urea nitrogen during the first 14 days after transplantation. TGF-beta, IL-2 and IFN-gamma serum levels were determined by an ELISA method using Bindermed system kits. The mean concentration of TGF-beta before transplantation tended to be lower among patients with acute rejection episodes compared to those with stable graft (75,265 versus 85,394 pg/mL; P = .34) and at 1 week after transplantation (77,558 versus 84,390 pg/mL), although the differences were not significant. Among patients with rejection the mean IL-2 concentration was significantly higher before, at 1 week, and at 2 weeks after transplantation (15.0 versus 6.8 pg/mL, P = .005; 19.0 versus 4.9 pg/mL, P = .001; and 21.1 versus 4.7 pg/mL, P = .0001). The mean concentration of IFN-gamma was significantly higher pre- and at 1 and 2 weeks posttransplantation in patients with acute rejection episodes (161.1 versus 65.2, 175.6 versus 66.5 and 173.7 versus 77.1 pg/mL, all P < .001). In conclusion, evaluation of Th1 cytokines before transplantation may represent valuable predictive marker for an acute rejection episode.

Markers of Inflammation Before and After Renal Transplantation

BACKGROUND

This study aims to compare serum C-reactive protein (CRP), interleukin (IL-6), and tumor necrosis factor (TNF)-alpha in end-stage renal disease (ESRD) patients before versus after receiving renal transplantation (RT) and versus donors.

METHODS

Serum samples from 37 ESRD patients (24 male, age 34+/-13 years) were collected before and after RT; in addition, samples from 31 donors were obtained at transplantation. CRP concentrations were measured using nephelometry, and TNF-alpha and IL-6 were measured by enzyme-linked immunoadsorbent assay.

RESULTS

Ninety-two percent of recipients had a living donor, 73% received cyclosporine A, 27% tacrolimus, and 70% induction with daclizumab. Thirteen percent had acute rejection and 16% chronic allograft nephropathy. All inflammation markers decreased 6 months after RT, but only CRP was below baseline values (baseline: 5.0+/-3.5; 6 months: 3.0+/-0; 12 months: 3.2+/-0.7; 18 months: 3.2+/-0.6; donors: 3.6+/-1.5 mg/L; P<0.05), whereas median TNF-alpha (baseline: 0.1 [0.03-0.2]; 6 months: 0 [0-0.1]; 12 months: 0.3 [0.1-2.6]; 18 months: 0.6 [0.1-1.9]; donors: 0 [0-0.1] pg/mL; P<0.05) and IL-6 (baseline: 1.9 [1.2-7.1]; 6 months: 1.2 [0.6-28.3]; 12 months: 2.6 [1.3-3.4]; 18 months: 2.7 [1.7-4.2]; donors: 1.1 [0.6-1.9] pg/mL; P<0.05) significantly increased up to the end of follow-up. Before RT, CRP correlated with age (r 0.45, P=0.006) and albumin (r -0.36, P=0.04). TNF-alpha and IL-6 were correlated before (r 0.34, P=0.04) and after (r 0.55, P=0.02) RT. Inflammation markers were not different in patients who had acute rejection episodes or chronic nephropathy.

CONCLUSIONS

Compared with controls, patients displayed an inflammatory phenomenon before receiving RT. Serum CRP decreased significantly after RT, whereas TNFalpha and IL-6 increased.

Soluble interleukin-2 receptors increase during the active periods in cluster headache

OBJECTIVE

To investigate whether cytokines are altered during the active period of cluster headache.

BACKGROUND

Patients with cluster headache show activation of the hypothalamus in PET studies and via endocrinologic parameters. Data also suggest an inflammatory process occurs in cluster headache. A connection between the presumed inflammatory cause, an immunological activation, and the hypothalamus could be generated by certain cytokines.

DESIGN AND METHODS

ELISA was used to determine the serum levels of soluble interleukin-2 receptors, interleukin-1, interleukin-6, and 2 soluble interleukin-6 receptors (sIL-6R and soluble gp130) in 18 patients with cluster headache (6 women and 12 men) during the cluster period and in 17 healthy controls who were headache-free (3 women and 14 men).

RESULTS

Patients with cluster headache had significantly increased soluble interleukin-2 receptors (413.6+/-223 U/mL vs. 290.0+/-112 U/mL; P <.05) compared with controls. Serum levels of interleukin-1 (0.29+/-0.30 pg/mL vs. 0.13+/-0.13 pg/mL, n.s.), interleukin-6 (0.87+/-0.6 pg/mL vs. 0.91+/-0.7 pg/ml; n.s.), soluble interleukin-6 receptors (33,131+/-8,349 pg/mL vs. 35,063+/-7,606 pg/mL; n.s.), or soluble gp130 (289+/-59 pg/mL vs. 283+/-20 pg/mL; n.s.) did not differ between the 2 groups, although patients with cluster tended to have higher interleukin-1 values.

CONCLUSIONS

Because elevated soluble interleukin-2 receptors indicate T cell activation, our findings suggest immune activation during cluster headache. Because interleukin-2 can activate the hypothalamus and stimulate the release of Corticotropin-releasing Factor (CRF), interleukin-2 could link a putative immunological cause of cluster headache with the observed hypothalamic activation. Systemic changes of interleukin-1 or the interleukin-6 system do not seem to play a role in cluster headache, as no alterations of serum levels were observed. Even so, unchanged serum levels do not exclude limited local production.

MicroCRP: a highly sensitive CRP method applied in the monitoring of renal allograft recipients

A new ultrasensitive fluoroimmunometric assay for C-reactive protein (CRP), called MicroCRP assay, has a lower detection limit of 0.05 mg/l, and a CV of 7.6% at concentration 0.25 mg/l. The microCRP levels in healthy adults show a skewed distribution, median 0.90 mg/l and mean 1.4 mg/l, with 2.5th and 97.5th percentiles of 0.17 and 4.7 mg/l, respectively, and no gender-related or age differences. Serial microCRP was applied in the monitoring of 37 renal allograft recipients. The operative trauma gave rise to an initial CRP peak, usually on day 2 after transplantation, with a return to preoperative value 1 week after surgery. There were significant CRP elevations (>25%) in all cases of rejections, indicating 100% sensitivity. The microCRP values started to increase about 3 days (range -1 to 9 days) before the rise in creatinine. The microCRP peak tended to be higher in rejection episodes with a vascular component, compared with episodes of cellular rejection (p=0.05). A rise in microCRP at days 7-12 after transplantation seems to predict the risk of rejections later on, and probably reflects the primary immune response to the graft. Recipients without this primary CRP response (only 6 of 37 patients) subsequently had uncomplicated courses. Tracking of values below the traditional lower limit is essential in order to recognize the different CRP peaks. Serial monitoring of microCRP is well suited for clinical use and provides clinical information previously unattainable with other assay systems.