Renal transplantation in HLA sensitized patients: Traversing the immunological barrier

Successful renal transplantation across HLA barrier in sensitized individuals has been on the rise during the past decade, primarily due to improved desensitization regimes. The aim of this study was to share outcome of desensitization in renal transplant recipients with donor‐specific anti‐HLA antibodies (DSA). This was a retrospective analysis of all HLA immunized individuals who were prospective renal transplant recipients. All such patients underwent preconditioning as per the institutional desensitization protocol. Complement‐dependent cytoxicity‐based crossmatch (CDC‐XM), luminex‐based crossmatch (LM‐XM) and flowcytometry‐based crossmatch (FC‐XM) were done in all cases. If any of these tests turned out positive, single antigen bead assay (SAB) was performed. Desensitization for DSA was performed in 55 patients and all patients were followed‐up for 1 year to assess graft function and patient outcome. CDC‐XM being a less sensitive assay, could not detect incompatibility in 29 (52.73%) cases. After desensitization, even though SAB and LM‐XM results revealed an MFI within acceptable range, FC‐XM being an extremely sensitive assay, continued to give a positive result in eight (14.55%) cases. The mean ± SD number of pretransplant TPE were 3.44 ± 0.98 (2‐11). Out of 55, there were 10 patients who were lost to follow up. Patient and graft survival of 45 patients at 1 year was found to be 100%. Preconditioning for renal transplants in the form of immunosuppression with TPE is an extremely useful auxiliary for transplantation in HLA sensitized renal transplant recipients.     

Calpains promote neutrophil recruitment and bacterial clearance in an acute bacterial peritonitis model

Activation of the innate immune system is critical for clearance of bacterial pathogens to limit systemic infections and host tissue damage. Here, we report a key role for calpain proteases in bacterial clearance in mice with acute peritonitis. Using transgenic mice expressing Cre recombinase primarily in innate immune cells (fes‐Cre), we generated conditional capns1 knockout mice. Consistent with capns1 being essential for stability and function of the ubiquitous calpains (calpain‐1, calpain‐2), peritoneal cells from these mice had reduced levels of calpain‐2/capns1, and reduced proteolysis of their substrate selenoprotein K. Using an acute bacterial peritonitis model, we observed impaired bacterial killing within the peritoneum and development of bacteremia in calpain knockout mice. These defects correlated with significant reductions in IL‐1α release, neutrophil recruitment, and generation of reactive oxygen species in calpain knockout mice with acute bacterial peritonitis. Peritoneal macrophages from calpain knockout mice infected with enterobacteria ex vivo, were competent in phagocytosis of bacteria, but showed impaired clearance of intracellular bacteria compared with control macrophages. Together, these results implicate calpains as key mediators of effective innate immune responses to acute bacterial infections, to prevent systemic dissemination of bacteria that can lead to sepsis.     

A splice variant of the two-pore domain potassium channel TREK-1 with only one pore domain reduces the surface expression of full-length TREK-1 channels

We have identified a novel splice variant of the human and rat two-pore domain potassium (K_2P) channel TREK-1. The splice variant TREK-1e results from skipping of exon 5, which causes a frame shift in exon 6. The frame shift produces a novel C-terminal amino acid sequence and a premature termination of translation, which leads to a loss of transmembrane domains M3 and M4 and of the second pore domain. RT-PCR experiments revealed a preferential expression of TREK-1e in kidney, adrenal gland, and amygdala. TREK-1e was nonfunctional when expressed in Xenopus oocytes. However, both the surface expression and the current density of full-length TREK-1 were reduced by co-expression of TREK-1e. Live cell imaging in COS-7 cells transfected with GFP-tagged TREK-1e showed that this splice variant was retained in the endoplasmic reticulum (ER). Attachment of the C-terminus of TREK-1e to two different reporter proteins (Kir2.1 and CD8) led to a strong reduction in the surface expression of these fusion proteins. Progressive truncation of the C-terminus of TREK-1e in these reporter constructs revealed a critical region (amino acids 198 to 205) responsible for the intracellular retention. Mutagenesis experiments indicated that amino acids I204 and W205 are key residues mediating the ER retention of TREK-1e. Our results suggest that the TREK-1e splice variant may interfere with the vesicular traffic of full-length TREK-1 channels from the ER to the plasma membrane. Thus, TREK-1e might modulate the copy number of functional TREK-1 channels at the cell surface, providing a novel mechanism for fine tuning of TREK-1 currents.     

Pharmacodynamic effects of intravenous alcohol on hepatic and gonadal hormones: influence of age and sex

Background: Growth hormone (GH)–insulin‐like growth factor‐1 (IGF‐1) axis and gonadal hormones demonstrate extensively associated regulation; however, little is known about the effects of acute alcohol exposure on these hormones. This study examined the effects of intravenous alcohol on the GH–IGF‐1 axis and gonadal hormone concentrations, and the influence of age and sex on their regulation. Methods: Forty‐eight healthy volunteers (24 men and 24 women each in the 21 to 25 and 55 to 65 year age groups) underwent a 2‐session single‐blinded study. Subjects received in randomized counter‐balanced order, alcohol infusions, individually computed based on a physiologically based pharmacokinetic model, to maintain a steady‐state (“clamped”) exposure of 50 mg% or saline for 3 hours in separate sessions. Blood samples collected at baseline and postinfusion in each session were assayed for levels of GH, IGF‐1, free testosterone, and estradiol. Results: Acute alcohol administration resulted in changes in gonadal hormones that differed by sex. Change in free testosterone showed a significant treatment × baseline interaction (p < 0.001), indicating that alcohol‐induced suppression of testosterone occurred predominantly in men. On the other hand, change in estradiol showed a significant treatment × sex interaction (p = 0.028), indicating that alcohol‐induced increases in estradiol occurred predominantly in women. There was a trend for alcohol‐induced decreases in IGF‐1 levels. Change in GH showed a significant main effect of baseline (p < 0.001) and a trend for treatment by baseline interaction, suggesting an alcohol‐induced decrease in individuals with high baseline GH values. There was also a significant main effect of sex (p = 0.046) indicating that men had greater changes in GH across treatment compared with women. Conclusions: Alcohol induced a complex pattern of hormonal responses that varied between younger and older men and women. Some of the observed sex‐based differences may help improve our understanding of the greater susceptibility to alcohol‐related hepatic damage seen in women.     

Human facial allotransplantation: patient selection and pertinent considerations

Devastating facial deformities can cause significant functional and psychosocial injury. Significant facial disfigurement can preclude meaningful human interaction. Allotransplantation of facial tissues for reconstruction of devastating deformities has become a clinical reality, with 15 transplants performed at various centers around the world. Restoration of aesthetics and functionality has been superior to that achieved by conventional reconstruction, without the morbidity of multiple surgeries. Unlike solid organ transplantation which can be life saving, facial transplantation is considered by many to be life enhancing, highlighting the ethical argument against justification of these procedures given the risks of lifelong immunosuppression. Meticulous patient selection is mandatory, and a multidisciplinary team approach is key for the program's success. The overriding goal of screening for candidacy is to identify and select subjects who have the best chance for a positive immunologic, functional, and quality-of-life outcome. This article reviews the pertinent considerations and screening approach for appropriate patient selection in facial tissue transplantation.     

Effect of occlusal splint therapy on maximum bite force in individuals with moderate to severe attrition of teeth

ObjectiveThe purpose of the pilot study was to determine the effect of restoring lost occlusal vertical dimension (OVD) due to attrition on maximum bite force in humans.MethodologyA total of 124 subjects in age range of 25–40 years, with moderate to severe attrition, having full complement of teeth were screened according to inclusion and exclusion criteria. After consent, occlusal vertical dimension was assessed by employing mechanical and physiological methods in the experimental group and a maxillary canine guided hard splint was fabricated for each subjects fulfilling inclusion criteria and with positive consent (78). Bite force in experimental group was measured before, immediately after delivery of splint and subsequently at an interval of four, eight, and twelve weeks. Due loss during follow up, only 50 subjects could be available for bite force recording till 12 weeks. Bite force of age, gender, height and weight matched controls with no signs of attrition was also measured for comparison.ResultsBite force of the experimental group was found to be significantly less than the matched controls (P = 0.000) initially. After delivery of splint, bite force values increased progressively till twelve weeks. However comparison of bite force values of experimental group with control group showed no significant difference at end of eight (P = 0.008) and twelve weeks (P = 0.162).ConclusionIt was concluded that maximum bite force increases with restoration of lost vertical using splint therapy. A time period of 8–12 weeks is required to restore the maximum bite force value approximately similar to matched controls.