Atopy as an independent predictor for long-term patient and graft survival after kidney transplantation.

Background: Atopy is a genetic condition predisposing individuals to develop immunoglobulin E (IgE) against common allergens through T-helper 2 (Th2) polarization mechanisms. The impact of atopy on graft survival in solid organ transplantation is unknown. Methodology: We analyzed 268 renal allograft recipients from the Swiss Transplant Cohort Study, a prospective multicenter cohort studying patients after solid organ transplantation, with a 9-year median follow-up (IQR 3.0). We used the Phadiatop assay to measure IgE antibodies against a mixture of common inhaled allergens (grass, tree, herbs, spores, animals, and mites) to identify pre-transplantation atopic patients (>0.35 KU/L). Results: Of 268 kidney transplant recipients, 66 individuals were atopic (24.6%). Atopic patients were significantly younger than non-atopic patients (49.6 vs 58.0 years old, P = 0.002). No significant difference was found for gender, cold/warm ischemia time, preformed donor-specific antibodies (DSA), HLA mismatches, induction and maintenance immunosuppressive therapy, CMV serostatus, or cause of kidney failure. Patient and graft survival at ten years of follow-up were significantly better in the atopic group, 95.2% versus 69.2% patient survival (P < 0.001), and 87.9% versus 60.8% graft survival (P < 0.001), respectively. A multivariate Cox analysis revealed that atopy predicted recipient and graft survival independently of age and living donor donation. Finally, we found similar rates of biopsy-proven acute cellular and antibody-mediated rejections between atopic and non-atopic recipients. Conclusion: Atopy was associated with better long-term patient and graft survival, independently of age and living donor donation after kidney transplantation. Yet, atopy should not be used as a predictor for acute rejection.

Therapeutic Potential of Targeting Malt1-Dependent TCR Downstream Signaling to Promote the Survival of MHC-Mismatched Allografts.

Strategies targeting T cells are the cornerstone of immunosuppression after solid organ transplantation. The transcription factor NF-κB is a key regulator of downstream T-cell activation and induction of inflammatory mediators; its full activation via antigen receptor engagement requires both the scaffold and the protease activity of the paracaspase Malt1. Experimental studies have highlighted that Malt1-deficient mice were resistant to experimental autoimmune encephalomyelitis, although they lacked peripheral regulatory T cells (Treg). Here, we compared targeting Malt1 versus using calcineurin inhibitors as immunosuppression in a stringent experimental transplantation model. We found that Malt1-deficiency impaired Th1-mediated alloresponses in vitro and in vivo and significantly prolonged MHC-mismatched skin allograft survival, compared to cyclosporine. However, it paradoxically enhanced Th17 differentiation in the transplantation setting. Interestingly, more selective inhibition of Malt1 protease activity in wild-type mouse and human peripheral T cells in vitro led to attenuation of alloreactive Th1 cells, while preserving preexisting Treg in the peripheral T-cell pool, and without promoting Th17 differentiation. Thus, there is a place for further investigation of the role of Malt1 signaling in the setting of transplantation.

Differential Effects of the Mitochondria-Active Tetrapeptide SS-31 (D-Arg-dimethylTyr-Lys-Phe-NH2) and Its Peptidase-Targeted Prodrugs in Experimental Acute Kidney Injury.

The mitochondria-active tetrapeptide SS-31 can control oxidative tissue damage in kidney diseases. To investigate other potential beneficial nephroprotective effects of SS-31, in vivo murine models of acute tubular injury and glomerular damage were developed. Reduction of acute kidney injury was demonstrated in mice treated with SS-31. The expression of mRNAs involved in acute inflammatory and oxidative stress responses in the diseased kidneys confirmed that SS-31 could regulate these pathways in our in vivo models. Furthermore, ex vivo histoenzymography of mouse kidneys showed that aminopeptidase A (APA), the enzyme involved in the processing of angiotensin (Ang) II to Ang III, was induced in the diseased kidneys, and its activity was inhibited by SS-31. As the renin-angiotensin system (RAS) is a main regulator of kidney functions, the modulation of Ang receptors (ATR) and APA by SS-31 was further investigated using mRNAs extracted from diseased kidneys. Following acute tubular and/or glomerular damage, the expression of the AT1R mRNA was upregulated, which could be selectively downregulated upon SS-31 administration to the animals. At the same time, SS-31 was able to increase the expression of the AT2R, which may contribute to limit renal damage. Consequently, SS-31-based prodrugs were developed as substrates and/or inhibitors for APA and were screened using cells expressing high levels of APA, showing its selective regulation by α-Glu-SS-31. Thus, a link between SS-31 and the RAS opens new therapeutic implications for SS-31 in kidney diseases.

Fibrogenic Disorders in Human Diseases: From Inflammation to Organ Dysfunction.

Fibrosis is an inadequate response to tissue stress with very few therapeutic options to prevent its progression to organ dysfunction. There is an urgent need to identify drugs with a therapeutic potential for fibrosis, either by designing and developing new compounds or by repurposing drugs already in clinical use which were developed for other indications. In this Perspective, we summarize some pathways and biological targets involved in fibrosis development and maintenance, focusing on common mechanisms between organs and diseases. We review the therapeutic agents under experimental development, clinical trials, or in clinical use for the treatment of fibrotic disorders, evaluating the reasons for the discrepancies observed between preclinical and clinical results. We also discuss the improvement that we envision in the development of therapeutic molecules able to achieve improved potential for treatment, including indirect modulators, targeting approaches, or drug combinations.

Targeted γ-secretase inhibition of Notch signaling activation in acute renal injury.

The Notch pathway has been reported to control tissue damage in acute kidney diseases. To investigate potential beneficial nephroprotective effects of targeting Notch, we developed chemically functionalized γ-secretase inhibitors (GSIs) targeting γ-glutamyltranspeptidase (γ-GT) and/or γ-glutamylcyclotransferase (γ-GCT), two enzymes overexpressed in the injured kidney, and evaluated them in in vivo murine models of acute tubular and glomerular damage. Exposure of the animals to disease-inducing drugs together with the functionalized GSIs improved proteinuria and, to some extent, kidney dysfunction. The expression of genes involved in the Notch pathway, acute inflammatory stress responses, and the renin-angiotensin system was enhanced in injured kidneys, which could be downregulated upon administration of functionalized GSIs. Immunohistochemistry staining and Western blots demonstrated enhanced activation of Notch1 as detected by its cleaved active intracellular domain during acute kidney injury, and this was downregulated by concomitant treatment with the functionalized GSIs. Thus targeted γ-secretase-based prodrugs developed as substrates for γ-GT/γ-GCT have the potential to selectively control Notch activation in kidney diseases with subsequent regulation of the inflammatory stress response and the renin-angiotensin pathways.

SIgA-Shigella Immune Complexes Interact with Dectin-1 and SIGNR3 to Differentially Regulate Mouse Peyer's Patch and Mesenteric Lymph Node Dendritic Cell's Responsiveness.

In addition to contributing to immune exclusion at mucosal surfaces, secretory IgA (SIgA) made of polymeric IgA and secretory component is able to selectively reenter via microfold cells into Peyer's patches (PPs) present along the intestine and to associate with dendritic cells (DCs) of the CD11c+CD11b+MHCII+F4/80-CD8-phenotype in the subepithelial dome region and the draining mesenteric lymph nodes (MLNs). However, the nature of the receptor(s) for SIgA on murine PP and MLN DCs is unknown. We find that glycosylated secretory component moiety and polymeric IgA are both involved in the specific interaction with these cells. Using blocking antibodies and competition experiments, we identify Dectin-1 and specific intercellular adhesion molecule-3 grabbing non-integrin receptor 3 (SIGNR3) as receptors for SIgA. While SIgA-commensal immune complexes (ICs) contribute to local homeostasis upon interaction with mucosal DCs, the picture is less clear for pathogenic agents. We find that in comparison with incubation of Shigella flexneri alone, association of the enteropathogen with SIgA prompts freshly isolated DCs from PPs and MLNs to invert the production of pro- versus non-inflammatory cytokines/chemokines. The sum of the data suggests that in contrast to IgG-based ICs boosting immune reactivity of antigen-presenting cells, SIgA produced during an ongoing immune response can, in addition to its known function of immune exclusion, modulate mucosal DC conditioning via specific interaction with Dectin-1 and SIGNR3.

Secretory IgA in complex with Lactobacillus rhamnosus potentiates mucosal dendritic cell-mediated Treg cell differentiation via TLR regulatory proteins, RALDH2 and secretion of IL-10 and TGF-ß.

The importance of secretory IgA in controlling the microbiota is well known, yet how the antibody affects the perception of the commensals by the local immune system is still poorly defined. We have previously shown that the transport of secretory IgA in complex with bacteria across intestinal microfold cells results in an association with dendritic cells in Peyer's patches. However, the consequences of such an interaction on dendritic cell conditioning have not been elucidated. In this study, we analyzed the impact of the commensal Lactobacillus rhamnosus, alone or associated with secretory IgA, on the responsiveness of dendritic cells freshly recovered from mouse Peyer's patches, mesenteric lymph nodes, and spleen. Lactobacillus rhamnosus-conditioned mucosal dendritic cells are characterized by increased expression of Toll-like receptor regulatory proteins [including single immunoglobulin interleukin-1 receptor-related molecule, suppressor of cytokine signaling 1, and Toll-interacting molecule] and retinaldehyde dehydrogenase 2, low surface expression of co-stimulatory markers, high anti- versus pro-inflammatory cytokine production ratios, and induction of T regulatory cells with suppressive function. Association with secretory IgA enhanced the anti-inflammatory/regulatory Lactobacillus rhamnosus-induced conditioning of mucosal dendritic cells, particularly in Peyer's patches. At the systemic level, activation of splenic dendritic cells exposed to Lactobacillus rhamnosus was partially dampened upon association with secretory IgA. These data suggest that secretory IgA, through coating of commensal bacteria, contributes to the conditioning of mucosal dendritic cells toward tolerogenic profiles essential for the maintenance of intestinal homeostasis.

Comparative genome analysis of Pseudomonas knackmussii†B13, the first bacterium known to degrade chloroaromatic compounds.

Pseudomonas knackmussii B13 was the first strain to be isolated in 1974 that could degrade chlorinated aromatic hydrocarbons. This discovery was the prologue for subsequent characterization of numerous bacterial metabolic pathways, for genetic and biochemical studies, and which spurred ideas for pollutant bioremediation. In this study, we determined the complete genome sequence of B13 using next generation sequencing technologies and optical mapping. Genome annotation indicated that B13 has a variety of metabolic pathways for degrading monoaromatic hydrocarbons including chlorobenzoate, aminophenol, anthranilate and hydroxyquinol, but not polyaromatic compounds. Comparative genome analysis revealed that B13 is closest to Pseudomonas denitrificans and Pseudomonas aeruginosa. The B13 genome contains at least eight genomic islands [prophages and integrative conjugative elements (ICEs)], which were absent in closely related pseudomonads. We confirm that two ICEs are identical copies of the 103 kb self-transmissible element ICEclc that carries the genes for chlorocatechol metabolism. Comparison of ICEclc showed that it is composed of a variable and a 'core' region, which is very conserved among proteobacterial genomes, suggesting a widely distributed family of so far uncharacterized ICE. Resequencing of two spontaneous B13 mutants revealed a number of single nucleotide substitutions, as well as excision of a large 220 kb region and a prophage that drastically change the host metabolic capacity and survivability.