Mitochondrial transplantation enhances murine lung viability and recovery after ischemia-reperfusion injury.

The most common cause of acute lung injury is ischemia-reperfusion injury (IRI), during which mitochondrial damage occurs. We have previously demonstrated that mitochondrial transplantation is an efficacious therapy to replace or augment mitochondria damaged by IRI, allowing for enhanced muscle viability and function in cardiac tissue. Here, we investigate the efficacy of mitochondrial transplantation in a murine lung IRI model using male C57BL/6J mice. Transient ischemia was induced by applying a microvascular clamp on the left hilum for 2 h. Upon reperfusion mice received either vehicle or vehicle-containing mitochondria either by vascular delivery (Mito V) through the pulmonary artery or by aerosol delivery (Mito Neb) via the trachea (nebulization). Sham control mice underwent thoracotomy without hilar clamping and were ventilated for 2 h before returning to the cage. After 24 h recovery, lung mechanics were assessed and lungs were collected for analysis. Our results demonstrated that at 24 h of reperfusion, dynamic compliance and inspiratory capacity were significantly increased and resistance, tissue damping, elastance, and peak inspiratory pressure (Mito V only) were significantly decreased (P < 0.05) in Mito groups as compared with their respective vehicle groups. Neutrophil infiltration, interstitial edema, and apoptosis were significantly decreased (P < 0.05) in Mito groups as compared with vehicles. No significant differences in cytokines and chemokines between groups were shown. All lung mechanics results in Mito groups except peak inspiratory pressure in Mito Neb showed no significant differences (P > 0.05) as compared with Sham. These results conclude that mitochondrial transplantation by vascular delivery or nebulization improves lung mechanics and decreases lung tissue injury.

Alloreactivity and allorecognition of syngeneic and allogeneic mitochondria.

Previously, we have demonstrated that the transplantation of autologous mitochondria is cardioprotective. No immune or autoimmune response was detectable following the single injection of autologous mitochondria. To expand the therapeutic potential and safety of mitochondrial transplantation, we now investigate the immune response to single and serial injections of syngeneic and allogeneic mitochondria delivered by intraperitoneal injection. Our results demonstrate that there is no direct or indirect, acute or chronic alloreactivity, allorecognition or damage-associated molecular pattern molecules (DAMPs) reaction to single or serial injections of either syngeneic or allogeneic mitochondria.

Prevalence of nephropathy in type 1 diabetes in the Arab world: A systematic review and meta-analysis.

The aim of this study was to conduct a systematic review and meta-analysis and determine the prevalence of diabetic nephropathy (DN) among Arab patients with T1D. A systematic literature search was conducted using 4 different literature databases (PubMed, ScienceDirect, Web of Science, and Embase) to capture all relevant data about Arab patients with T1D that had DN. Meta-analysis and systematic review were performed using the random effect model, and the heterogeneity of the studies was assessed using the Q-test, I2, and Tau-squared statistics. Publication bias was assessed using the funnel-plot test. Our search strategy captured 372 studies in only 10 out of the 22 Arab countries in a period of 48 years (1969-2017); of which, 41 met our inclusion criteria for full article analysis, of those, 15 were eligible for meta-analysis. We estimated the prevalence of DN among Arab people with T1D to be 18.2% (95% confidence interval 13.1%-24.8%). In conclusion, DN prevalence is underexplored among Arab patients with T1D and represents a significant risk for the well-being of Arab patients with T1D. Therefore, there is an urgent need for comprehensive epidemiological studies for DN among Arab patients with T1D.

Inhibition of the purinergic pathway prolongs mouse lung allograft survival.

Lung transplantation has limited survival with current immunosuppression. ATP is released from activated T cells, which act as costimulatory molecules through binding to the purinergic receptor P2XR7. We investigated the role of blocking the ATP/purinergic pathway, primarily P2XR7, using its inhibitor oxidized ATP (oATP) in modulating rejection of mouse lung allografts. Mouse lung transplants were performed using mice with major histocompatibility complex mismatch, BALB/c to C57BL6. Recipients received suramin or oATP, and lung allografts were evaluated 15 to ≥ 60 days after transplantation. Recipients were also treated with oATP after the onset of moderate to severe rejection to determine its ability to rescue lung allografts. Outcomes measures included lung function, histology, thoracic imaging, and allo-immune responses. Blocking purinergic receptors with the nonselective inhibitor suramin or with the P2XR7-selective inhibitor oATP reduced acute rejection and prolonged lung allograft survival for ≥ 60 days with no progression in severity. There were fewer inflammatory cells within lung allografts, less rejection, and improved lung function, which was maintained over time. CD4 and CD8 T cells were reduced within lung allografts with impaired activation with prolonged impairment of CD8 responses. In vitro, oATP reduced CD8 activation of Th1 inflammatory cytokines IFN-γ and TNF-α and cytolytic machinery, granzyme B. Cotreatment with immunosuppressive agents, cyclosporine, rapamycin, or CTLA-4Ig resulted in no additive benefits, and oATP alone resulted in better outcomes than cyclosporine alone. This study illustrates a potential new pathway to target in hopes of prolonging survival of lung transplant recipients.

Indoleamine 2,3-dioxygenase and metabolites protect murine lung allografts and impair the calcium mobilization of T cells.

The enzyme indoleamine 2,3-dioxygenase (IDO) converts tryptophan into kynurenine metabolites that suppress effector T-cell function. In this study, we investigated IDO and its metabolite, 3-hydroxyanthranilic acid (3HAA), in regulating lung allograft rejection, using a murine orthotopic lung transplant model with a major mismatch (BALB/c donor and C57BL6 recipient). IDO was overexpressed in murine donor lungs, using an established nonviral (polyethylenimine carrier)-based gene transfer approach, whereas 3HAA was delivered daily via intraperitoneal injection. Increased IDO expression or its metabolite, 3HAA, resulted in a remarkable therapeutic effect with near normal lung function and little acute rejection, approximately A1, compared with A3 in untreated allografts (grading based on International Society for Heart and Lung Transplantation guidelines). We found that a high IDO environment for 7 days in lung allografts resulted in impaired T-cell activation, the production of multiple effector cytokines (IL-2, IL-4, IL-5, IL-6, IFN-γ, TNF-α, IL-12, and IL-13), and the generation of effector memory T cells (CD62L(lo)CD44(hi) phenotype). In isolated murine splenocytes, we observed that IDO/3HAA impaired T-cell receptor (TCR)-mediated T-cell activation, and more importantly, a decrease of intracellular calcium, phospholipase C-γ1 phosphorylation, and mitochondrial mass was evident. This work further illustrates the potential role of a high IDO environment in lung transplantation, and that the high IDO environment directly impairs TCR activation via the disruption of calcium signaling.

Apoptosis of activated CD4+ and CD8+ T cells is enhanced by co-culture with hepatocytes expressing hepatitis C virus (HCV) structural proteins through FasL induction.

A central unresolved issue in hepatitis C virus (HCV) infection is how the virus establishes chronic infection. Recent studies suggest that the liver microenvironment leads to apoptosis of activated T cells, which may be involved in the tolerance to liver allograft. Here, We report that murine hepatocytes expressing a transgene encoding the HCV structural proteins core, envelope 1 (E1) and envelope 2 (E2) enhance apoptosis of activated T cells. Unlike normal liver, which appears to selectively remove only activated CD8+ T cells, enhanced apoptosis was seen for both CD4+ and CD8+ T cells. Enhanced apoptosis of activated T lymphocytes was associated with upregulation of FasL by HCV transgenic hepatocytes and was specifically inhibited by anti-FasL blocking antibody. Increased apoptosis of activated T cells induced by HCV structural proteins could amplify the ability of the liver to down-modulate T cell responses, leading to attenuation of anti-viral responses and facilitating viral persistence.

EP 80317, a ligand of the CD36 scavenger receptor, protects apolipoprotein E-deficient mice from developing atherosclerotic lesions.

CD36, a type B scavenger receptor expressed on macrophages, appears to play a major role in fatty streak formation through scavenging oxidatively modified lipoproteins in the arterial wall. We tested the hypothesis that EP 80317, a novel CD36 ligand derived from the growth hormone (GH)-releasing peptide family but devoided of any GH releasing activity, exerts anti-atherosclerotic effects in apolipoprotein E-deficient (apoE-/-) mice fed an atherogenic diet from 6 wk of age. Daily subcutaneous injections of EP 80317 (300 microg/kg) or vehicle were initiated at 6, 10, 12, or 14 wk until death at 18 wk. En face analyses of the entire aortic tree revealed a striking reduction (up to 51%) of lesion areas in EP 80317-treated apoE-/- mice compared with controls. Chronic treatment with EP 80317 (12 wk) is also associated with a 30% decrease in total plasma cholesterol, suggesting potential effects of this drug on cholesterol metabolism at the intestine/hepatic levels. EP 80317 exerts both preventive and curative effects on atherosclerotic lesion progression that were shown to be reversible after cessation of treatment. At the macrophage level, EP 80317 reduced oxidized low density lipoproteins internalization and up-regulated genes involved in cholesterol efflux, including peroxisome proliferator-activated receptor gamma (PPARgamma), liver x receptor alpha (LXRalpha), and the ATP binding cassette (ABC) transporters ABCA1 and ABCG1, supporting a role in regulating peripheral cholesterol trafficking. Importantly, the effects of EP 80317 were shown to be CD36 dependent, inasmuch as no anti-atherosclerotic or hypocholesterolemic effects were observed in apoE/CD36 double-deficient mice. In addition, long-term treatment of apoE/CD36 double-deficient mice with EP 80317 did not modulate the expression of genes of the PPARgamma-LXRalpha-ABC transporters pathway. Our results suggest that EP 80317, as a CD36 ligand, might be a prototype for a novel class of anti-atherosclerotic agents.