Heme oxygenase-1 expression and its significance for acute rejection following kidney transplantation in rats

Effect of HO-1-modified BMMSCs on immune function in liver transplantation

We examined whether haem oxygenase-1 (HO-1) could enhance the immunosuppressive effects of bone marrow mesenchymal stem cells (BMMSCs) on the rejection of transplanted liver allografts in rats. The animals were divided into three groups: the normal saline (NS) group, BMMSC group and HO-1/BMMSCs group. In vitro, the extraction, culture and HO-1 transfection of BMMSCs were performed. Mixed lymphocyte response (MLR) analysis of HO-1/BMMSCs efficacy was performed. The rejection model of orthotopic liver transplantation in rats was established when BMMSCs and HO-1/BMMSCs were transfused via the portal vein. To reduce research bias, we established an isogenic Liver transplantation model of (LEW → LEW) and (BN → BN), which can achieve tolerance. Changes in histopathology and liver function in the transplanted liver and changes in regulatory T cell (Tregs), natural killer (NK) cells and cytokines after transplantation were observed in the different groups. The severe acute rejection after liver transplantation on postoperative Day 10 was observed in the NS group. The BMMSC group showed strong protective effects against rejection within the first 10 days after transplantation, while HO-1/BMMSCs showed stronger effects on rejection than BMMSCs alone. In addition, the activity of natural killer (NK) cells decreased significantly, the levels of regulatory T cells (Tregs), interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) increased significantly and the levels of interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-17 (IL-17), interleukin-23 (IL-23), tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) decreased significantly in the HO-1/BMMSC group compared with the BMMSC group. HO-1/BMMSCs showed better immunosuppressive effects after liver transplantation than the other treatments. Our findings reveal that HO-1 can enhance the effects of BMMSCs on inhibiting acute rejection in orthotopic liver transplantation in rats.

Heme oxygenase-1 attenuates acute pulmonary inflammation by decreasing the release of segmented neutrophils from the bone marrow

Recruiting polymorphonuclear neutrophil granulocytes (PMNs) from circulation and bone marrow to the site of inflammation is one of the pivotal mechanisms of the innate immune system. During inflammation, the enzyme heme oxygenase 1 (HO-1) has been shown to reduce PMN migration. Although these effects have been described in various models, underlying mechanisms remain elusive. Recent studies revealed an influence of HO-1 on different cells of the bone marrow. We investigated the particular role of the bone marrow in terms of HO-1-dependent pulmonary inflammation. In a murine model of LPS inhalation, stimulation of HO-1 by cobalt (III) protoporphyrin-IX-chloride (CoPP) resulted in reduced segmented PMN migration into the alveolar space. In the CoPP group, segmented PMNs were also decreased intravascularly, and concordantly, mature and immature PMN populations were higher in the bone marrow. Inhibition of the enzyme by tin protoporphyrin-IX increased segmented and banded PMN migration into the bronchoalveolar lavage fluid with enhanced PMN release from the bone marrow and aggravated parameters of tissue inflammation. Oxidative burst activity was significantly higher in immature compared with mature PMNs. The chemokine stromal-derived factor-1 (SDF-1), which mediates homing of leukocytes into the bone marrow and is decreased in inflammation, was increased by CoPP. When SDF-1 was blocked by the specific antagonist AMD3100, HO-1 activation was no longer effective in curbing PMN trafficking to the inflamed lungs. In conclusion, we show evidence that the anti-inflammatory effects of HO-1 are largely mediated by inhibiting the release of segmented PMNs from the bone marrow rather than direct effects within the lung.

PI3K/Akt-independent NOS/HO activation accounts for the facilitatory effect of nicotine on acetylcholine renal vasodilations: modulation by ovarian hormones

We investigated the effect of chronic nicotine on cholinergically-mediated renal vasodilations in female rats and its modulation by the nitric oxide synthase (NOS)/heme oxygenase (HO) pathways. Dose-vasodilatory response curves of acetylcholine (0.01–2.43 nmol) were established in isolated phenylephrine-preconstricted perfused kidneys obtained from rats treated with or without nicotine (0.5–4.0 mg/kg/day, 2 weeks). Acetylcholine vasodilations were potentiated by low nicotine doses (0.5 and 1 mg/kg/day) in contrast to no effect for higher doses (2 and 4 mg/kg/day). The facilitatory effect of nicotine was acetylcholine specific because it was not observed with other vasodilators such as 5′-N-ethylcarboxamidoadenosine (NECA, adenosine receptor agonist) or papaverine. Increases in NOS and HO-1 activities appear to mediate the nicotine-evoked enhancement of acetylcholine vasodilation because the latter was compromised after pharmacologic inhibition of NOS (L-NAME) or HO-1 (zinc protoporphyrin, ZnPP). The renal protein expression of phosphorylated Akt was not affected by nicotine. We also show that the presence of the two ovarian hormones is necessary for the nicotine augmentation of acetylcholine vasodilations to manifest because nicotine facilitation was lost in kidneys of ovariectomized (OVX) and restored after combined, but not individual, supplementation with medroxyprogesterone acetate (MPA) and estrogen (E2). Together, the data suggests that chronic nicotine potentiates acetylcholine renal vasodilation in female rats via, at least partly, Akt-independent HO-1 upregulation. The facilitatory effect of nicotine is dose dependent and requires the presence of the two ovarian hormones.

Detection and mechanism of action of ESM-1 in rat kidney transplantation under various immune states

OBJECTIVE

To investigate whether ESM-1 expression change reflects the impairment of endothelial cells and rejection after kidney transplantation, ESM-1 expression was detected under various immune states in this study.

METHODS

Kidney transplantations were performed from BN to LEW rats. Syngenic LEW-LEW grafts were used as controls. The LEW recipient rats were divided into acute rejection (AR) group, ciclosporin A (CsA) group and control group. In each group, 10 rats were sacrificed at 1, 5, and 7d after operation, respectively, and blood and kidney samples were collected. In the rat model of kidney transplantation, ESM-1 mRNA and ESM-1 protein expression were detected in various immune states to verify if ESM-1 can reflect endothelial cell impairment sensitively.

RESULTS

ESM-1 mRNA (1d vs. 3d, P<0.01;3d vs. 7d, P=0.018) and ESM-1 protein expression was upregulated significantly in the AR group (P<0.01, 5 and 7d), when compared to CsA group and control group. In CsA group, the cell apoptosis rate decreased when compared to AR group (P<0.01). Pathological impairment was more serious in AR group than in CsA group (P<0.01).

CONCLUSIONS

Peripheral blood ESM-1 mRNA and ESM-1 protein expression in kidney grafts can reflect the severity of endothelial cell impairment. Thus, ESM-1 may be used as a new indicator for AR prediction and diagnosis. Nevertheless, further investigation is required to test if it meets the criteria for clinical utility.

Transcriptome analysis of renal ischemia/reperfusion injury and its modulation by ischemic pre-conditioning or hemin treatment

Ischemia/reperfusion injury (IRI) is a leading cause of acute renal failure. The definition of the molecular mechanisms involved in renal IRI and counter protection promoted by ischemic pre-conditioning (IPC) or Hemin treatment is an important milestone that needs to be accomplished in this research area. We examined, through an oligonucleotide microarray protocol, the renal differential transcriptome profiles of mice submitted to IRI, IPC and Hemin treatment. After identifying the profiles of differentially expressed genes observed for each comparison, we carried out functional enrichment analysis to reveal transcripts putatively involved in potential relevant biological processes and signaling pathways. The most relevant processes found in these comparisons were stress, apoptosis, cell differentiation, angiogenesis, focal adhesion, ECM-receptor interaction, ion transport, angiogenesis, mitosis and cell cycle, inflammatory response, olfactory transduction and regulation of actin cytoskeleton. In addition, the most important overrepresented pathways were MAPK, ErbB, JAK/STAT, Toll and Nod like receptors, Angiotensin II, Arachidonic acid metabolism, Wnt and coagulation cascade. Also, new insights were gained about the underlying protection mechanisms against renal IRI promoted by IPC and Hemin treatment. Venn diagram analysis allowed us to uncover common and exclusively differentially expressed genes between these two protective maneuvers, underscoring potential common and exclusive biological functions regulated in each case. In summary, IPC exclusively regulated the expression of genes belonging to stress, protein modification and apoptosis, highlighting the role of IPC in controlling exacerbated stress response. Treatment with the Hmox1 inducer Hemin, in turn, exclusively regulated the expression of genes associated with cell differentiation, metabolic pathways, cell cycle, mitosis, development, regulation of actin cytoskeleton and arachidonic acid metabolism, suggesting a pleiotropic effect for Hemin. These findings improve the biological understanding of how the kidney behaves after IRI. They also illustrate some possible underlying molecular mechanisms involved in kidney protection observed with IPC or Hemin treatment maneuvers.