5-Aminolevulinic acid combined with ferrous iron induces carbon monoxide generation in mouse kidneys and protects from renal ischemia-reperfusion injury

Renal and Vascular Functional Decline in Aged Low Birth Weight Murine Adults

INTRODUCTION

Maternal undernutrition (MUN)-induced low birth weight (LBW) neonates are susceptible to the development of high blood pressure and kidney disease later in life, although the underlying pathological causes remain unclear. The study here investigated the role of renal oxidative stress, impairment of vascular function, and altered sensitivity to angiotensin II (Ang II) as factors that contribute to these pathologies in aged LBW mice.

METHODS

LBW offspring were generated using a combined protein and caloric restricted MUN mouse model. The resulting LBW offspring were examined 1 year after birth for mean arterial blood pressure (MABP) (carotid artery catheterization), renal blood flow (RBF) (laser Doppler flowmetry), glomerular filtration rate (GFR) (sinistrin clearance), vasoreactivity (myograph), renal vascular density (CD31 staining), and reactive oxygen species (ROS) (ROS probes). Immunoblotting examined Ang II type 1 receptor (AT1R), soluble guanylate cyclase (sGC), and antioxidant systems. Pharmacological agents delivered to animals included the sGC stimulator δ-aminolevulinic acid (ALA), the AT1R inhibitor losartan, the antioxidant ethyl pyruvate (EP), and the toll-like receptor 4 inhibitor TAK242.

RESULTS

After 1 year, MABP was increased, while RBF, GFR, vascular reactivity, renal vascular density, and sGC were all reduced in the LBW aged adult. All four pharmacological agents improved MABP, RBF, GFR, vascular density, and vascular reactivity. Renal ROS was increased in the LBW adult but was reduced by ALA, EP, and TAK242 treatment. AT1R was upregulated in the LBW adult, while sGC was decreased, an effect reversed by ALA treatment. Endogenous antioxidant systems, including SOD1, catalase, and glutathione were downregulated in the LBW adult.

CONCLUSION

MUN-induced LBW mice experience increased Ang II sensitivity and oxidative stress. The increased Ang II sensitivity and ROS generation influences vascular density and reactivity, which drive an increase in MABP, and a concomitantly decrease in RBF and glomerular filtration. Pharmacological intervention that inhibits AT1R, enhances levels of sGC, reduces ROS, or inhibits toll-like receptor 4 improves vascular and renal function in the LBW adult.

5-Aminolevulinic acid combined with ferrous iron ameliorates myocardial ischemia/reperfusion injury by increasing heme oxygenase-1

BACKGROUND

5-Aminolevulinic acid (5-ALA) is a naturally occurring metabolic precursor of heme, and 5-ALA combined with ferrous iron can induce heme oxygenase-1 (HO-1) in various cells. In this study, we investigated the cardioprotective effect of 5-ALA after myocardial ischemia/reperfusion (I/R) injury using a murine model.

METHODS AND RESULTS

Male C57BL/6 J mice (10-12 weeks of age and weighing 21-26 g) were pretreated with 100 mg/kg of 5-ALA hydrochloride and 157 mg/kg of sodium ferrous citrate (SFC) or vehicle 48 h, 24 h, and 1 h before I/R, and underwent 50 min of left coronary artery occlusion followed by reperfusion. Infarct area (IA) and area at risk (AAR) were determined by Evans blue and triphenyltetrazolium chloride double staining after reocclusion. Pre-administration with 5-ALA/SFC significantly reduced IA/AAR compared with placebo (34.0% vs. 51.7%, respectively; p = 0.001). Real-time PCR assay after reperfusion showed that mRNA expressions of TNF-α, IL-1β, and BNP were significantly lower, and that of HO-1 was significantly higher in the 5-ALA/SFC group than in the vehicle group in ischemic sites. An inhibition experiment revealed that zinc protoporphyrin IX, an inhibitor of HO-1, inhibited the cardioprotective effects of 5-ALA/SFC.

CONCLUSIONS

These results suggest that 5-ALA/SFC might play a cardioprotective role in myocardial I/R injury by attenuating the inflammatory reaction by increasing the expression of HO-1.

The Impact of 5-Aminolevulinic Acid Supplementation on Redox Balance and Aerobic Capacity

We examined the impact of 5-aminolevulinic acid (5-ALA) and sodium-ferrous-citrate supplementation on aerobic capacity and redox balance through a placebo-controlled, double-blind trial. Fourteen healthy volunteers were randomly assigned to Pla + ALA (4-week placebo followed by 4-week 5-ALA supplementation) or ALA + Pla (4-week 5-ALA supplement followed by a 4-week placebo) group and administered 5-ALA (25 mg/day) or placebo once daily. The participants underwent submaximal incremental cycling tests at weeks 0, 2, 4, 6, and 8. In the cycling test at week 0, individual load-intensity stages required for blood lactate levels >2 mmol/L (lactate threshold, LT) and 4 mmol/L (onset of blood lactate accumulation, OBLA) were determined. The heart rate (HR), blood lactate (La), and oxidative stress markers (diacron reactive oxygen metabolite, d-ROMs; biological antioxidant potential, BAP) were measured at resting, LT, and OBLA states in each cycling test. Marker values were not significantly different between the groups. HR, La, and d-ROMs at resting, LT, and OBLA states were not significantly different among the conditions. BAP and BAP/d-ROMs ratios were significantly different in the OBLA state at week 4 of the 5-ALA group compared with that of the placebo group (p < 0.05). In conclusion, 5-ALA supplementation might improve redox balance during high-intensity aerobic exercise.

Efficacy and safety of 5-aminolevulinic acid in adult-onset Still's disease: A preclinical study in mice and a pilot study in humans

The study aimed to investigate the therapeutic effects of 5-aminolevulinic acid/sodium ferrous citrate (5-ALA/SFC) on adult-onset Still's disease (AOSD), specifically focusing on arthritis and macrophage activation syndrome (MAS). We used mouse models to assess the impact of 5-ALA/SFC on collagen-induced arthritis (CIA) and MAS induced by synthetic oligonucleotides containing CpG motifs (CpG-S-ODN). Additionally, we conducted a pilot study with AOSD patients receiving prednisolone (PSL) treatment and 5-ALA/SFC administration to evaluate its efficacy and safety. The 5-ALA/SFC group exhibited significantly lower joint scores in CIA mice. In CpG-S-ODN-treated mice, 5-ALA/SFC administration led to reduced hemophagocytosis and splenomegaly. The anti-inflammatory properties of 5-ALA/SFC were attributed to the suppression of CCL4 and CXCL10 production in monocytes and the induction of M2 macrophages. AOSD patients treated with 5-ALA/SFC demonstrated successful PSL tapering without adverse events. Collectively, the administration of 5-ALA/SFC showed promising potential in ameliorating arthritis and MAS in AOSD patients.

Nrf2/HO-1 as a therapeutic target in renal fibrosis

Chronic kidney disease (CKD) is one of the most prevalent chronic diseases and affects between 10 and 14 % of the world's population. The World Health Organization estimates that by 2040, the disease will be fifth in prevalence. End-stage CKD is characterized by renal fibrosis, which can eventually lead to kidney failure and death. Renal fibrosis develops due to multiple injuries and involves oxidative stress and inflammation. In the human body, nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in the expression of antioxidant, anti-inflammatory, and cytoprotective genes, which prevents oxidative stress and inflammation damage. Heme oxygenase (HO-1) is an inducible homolog influenced by heme products and after exposure to cellular stress inducers such as oxidants, inflammatory chemokines/cytokines, and tissue damage as an outcome or downstream of Nrf2 activation. HO-1 is known for its antioxidative properties, which play an important role in regulating oxidative stress. In renal diseases-induced tissue fibrosis and xenobiotics-induced renal fibrosis, Nrf2/HO-1 has been targeted with promising results. This review summarizes these studies and highlights the interesting bioactive compounds that may assist in attenuating renal fibrosis mediated by HO-1 activation. In conclusion, Nrf2/HO-1 signal activation could have a renoprotective effect strategy against CKD caused by oxidative stress, inflammation, and consequent renal fibrosis.

Synergy of 5-aminolevulinate supplement and CX3CR1 suppression promotes liver regeneration via elevated IGF-1 signaling

Inadequate remnant volume and regenerative ability of the liver pose life-threatening risks to patients after partial liver transplantation (PLT) or partial hepatectomy (PHx), while few clinical treatments focus on safely accelerating regeneration. Recently, we discovered that supplementing 5-aminolevulinate (5-ALA) improves liver cold adaptation and functional recovery, leading us to uncover a correlation between 5-ALA metabolic activities and post-PLT recovery. In a mouse 2/3 PHx model, 5-ALA supplements enhanced liver regeneration, promoting infiltration and polarization of anti-inflammatory macrophages via P53 signaling. Intriguingly, chemokine receptor CX3CR1 functions to counterbalance these effects. Genetic ablation or pharmacological inhibition of CX3CR1 (AZD8797; phase II trial candidate) augmented the macrophagic production of insulin-like growth factor 1 (IGF-1) and subsequent hepatocyte growth factor (HGF) production by hepatic stellate cells. Thus, short-term treatments with both 5-ALA and AZD8797 demonstrated pro-regeneration outcomes superior to 5-ALA-only treatments in mice after PHx. Overall, our findings may inspire safe and effective strategies to better treat PLT and PHx patients.

5-Aminolevulinic acid combined with ferrous iron ameliorates scrotal heat stress-induced spermatogenic damage by enhancing HO-1 expression

OBJECTIVE

To explore whether 5-Aminolevulinic acid combined with ferrous iron (5-ALA/Fe²⁺) could protect testicular tissues damage of mice subjected to heat stress (HS) and provide its underlying mechanisms.

METHODS

5-ALA/Fe²⁺ was administered intragastrically to mice for 10 days, then exposed to a scrotal heat stress at 43°C for 20 min on third day. Testes were harvested for morphologic and histopathological examination, oxidative stress, apoptosis, heme oxygenase-1 (HO-1) and inflammation detection. The mitogen-activated protein kinases (MAPK) signaling pathway in testis and CD4⁺FoxP3⁺regulatory T (Treg) cells in spleen were also investigated.

RESULTS

Compared to control group, the testis weight decreased and histological damage severed in HS group. Besides, HS also increased the oxidative stress, apoptosis and inflammation in testis. However, these indicators were ameliorated after 5-ALA/Fe²⁺ treatment but deteriorated after receiving ZnPPIX. The expression of HO-1 was increased both in HS group and 5-ALA/Fe²⁺ group. The protein expression levels of MAPK proteins were activated by HS and inhibited by 5-ALA/Fe²⁺. The CD4⁺FoxP3⁺ Treg generation was reduced by HS and increased by 5-ALA/Fe²⁺.

CONCLUSION

In this study, we have demonstrated that 5-ALA/Fe²⁺ ameliorated the spermatogenic damage induced by scrotal heat stress via up-regulating the expression of HO-1 and inhibiting MAPK mediated oxidative stress and apoptosis and inducing CD4⁺Foxp3⁺ Tregs to inhibit the inflammation induced by HS in mice.

5-Aminolevulinic acid combined with sodium ferrous citrate mitigates effects of heat stress on bovine oocyte developmental competence

High summer temperatures have deleterious effects on oocyte developmental competence. The antioxidant and autophagy-related properties of 5-aminolevulinic acid (5-ALA) gives the compound a broad range of biological activities. This study aimed to evaluate the effects of: 1) a high temperature-humidity index (THI) on the developmental competence of bovine oocytes, and 2) 5-ALA administration in combination with sodium ferrous citrate (SFC) during in vitro maturation (IVM) on bovine oocyte developmental competence evaluated at high THI. Bovine ovaries were collected from a local slaughterhouse at moderate environmental temperature (MT; THI of 56.2) and high environmental temperature (HT; THI of 76.7) periods; cumulus-oocyte complexes (COCs) were aspirated from medium-sized follicles, matured in vitro for 22 h, fertilized, and cultured for 10 days. For COCs collected during the HT period, 0 (control), 0.01, 0.1, 0.5, or 1 µM 5-ALA was added to the maturation medium in combination with SFC at a molar ratio of 1:0.125. The results showed that HT adversely affected blastocyst and hatching rates compared with MT. Adding 5-ALA/SFC (1 µM/0.125 µM) to the maturation medium of oocytes collected during the HT period improved cumulus cell expansion and blastocyst rates compared with the no-addition control. In conclusion, this study showed that high THI can disrupt bovine oocyte developmental competence. Adding 5-ALA to SFC ameliorates this negative effect of heat stress and improves subsequent embryo development.

Renal hypoxia-HIF-PHD-EPO signaling in transition metal nephrotoxicity: friend or foe?

The kidney is the main organ that senses changes in systemic oxygen tension, but it is also the key detoxification, transit and excretion site of transition metals (TMs). Pivotal to oxygen sensing are prolyl-hydroxylases (PHDs), which hydroxylate specific residues in hypoxia-inducible factors (HIFs), key transcription factors that orchestrate responses to hypoxia, such as induction of erythropoietin (EPO). The essential TM ion Fe is a key component and regulator of the hypoxia–PHD–HIF–EPO (HPHE) signaling axis, which governs erythropoiesis, angiogenesis, anaerobic metabolism, adaptation, survival and proliferation, and hence cell and body homeostasis. However, inadequate concentrations of essential TMs or entry of non-essential TMs in organisms cause toxicity and disrupt health. Non-essential TMs are toxic because they enter cells and displace essential TMs by ionic and molecular mimicry, e. g. in metalloproteins. Here, we review the molecular mechanisms of HPHE interactions with TMs (Fe, Co, Ni, Cd, Cr, and Pt) as well as their implications in renal physiology, pathophysiology and toxicology. Some TMs, such as Fe and Co, may activate renal HPHE signaling, which may be beneficial under some circumstances, for example, by mitigating renal injuries from other causes, but may also promote pathologies, such as renal cancer development and metastasis. Yet some other TMs appear to disrupt renal HPHE signaling, contributing to the complex picture of TM (nephro-)toxicity. Strikingly, despite a wealth of literature on the topic, current knowledge lacks a deeper molecular understanding of TM interaction with HPHE signaling, in particular in the kidney. This precludes rationale preventive and therapeutic approaches to TM nephrotoxicity, although recently activators of HPHE signaling have become available for therapy.

Analysis of Factors Affecting 5-ALA Fluorescence Intensity in Visualizing Glial Tumor Cells-Literature Review

Glial tumors are one of the most common lesions of the central nervous system. Despite the implementation of appropriate treatment, the prognosis is not successful. As shown in the literature, maximal tumor resection is a key element in improving therapeutic outcome. One of the methods to achieve it is the use of fluorescent intraoperative navigation with 5-aminolevulinic acid. Unfortunately, often the level of fluorescence emitted is not satisfactory, resulting in difficulties in the course of surgery. This article summarizes currently available knowledge regarding differences in the level of emitted fluorescence. It may depend on both the histological type and the genetic profile of the tumor, which is reflected in the activity and expression of enzymes involved in the intracellular metabolism of fluorescent dyes, such as PBGD, FECH, UROS, and ALAS. The transport of 5-aminolevulinic acid and its metabolites across the blood–brain barrier and cell membranes mediated by transporters, such as ABCB6 and ABCG2, is also important. Accompanying therapies, such as antiepileptic drugs or steroids, also have an impact on light emission by tumor cells. Accurate determination of the factors influencing the fluorescence of 5-aminolevulinic acid-treated cells may contribute to the improvement of fluorescence navigation in patients with highly malignant gliomas.

Carbon Monoxide in Renal Physiology, Pathogenesis and Treatment of Renal Disease

Carbon monoxide (CO) is one of the endogenous gaseous messengers or gasotransmitters, and is a paramount mediator in physiological and disease conditions. In this review, we focus on the functions of CO in normal and pathological renal physiology. We discuss endogenous renal CO production and signaling in the normal kidney, the characteristic of CO-releasing molecules (CORMs) modalities, and outline its regulatory functions in renal physiology. This article summarizes the mechanisms as well as the effect of CO in the evolving field of renal diseases. We predict numerous innovative CO applications forevolvingcutting-edge scholarly work in the future.

Progressive Cellular Senescence Mediates Renal Dysfunction in Ischemic Nephropathy

BACKGROUND

Peripheral vascular diseases may induce chronic ischemia and cellular injury distal to the arterial obstruction. Cellular senescence involves proliferation arrest in response to stress, which can damage neighboring cells. Renal artery stenosis (RAS) induces stenotic-kidney dysfunction and injury, but whether these arise from cellular senescenceand their temporal pattern remain unknown.

METHODS

Chronic renal ischemia was induced in transgenic INK-ATTAC and wild type C57BL/6 mice by unilateral RAS, and kidney function (in vivo micro-MRI) and tissue damage were assessed. Mouse healthy and stenotic kidneys were analyzed using unbiased single-cell RNA-sequencing. To demonstrate translational relevance, cellular senescence was studied in human stenotic kidneys.

RESULTS

Using intraperitoneal AP20187 injections starting 1, 2, or 4 weeks after RAS, selective clearance of cells highly expressing p16^Ink4a attenuated cellular senescence and improved stenotic-kidney function; however, starting treatment immediately after RAS induction was unsuccessful. Broader clearance of senescent cells, using the oral senolytic combination dasatinib and quercetin, in C57BL/6 RAS mice was more effective in clearing cells positive for p21 (Cdkn1a) and alleviating renal dysfunction and damage. Unbiased, single-cell RNA sequencing in freshly dissociated cells from healthy and stenotic mouse kidneys identified stenotic-kidney epithelial cells undergoing both mesenchymal transition and senescence. As in mice, injured human stenotic kidneys exhibited cellular senescence, suggesting this process is conserved.

CONCLUSIONS

Maladaptive tubular cell senescence, involving upregulated p16 (Cdkn2a), p19 (Cdkn2d), and p21 (Cdkn1a) expression, is associated with renal dysfunction and injury in chronic ischemia. These findings support development of senolytic strategies to delay chronic ischemic renal injury.

5-aminolevulinic acid combined with sodium ferrous citrate ameliorated lupus nephritis in a mouse chronic graft-versus-host disease model

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the abnormal activation of immune cells and hypersecretion of autoantibodies and causes irreversible chronic damage, such as lupus nephritis. Chronic graft-versus-host-disease (cGvHD) in mice induced by the injection of parental mouse lymphocytes into F1 hybrids leads to a disease similar to SLE. 5-aminolevulinic acid (5-ALA) is a key progenitor of heme, and its combination with sodium ferrous citrate (SFC) can up-regulate the heme oxygenase (HO-1) expression, resulting in an anti-inflammatory effect. While HO-1 had been reported to be involved in T cell activation and can limit immune-based tissue damage through Treg suppression, which promotes effector response. Thus, we hypothesized that treatment with 5-ALA/SFC could ameliorate lupus nephritis in a mouse cGvHD model. Our results showed that 5-ALA/SFC-treatment significantly decreased the anti-double-stranded DNA (ds-DNA) autoantibodies, blood urea nitrogen (BUN) and creatinine (Cre) levels, reduced kidney inflammatory dendritic cells (DCs) and B cell activation, and increased the regulatory T cells (Tregs) at nine weeks. Furthermore, 5-ALA/SFC suppressed mRNA expression of TNF-α, IL-1β, IFN-γ and markers on DCs. In addition, we also found that 5-ALA/SFC treatment increased the HO-1 expression on donor-derived DCs and Tregs concurrently, increased the number of Tregs, and reduced the population of activated DCs, B cells and CD8+ T cells at three weeks (early stage of the disease). We thus identified a novel role of 5-ALA/SFC for therapeutically improving the symptoms of lupus nephritis in a mouse cGvHD model and expanded the current understanding of how this immunoregulatory agent can be used to generate beneficial immune responses and treat autoimmune disease.

5-Aminolevulinic Acid as a Novel Therapeutic for Inflammatory Bowel Disease

5-Aminolevulinic acid (5-ALA) is a naturally occurring nonprotein amino acid licensed as an optical imaging agent for the treatment of gliomas. In recent years, 5-ALA has been shown to possess anti-inflammatory and immunoregulatory properties through upregulation of heme oxygenase-1 via enhancement of porphyrin, indicating that it may be beneficial for the treatment of inflammatory conditions. This study systematically examines 5-ALA for use in inflammatory bowel disease (IBD). Firstly, the ex vivo colonic stability and permeability of 5-ALA was assessed using human and mouse fluid and tissue. Secondly, the in vivo efficacy of 5-ALA, in the presence of sodium ferrous citrate, was investigated via the oral and intracolonic route in an acute DSS colitis mouse model of IBD. Results showed that 5-ALA was stable in mouse and human colon fluid, as well as in colon tissue. 5-ALA showed more tissue restricted pharmacokinetics when exposed to human colonic tissue. In vivo dosing demonstrated significantly improved colonic inflammation, increased local heme oxygenase-1 levels, and decreased concentrations of proinflammatory cytokines TNF-α, IL-6, and IL-1β in both plasma and colonic tissue. These effects were superior to that measured concurrently with established anti-inflammatory treatments, ciclosporin and 5-aminosalicylic acid (mesalazine). As such, 5-ALA represents a promising addition to the IBD armamentarium, with potential for targeted colonic delivery.

5-Aminolevulinic acid combined with sodium ferrous citrate (5-ALA/SFC) ameliorated liver injury in a murine acute graft-versus-host disease model by reducing inflammation responses through PGC1-α activation

Acute graft-versus-host disease (aGvHD) remains lethal as a life-threatening complication after allogeneic hematopoietic stem cell transplantation (HSCT). Inflammatory responses play an important role in aGvHD. 5-Aminolevulinic acid combined with sodium ferrous citrate (5-ALA/SFC) has been widely reported to have a major effect on the anti-inflammatory response; however, these effects in aGvHD models have never been reported. In this study, a murine aGvHD model was developed by transferring spleen cells from donor B6/N (H-2kb) mice into recipient B6D2F1 (H-2kb/d) mice. In addition to evaluating manifestations in aGvHD mice, we analyzed the serum ALT/AST levels, liver pathological changes, infiltrating cells and mRNA expression of inflammation-related cytokines and chemokines. 5-ALA/SFC treatment significantly ameliorated liver injury due to aGvHD and decreased the population of liver-infiltrating T cells, resulting in a reduced expression of pro-inflammatory cytokines and chemokines. Furthermore, the mRNA expression proliferator-activated receptor-γcoactivator (PGC-1α) was enhanced, which might explain why 5-ALA/SFC treatment downregulates inflammatory signaling pathways. Our results indicated that 5-ALA/SFC can ameliorate liver injury induced by aGvHD through the activation of PGC-1α and modulation of the liver mRNA expression of inflammatory-related cytokines and chemokines. This may be a novel strategy for treating this disease.

The Correlation of Fluorescence of Protoporphyrinogen IX and Status of Isocitrate Dehydrogenase in Gliomas

BACKGROUND

The extent of resection has been reported to be associated with overall survival in gliomas. The use of 5-aminolevulinic acid (5-ALA) has been recognized to increase the extent of tumor resection.

OBJECTIVE

To evaluate what factors affect the intraoperative fluorescence after administration of 5-ALA in gliomas.

METHODS

Correlation of intraoperative fluorescence and several clinical, radiographic, molecular biologic, and histopathologic characters was retrospectively evaluated in 104 patients (53 males and 51 females; mean age 54.2 yr) with gliomas at our institution. To clarify the mechanisms that mutant isocitrate dehydrogenase (IDH) affect the intraoperative fluorescence, in Vitro experiments using genetically engineered glioma cells harboring mutant IDH1 were performed.

RESULTS

Intraoperative fluorescence was observed in 82 patients (78.8%). In addition to age, magnetic resonance imaging enhancement, World Health Organization grades, and MIB-1 index, the status of IDH was revealed to be correlated with intraoperative fluorescence. In Vitro assay revealed that mutant IDH indirectly reduced the amount of exogenous 5-ALA-derived protoporphyrinogen IX in glioma cells by increasing activity of ferrochelatase and heme oxygenase 1.

CONCLUSION

Mutant IDH1/2-induced metabolite changes of exogenous 5-ALA were suggested to contribute to the lesser intraoperative fluorescence in gliomas with mutant IDH1/2 than in those without.

Protective effects of 5-aminolevulinic acid on heat stress in bovine mammary epithelial cells

OBJECTIVE

Cells have increased susceptibility to activation of apoptosis when suffering heat stress (HS). An effective supplementation strategy to mimic heat-induced apoptosis of bovine mammary epithelial cells (MECs) is necessary to maintain optimal milk production. This study aimed to investigate possible protective effects of the anti-apoptotic activity of 5-aminolevulinic acid (5-ALA) against HS-induced damage of bovine MECs.

METHODS

Bovine MECs were pretreated with or without 5-ALA at concentrations of 10, 100, and 500 μM for 24 h followed by HS (42.5°C for 24 h and 48 h). Cell viability was measured with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Real-time quantitative polymerase chain reaction and Western blotting were used to explore the regulation of genes associated with apoptosis, oxidative stress, and endoplasmic reticulum (ER) stress genes.

RESULTS

We found that 5-ALA induces cytoprotection via inhibition of apoptosis markers after HS-induced damage. Pretreatment of bovine MECs with 5-ALA resulted in dramatic upregulation of mRNA for nuclear factor erythroid-derived 2-like factor 2, heme oxygenase-1, and NAD(P)H quinone oxidoreductase 1, all of which are antioxidant stress genes. Moreover, 5-ALA pretreatment significantly suppressed HS-induced ER stress-associated markers, glucose-regulated protein 78, and C/EBP homologous protein expression levels.

CONCLUSION

5-ALA can ameliorate the ER stress in heat stressed bovine MEC via enhancing the expression of antioxidant gene.

5-ALA/SFC enhances HO-1 expression through the MAPK/Nrf2 antioxidant pathway and attenuates murine tubular epithelial cell apoptosis

Cyclosporin A (CsA) is a common immunosuppressant, but its use is limited as it can cause chronic kidney injury. Oxidative stress and apoptosis play a key role in CsA-induced nephrotoxicity. This study investigated the protective effect of 5-aminolevulinic acid and iron (5-ALA/SFC) on CsA-induced injury in murine proximal tubular epithelial cells (mProx24). 5-ALA/SFC significantly inhibited apoptosis in CsA-treated mProx24 cells with increases in heme oxygenase (HO)-1, nuclear factor E2-related factor 2 (Nrf2), and p38, and Erk-1/2 phosphorylation. Moreover, 5-ALA/SFC suppressed production of reactive oxygen species in CsA-exposed cells and inhibition of HO-1 suppressed the protective effects of 5-ALA/SFC. In summary, 5-ALA/SFC may have potential for development into a treatment for the anti-nephrotoxic/apoptotic effects of CsA.

5-ALA/SFC Attenuated Binge Alcohol-Induced Gut Leakiness and Inflammatory Liver Disease in HIV Transgenic Rats

BACKGROUND

This study aimed to investigate the protective effect of 5-aminolevulinic acid (5-ALA) and sodium ferrous citrate (SFC) against binge alcohol-induced gut leakiness and inflammatory liver disease in HIV transgenic (TG) rats.

METHODS

TG rats were treated with 3 consecutive doses of binge ethanol (EtOH) with or without 5-ALA/SFC. Blood and liver tissue samples were collected at 6 hours following the last dose of EtOH.

RESULTS

Compared with the wild-type (WT) rats, the TG rats showed increased sensitivity to alcohol-mediated inflammation, as evidenced by the significantly elevated levels of serum endotoxin, AST, ALT, ED1, and ED2 staining in liver. In contrast, 5-ALA/SFC improved the above biochemical and histochemical profiles. 5-ALA/SFC also attenuated the up-regulated mRNA expression of leptin and CCL2. Furthermore, down-regulated intestinal ZO-1 protein expression was also inhibited by 5-ALA/SFC. Moreover, the expressions of HO-1, HO-2, Sirt1, and related signal transduction molecules in liver were increased by 5-ALA/SFC. These results demonstrated that 5-ALA/SFC treatment ameliorated binge alcohol exposure liver injury in a rat model of HIV-infected patients by reducing macrophage activation and expression of inflammatory cytokines/chemokines, and by inducing HO-1, HO-2, and Sirt1 expression.

CONCLUSIONS

Taken together, these findings suggested that treatment with 5-ALA/SFC has a potential therapeutic effect for binge alcohol exposure liver injury in HIV-infected patients.

Protective role of heme oxygenase-1 in fatty liver ischemia-reperfusion injury

Ischemia-reperfusion (IR) injury is a kind of injury resulting from the restoration of the blood supply after blood vessel closure during liver transplantation and is the main cause of graft failure. The pathophysiological mechanisms of hepatic IR include a variety of oxidative stress responses. Hepatic IR is characterized by ischemia and hypoxia inducing oxidative stress, immune response and apoptosis. Fat-denatured livers are also used as donors due to the lack of liver donors. Fatty liver is less tolerant to IR than normal liver. Heme oxygenase (HO) is an enzyme that breaks down hemoglobin to bilirubin, ferrous iron and carbon monoxide (CO). Inducible HO subtype HO-1 is an important protective molecule in mammalian cells used to improve acute and chronic liver injury owing to its characteristic anti-inflammatory and anti-apoptotic qualities. HO-1 degrades heme, and its reaction product CO has been shown to reduce hepatic IR injury and increase the survival rate of grafts. As an induced form of HO, HO-1 also exerts a protective effect against liver IR injury and may be useful as a new strategy of ameliorating this kind of damage. This review summarizes the protective effects of HO-1 in liver IR injury, especially in fatty liver.

Noninvasive Monitoring and Evaluation of the Renal Structure and Function in a Mouse Model of Unilateral Ureteral Occlusion Using Microcomputed Tomography

Mouse unilateral ureteral occlusion (UUO) is widely used as a model of renal experimental obstructive nephropathy with interstitial fibrosis. Microcomputed tomography (micro-CT) imaging has the potential to produce quantitative images. The aim of this study was to establish standard images of micro-CT for renal anatomic and functional evaluations in a mouse model of UUO. UUO was induced in adult male mice BALB/c. In total, 27 mice were used in this study. Three mice per group (a total of 6 groups) were examined with contrast-enhanced micro-CT prior to UUO (day 0) and on days 1, 3, 5, 7, 10, and 14 after UUO. In order to determine the histopathologic correlations at each point in time, contrast-enhanced micro-CT imaging was performed in the 18 remaining mice. All animals were sacrificed, and both kidneys were harvested after the final micro-CT examination. UUO resulted in hydronephrosis and changes in the renal parenchyma. The predominant alteration was substantial changes in the hemodynamics of the renal vascular system after ureteral obstruction for 24 hours or longer, which may be resulting from increased action of vasoconstrictors versus vasodilators. The renal parenchyma was significantly reduced after 1 week, and the features of the histologic changes supported the findings of the micro-CT images. In the contralateral unobstructed kidneys, the images showed a normal structure and function and the pathohistology revealed a normal histoarchitecture. Micro-CT is a useful tool for providing noninvasive monitoring and evaluating the renal structure and function.

5-Aminolevulinic acid exerts renoprotective effect via Nrf2 activation in murine rhabdomyolysis-induced acute kidney injury

AIM

Acute kidney injury (AKI) is associated with chronic kidney disease, as well as high mortality, but effective treatments for AKI are still lacking. A recent study reported the prevention of renal injury, such as ischemia-reperfusion injury, by 5-aminolevulinic acid (ALA), which induces an antioxidant effect. The current study aimed to investigate the effect of ALA in a rhabdomyolysis-induced mouse model of AKI created by intramuscular injection of 50% glycerol.

METHODS

Rhabdomyolysis-induced AKI was induced by an intramuscular injection of glycerol (5 mL/kg body weight) into mice. Administration of ALA (30 mg/kg, by gavage) was started from 48 h before or 24 h after glycerol injection. The mice were sacrificed at 72 h after glycerol injection. The roles of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), which is one of the Nrf2-related antioxidants, were further investigated through in vivo and in vitro methods.

RESULTS

5-aminolevulinic acid markedly reduced renal dysfunction and tubular damage in mice with rhabdomyolysis-induced AKI. ALA administration decreased oxidative stress, macrophage infiltration, and inflammatory cytokines and apoptosis. The expression of Nrf2 was upregulated by ALA administration. However, administration of Zinc protoporphyrin-9 (ZnPPIX) to inhibit HO-1 activity did not abolish these improvements by ALA. The expression of Nrf2-associated antioxidant factors other than HO-1 was also increased.

CONCLUSION

These findings indicate that ALA exerts its antioxidant activity via Nrf2-associated antioxidant factors to provide a renoprotective effect against rhabdomyolysis-induced AKI.

Dual benefit of supplementary oral 5-aminolevulinic acid to pelvic radiotherapy in a syngenic prostate cancer model

BACKGROUND

Normal tissue damage caused by radiotherapy remains the largest dose-limiting factor in radiotherapy for cancer. Therefore, the aim of this study was to investigate the supplementary oral 5-aminolevulinic acid (ALA) to standard radiation therapy as a novel radioprotective approach that would not compromise the antitumor effect of radiation in normal rectal and bladder mucosa in a syngenic prostate cancer (PCa) model.

METHODS

To evaluate the radiosensitizing effect of ALA in vitro, clonogenic survival assays were performed in DU145, PC3, and MyC-CaP cell lines. To evaluate the effect of ALA in vivo a single dose (25 Gy) of radiation with or without ALA was given to healthy mice. Next, a syngenic PCa model of MyC-CaP cells in FVB mice was created, and multiple doses (12 Gy total) of radiation were administered to the mouse pelvic area with or without ALA administration. Resected tumors, recta, and urinary bladders were immunostained with antibodies against Ki-67, γ-H2AX, CD204, and uroplakin-III. Total RNA levels in recta and urinary bladders were analyzed via RT2 Profiler polymerase chain reaction (PCR) arrays related to "Stress & Toxicity PathwayFinder," "Mitochondria," and "Inflammasomes."

RESULTS

The addition of in vitro single or in vivo repeated administration of exogenous ALA acted as a radiosensitizer for PCa cells. Rectal toxicity was characterized by histological changes including loss of surface epithelium, fibrosis, severe DNA damage, and the aggregation of M2 macrophages. Urinary bladder toxicity was characterized by bladder wall thickening and urothelium denuding. The higher dose (300 mg/kg/day) of ALA exerted a better radioprotective profile than the lower dose (30 mg/kg/day) in normal recta and urinary bladders. Out of the 252 genes tested, 35 (13.4%) were detected as relevant genes which may be involved in the radioprotective role of ALA administration. These included interleukin-1a (IL-1a), IL-1b, IL-12, chemokine (C-X-C motif) ligand 1 (CXCL1), CXCL3, and NLRP3.

CONCLUSIONS

Our study provides novel and comprehensive insights into the dual benefits including radiosensitizing PCa tumor tissues and radioprotection of normal pelvic organs from radiation therapy. Knowledge of the underlying mechanism will facilitate the search for optimal treatment parameters for supplemental oral ALA during radiotherapy for PCa.

5-aminolaevulinic acid (ALA), enhances heme oxygenase (HO)-1 expression and attenuates tubulointerstitial fibrosis and renal apoptosis in chronic cyclosporine nephropathy

BACKGROUND

Cyclosporine-A (CsA) is an immunosuppressant indicated for various immunological diseases; however, it can induce chronic kidney injury. Oxidative stress and apoptosis play a crucial role in CsA-induced nephrotoxicity. The present study evaluated the protective effect of combining 5-aminolaevulinic acid with iron (5-ALA/SFC), a precursor of heme synthesis, to enhance HO-1 activity against CsA-induced chronic nephrotoxicity.

METHODS

Mice were divided into three groups: the control group (using olive oil as a vehicle), CsA-only group, and CsA+5-ALA/SFC group. After 28 days, the mice were sacrificed, and blood and kidney samples were collected. In addition to histological and biochemical examination, the mRNA expression of proinflammatory and profibrotic cytokines was assessed.

RESULTS

Renal function in the 5-ALA/SFC treatment group as assessed by the serum creatinine and serum urea nitrogen levels was superior to that of the CsA-only treatment group, demonstrating that 5-ALA/SFC significantly attenuated CsA-induced kidney tissue inflammation, fibrosis, apoptosis, and tubular atrophy, as well as reducing the mRNA level of TNF-α, IL-6, TGF-β1, and iNOS while increasing HO-1.

CONCLUSION

The activity of 5-ALA/SFC has important implications for clarifying the mechanism of HO-1 activity in CsA-induced nephrotoxicity and may provide a favorable basis for clinical therapy.

Effects of 5-Aminolevulinic Acid on Gene Expression, Immunity, and ATP Levels in Pacific White Shrimp, Litopenaeus vannamei

With the emergence of several infectious diseases in shrimp aquaculture, there is a growing interest in the use of feed additives to enhance shrimp immunity. Recently, the use of 5-aminolevulinic acid (5-ALA), a non-protein amino acid that plays a rate-limiting role in heme biosynthesis, has received attention for its positive effect on immunity in livestock animals. To evaluate the effect of 5-ALA in the Pacific white shrimp, Litopenaeus vannamei, we conducted microarray analysis, a Vibrio parahaemolyticus immersion challenge test, an ATP level assay, and gene expression analysis of some hemoproteins and genes associated with heme synthesis and degradation. Out of 15,745 L. vannamei putative genes on the microarray, 101 genes were differentially expressed by more than fourfold (p < 0.05) between 5-ALA-supplemented and control shrimp hepatopancreas. 5-ALA upregulated 99 of the 101 genes, 41 of which were immune- and defense-related genes based on sequence homology. Compared to the control, the 5-ALA-supplemented group had a higher survival rate in the challenge test, higher transcript levels of porphobilinogen synthase, ferrochelatase, catalase, nuclear receptor E75, and heme oxygenase-1 and higher levels of ATP. These findings suggest that dietary 5-ALA enhanced the immune response of L. vannamei to V. parahaemolyticus, upregulated immune- and defense-related genes, and enhanced aerobic energy metabolism, respectively. Further studies are needed to elucidate the extent of 5-ALA use in shrimp culture.

5-Aminolevulinic acid with ferrous iron improves early renal damage and hepatic steatosis in high fat diet-induced obese mice

5-Aminolevulinic acid, a natural amino acid, activates mitochondrial respiration and induces heme oxygenase-1 expression. Obesity and type 2 diabetes mellitus are associated with age-related mitochondrial respiration defect, oxidative stress and inflammation. The aim of this study is to investigate the effects of 5-aminolevulinic acid with sodium ferrous citrate on early renal damage and hepatic steatosis. 7-Month-old C57BL/6 mice were fed with a standard diet or high fat diet for 9 weeks, which were orally administered 300 mg/kg 5-aminolevulinic acid combined with 47 mg/kg sodium ferrous citrate (5-aminolevulinic acid/sodium ferrous citrate) or vehicle for the last 5 weeks. We observed that 5-aminolevulinic acid/sodium ferrous citrate significantly decreased body weight, fat weight, hepatic lipid deposits and improved levels of blood glucose and oral glucose tolerance test. In addition, 5-aminolevulinic acid/sodium ferrous citrate suppressed increased glomerular tuft area in high fat diet-fed mice, which was associated with increased heme oxygenase-1 protein expression. Our findings demonstrate additional evidence that 5-aminolevulinic acid/sodium ferrous citrate could improve glucose and lipid metabolism in diabetic mice. 5-Aminolevulinic acid/sodium ferrous citrate has potential application in obesity or type 2 diabetes mellitus-associated disease such as diabetic nephropathy and nonalcoholic fatty liver disease.

Carbon monoxide protects the kidney through the central circadian clock and CD39

Ischemia reperfusion injury (IRI) is the predominant tissue insult associated with organ transplantation. Treatment with carbon monoxide (CO) modulates the innate immune response associated with IRI and accelerates tissue recovery. The mechanism has been primarily descriptive and ascribed to the ability of CO to influence inflammation, cell death, and repair. In a model of bilateral kidney IRI in mice, we elucidate an intricate relationship between CO and purinergic signaling involving increased CD39 ectonucleotidase expression, decreased expression of Adora1, with concomitant increased expression of Adora2a/2b. This response is linked to a >20-fold increase in expression of the circadian rhythm protein Period 2 (Per2) and a fivefold increase in serum erythropoietin (EPO), both of which contribute to abrogation of kidney IRI. CO is ineffective against IRI in Cd39^-/- and Per2^-/- mice or in the presence of a neutralizing antibody to EPO. Collectively, these data elucidate a cellular signaling mechanism whereby CO modulates purinergic responses and circadian rhythm to protect against injury. Moreover, these effects involve CD39- and adenosinergic-dependent stabilization of Per2. As CO also increases serum EPO levels in human volunteers, these findings continue to support therapeutic use of CO to treat IRI in association with organ transplantation, stroke, and myocardial infarction.

Dynamics of absorption, metabolism, and excretion of 5-aminolevulinic acid in human intestinal Caco-2 cells

5-Aminolevulinic acid (ALA) is a precursor for the biosynthesis of porphyrins and heme. Although the oral administration of ALA has been widely applied in clinical settings, the dynamics of its absorption, metabolism, and excretion within enterocytes remain unknown. In this study, after enterocytic differentiation, Caco-2 cells were incubated with 200 µM ALA and/or 100 µM sodium ferrous citrate (SFC) for up to 72 h. Both ALA and the combination of ALA and SFC promoted the synthesis of heme, without affecting the expression of genes involved in intestinal iron transport, such as DMT1 and FPN. The enhanced heme synthesis in Caco-2 cells was more pronounced under the effect of the combination of ALA and SFC than under the effect of ALA alone, as reflected by the induced expression of heme oxygenase 1 (HO-1), as well as a reduced protein level of the transcriptional corepressor Bach1. Chromatin immunoprecipitation analysis confirmed Bach1 chromatin occupancy at the enhancer regions of HO-1, which were significantly decreased by the addition of ALA and SFC. Finally, Transwell culture of Caco-2 cells suggested that the administered ALA to the intestinal lumen was partially transported into vasolateral space. These findings enhance our understanding of the absorption and metabolism of ALA in enterocytes, which could aid in the development of a treatment strategy for various conditions such as anemia.

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Combination of ALA and SFC promotes heme synthesis than ALA alone in Caco-2 cells.

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Heme induces HO-1 by inhibiting transcriptional corepressor Bach1 in Caco-2 cells.

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Addition of ALA to intestinal lumen was partially transported to vasolateral space.

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Our data enhance the understanding of the dynamics of ALA in enterocytes.

Prolonged Mouse Cardiac Graft Cold Storage via Attenuating Ischemia-Reperfusion Injury Using a New Antioxidant-Based Preservation Solution

BACKGROUND

One of the major events in ischemia-reperfusion (I/R)-induced heart injury in cardiac transplantation is the generation of reactive oxygen species. We hypothesized that a novel preservation solution called SBI-SEIIKU II (SS-II) contains 3 antioxidant reagents: L-cysteine, glycine, ascorbic acid/ascorbic acid-2-phosphate magnesium, which can block the generation of reactive oxygen species to result in a prolongation of the cold storage time via attenuating I/R injury.

METHODS

C57BL/6CrSlc(B6) mice underwent syngeneic mice heterotopic heart transplantation, and the animals were derived into 3 groups: recipients with nonpreserved grafts (control group), recipients with grafts preserved in histidine-tryptophan-ketoglutarate (HTK) for 24 and 48 hours (HTK group), and recipients with grafts preserved in SS-II for 24 and 48 hours (SS-II group).

RESULTS

After 48 hours of preservation, there were no grafts that survived in the HTK group; however, the SS-II group had a high survival rate. After 24 hours of preservation, SS-II decreased the oxidative damage, myocardial apoptosis, and the infiltration of macrophages and neutrophils in the cardiac grafts in the early phase and suppressed the development of myocardial fibrosis in long-term grafts compared with HTK.

CONCLUSIONS

The SS-II prolongs the acceptable cold storage time and protects the myocardium from I/R injury via inhibiting oxidative stress-associated damage. We believe that this novel preservation solution may be simple and safe for use in the clinical transplantation field.

5-Aminolevulinic acid with sodium ferrous citrate induces autophagy and protects cardiomyocytes from hypoxia-induced cellular injury through MAPK-Nrf-2-HO-1 signaling cascade

BACKGROUND

Hypoxia causes cardiac disease via oxidative stress and mitochondrial dysfunction. 5-Aminolevulinic acid in combination with sodium ferrous citrate (ALA/SFC) has been shown to up-regulate heme oxygenase-1 (HO-1) and decrease macrophage infiltration and renal cell apoptosis in renal ischemia injury mice. However, its underlying mechanism remains largely unknown. The aim of this study was to investigate whether ALA/SFC could protect cardiomyocytes from hypoxia-induced apoptosis by autophagy via HO-1 signaling.

MATERIALS & METHODS

Murine atrial cardiomyocyte HL-1 cells were pretreated with ALA/SFC and then exposed to hypoxia.

RESULTS

ALA/SFC pretreatment significantly attenuated hypoxia-induced cardiomyocyte apoptosis, reactive oxygen species production, and mitochondrial injury, while it increased cell viability and autophagy levels. HO-1 expression by ALA/SFC was associated with up-regulation and nuclear translocation of Nrf-2, whereas Nrf-2 siRNA dramatically reduced HO-1 expression. ERK1/2, p38, and SAPK/JNK pathways were activated by ALA/SFC and their specific inhibitors significantly reduced ALA/SFC-mediated HO-1 upregulation. Silencing of either Nrf-2 or HO-1and LY294002, inhibitor of autophagy, abolished the protective ability of ALA/AFC against hypoxia-induced injury and reduced ALA/SFC-induced autophagy.

CONCLUSION

Taken together, our data suggest that ALA/SFC induces autophagy via activation of MAPK/Nrf-2/HO-1 signaling pathway to protect cardiomyocytes from hypoxia-induced apoptosis.

Combination of 5-aminolevulinic acid and ferrous ion reduces plasma glucose and hemoglobin A1c levels in Zucker diabetic fatty rats

Mitochondrial dysfunction is associated with type 2 diabetes mellitus (T2DM). 5‐Aminolevulinic acid (ALA), a natural amino acid produced only in the mitochondria, is a precursor of heme. Cytochromes that contain heme play an important role in aerobic energy metabolism. Thus, ALA may help reduce T2DM‐associated hyperglycemia. In this study, we investigated the effect of ALA combined with sodium ferrous citrate (SFC) on hyperglycemia in Zucker diabetic fatty (ZDF) rats. We found that the gavage administration of ALA combined with SFC (ALA/SFC) for 6 weeks reduced plasma glucose and hemoglobin A1c (HbA1c) levels in rats without affecting plasma insulin levels. The glucose‐lowering effect depended on the amount of ALA/SFC administered per day. Furthermore, the glucose tolerance was also significantly improved by ALA/SFC administration. Although food intake was slightly reduced in the rats administered ALA/SFC, there was no effect on their body weight. Importantly, ALA/SFC administration induced heme oxygenase‐1 (HO‐1) expression in white adipose tissue and liver, and the induced expression levels of HO‐1 correlated with the glucose‐lowering effects of ALA/SFC. Taken together, these results suggest that ALA combined with ferrous ion is effective in reducing hyperglycemia of T2DM without affecting plasma insulin levels. HO‐1 induction may be involved in the mechanisms underlying the glucose‐lowering effect of ALA/SFC.

Potential role of mitochondrial superoxide decreasing ferrochelatase and heme in coronary artery soluble guanylate cyclase depletion by angiotensin II

Oxidation of the soluble guanylate cyclase (sGC) heme promotes loss of regulation by nitric oxide (NO) and depletion of sGC. We hypothesized that angiotensin II (ANG II) stimulation of mitochondrial superoxide by its type 1 receptor could function as a potential inhibitor of heme biosynthesis by ferrochelatase, and this could decrease vascular responsiveness to NO by depleting sGC. These processes were investigated in a 24-h organoid culture model of bovine coronary arteries (BCA) with 0.1 μM ANG II. Treatment of BCA with ANG II increased mitochondrial superoxide, depleted mitochondrial superoxide dismutase (SOD2), ferrochelatase, and cytochrome oxidase subunit 4, and sGC, associated with impairment of relaxation to NO. These processes were attenuated by organoid culture with 8-bromo-cGMP and/or δ-aminolevulinic acid (a stimulator of sGC by protoporphyrin IX generation and heme biosynthesis). Organoid culture with Mito-TEMPOL, a scavenger of mitochondrial matrix superoxide, also attenuated ANG II-elicited ferrochelatase depletion and loss of relaxation to NO, whereas organoid culture with Tempol, an extramitochondrial scavenger of superoxide, attenuated the loss of relaxation to NO by ANG II, but not ferrochelatase depletion, suggesting cytosolic superoxide could be an initiating factor in the loss of sGC regulation by NO. The depletion of cytochrome oxidase subunit 4 and sGC (but not catalase) suggests that sGC expression may be very sensitive to depletion of heme caused by ANG II disrupting ferrochelatase activity by increasing mitochondrial superoxide. In addition, cGMP-dependent activation of protein kinase G appears to attenuate these ANG II-stimulated processes through both preventing SOD2 depletion and increases in mitochondrial and extramitochondrial superoxide.

5-Aminolevulinic acid combined with ferrous iron ameliorate ischemia-reperfusion injury in the mouse fatty liver model

BACKGROUND

The fatty liver could increase the risk of serious acute ischemia reperfusion (I/R) injury, and hepatic steatosis is indeed a major risk factor for hepatic failure after grafting a fatty liver.

MATERIALS & METHODS

Fatty liver models of methionine- and choline-deficient high-fat mice were subjected to I/R injury with or without 5-aminolevulinic acid (5-ALA)/sodium ferrous citrate (SFC) treatment. Levels of hepatic enzymes, lipid peroxidation and apoptosis, inflammatory cytokines and heme oxygenase (HO)-1, and the carbon monoxide (CO) in the liver, and reactive oxygen species (ROS), inflammatory cytokines and members of the signaling pathway in isolated Kupffer were assessed.

RESULTS

Alanine aminotransferase and aspartate aminotransferase levels, the number of necrotic areas, thiobarbituric acid reactive substance content, TUNEL-positive cells, infiltrated macrophages, and the inflammatory cytokine expression after I/R injury were dramatically decreased, whereas the endogenous CO concentrations and the HO-1 expression were significantly increased by 5-ALA/SFC treatment. The expression of toll-like receptors 2 and 4, NF-κB and inflammatory cytokines and ROS production in Kupffer cells were significantly decreased with 5-ALA/SFC treatment.

CONCLUSION

5-ALA/SFC significantly attenuates the injury level in the fatty liver after I/R injury.

5-Aminolevulinic acid regulates the inflammatory response and alloimmune reaction

5-Aminolevulinic acid (5-ALA) is a naturally occurring amino acid and precursor of heme and protoporphyrin IX (PpIX). Exogenously administrated 5-ALA increases the accumulation of PpIX in tumor cells specifically due to the compromised metabolism of 5-ALA to heme in mitochondria. PpIX emits red fluorescence by the irradiation of blue light and the formation of reactive oxygen species and singlet oxygen. Thus, performing a photodynamic diagnosis (PDD) and photodynamic therapy (PDT) using 5-ALA have given rise to a new strategy for tumor diagnosis and therapy. In addition to the field of tumor therapy, 5-ALA has been implicated in the treatment of inflammatory disease, autoimmune disease and transplantation due to the anti-inflammation and immunoregulation properties that are elicited with the expression of heme oxygenase (HO)-1, an inducible enzyme that catalyzes the rate-limiting step in the oxidative degradation of heme to free iron, biliverdin and carbon monoxide (CO), in combination with sodium ferrous citrate (SFC), because an inhibitor of HO-1 abolishes the effects of 5-ALA. Furthermore, NF-E2-related factor 2 (Nrf2), mitogen-activated protein kinase (MAPK), and heme are involved in the HO-1 expression. Biliverdin and CO are also known to have anti-apoptotic, anti-inflammatory and immunoregulatory functions. We herein review the current use of 5-ALA in inflammatory diseases, transplantation medicine, and tumor therapy.

Dihydroquercetin (DHQ) ameliorated concanavalin A-induced mouse experimental fulminant hepatitis and enhanced HO-1 expression through MAPK/Nrf2 antioxidant pathway in RAW cells

Autoimmune hepatitis represents a ubiquitous human health problem and has a poor prognosis. Dihydroquercetin (DHQ), a well-known antioxidant, significantly inhibits fulminant hepatitis through anti-oxidant and anti-inflammation mechanisms. In this study, we show that administration of DHQ ameliorated concanavalin A (ConA)-induced mouse liver injury by increasing the survival rate, reducing the serum ALT and AST level, preventing histopathological injuries and decreasing pro-inflammatory cytokine mRNA expression in hepatic tissue. As macrophages/Kupffer cells in oxidative stress and pro-inflammatory mediators play an important role in the pathogenesis of immune-mediated hepatitis, we further exposed mouse RAW264 macrophage cell lines to ConA in vitro and found that DHQ significantly inhibited mRNA expression and secretion of IFN-γ and TNF-α in cell culture supernatant. In addition, DHQ significantly enhanced heme oxygenase-1 (HO-1) expression in a dose- and time-dependent manner via increased Nrf2 expression in cytoplasm and nuclear translocation. Furthermore, DHQ enhanced phosphorylation of three members of the mitogen-activated protein kinase (MAPK) family, and cell treatment with MEK/ERK (PD98059), p38 (SB203580) and JNK (SP600125) inhibitors reduced DHQ-induced HO-1 expression. These results indicate that DHQ possesses hepatoprotective properties against ConA-induced liver injury, which are attributed to its ability to scavenge oxidative stress and to inhibit the release of inflammatory mediators via upregulation of HO-1 activity through the MAPK/Nrf2 signaling pathway in macrophages/Kupffer cells.

5-aminolevulinic acid combined with sodium ferrous citrate ameliorates H2O2-induced cardiomyocyte hypertrophy via activation of the MAPK/Nrf2/HO-1 pathway

Hydrogen peroxide (H2O2) causes cell damage via oxidative stress. Heme oxygenase-1 (HO-1) is an antioxidant enzyme that can protect cardiomyocytes against oxidative stress. In this study, we investigated whether the heme precursor 5-aminolevulinic acid (5-ALA) with sodium ferrous citrate (SFC) could protect cardiomyocytes from H2O2-induced hypertrophy via modulation of HO-1 expression. HL-1 cells pretreated with/without 5-ALA and SFC were exposed to H2O2 to induce a cardiomyocyte hypertrophy model. Hypertrophy was evaluated by planar morphometry, (3)H-leucine incorporation, and RT-PCR analysis of hypertrophy-related gene expressions. Reactive oxygen species (ROS) production was assessed by 5/6-chloromethyl-2',7'-ichlorodihydrofluorescein diacetate acetylester. HO-1 and nuclear factor erythroid 2-related factor 2 (Nrf2) protein expressions were analyzed by Western blot. In our experiments, HL-1 cells were transfected with Nrf2 siRNA or treated with a signal pathway inhibitor. We found several results. 1) ROS production, cell surface area, protein synthesis, and expressions of hypertrophic marker genes, including atrial natriuretic peptide, brain natriuretic peptide, atrial natriuretic factor, and β-myosin heavy chain, were decreased in HL-1 cells pretreated with 5-ALA and SFC. 2) 5-ALA and SFC increased HO-1 expression in a dose- and time-dependent manner, associated with upregulation of Nrf2. Notably, Nrf2 siRNA dramatically reduced HO-1 expression in HL-1 cells. 3) ERK1/2, p38, and SAPK/JNK signaling pathways were activated and modulate 5-ALA- and SFC-enhanced HO-1 expression. SB203580 (p38 kinase), PD98059 (ERK), or SP600125 (JNK) inhibitors significantly reduced this effect. In conclusion, our data suggest that 5-ALA and SFC protect HL-1 cells from H2O2-induced cardiac hypertrophy via activation of the MAPK/Nrf2/HO-1 signaling pathway.

5-Aminolevulinic acid with ferrous iron induces permanent cardiac allograft acceptance in mice via induction of regulatory cells

BACKGROUND

5-Aminolevulinic acid (5-ALA), a precursor of heme biosynthesis, plays a fundamentally important role in aerobic energy metabolism. Heme oxygenase (HO)-1 cleaves heme to form biliverdin, carbon monoxide (CO) and iron (Fe(2+)). The anti-inflammatory properties of biliverdin and CO help to alleviate ischemia/reperfusion injury as well as acute and/or chronic allograft rejection. We investigated whether 5-ALA and Fe(2+) exerts salutary effects in the setting of organ transplantation.

METHODS

An in vitro mixed-lymphocyte reaction (MLR) assay and cardiac allotransplantation model (CBA to C57BL/10) were used to evaluate the effects of 5-ALA and Fe(2+) on transplantation tolerance.

RESULTS

Treatment with 5-ALA and sodium ferrous citrate (SFC) resulted in permanent acceptance in the murine cardiac allografts in a dose-, SFC- and HO-1-dependent manner. The number of graft-infiltrating CD8 T cells was lower and the survival response of recipient spleen T cells to donor-type alloantigens was less compared with control recipients; however, numbers of both regulatory T cells and dendritic cells were significantly increased in 5-ALA/SFC-treated recipients.

CONCLUSIONS

Our findings show that 5-ALA/SFC inhibits T-cell proliferation in response to alloantigens and an increased number of regulatory cells, resulting in permanent cardiac allograft acceptance in mice. These findings highlight the major roles of CO and/or HO-1 in inducing tolerance and suggest that 5-ALA/SFC may be a clinically effective treatment for allograft rejection.

5-Aminolevulinic acid combined with ferrous iron enhances the expression of heme oxygenase-1

5-Aminolevulinic acid (5-ALA) is the naturally occurring metabolic precursor of heme. Heme negatively regulates the Maf recognition element (MARE) binding- and repressing-activity of the Bach1 transcription factor through its direct binding to Bach1. Heme oxygenase (HO)-1 is an inducible enzyme that catalyzes the rate-limiting step in the oxidative degradation of heme to free iron, biliverdin and carbon monoxide. These metabolites of heme protect against apoptosis, inflammation and oxidative stress. Monocytes and macrophages play a critical role in the initiation, maintenance and resolution of inflammation. Therefore, the regulation of inflammation in macrophages is an important target under various pathophysiological conditions. In order to address the question of what is responsible for the anti-inflammatory effects of 5-ALA, the induction of HO-1 expression by 5-ALA and sodium ferrous citrate (SFC) was examined in macrophage cell line (RAW264 cells). HO-1 expression induced by 5-ALA combined with SFC (5-ALA/SFC) was partially inhibited by MEK/ERK and p38 MAPK inhibitor. The NF-E2-related factor 2 (Nrf2) was activated and translocated from the cytosol to the nucleus in response to 5-ALA/SFC. Nrf2-specific siRNA reduced the HO-1 expression. In addition, 5-ALA/SFC increased the intracellular levels of heme in cells. The increased heme indicated that the inactivation of Bach1 by heme supports the upregulation of HO-1 expression. Taken together, our data suggest that the exposure of 5-ALA/SFC to RAW264 cells enhances the HO-1 expression via MAPK activation along with the negative regulation of Bach1.