KLF6 alleviates hepatic ischemia-reperfusion injury by inhibiting autophagy

m6A reader YTHDC1 mediates MAFF nuclear export to induce VMP1 transcription and alleviate I/R-induced oxidative stress injury in hepatocytes

Hepatic ischemia/reperfusion (I/R) injury occurs after liver resection surgery, trauma, shock, and transplantation. This study aimed to identify and characterize the role of the YTH domain-containing protein 1 (YTHDC1)/MAFF/vacuole membrane protein 1 (VMP1) axis in hepatic I/R injury. YTHDC1, MAFF, and VMP1 were significantly overexpressed in the hepatic tissues of mice with I/R and hepatocytes exposed to hypoxia-reoxygenation (H/R). Knockdown of MAFF exacerbated oxidative stress and inflammatory injury in mice induced with hepatic I/R, which were reversed by overexpression of VMP1. Similarly, I/R-associated injury mitigated by YTHDC1 overexpression was reversed by MAFF knockdown. Mechanistically, YTHDC1 mediated the nuclear export and stability of MAFF mRNA and promoted MAFF translation. Collectively, the findings establish that YTHDC1-mediated m6A-dependent MAFF expression determines hepatocyte oxidative stress via VMP1, providing valuable insights into the potential mechanisms underlying hepatic I/R injury and offering potential therapeutic strategies for its treatment.

Pharmacological inhibition of ENaC or NCX can attenuate hepatic ischemia-reperfusion injury exacerbated by hypernatremia

Donors with a serum sodium concentration of >155 mmol/L are extended criteria donors for liver transplantation (LT). Elevated serum sodium of donors leads to an increased incidence of hepatic dysfunction in the early postoperative period of LT; however, the exact mechanism has not been reported. We constructed a Lewis rat model of 70% hepatic parenchymal area subjected to ischemia-reperfusion (I/R) with hypernatremia and a BRL-3A cell model of hypoxia-reoxygenation (H/R) with high-sodium (HS) culture medium precondition. To determine the degree of injury, biochemical analysis, histological analysis, and oxidative stress and apoptosis detection were performed. We applied specific inhibitors of the epithelial sodium channel (ENaC) and Na+/Ca2+ exchanger (NCX) in vivo and in vitro to verify their roles in injury. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) levels and the area of hepatic necrosis were significantly elevated in the HS+I/R group. Increased reactive oxygen species (ROS) production, myeloperoxidase (MPO)‍-positive cells, and aggravated cellular apoptosis were detected in the HS+I/R group. The HS+H/R group of BRL-3A cells showed significantly increased cellular apoptosis and ROS production compared to the H/R group. The application of amiloride (Amil), a specific inhibitor of ENaC, reduced ischemia-reperfusion injury (IRI) aggravated by HS both in vivo and in vitro, as evidenced by decreased serum transaminases, inflammatory cytokines, apoptosis, and oxidative stress. SN-6, a specific inhibitor of NCX, had a similar effect to Amil. In summary, hypernatremia aggravates hepatic IRI, which can be attenuated by pharmacological inhibition of ENaC or NCX.

GPX4 degradation contributes to heat stress-induced liver injury via chaperone-mediated autophagy

Heat stress (HS) is a significant health concern that adversely affects both human and animal health, particularly impacting liver function due to its central metabolic role. This study investigated the mechanisms underlying HS-induced liver injury, focusing on the role of ferroptosis, an iron-dependent form of cell death characterized by lipid peroxidation and cellular iron accumulation. Using mouse and cellular HS models, the results demonstrated that HS induced liver injury through ferroptosis, as evidenced by increased levels of malondialdehyde (MDA), oxidized glutathione (GSSG), and iron, alongside decreased glutathione (GSH) and glutathione peroxidase 4 (GPX4) expression. The ferroptosis inhibitor Ferrostatin-1 (Fer-1) effectively mitigated HS-induced liver damage, reducing oxidative stress and restoring GPX4 levels. Furthermore, HS promoted the lysosomal degradation of GPX4 via the chaperone-mediated autophagy (CMA) pathway, which was regulated by heat shock cognate protein 70 (HSC70) and lysosome-associated membrane protein 2A (LAMP2A). Knockdown of LAMP2A in hepatocytes significantly suppressed HS-induced GPX4 degradation, confirming the critical role of CMA in this process. Inhibition of CMA using Apoptozole, an HSC70 inhibitor, or Bafilomycin A1 (Baf-A1), a lysosomal inhibitor, further attenuated HS-induced ferroptosis and liver injury. These findings highlight the critical role of CMA-mediated GPX4 degradation in HS-induced ferroptosis and liver injury, providing potential therapeutic targets for mitigating HS-related liver damage.

Single-Cell RNA Sequencing of the Primary Visual Cortex in Mice With Optic Nerve Injury

Purpose

Glial cells play a critical role in primary visual cortex (V1 region) damage caused by optic nerve injury, but the mechanisms driving progression of V1 region injury and glial cell heterogeneity remain poorly understood. This study aimed to investigate the damage changes in the V1 region of mice after optic nerve crush (ONC) by single-cell RNA sequencing (scRNA-seq).

Methods

Hematoxylin and eosin (H&E) and immunofluorescence staining were used to evaluate the changes of retinal thickness, astrocytes, and microglia in the V1 region after ONC in mice. Single cell suspensions in the V1 region of mice were prepared and analyzed by scRNA-seq with Seurat, cellchat, CytoTRACE in R software. The expression of PTGDS and CRYAB was measured by qPCR, Western blot, and immunofluorescence.

Results

After unilateral ONC, retinal thinning in both eyes and activation of astrocytes and microglia in contralateral V1 region were observed. Genes related to neuroinflammation and apoptosis in the bilateral V1 region were upregulated, and the related pathways included MAPK, TNF, and apoptosis signaling pathways. Notably, the V1 region contralateral to the ONC eye exhibited more pronounced differential gene expression, and the protein expression of neuroinflammation-related genes Ptgds and Cryab increased. We further investigated the heterogeneity and pseudotime trajectories of astrocytes and microglia, demonstrating the key branches that dominate neuroinflammation.

Conclusions

This study generates an atlas of the V1 region of the mouse brain, highlighting the role of astrocytes and microglia in the damage changes in the V1 region after ONC, and suggesting Ptgds and Cryab as potential targets to reduce neuroinflammation.

Protective effect of irbesartan against hepatic ischemia-reperfusion injury in rats: role of ERK, STAT3, and PPAR-γ inflammatory pathways in rats

This study aimed to elucidate the possible hepatocellular protective role of irbesartan during hepatic ischemia-reperfusion injury (HIRI) and the probable underlying mechanisms. Wistar rats were allocated into four groups: sham; HIRI (control); irbesartan (50 mg/kg) + HIRI; irbesartan (100 mg/kg) + HIRI; irbesartan + GW9662 (1 mg/kg, i.p.) + HIRI. Rats pretreated orally with irbesartan or vehicle for 14 days underwent 45-min hepatic ischemia followed by 60-min reperfusion. Irbesartan preconditioning diminished alanine transaminase (ALT) and aspartate transaminase (AST) serum levels, and reduced extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3). Irbesartan decreased proapoptotic BAX (bcl-2-like protein 4), increased anti-apoptotic B-cell lymphoma 2 (BCL2) hepatic content, and thereby reduced BAX/BCL2 ratio. Moreover, irbesartan preconditioning reduced autophagy-related proteins Beclin1 and LC3 II, and elevated p62 (protein responsible for autophagosome degradation). It elevated proliferator-activated receptor γ (PPAR-γ), and reduced tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) hepatic gene expression. Also, hepatic protein expressions of nuclear factor kappa-B p65 (NF-κB p65) and caspase-3 were lessoned by irbesartan pretreatment in HIRI rats. However, GW9662 abrogated irbesartan's effect on HIRI. The protective effect of irbesartan on HIRI may be mediated by alleviation of ERK, STAT3, and PPAR-γ inflammatory pathways, exerting anti-apoptotic and anti-autophagic effects in HIRI in rats.

Betaine-homocysteine methyltransferase attenuates liver ischemia-reperfusion injury by targeting TAK1

Liver ischemia-reperfusion (IR) injury is a common complication following liver surgery, significantly impacting the prognosis of liver transplantation and other liver surgeries. Betaine-homocysteine methyltransferase (BHMT), a crucial enzyme in the methionine cycle, has been previously confirmed the pivotal role in hepatocellular carcinoma, and it has also been demonstrated that BHMT inhibits inflammation, apoptosis, but its role in liver IR injury remains unknow. Following I/R injury, we found that BHMT expression was significantly upregulated in human liver transplant specimens, mice and hepatocytes. Utilizing BHMT knockout mice, we established an in vivo model of liver IR injury, and with BHMT knockout and overexpression AML12 cell lines, we created an in vitro hypoxia-reoxygenation model. Our findings reveal that BHMT deficiency exacerbates liver IR injury, leading to increased reactive oxygen species, apoptosis and inflammation, whereas BHMT overexpression mitigates these effects. We observed that BHMT inhibits the c-Jun N-terminal kinase (JNK)/p38 signaling pathway in liver IR injury by interacting with TAK1 and inhibiting its activity. The application of 5z-7-ox, a TAK1 inhibitor, reversed the worsening of liver IR injury and the activation of the JNK/p38 pathway associated with BHMT deficiency. These results demonstrate that BHMT protects against liver IR injury by targeting TAK1 and inhibiting the JNK/p38 signaling pathway. Our findings suggest that BHMT may be a promising therapeutic target for preventing liver IR injury.

Exploring the roles and therapeutic implications of melatonin-mediated KLF6 in the development of intracranial aneurysm

BACKGROUND

Intracranial aneurysm (IA) is a cerebrovascular disease with a high mortality rate due to ruptured subarachnoid hemorrhage. While Krüppel-like factor 6 (KLF6) dysregulation has been implicated in cancer and cardiovascular diseases, its role in IA remains unclear.

MATERIALS AND METHODS

The GSE122897 and GSE15629 datasets were downloaded from the Gene Expression Omnibus database. Immune cell infiltration and hypoxia analysis were performed to explore the effects of KLF6 on IA. Weighted gene co-expression network analysis was used to identify hub genes related to KLF6 expression for subsequent analyses. Hypoxia-related genes were identified. Drug prediction was performed for IA. Samples from healthy individuals and patients with IA were collected to detect the expression of endothelin-1 (ET-1), vascular hematoma factor (vWF), and KLF6. A model of H2O2-induced human brain vascular smooth muscle cells (HBVSMC) injury was constructed to explore the effects of KLF6 and melatonin to treat IA.

RESULTS

T cells CD4 memory resting and monocytes were significantly different in the KLF6 high and low expression groups. Four hypoxia-related gene sets were significantly enriched in the KLF6 high-expression group. Six hypoxia-related hub genes were obtained, which were significantly associated with KLF6. Drug prediction showed that melatonin may be a potential drug for IA. The levels of ET-1, vWF, and KLF6 were significantly upregulated in patients with IA. KLF6 exacerbates H2O2-induced injury in HBVSMC, ameliorated by melatonin.

CONCLUSION

KLF6 may be a potential target for IA treatment, with melatonin-mediated KLF6 effects playing a crucial role in the development of IA.

JuA alleviates liver ischemia-reperfusion injury by activating AKT/NRF2/HO-1 pathways

Liver ischemia-reperfusion (I/R) injury is a detrimental complication of organ transplantation, shock, and sepsis. However, the available drugs to mitigate I/R injury remain limited. Jujuboside A (JuA) is renowned for its antioxidant, anti-inflammatory, and anti-apoptotic properties; nevertheless, its potential in liver I/R injury remains unknown. Thus, this study aimed to explore the role and underlying mechanisms of JuA in liver I/R injury. Mouse models of I/R and AML12 cell models of hypoxia/reoxygenation (H/R) were constructed. Haematoxylin and eosin staining, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) detection, and cell viability analysis were used to assess liver injury. To evaluate oxidative stress, inflammation, apoptosis, and mitochondrial damage, immunofluorescence staining, transmission electron microscopy analysis, enzyme-linked immunosorbent assay, and flow cytometry were conducted. Moreover, molecular docking techniques and western blot were employed to identify downstream target molecules and pathways affected by JuA. The results showed that JuA pretreatment effectively attenuated liver necrosis and ALT and AST level elevations induced by I/R while enhancing AML12 cell viability following H/R. Furthermore, JuA pretreatment suppressed oxidative stress triggered by I/R and H/R, thereby inhibiting the level of pro-inflammatory factors and NLRP3 inflammasome activation. Notably, JuA pretreatment alleviated mitochondrial damage and apoptosis. Mechanistically, JuA pretreatment resulted in the activation of the AKT/NRF2/HO-1 signalling pathways, whereas MK2206, the inhibitor of AKT, partially reversed the hepatoprotective effects of JuA during liver I/R. Collectively, our findings illustrated that JuA mitigated oxidative stress, inflammation, apoptosis, and mitochondrial damage by facilitating the AKT/NRF2/HO-1 signalling pathway, thereby alleviating liver I/R injury.

Icaritin attenuates ischemia-reperfusion injury by anti-inflammation, anti-oxidative stress, and anti-autophagy in mouse liver

BACKGROUND

Hepatic ischemia-reperfusion (IR) injury is a major complication of liver transplantation and gravely affects patient prognosis. Icaritin (ICT), the primary plasma metabolite of icariin (ICA), plays a critical role in anti-inflammatory and immunomodulatory processes. However, the role of ICT in hepatic IR injury remains largely undefined. In this study, we aimed to elucidate the role of ICT in hepatic IR injury.

METHODS

We established hepatic IR injury models in animals, as well as an oxygen-glucose deprivation/reperfusion (OGD/R) cell model. Liver injury in vivo was assessed by measuring serum alanine aminotransferase (ALT) levels, necrotic areas by liver histology and local hepatic inflammatory responses. For in vitro analyses, we implemented flow-cytometric and western blot analyses, transmission electron microscopy, and an mRFP-GFP-LC3 adenovirus reporter assay to assess the effects of ICT on OGD/R injury in AML12 and THLE-2 cell lines. Signaling pathways were explored in vitro and in vivo to identify possible mechanisms underlying ICT action in hepatic IR injury.

RESULTS

Compared to the mouse model group, ICT preconditioning considerably protected the liver against IR stress, and diminished the levels of necrosis/apoptosis and inflammation-related cytokines. In additional studies, ICT treatment dramatically boosted the expression ratios of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR proteins in hepatic cells following OGD/R damage. We also applied LY294002 (a PI3K inhibitor) and RAPA (rapamycin, an mTOR inhibitor), which blocked the protective effects of ICT in hepatocytes subjected to OGD/R.

CONCLUSION

This study indicates that ICT attenuates ischemia-reperfusion injury by exerting anti-inflammation, anti-oxidative stress, and anti-autophagy effects, as demonstrated in mouse livers. We thus posit that ICT could have therapeutic potential for the treatment of hepatic IR injury.

Krüppel-like factors family in health and disease

Krüppel-like factors (KLFs) are a family of basic transcription factors with three conserved Cys2/His2 zinc finger domains located in their C-terminal regions. It is acknowledged that KLFs exert complicated effects on cell proliferation, differentiation, survival, and responses to stimuli. Dysregulation of KLFs is associated with a range of diseases including cardiovascular disorders, metabolic diseases, autoimmune conditions, cancer, and neurodegenerative diseases. Their multidimensional roles in modulating critical pathways underscore the significance in both physiological and pathological contexts. Recent research also emphasizes their crucial involvement and complex interplay in the skeletal system. Despite the substantial progress in understanding KLFs and their roles in various cellular processes, several research gaps remain. Here, we elucidated the multifaceted capabilities of KLFs on body health and diseases via various compliable signaling pathways. The associations between KLFs and cellular energy metabolism and epigenetic modification during bone reconstruction have also been summarized. This review helps us better understand the coupling effects and their pivotal functions in multiple systems and detailed mechanisms of bone remodeling and develop potential therapeutic strategies for the clinical treatment of pathological diseases by targeting the KLF family.

miRNA‑21 promotes the progression of acute liver failure via the KLF6/autophagy/IL‑23 signaling pathway

Acute liver failure (ALF) is a complex syndrome characterized by overactivation of innate immunity, and the recruitment and differentiation of immune cells at inflammatory sites. The present study aimed to explore the role of microRNA (miRNA/miR)‑21 and its potential mechanisms underlying inflammatory responses in ALF. Baseline serum miR‑21 was analyzed in patients with ALF and healthy controls. In addition, miR‑21 antagomir was injected via the tail vein into C57BL/6 mice, and lipopolysaccharide/D‑galactosamine (LPS/GalN) was injected into mice after 48 h. The expression levels of miR‑21, Krüppel‑like‑factor‑6 (KLF6), autophagy‑related proteins and interleukin (IL)‑23, and hepatic pathology were then assessed in the liver tissue. Furthermore, THP‑1‑derived macrophages were transfected with a miRNA negative control, miR‑21 inhibitor, miR‑21 mimics or KLF6 overexpression plasmid, followed by treatment with or without rapamycin, and the expression levels of miR‑21, KLF6, autophagy‑related proteins and IL‑23 were evaluated. The results revealed that baseline serum miR‑21 levels were significantly upregulated in patients with ALF. In addition, LPS/GalN‑induced ALF was attenuated in the antagomir‑21 mouse group. KLF6 was identified as a target of miR‑21‑5p with one putative seed match site identified by TargetScan. A subsequent luciferase activity assay demonstrated a direct interaction between miR‑21‑5p and the 3'‑UTR of KLF6 mRNA. Further experiments suggested that miR‑21 promoted the expression of IL‑23 via inhibiting KLF6, which regulated autophagy. In conclusion, in the present study, baseline serum miR‑21 levels were highly upregulated in patients with ALF, antagomir‑21 attenuated LPS/GalN‑induced ALF in a mouse model, and miR‑21 could promote the expression of IL‑23 via inhibiting KLF6.

Lipid droplets, autophagy, and ER stress as key (survival) pathways during ischemia-reperfusion of transplanted grafts

Ischemia-reperfusion injury is an event concerning any organ under a procedure of transplantation. The early result of ischemia is hypoxia, which causes malfunction of mitochondria and decrease in cellular ATP. This leads to disruption of cellular metabolism. Reperfusion also results in cell damage due to reoxygenation and increased production of reactive oxygen species, and later by induced inflammation. In damaged and hypoxic cells, the endoplasmic reticulum (ER) stress pathway is activated by increased amount of damaged or misfolded proteins, accumulation of free fatty acids and other lipids due to inability of their oxidation (lipotoxicity). ER stress is an adaptive response and a survival pathway, however, its prolonged activity eventually lead to induction of apoptosis. Sustaining cell functionality in stress conditions is a great challenge for transplant surgeons as it is crucial for maintaining a desired level of graft vitality. Pathways counteracting negative consequences of ischemia-reperfusion are autophagy and lipid droplets (LD) metabolism. Autophagy remove damaged organelles and molecules driving them to lysosomes, digested simpler compounds are energy source for the cell. Mitophagy and ER-phagy results in improvement of cell energetic balance and alleviation of ER stress. This is important in sustaining metabolic homeostasis and thus cell survival. LD metabolism is connected with autophagy as LD are degraded by lipophagy, a source of free fatty acids and glycerol-thus autophagy and LD can readily remove lipotoxic compounds in the cell. In conclusion, monitoring and pharmaceutic regulation of those pathways during transplantation procedure might result in increased/improved vitality of transplanted organ.

PPARβ/δ activation protects against hepatic ischaemia-reperfusion injury

BACKGROUND AND AIMS

Hepatic ischaemia/reperfusion injury (HIRI) is a pathophysiological process that occurs during the liver resection and transplantation. Reportedly, peroxisome proliferator-activated receptor β/δ (PPARβ/δ) can ameliorate kidney and myocardial ischaemia/reperfusion injury. However, the effect of PPARβ/δ in HIRI remains unclear.

METHODS

Mouse hepatic ischaemia/reperfusion (I/R) models were constructed for in vivo study. Primary hepatocytes and Kupffer cells (KCs) isolated from mice and cell anoxia/reoxygenation (A/R) injury model were constructed for in vitro study. Liver injury and inflammation were investigated. Small molecular compounds (GW0742 and GSK0660) and adenoviruses were used to interfere with PPARβ/δ.

RESULTS

We found that PPARβ/δ expression was increased in the I/R and A/R models. Overexpression of PPARβ/δ in hepatocytes alleviated A/R-induced cell apoptosis, while knockdown of PPARβ/δ in hepatocytes aggravated A/R injury. Activation of PPARβ/δ by GW0742 protected against I/R-induced liver damage, inflammation and cell death, whereas inhibition of PPARβ/δ by GSK0660 had the opposite effects. Consistent results were obtained in mouse I/R models through the tail vein injection of adenovirus-mediated PPARβ/δ overexpression or knockdown vectors. Furthermore, knockdown and overexpression of PPARβ/δ in KCs aggravated and ameliorated A/R-induced hepatocyte injury, respectively. Gene ontology and gene set enrichment analysis showed that PPARβ/δ deletion was significantly enriched in the NF-κB pathway. PPARβ/δ inhibited the expression of p-IKBα and p-P65 and decreased NF-κB activity.

CONCLUSIONS

PPARβ/δ exerts anti-inflammatory and anti-apoptotic effects on HIRI by inhibiting the NF-κB pathway, and hepatocytes and KCs may play a synergistic role in this phenomenon. Thus, PPARβ/δ is a potential therapeutic target for HIRI.

Skimmianine attenuates liver ischemia/reperfusion injury by regulating PI3K-AKT signaling pathway-mediated inflammation, apoptosis and oxidative stress

Liver ischemia/reperfusion (I/R) injury is a common injury after liver transplantation and hepatectomy. Skimmianine (Ski) has antibacterial, antiviral pharmacological effects. However, it is not clear whether Ski has a protective effect against liver I/R injury. In the present study, we established a mouse liver I/R model and an AML12 cell hypoxia-reoxygenation (H/R) model, both pretreated with different concentrations of Ski. Serum transaminase levels, necrotic liver area, cell viability, inflammatory factors, oxidative stress and apoptosis-related levels were measured to assess the protective effect of Ski against liver I/R injury. Western blotting was used to detect apoptosis-related proteins and PI3K-AKT pathway-related proteins. Mice and cells were also treated with PI3K inhibitor LY294002 to assess changes in indicators of liver injury. The results showed that Ski significantly reduced transaminase levels, liver necrosis area, oxidative stress, and apoptosis levels in mice with I/R. Ski also inhibited cell injury and apoptosis after H/R. Moreover, Ski activated phosphorylation of PI3K-AKT pathway-related proteins after liver I/R and cell H/R. Importantly, the PI3K inhibitor LY294002 effectively reversed the alleviation of I/R injury caused by Ski. These results confirm that Ski exerts a protective effect against liver I/R injury through activation of the PI3K-AKT pathway.

Unveiling the Crucial Roles of O2•- and ATP in Hepatic Ischemia-Reperfusion Injury Using Dual-Color/Reversible Fluorescence Imaging

Hepatic ischemia-reperfusion injury (HIRI) is mainly responsible for morbidity or death due to graft rejection after liver transplantation. During HIRI, superoxide anion (O2•-) and adenosine-5'-triphosphate (ATP) have been identified as pivotal biomarkers associated with oxidative stress and energy metabolism, respectively. However, how the temporal and spatial fluctuations of O2•- and ATP coordinate changes in HIRI and particularly how they synergistically regulate each other in the pathological mechanism of HIRI remains unclear. Herein, we rationally designed and successfully synthesized a dual-color and dual-reversible molecular fluorescent probe (UDP) for dynamic and simultaneous visualization of O2•- and ATP in real-time, and uncovered their interrelationship and synergy in HIRI. UDP featured excellent sensitivity, selectivity, and reversibility in response to O2•- and ATP, which rendered UDP suitable for detecting O2•- and ATP and generating independent responses in the blue and red fluorescence channels without spectral crosstalk. Notably, in situ imaging with UDP revealed for the first time synchronous O2•- bursts and ATP depletion in hepatocytes and mouse livers during the process of HIRI. Surprisingly, a slight increase in ATP was observed during reperfusion. More importantly, intracellular O2•-─succinate dehydrogenase (SDH)─mitochondrial (Mito) reduced nicotinamide adenine dinucleotide (NADH)─Mito ATP─intracellular ATP cascade signaling pathway in the HIRI process was unveiled which illustrated the correlation between O2•- and ATP for the first time. This research confirms the potential of UDP for the dynamic monitoring of HIRI and provides a clear illustration of HIRI pathogenesis.