Cathelicidin attenuates hyperoxia-induced kidney injury in newborn rats

The Mechanism of Hyperoxia-Induced Neonatal Renal Injury and the Possible Protective Effect of Resveratrol

With recent advances in neonatal intensive care, preterm infants are surviving into adulthood. Nonetheless, epidemiological data on the health status of these preterm infants have begun to reveal a worrying theme; prematurity and the supplemental oxygen therapy these infants receive after birth appear to be risk factors for kidney disease in adulthood, affecting their quality of life. As the incidence of chronic kidney disease and the survival time of preterm infants both increase, the management of the hyperoxia-induced renal disease is becoming increasingly relevant to neonatologists. The mechanism of this increased risk is currently unknown, but prematurity itself and hyperoxia exposure after birth may predispose to disease by altering the normal trajectory of kidney maturation. This article reviews altered renal reactivity due to hyperoxia, the possible mechanisms of renal injury due to hyperoxia, and the role of resveratrol in renal injury. KEY POINTS: · Premature infants commonly receive supplementary oxygen.. · Hyperoxia can cause kidney damage via signal pathways.. · We should reduce the occurrence of late sequelae..

A Self-Healing Multifunctional Hydrogel System Accelerates Diabetic Wound Healing through Orchestrating Immunoinflammatory Microenvironment

Developing an effective treatment strategy of drug delivery to improve diabetic wound healing remains a major challenge in clinical practice nowadays, due to multidrug-resistant bacterial infections, angiopathy, and oxidative damage in the wound microenvironment. Herein, an effective and convenient strategy was designed through a self-healing multiple-dynamic-bond cross-linked hydrogel with interpenetrating networks, which was formed by multiple-dynamic-bond cross-linking of reversible catechol-Fe³⁺ coordinate bonds, hydrogen bonding, and Schiff base bonds. The excellent autonomous healing of the hydrogel was initiated and accelerated by Schiff bonds with reversible breakage between 3,4-dihydroxybenzaldehyde containing catechol and aldehyde groups and chitosan chains, and further consolidated by the co-optation of other noncovalent interactions contributed of hydrogen bonding and Fe³⁺ coordinate bonds. Intriguingly, cathelicidin LL-37 was introduced and uniformly dispersed in the dynamic interpenetrating networks of the hydrogel as a bioactive molecular to orchestrate the diabetic wound healing microenvironment. This multifunctional wound dressing can significantly promote diabetic wound healing by antibacterial activity, immunomodulation, anti-inflammation, neovascularization, and antioxidant activity. Therefore, this study provided an effective and safe strategy for guiding the diabetic wound treatment in clinical applications.

Antimicrobial peptide cathelicidin LL-37 preserves intestinal barrier and organ function in rats with heat stroke

Global warming increases the incidence of heat stroke (HS) and HS causes the reduction of visceral blood flow during hyperthermia, leading to intestinal barrier disruption, microbial translocation, systemic inflammation and multiple organ failure. Cathelicidin LL-37 exhibits antimicrobial activities, helps innate immunity within the gut to maintain intestinal homeostasis, and augments intestinal wound healing and barrier function. Thus, we evaluated the effects and possible mechanisms of cathelicidin LL-37 on HS. Wistar rats were placed in a heating-chamber of 42 ̊C to induce HS. Changes in rectal temperature, hemodynamic parameters, and survival rate were measured during the experimental period. Blood samples and ilea were collected to analyze the effects of LL-37 on systemic inflammation, multiple organ dysfunction, and intestinal injury. Furthermore, LS174T and HT-29 cells were used to assess the underlying mechanisms. Our data showed cathelicidin LL-37 ameliorated the damage of intestinal cells induced by HS. Intestinal injury, systemic inflammation, and nitrosative stress (high nitric oxide level) caused by continuous hyperthermia were attenuated in HS rats treated with cathelicidin LL-37, and hence, improved multiple organ dysfunction, coagulopathy, and survival rate. These beneficial effects of cathelicidin LL-37 were attributed to the protection of intestinal goblet cells (by increasing transepithelial resistance, mucin-2 and Nrf2 expression) and the improvement of intestinal barrier function (less cyclooxygenase-2 expression and FITC-dextran translocation). Interestingly, high cathelicidin expression in the ileal samples of inflammatory bowel disease patients was associated with better clinical outcome. These results suggest that cathelicidin LL-37 could prevent heat stress-induced intestinal damage and heat-related illnesses.

Kidney Injuries and Evolution of Chronic Kidney Diseases Due to Neonatal Hyperoxia Exposure Based on Animal Studies

Preterm birth interrupts the development and maturation of the kidneys during the critical growth period. The kidneys can also exhibit structural defects and functional impairment due to hyperoxia, as demonstrated by various animal studies. Furthermore, hyperoxia during nephrogenesis impairs renal tubular development and induces glomerular and tubular injuries, which manifest as renal corpuscle enlargement, renal tubular necrosis, interstitial inflammation, and kidney fibrosis. Preterm birth along with hyperoxia exposure induces a pathological predisposition to chronic kidney disease. Hyperoxia-induced kidney injuries are influenced by several molecular factors, including hypoxia-inducible factor-1α and interleukin-6/Smad2/transforming growth factor-β, and Wnt/β-catenin signaling pathways; these are key to cell proliferation, tissue inflammation, and cell membrane repair. Hyperoxia-induced oxidative stress is characterized by the attenuation or the induction of multiple molecular factors associated with kidney damage. This review focuses on the molecular pathways involved in the pathogenesis of hyperoxia-induced kidney injuries to establish a framework for potential interventions.

Hyperoxia and Acute Kidney Injury: A Tale of Oxygen and the Kidney

Although oxygen supplementation is beneficial to support life in the clinic, excessive oxygen therapy also has been linked to damage to organs such as the lung or the eye. However, there is a lack of understanding of whether high oxygen therapy directly affects the kidney, leading to acute kidney injury, and what molecular mechanisms may be involved in this process. In this review, we revise our current understanding of the mechanisms by which hyperoxia leads to organ damage and highlight possible areas of investigation for the scientific community interested in novel mechanisms of kidney disease. Overall, we found a significant need for both animal and clinical studies evaluating the role of hyperoxia in inducing kidney damage. Thus, we urge the research community to further investigate oxygen therapy and its impact on kidney health with the goal of optimizing oxygen therapy guidelines and improving patient care.

Cathelicidin-NV from Nanorana ventripunctata effectively protects HaCaT cells, ameliorating ultraviolet B-induced skin photoaging

Cathelicidins are diverse effector molecules in the vertebrate immune system and are related to immune regulation, inflammatory response, wound healing, and blood vessel formation. However, little is known about their free radical scavenging ability, especially in vivo. In this study, a cathelicidin molecule (cathelicidin-NV, ARGKKECKDDRCRLLMKRGSFSYV) previously identified from the spot-bellied plateau frog (Nanorana ventripunctata) (Anura, Dicroglossidae, Dicroglossinae) by us was shown to alleviate ultraviolet B (UVB)-induced skin photoaging in mice. Cathelicidin-NV effectively suppressed cytotoxicity, DNA fragmentation, apoptosis and reduced the protein expression levels of JNK, c-Jun, and MMP-1, which are involved in the regulation of collagen degradation in HaCaT cells induced by UVB irradiation. Furthermore, cathelicidin-NV also scavenged UVB-induced intracellular reactive oxygen species (ROS). Taken together, cathelicidin-NV directly scavenged excessive intracellular ROS to protect HaCaT cells, and subsequently alleviated UVB-induced skin photoaging. This study extends reports on the antioxidant function of the cathelicidin family. In addition, the properties of cathelicidin-NV make it an excellent candidate for the prevention and treatment of UV-induced skin photoaging.

Anti-Tn Monoclonal Antibody Ameliorates Hyperoxia-Induced Kidney Injury by Suppressing Oxidative Stress and Inflammation in Neonatal Mice

The Tn antigen, an N-acetylgalactosamine structure linked to serine or threonine, has been shown to induce high-specificity, high-affinity anti-Tn antibodies in mice. Maternal immunization with the Tn vaccine increases serum anti-Tn antibody titers and attenuates hyperoxia-induced kidney injury in neonatal rats. However, immunizing mothers to treat neonatal kidney disease is clinically impractical. This study is aimed at determining whether anti-Tn monoclonal antibody treatment ameliorates hyperoxia-induced kidney injury in neonatal mice. Newborn BALB/c mice were exposed to room air (RA) or normobaric hyperoxia (85% O₂) for 1 week. On postnatal days 2, 4, and 6, the mice were injected intraperitoneally with PBS alone or with anti-Tn monoclonal antibodies at 25 μg/g body weight in 50 μL phosphate-buffered saline (PBS). The mice were divided into four study groups: RA + PBS, RA + anti-Tn monoclonal antibody, O₂ + PBS, and O₂ + anti-Tn monoclonal antibody. The kidneys were excised for histology, oxidative stress, cytokine, and Western blot analyses on postnatal day 7. The O₂ + PBS mice exhibited significantly higher kidney injury scores, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and nuclear factor-κB (NF-κB) expression, and cytokine levels than did the RA + PBS mice or RA + anti-Tn mice. Anti-Tn monoclonal antibody treatment reduced kidney injury and cytokine levels to normoxic levels. The attenuation of kidney injury was accompanied by a reduction of oxidative stress and NF-κB expression. Therefore, we propose that anti-Tn monoclonal antibody treatment ameliorates hyperoxia-induced kidney injury by suppressing oxidative stress and inflammation in neonatal mice.

Cathelicidin attenuates hyperoxia-induced lung injury by inhibiting oxidative stress in newborn rats

PURPOSE

High concentrations of oxygen administered to newborn infants with respiratory failure increases oxidant stress and leads to lung injury, characterized by decreased alveolar and capillary development. Cathelicidin belongs to an important group of human antimicrobial peptides that exhibit antioxidant activity; its overexpression reduces hyperoxia-induced oxidative stress. This study evaluated the therapeutic effects of cathelicidin in hyperoxia-induced lung injury in newborn rats.

METHODS AND MATERIALS

Sprague Dawley rat pups were reared in either room air (RA) or hyperoxia (85% O₂) and then randomly treated with low-dose (4 mg/kg) and high-dose (8 mg/kg) cathelicidin in 0.05 mL of normal saline (NS) administered intraperitoneally on postnatal days 1-6. The following six groups were obtained: RA + NS, RA + low-dose cathelicidin, RA + high-dose cathelicidin, O₂ + NS, O₂ + low-dose cathelicidin, and O₂ + high-dose cathelicidin. Lungs were harvested for Western blot and histological analyses on postnatal day 7.

RESULTS

Compared with the RA-reared rats, the hyperoxia-reared rats exhibited significantly lower body weights, higher mean linear intercept (MLI), lung injury score, interleukin-6, and oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) expression but lower superoxide dismutase 1 (SOD1) and vascular endothelial growth factor (VEGF) protein expression and vascular density. Cathelicidin treatment attenuated hyperoxia-induced lung injury as demonstrated by lower MLI and injury score and higher VEGF expression and vascular density.

CONCLUSIONS

Cathelicidin attenuated hyperoxia-induced lung injury and caused a decrease in 8-OHdG and SOD1 protein expression, most likely by inhibiting oxidative stress in the lung.