Carbon Monoxide Regulates Macrophage Differentiation and Polarization toward the M2 Phenotype through Upregulation of Heme Oxygenase 1

Reprogram to heal: Macrophage phenotypes as living therapeutics

Macrophages represent a crucial cell type within the immune system, exhibiting significant adaptability that allows for the transformation into various phenotypes in response to their surrounding environment. This review investigates the characteristics of various macrophage phenotypes and their functional roles in disease pathogenesis and resolution. The M1 phenotype, recognized for its inflammatory attributes, plays a pivotal role in combating infections and tumors; however, it may also contribute to tissue injury, persistent inflammation, and the pathogenesis of autoimmune and inflammatory diseases. Conversely, the M2 phenotype is associated with anti-inflammatory activities and tissue repair processes. But this is not the end of the story and researches illustrated novel phenotypes that may provide new approaches and therapeutic opportunities. Recent progress in characterizing distinct macrophage phenotypes has enabled the development of innovative therapeutic strategies for chronic inflammatory conditions, autoimmune disorders, and cancers. This review underscores the critical role of macrophage polarization, illustrating how various stimuli can influence macrophage fate and modify their responses. Additionally, it explores the implications of macrophage plasticity on disease progression and treatment efficacy. A comprehensive understanding of these dynamics is essential for the advancement of targeted immunotherapies, which possess the potential to transform treatment strategies for a variety of medical conditions.

Carbon Monoxide Stimulates Chondrocyte Mitochondria and Protects Mitochondria During Cartilage Injury

Objective: Joint injury precipitates post-traumatic osteoarthritis (PTOA) via chondrocyte mitochondrial oxidative damage. Carbon monoxide (CO) is a small molecule with potent antioxidant and mitochondrial benefits in other tissues that have not been explored in healthy chondrocytes. We hypothesized that CO would subvert the mitochondrial effects of articular cartilage injuries upon resident chondrocytes. Design: We evaluated intra-articular delivery of a novel carbon monoxide-containing foam (COF). We used in vitro impact injuries to explore mitochondrial and redox endpoints after CO exposure. We then applied intra-articular injections of COF or control room air foam (RAF) to assess safety, efficacy, and other intra-articular responses. Results: COF increased the expression of HO1 and mitofusin-1 within 1 h and this increase was sustained for 12 h in vitro. COF increased chondrocyte mitochondrial respiration by 40% and increased reduced (not oxidized) thiols by 50% following in vitro injury to osteochondral explants. After cartilage injury, COF prevented the formation of 3-nitrotyrosine and the loss of articular chondrocyte mitochondria. When injected intra-articularly, COF was retained for 24 h post-injection in mouse stifle joints. It increased HO1 in those joints, enhanced reduced thiol levels in rabbit stifle joints, and exhibited no toxicity 1 and 4 weeks after injection. Conclusions: This study supports the hypothesis that CO functions as an antioxidant for articular chondrocytes by supporting mitochondria and intracellular GSH in the presence or absence of cartilage injury. Challenges in delivering exogenous CO have limited its preclinical development, but new CO-releasing materials like COF may enable new examinations of this promising small molecule.

Guardians of the Lung: The Multifaceted Roles of Macrophages in Cancer and Infectious Disease

The lung as an organ that is fully exposed to the external environment for extended periods, comes into contact with numerous inhaled microorganisms. Lung macrophages are crucial for maintaining lung immunity and operate primarily through signaling pathways such as toll-like receptor 4 and nuclear factor-κB pathways. These macrophages constitute a diverse population with significant plasticity, exhibiting different phenotypes and functions on the basis of their origin, tissue residence, and environmental factors. During lung homeostasis, they are involved in the clearance of inhaled particles, cellular remnants, and even participate in metabolic processes. In disease states, lung macrophages transition from the inflammatory M1 phenotype to the anti-inflammatory M2 phenotype. These distinct phenotypes have varying transcriptional profiles and serve different functions, from combating pathogens to repairing inflammation-induced damage. However, macrophages can also exacerbate lung injury during prolonged inflammation or exposure to antigens. In this review, we delve into the diverse roles of pulmonary macrophages the realms in homeostasis, pneumonia, tuberculosis, and lung tumors.

The Role of the Immune Response to Helicobacter pylori Antigens and Its Relevance in Gastric Disorders

Helicobacter pylori (H.p.) is a Gram-negative bacterium endowed with gastric tropism. H.p. infection is widely spread throughout the world, accounting for various pathologies, such as peptic ulcer, gastric cancer, mucosa-associated lymphoid tissue lymphoma, and extra-gastric manifestations. This bacterium possesses several virulence factors, e.g., lipopolysaccharides (LPS), the toxins CagA and VacA, and adhesins, which elicit a robust immune response during the initial phase of the infection. Of note, the lipid A moiety of the LPS exhibits a lower endotoxic potency than that of other LPSs, thus facilitating infection through a mechanism of immune escape. H.p. colonization of the gastric mucosa induces an initial protective immune response with innate immune cells, e.g., neutrophils, monocytes, and macrophages, which engulf and kill bacteria. Moreover, the same cells, along with gastric epithelial cells, secrete cytokines and chemokines, which recruit T cells [T helper (h)1 and Th17 cells] to the site of infection, thus leading to H.p. eradication. In a large subset of individuals, the perturbation of such an immune equilibrium leads to a harmful response, with an expansion of T regulatory (TREG) cells, which suppress the protective immune response. In fact, TREG cells, via the production of interleukin (IL)-10, downregulate Th1- and Th17-related cytokines, thus allowing H.p. survival and the perpetuation of inflammation. As far as the humoral immune response is concerned, B cells, upon H.p. stimulation, produce autoreactive antibodies, and IgG anti-Lex antibodies are harmful to the gastric mucosa. In this review, the structure and function of H.p. antigenic components and immune mechanisms elicited by this bacterium will be described in relation to gastric damage.

The Neural Palette of Heme: Altered Heme Homeostasis Underlies Defective Neurotransmission, Increased Oxidative Stress, and Disease Pathogenesis

Heme, a complex iron-containing molecule, is traditionally recognized for its pivotal role in oxygen transport and cellular respiration. However, emerging research has illuminated its multifaceted functions in the nervous system, extending beyond its canonical roles. This review delves into the diverse roles of heme in the nervous system, highlighting its involvement in neural development, neurotransmission, and neuroprotection. We discuss the molecular mechanisms by which heme modulates neuronal activity and synaptic plasticity, emphasizing its influence on ion channels and neurotransmitter receptors. Additionally, the review explores the potential neuroprotective properties of heme, examining its role in mitigating oxidative stress, including mitochondrial oxidative stress, and its implications in neurodegenerative diseases. Furthermore, we address the pathological consequences of heme dysregulation, linking it to conditions such as Alzheimer's disease, Parkinson's disease, and traumatic brain injuries. By providing a comprehensive overview of heme's multifunctional roles in the nervous system, this review underscores its significance as a potential therapeutic target and diagnostic biomarker for various neurological disorders.

Signaling Pathways Triggering Therapeutic Hydrogels in Promoting Chronic Wound Healing

In recent years, there has been a significant increase in the prevalence of chronic wounds, such as pressure ulcers, diabetic foot ulcers, and venous ulcers of the lower extremities. The main contributors to chronic wound formation are bacterial infection, prolonged inflammation, and peripheral vascular disease. However, effectively treating these chronic wounds remains a global challenge. Hydrogels have extensively explored as wound healing dressing because of their excellent biocompatibility and structural similarity to extracellular matrix (ECM). Nonetheless, much is still unknown how the hydrogels promote wound repair and regeneration. Signaling pathways play critical roles in wound healing process by controlling and coordinating cells and biomolecules. Hydrogels, along with their therapeutic ingredients that impact signaling pathways, have the potential to significantly enhance the wound healing process and its ultimate outcomes. Understanding this interaction will undoubtedly provide new insights into developing advanced hydrogels for wound repair and regeneration. This paper reviews the latest studies on classical signaling pathways and potential targets influenced by hydrogel scaffolds in chronic wound healing. This work hopes that it will offer a different perspective in developing more efficient hydrogels for treating chronic wounds.

Strategies of Helicobacter pylori in evading host innate and adaptive immunity: insights and prospects for therapeutic targeting

Helicobacter pylori (H. pylori) is the predominant pathogen causing chronic gastric mucosal infections globally. During the period from 2011 to 2022, the global prevalence of H. pylori infection was estimated at 43.1%, while in China, it was slightly higher at approximately 44.2%. Persistent colonization by H. pylori can lead to gastritis, peptic ulcers, and malignancies such as mucosa-associated lymphoid tissue (MALT) lymphomas and gastric adenocarcinomas. Despite eliciting robust immune responses from the host, H. pylori thrives in the gastric mucosa by modulating host immunity, particularly by altering the functions of innate and adaptive immune cells, and dampening inflammatory responses adverse to its survival, posing challenges to clinical management. The interaction between H. pylori and host immune defenses is intricate, involving evasion of host recognition by modifying surface molecules, manipulating macrophage functionality, and modulating T cell responses to evade immune surveillance. This review analyzes the immunopathogenic and immune evasion mechanisms of H. pylori, underscoring the importance of identifying new therapeutic targets and developing effective treatment strategies, and discusses how the development of vaccines against H. pylori offers new hope for eradicating such infections.

The Oxygen-Ozone Adjunct Medical Treatment According to the Protocols from the Italian Scientific Society of Oxygen-Ozone Therapy: How Ozone Applications in the Blood Can Influence Clinical Therapy Success via the Modulation of Cell Biology and Immunity

BACKGROUND

Ozone is an allotrope of oxygen whose use in medicine has rapidly grown in recent years. Ozonated blood allows for the use of ozone in a safe modality, as plasma and blood cells are endowed with an antioxidant system able to quench ozone's pro-oxidant property and to elicit the Nrf2/Kwap1/ARE pathway.

METHODS

We present two clinical studies, a case-series (six patients) observational study adopting ozone as a major autohemotherapy and topical ozone to address infected post-surgical wounds with multi-drug resistant bacteria and an observational study (250 patients) using ozonated blood for treating knee osteoarthritis.

RESULTS

Ozonated blood via major autohemotherapy reduced the extent of infections in wounds, reduced the inflammatory biomarkers by more than 75% and improved patients' QoL, whereas ozonated blood via minor autohemotherapy improved significantly (p < 0.001) WOMAC and Lequesne's parameters in knee osteoarthritis.

CONCLUSIONS

The models described, i.e., ozone autohemotherapy in wound antimicrobial treatment and ozonated blood in knee osteoarthrosis, following our protocols, share the outstanding ability of ozone to modulate the innate immune response and address bacterial clearance as well as inflammation and pain.

Activation of the Nrf-2/HO-1 signalling axis can alleviate metabolic syndrome in cardiovascular disease

Background: Cardiovascular disease (CVD) is widely observed in modern society. CVDs are responsible for the majority of fatalities, with heart attacks and strokes accounting for approximately 80% of these cases. Furthermore, a significant proportion of these deaths, precisely one-third, occurs in individuals under 70. Metabolic syndrome encompasses a range of diseases characterized by various physiological dysfunctions. These include increased inflammation in adipose tissue, enhanced cholesterol synthesis in the liver, impaired insulin secretion, insulin resistance, compromised vascular tone and integrity, endothelial dysfunction, and atheroma formation. These factors contribute to the development of metabolic disorders and significantly increase the likelihood of experiencing cardiovascular complications.Method: We selected studies that proposed hypotheses regarding metabolic disease syndrome and cardiovascular disease (CVD) and the role of Nrf2/HO-1 and factor regulation in CVD research investigations based on our searches of Medline and PubMed.Results: A total of 118 articles were included in the review, 16 of which exclusively addressed hypotheses about the role of Nrf2 on Glucose regulation, while 16 involved Cholesterol regulation. Likewise, 14 references were used to prove the importance of mitochondria on Nrf2. Multiple studies have provided evidence suggesting the involvement of Nrf2/HO-1 in various physiological processes, including metabolism and immune response. A total of 48 research articles and reviews have been used to highlight the role of metabolic syndrome and CVD.Conclusion: This review provides an overview of the literature on Nrf2/HO-1 and its role in metabolic disease syndrome and CVD.

The Role of Ozone as an Nrf2-Keap1-ARE Activator in the Anti-Microbial Activity and Immunity Modulation of Infected Wounds

Ozone is an allotrope of oxygen, widely known to exert an anti-oxidant potential. The ability of low, controlled and standardized doses of ozone in the ozone adjunct treatment of bacterial infections, which occur in wounds, is engaging clinical research to deepen the role of ozone in eradicating even multidrug-resistant bacteria. Ozone activates the nuclear factor erythroid 2-related factor 2 (Nrf2), and this activation triggers a complex cascade of events, which ultimately leads to macrophage training and an improvement in their ability to operate a clearance of bacteria in the patient's anatomical districts. In this review, we try to elucidate the recent evidence about the mechanisms with which ozone can actually remove bacteria and even multi-drug-resistant (MDR) bacteria, accounting on its complex ability in modulating immunity.

Heme oxygenase-1: The roles of both good and evil in neurodegenerative diseases

Heme oxygenase-1 (HO-1) is the only way for cells to decompose heme. It can cleave heme to produce carbon monoxide (CO), ferrous iron (Fe2+ ), and biliverdin (BV). BV is reduced to bilirubin (BR) by biliverdin reductase(BVR). In previous studies, HO-1 was considered to have protective effects because of its anti-inflammatory, anti-apoptosis, and antiproliferation functions. However, emerging experimental studies have found that the metabolites derived from HO-1 can cause increase iin intracellular oxidative stress, mitochondrial damage, iron death, and autophagy. Because of its particularity, it is very meaningful to understand its exact mechanism. In this review, we summarized the protective and toxic effects of HO-1, its potential mechanism, its role in neurodegenerative diseases and related drug research. This knowledge may be beneficial to the development of new therapies for neurodegenerative diseases and is crucial to the development of new therapeutic strategies and biomarkers.

Carbon Monoxide-Loaded Red Blood Cell Prevents the Onset of Cisplatin-Induced Acute Kidney Injury

Cisplatin-induced acute kidney injury (AKI) is an important factor that limits the clinical use of this drug for the treatment of malignancies. Oxidative stress and inflammation are considered to be the main causes of not only cisplatin-induced death of cancer cells but also cisplatin-induced AKI. Therefore, developing agents that exert antioxidant and anti-inflammatory effects without weakening the anti-tumor effects of cisplatin is highly desirable. Carbon monoxide (CO) has recently attracted interest due to its antioxidant, anti-inflammatory, and anti-tumor properties. Herein, we report that CO-loaded red blood cell (CO-RBC) exerts renoprotective effects on cisplatin-induced AKI. Cisplatin treatment was found to reduce cell viability in proximal tubular cells via oxidative stress and inflammation. Cisplatin-induced cytotoxicity, however, was suppressed by the CO-RBC treatment. The intraperitoneal administration of cisplatin caused an elevation in the blood urea nitrogen and serum creatinine levels. The administration of CO-RBC significantly suppressed these elevations. Furthermore, the administration of CO-RBC also reduced the deterioration of renal histology and tubular cell injury through its antioxidant and anti-inflammatory effects in cisplatin-induced AKI mice. Thus, our data suggest that CO-RBC has the potential to substantially prevent the onset of cisplatin-induced AKI, which, in turn, may improve the usefulness of cisplatin-based chemotherapy.

Research progress on gas signal molecular therapy for Parkinson's disease

The pathogenesis of Parkinson's disease (PD) remains unclear. Among the pathological manifestations is the progressive degeneration of the nigrostriatal dopaminergic pathway, leading to massive loss of neurons in the substantia nigra pars compacta and dopamine (DA) depletion. Therefore, the current drug treatment is primarily based on DA supplementation and delaying the progression of the disease. However, as patients' symptoms continue to worsen, the drug effect will gradually decrease or even disappear, thereby further aggravating clinical symptoms. Gas signaling molecules, such as hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and hydrogen (H2), exhibit pleiotropic biological functions and play crucial roles in physiological and pathological effects. In common neurodegenerative diseases including Alzheimer's disease and PD, gas signal molecules can prevent or delay disease occurrence via the primary mechanisms of antioxidation, anti-inflammatory response, and antiapoptosis. This article reviews the therapeutic progress of gas signaling molecules in PD models and discusses the possibility of their clinical applications.

Oral Nanotherapeutics of Andrographolide/Carbon Monoxide Donor for Synergistically Anti-inflammatory and Pro-resolving Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology affecting the colon and rectum. Current therapeutics are focused on suppressing inflammation but are ineffective. Combining anti-inflammatory therapeutic approaches with pro-resolution might be a superior strategy for UC treatment. Andrographolide (AG), an active compound from the plant Andrographis paniculata, presented anti-inflammatory effects in various inflammatory diseases. Gaseous mediators, such as carbon monoxide (CO), have a role in inflammatory resolution. Herein, we developed a dextran-functionalized PLGA nanocarrier for efficient delivery of AG and a carbon monoxide donor (CORM-2) for synergistically anti-inflammatory/pro-resolving treatment of UC (AG/CORM-2@NP-Dex) based on PLGA with good biocompatibility, slow drug release, efficient targeting, and biodegradability. The resulting nanocarrier had a nano-scaled diameter of ∼200 nm and a spherical shape. After being coated with dextran (Dex), the resulting AG/CORM-2@NP-Dex could be efficiently internalized by Colon-26 and Raw 264.7 cells in vitro and preferentially localized to the inflamed colon with chitosan/alginate hydrogel protection by gavage. AG/CORM-2@NP-Dex performed anti-inflammatory effects by eliminating the over-production of pro-inflammatory mediator, nitric oxide (NO), and down-regulating the expression of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), while it showed pro-resolving function by accelerating M1 to M2 macrophage conversion and up-regulating resolution-related genes (IL-10, TGF-β, and HO-1). In the colitis model, oral administration of AG/CORM-2@NP-Dex in a chitosan/alginate hydrogel also showed synergistically anti-inflammatory/pro-resolving effects, therefore relieving UC effectively. Without appreciable systemic toxicity, this bifunctional nanocarrier represents a novel therapeutic approach for UC and is expected to achieve long-term inflammatory remission.

Metalloporphyrins as Tools for Deciphering the Role of Heme Oxygenase in Renal Immune Injury

Renal immune injury is a frequent cause of end-stage renal disease, and, despite the progress made in understanding underlying pathogenetic mechanisms, current treatments to preserve renal function continue to be based mainly on systemic immunosuppression. Small molecules, naturally occurring biologic agents, show considerable promise in acting as disease modifiers and may provide novel therapeutic leads. Certain naturally occurring or synthetic Metalloporphyrins (Mps) can act as disease modifiers by increasing heme oxygenase (HO) enzymatic activity and/or synthesis of the inducible HO isoform (HO-1). Depending on the metal moiety of the Mp employed, these effects may occur in tandem or can be discordant (increased HO-1 synthesis but inhibition of enzyme activity). This review discusses effects of Mps, with varying redox-active transitional metals and cyclic porphyrin cores, on mechanisms underlying pathogenesis and outcomes of renal immune injury.

Carbon monoxide therapy: a promising strategy for cancer

Cancer is one of the acute life-threatening diseases endangering the whole of humanity. The treatment modalities for cancer are various. However, in most cases, a single treatment choice provides multiple side effects, poor targeting, and ineffective treatment. In recent years, the physiological regulatory function of carbon monoxide (CO) in the cancer process has been reported gradually, and CO-related nano-drugs have been explored. It shows better application prospects in cancer treatment and provides new ideas for treatment. The present review introduces the pathophysiological role of CO. The recent advances in cancer therapy, such as CO-mediated gas therapy, combined application of CO chemotherapy, photodynamic therapy (PDT), photothermal therapy (PTT), and immunotherapy, are described. Current challenges and future developments in CO-based treatment are also discussed. This review provides comprehensive information on recent advances in CO therapy and also some valuable guidance for promoting the progress of gas therapy nanomedicine.

HO-1: a new marker for predicting postoperative recurrence of CRSwNP

BACKGROUND

Chronic rhinosinusitis with polyps (CRSwNP) is a subtype of chronic rhinosinusitis and is highly prone to recurrence; therefore, it is urgent to find appropriate markers to predict recurrence of CRSwNP after surgery.

PURPOSE

We aim to investigate the expression of HO-1 in CRSwNP and assess its value of predicting postoperative recurrence of CRSwNP.

METHODS

We recruited 77 participants and collected clinical data of all. We use Immunohistochemical staining to determine the expression of HO-1 in tissues. We use Spearman correlation test to analyze the correlation between HO-1 positive cell count and clinical score, and ROC curve to assess the value of HO-1 positive cell count in predicting recurrence of CRSwNP.

RESULTS

HO-1 positive cells were macrophages and significantly increased in CRSwNP; HO-1 positive cell count was negatively correlated with preoperative SNOT-22 score; HO-1 can predict postoperative recurrence of CRSwNP, AUC = 0.80, p = 0.004.

CONCLUSION

HO-1 is a biochemical marker of CRSwNP and can predict postoperative recurrence of CRSwNP.

Heme oxygenase-1 ameliorates endotoxin-induced acute lung injury by modulating macrophage polarization via inhibiting TXNIP/NLRP3 inflammasome activation

Acute lung injury (ALI) remains a global public health issue without specific and effective treatment options available in the clinic. Alveolar macrophage polarization is involved in the initiation, development and progression of ALI; however, the underlying mechanism remains poorly understood. Heme oxygenase-1 (HO-1) acts as an antioxidant in pulmonary inflammation and has been demonstrated to be linked with the severity and prognosis of ALI. In this study, the therapeutic effects of HO-1 were examined, along with the mechanisms involved, mainly focusing on alveolar macrophage polarization. HO-1 depletion induced higher iNOS and CD86 (M1 phenotype) expression but was significantly decreased in Arg-1 and CD206 (M2 phenotype) expression in BALF alveolar macrophages after equivalent LPS stimulation. We also found that HO-1 deletion distinctly accelerated the expression of inflammasome-associated components NLRP3, ASC and caspase-1 in vivo and in vivo and in vitro. Moreover, on the basis of LPS for MH-S cells, levels of TXNIP, NLRP3, ASC and caspase-1 were increased and HO-1 depletion exacerbated these changes, whereas double depletion of HO-1 and TXNIP partially mitigated these elevations. Also, HO-1 knockdown induced more M1 phenotype and less M2 phenotype compared with LPS alone, whereas double silence of HO-1 and TXNIP partially changed the polarization state. Taken together, we demonstrated that HO-1 could modulate macrophage polarization via TXNIP/NLRP3 signaling pathway, which could be a potential therapeutic target for ALI treatment.

Signaling pathways in cutaneous wound healing

Wound healing is a very complex process, where variety of different pathways is activated, depending on the phase of healing. Improper or interrupted healing might result in development of chronic wounds. Therefore, novel approaches based on detailed knowledge of signalling pathways that are activated during acute or chronic cutaneous wound healing enables quicker and more effective healing. This review outlined new possibilities of cutaneous wound healing by modulation of some signalling molecules, e.g., gasotransmitters, or calcium. Special focus is given to gasotransmitters, since these bioactive signalling molecules that can freely diffuse into the cell and exert antioxidative effects. Calcium is an important booster of immune system and it can significantly contribute to healing process. Special interest is given to chronic wounds caused by diabetes mellitus and overcoming problems with the inflammation.

Microporous structures on mineralized collagen mediate osteogenesis by modulating the osteo-immune response of macrophages

It is a new hot pot in tissue engineering and regenerative medicine to study the effects of physicochemical properties of implanted biomaterials on regulating macrophage polarization to promote bone regeneration. In this study, we designed and fabricated mineralized collagen (MC) with different microporous structures via in vitro biomimetic mineralization method. The microporous structures, mechanical properties, shore hardness and water contact angle measurements were tested. Live/dead cell staining, CCK-8 assay, phalloidine staining, staining of focal adhesions were used to detect cell behavior. ELISA, qRT-PCR, ALP, and alizarin red staining (ARS) were performed to appraise osteogenic differentiation and investigated macrophage response and their subsequent effects on the osteogenic differentiation. The results showed that RAW264.7 and MC3T3-E1 cells were able to survive on the MC. MC with the microporous structure of approximately 84 μm and 70%–80% porosity could promote M2 macrophage polarization and increase the expression level of TGF-β and VEGF. Moreover, the gene expression of the osteogenic markers ALP, COL-1, and OCN increased. Therefore, MC with different microporous structures mediated osteoimmunomodulation in bone regeneration. These data will provide a new idea of biomaterials inducing bone repair and direct the optimal design of novel immune biomaterials, development, and rational usage.