The Morphology of Nasal Polyps in Different Age Groups: Histopathological Features

BACKGROUND

Nasal polyps (NPs) represent the end-stage manifestation of chronic rhinosinusitis (CRS), a relatively common pathological condition encountered in all ages of life.

METHODOLOGY

The aim of our study was to evaluate the histological features and inflammatory cellular components of NPs in a retrospective cohort (143 cases) of pediatric, adult and elderly populations in order to discuss the possible morphological age-related differences statistically documented.

RESULTS

In the pediatric group, the inflammatory infiltrate presented many eosinophils mixed with lymphocytes, while in the adult population, lymphocytes and plasma cells were mainly evident, frequently with a perivascular distribution or with the formation of subepithelial lymphoid nodules. In the elderly population, inflammation was less evident and was associated with cavernous-like angecthatic structures with thrombotic stratification. Nearly all morphological findings exhibited statistically significant values among differently aged subgroups.

CONCLUSIONS

Our results support the presence of histological specificities of NPs at different ages of life, providing new insight into the etiopathogenesis of NPs. The future role of biological therapies, mainly in cases refractory to already available standard medical and surgical treatments, may be analyzed by a prospective study using a larger cohort with a long-term evaluation also in relation to a possible relapse.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

A new approach for the treatment of bleomycin-induced rat pulmonary injury by combined protein fraction of major royal jelly protein 2 and its isoform X1

Nowadays, royal jelly (RJ) has gained great interest as a functional food due to its valuable pharmacological effects. We investigated the therapeutic potency of combined protein fraction (PF50) of major RJ protein 2 and its isoform X1 on bleomycin (Bleo)-induced pulmonary injury in rats. Our study examined the impact of PF50 on pulmonary oxidative and inflammatory stress as well as smooth muscle alpha-actin (α-SMA). In addition, the predicted impacts of this PF on the activity of matrix metalloproteinase (MMP)- 8 and 15-prostaglandin dehydrogenase (15-PGDH) and the E-type prostanoid 2 (EP2) and IL-13 α2 subunit (IL13α2R) receptors, were evaluated using molecular docking. The results showed that PF50 reduced pulmonary inflammatory cells and their secreted pro-inflammatory mediators, including NF-κB, IKK, IL-4, IL-6, and NO. Additionally, the levels of IgE and mucin were diminished after treatment with PF50. Moreover, PF50 treatment improved pulmonary oxidative stress indices such as lipid peroxidation, GSH, SOD, and GPX. The histopathological findings, chest conventional X-ray, and immunohistochemistry of α-SMA confirmed the ameliorating effect of PF50. The docking outcomes reported the probable competitive inhibitory influence of PF50 on MMP-8 and a postulated blocking effect on EP2 and IL13α2R. Thus, PF50 could be a novel approach for treating pulmonary injuries.

Polysulfide nanoparticles inhibit fibroblast-to-myofibroblast transition via extracellular ROS scavenging and have potential anti-fibrotic properties

This paper is about the effects of reactive oxygen species (ROS) - and of their nanoparticle-mediated extracellular removal - in the TGF-β1-induced differentiation of fibroblasts (human dermal fibroblasts - HDFa) to more contractile myofibroblasts, and in the maintenance of this phenotype. Here, poly(propylene sulfide) (PPS) nanoparticles have been employed on 2D and 3D in vitro models, showing extremely low toxicity and undergoing negligible internalization, thereby ensuring an extracellular-only action. Firstly, PPS nanoparticles abrogated ROS-mediated downstream molecular events such as glutathione oxidation, NF-κB activation, and heme oxidase-1 (HMOX) overexpression. Secondly, PPS nanoparticles were also capable to inhibit, prevent and reverse the TGF-β1-induced upregulation of key biomechanical elements, such as ED-a fibronectin (EF-A FN) and alpha-smooth muscle actin (α-SMA), respectively markers of protomyofibroblastic and of myofibroblastic differentiation. We also confirmed that ROS alone are ineffective promoters of the myofibroblastic transition, although their presence contributes to its stabilization. Finally, the particles also countered TGF-β1-induced matrix- and tissue-level phenomena, e.g., the upregulation of collagen type 1, the development of aberrant collagen type 1/3 ratios and the contracture of HDFa 3D-seeded fibrin constructs. In short, experimental data at molecular, cellular and tissue levels show a significant potential in the use of PPS nanoparticles as anti-fibrotic agents.

The role of hypoxia in the pathophysiology of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal cavity characterized by excessive nasal mucus secretion and nasal congestion. The development of CRS is related to pathological mechanisms induced by hypoxia. Under hypoxic conditions, the stable expression of both Hypoxia inducible factor-1 (HIF-1) α and HIF-2α are involved in the immune response and inflammatory pathways of CRS. The imbalance in the composition of nasal microbiota may affect the hypoxic state of CRS and perpetuate existing inflammation. Hypoxia affects the differentiation of nasal epithelial cells such as ciliated cells and goblet cells, induces fibroblast proliferation, and leads to epithelial-mesenchymal transition (EMT) and tissue remodeling. Hypoxia also affects the proliferation and differentiation of macrophages, eosinophils, basophils, and mast cells in sinonasal mucosa, and thus influences the inflammatory state of CRS by regulating T cells and B cells. Given the multifactorial nature in which HIF is linked to CRS, this study aims to elucidate the effect of hypoxia on the pathogenic mechanisms of CRS.

Immunological Aspects of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is related to persistent inflammation with a dysfunctional relationship between environmental agents and the host immune system. Disturbances in the functioning of the sinus mucosa lead to common clinical symptoms. The major processes involved in the pathogenesis of CRS include airway epithelial dysfunctions that are influenced by external and host-derived factors which activate multiple immunological mechanisms. The molecular bases for CRS remain unclear, although some factors commonly correspond to the disease: bacterial, fungal and viral infections, comorbidity diseases, genetic dysfunctions, and immunodeficiency. Additionally, air pollution leads increased severity of symptoms. CRS is a heterogeneous group of sinus diseases with different clinical courses and response to treatment. Immunological pathways vary depending on the endotype or genotype of the patient. The recent knowledge expansion into mechanisms underlying the pathogenesis of CRS is leading to a steadily increasing significance of precision medicine in the treatment of CRS. The purpose of this review is to summarize the current state of knowledge regarding the immunological aspects of CRS, which are essential for ensuring more effective treatment strategies.

Hypoxia induces proliferation via NOX4-Mediated oxidative stress and TGF-β3 signaling in uterine leiomyoma cells

Uterine leiomyomas, the most common tumors of the female reproductive system, are known to have a hypoxic microenvironment. However, the role of such environment in leiomyoma pathobiology remains unknown. The objective was to determine the effects of hypoxia on leiomyoma cells, and the mechanisms. We found that hypoxia induces proliferation and inhibits apoptosis in human leiomyoma cells. This pro-proliferative effect was accompanied by an increase in reactive oxygen species (ROS) generation and the expression of NADPH oxidase 4 (NOX4). The specific NOX4 inhibitor GLX351322 abrogated this hypoxia-induced ROS generation, cellular proliferation, and apoptosis inhibition. To further investigate the mechanism of NOX4-mediated proliferation, we treated leiomyoma cells grown in normoxia with media from leiomyoma cells cultured under hypoxia. This resulted in increased ROS generation and NOX4 expression, suggesting the hypoxia-induced effects are mediated by an autocrine mechanism. We worked to identify the nature of this autocrine factor. We found that the expression of TGF-β3 and its downstream signaling target pSmad3, are increased in hypoxic leiomyoma cells. To examine the hypothesis that TGF-β3 is, at least, a part of this autocrine mechanism, we treated hypoxic leiomyoma cells with the HIF-1α inhibitor KC7F2 which we discovered to ameliorate the hypoxia-induced TGF-β3 expression. Furthermore, pharmacologic inhibition with the TGF-β/Smad inhibitor SB431542 reduced hypoxia-induced NOX4 expression and ROS generation and attenuated cell proliferation. Thus, we have identified a novel mechanism by which hypoxia induces proliferation in leiomyoma cells. This finding adds to our understanding of leiomyoma pathobiology and can help in identifying new therapeutic targets.

Therapeutic potential of topical administration of acriflavine against hypoxia-inducible factors for corneal fibrosis

Transdifferentiation of keratocytes into fibroblasts or further into myofibroblasts, which produced denser and more disorganized extracellular matrix, is the major cause of corneal fibrosis and scarring, leading to corneal blindness. TGF-β1 is the critical cytokine for the myofibroblast's transdifferentiation and survival. Hypoxia Inducible Factor (HIF) was found to play an important role in promoting fibrosis in lung, kidney, and dermal tissues recently. Our preliminary study demonstrated that topical administration of the acriflavine (ACF), a drug inhibiting HIF dimerization, delayed corneal opacity and neovascularization after the alkali burn. To know whether ACF could prevent corneal fibrosis and improve corneal transparency, we created a mouse mechanical corneal injury model and found that topical administration of ACF significantly inhibited corneal fibrosis at day 14 post-injury. The reduction of myofibroblast marker α-SMA, and fibronectin, one of the disorganized extracellular matrix molecules, in the corneal stroma were confirmed by the examination of immunohistochemistry and real-time PCR. Furthermore, the ACF inhibited the expression of α-SMA and fibronectin in both TGF-β1 stimulated or unstimulated fibroblasts in vitro. This effect was based on the inhibition of HIF signal pathways since the levels of the HIF-1α downstream genes including Slc2a1, Bnip3 and VEGFA were downregulated. To our knowledge, this is the first time to implicate that HIFs might be a new treatment target for controlling corneal fibrosis in mechanical corneal injuries.

NADPH oxidase 4 mediates TGF-β1/Smad signaling pathway induced acute kidney injury in hypoxia

Hypoxia is an important cause of acute kidney injury (AKI) in various conditions because kidneys are one of the most susceptible organs to hypoxia. In this study, we investigated whether nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidase 4 (Nox4) plays a role in hypoxia induced AKI in a cellular and animal model. Expression of Nox4 in cultured human renal proximal tubular epithelial cells (HK-2) was significantly increased by hypoxic stimulation. TGF-β1 was endogenously secreted by hypoxic HK-2 cells. SB4315432 (a TGF-β1 receptor I inhibitor) significantly inhibited Nox4 expression in HK-2 cells through the Smad-dependent cell signaling pathway. Silencing of Nox4 using Nox4 siRNA and pharmacologic inhibition with GKT137831 (a specific Nox1/4 inhibitor) reduced the production of ROS and attenuated the apoptotic pathway. In addition, knockdown of Nox4 increased cell survival in hypoxic HK-2 cells and pretreatment with GKT137831 reproduce these results. This study demonstrates that hypoxia induces HK-2 cell apoptosis through a signaling pathway involving TGF-β1 via Smad pathway induction of Nox4-dependent ROS generation. In an ischemia/reperfusion rat model, pretreatment of GKT137831 attenuated ischemia/reperfusion induced acute kidney injury as indicated by preserved kidney function, attenuated renal structural damage and reduced apoptotic cells. Therapies targeting Nox4 may be effective against hypoxia-induced AKI.

Scleral hypoxia is a target for myopia control

Worldwide, myopia is the leading cause of visual impairment. It results from inappropriate extension of the ocular axis and concomitant declines in scleral strength and thickness caused by extracellular matrix (ECM) remodeling. However, the identities of the initiators and signaling pathways that induce scleral ECM remodeling in myopia are unknown. Here, we used single-cell RNA-sequencing to identify pathways activated in the sclera during myopia development. We found that the hypoxia-signaling, the eIF2-signaling, and mTOR-signaling pathways were activated in murine myopic sclera. Consistent with the role of hypoxic pathways in mouse model of myopia, nearly one third of human myopia risk genes from the genome-wide association study and linkage analyses interact with genes in the hypoxia-inducible factor-1α (HIF-1α)-signaling pathway. Furthermore, experimental myopia selectively induced HIF-1α up-regulation in the myopic sclera of both mice and guinea pigs. Additionally, hypoxia exposure (5% O₂) promoted myofibroblast transdifferentiation with down-regulation of type I collagen in human scleral fibroblasts. Importantly, the antihypoxia drugs salidroside and formononetin down-regulated HIF-1α expression as well as the phosphorylation levels of eIF2α and mTOR, slowing experimental myopia progression without affecting normal ocular growth in guinea pigs. Furthermore, eIF2α phosphorylation inhibition suppressed experimental myopia, whereas mTOR phosphorylation induced myopia in normal mice. Collectively, these findings defined an essential role of hypoxia in scleral ECM remodeling and myopia development, suggesting a therapeutic approach to control myopia by ameliorating hypoxia.

Reciprocal regulation of TGF-β and reactive oxygen species: A perverse cycle for fibrosis

Transforming growth factor beta (TGF-β) is the most potent pro-fibrogenic cytokine and its expression is increased in almost all of fibrotic diseases. Although signaling through Smad pathway is believed to play a central role in TGF-β's fibrogenesis, emerging evidence indicates that reactive oxygen species (ROS) modulate TGF-β's signaling through different pathways including Smad pathway. TGF-β1 increases ROS production and suppresses antioxidant enzymes, leading to a redox imbalance. ROS, in turn, induce/activate TGF-β1 and mediate many of TGF-β's fibrogenic effects, forming a vicious cycle (see graphic flow chart on the right). Here, we review the current knowledge on the feed-forward mechanisms between TGF-β1 and ROS in the development of fibrosis. Therapeutics targeting TGF-β-induced and ROS-dependent cellular signaling represents a novel approach in the treatment of fibrotic disorders.

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TGF-β1 is the most potent ubiquitous profibrogenic cytokine.

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TGF- β 1 induces redox imbalance by ↑ ROS production and ↓ anti-oxidant defense system

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Redox imbalance, in turn, activates latent TGF-β1 and induces TGF-β1 expression.

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Redox imbalance also mediates many of TGF-β1’s profibrogenic effects

Complement-dependent NADPH oxidase enzyme activation in renal ischemia/reperfusion injury

NADPH oxidase plays a central role in mediating oxidative stress during heart, liver, and lung ischemia/reperfusion injury, but limited information is available about NADPH oxidase in renal ischemia/reperfusion injury. Our aim was to investigate the activation of NADPH oxidase in a swine model of renal ischemia/reperfusion damage. We induced renal ischemia/reperfusion in 10 pigs, treating 5 of them with human recombinant C1 inhibitor, and we collected kidney biopsies before ischemia and 15, 30, and 60 min after reperfusion. Ischemia/reperfusion induced a significant increase in NADPH oxidase 4 (NOX-4) expression at the tubular level, an upregulation of NOX-2 expression in infiltrating monocytes and myeloid dendritic cells, and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis along with a marked upregulation of NADPH-dependent superoxide generation. This burden of oxidative stress was associated with an increase in tubular and interstitial expression of the myofibroblast marker α-smooth muscle actin (α-SMA). Interestingly, NOX-4 and NOX-2 expression and the overall NADPH oxidase activity as well as α-SMA expression and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis were strongly reduced in C1-inhibitor-treated animals. In vitro, when we incubated tubular cells with the anaphylotoxin C3a, we observed an enhanced NADPH oxidase activity and α-SMA protein expression, which were both abolished by NOX-4 silencing. In conclusion, our findings suggest that NADPH oxidase is activated during ischemia/reperfusion in a complement-dependent manner and may play a potential role in the pathogenesis of progressive renal damage in this setting.

Hypoxia preconditioned mesenchymal stem cells prevent cardiac fibroblast activation and collagen production via leptin

AIMS

Activation of cardiac fibroblasts into myofibroblasts constitutes a key step in cardiac remodeling after myocardial infarction (MI), due to interstitial fibrosis. Mesenchymal stem cells (MSCs) have been shown to improve post-MI remodeling an effect that is enhanced by hypoxia preconditioning (HPC). Leptin has been shown to promote cardiac fibrosis. The expression of leptin is significantly increased in MSCs after HPC but it is unknown whether leptin contributes to MSC therapy or the fibrosis process. The objective of this study was to determine whether leptin secreted from MSCs modulates cardiac fibrosis.

METHODS

Cardiac fibroblast (CF) activation was induced by hypoxia (0.5% O2). The effects of MSCs on fibroblast activation were analyzed by co-culturing MSCs with CFs, and detecting the expression of α-SMA, SM22α, and collagen IαI in CFs by western blot, immunofluorescence and Sirius red staining. In vivo MSCs antifibrotic effects on left ventricular remodeling were investigated using an acute MI model involving permanent ligation of the left anterior descending coronary artery.

RESULTS

Co-cultured MSCs decreased fibroblast activation and HPC enhanced the effects. Leptin deficit MSCs from Ob/Ob mice did not decrease fibroblast activation. Consistent with this, H-MSCs significantly inhibited cardiac fibrosis after MI and mediated decreased expression of TGF-β/Smad2 and MRTF-A in CFs. These effects were again absent in leptin-deficient MSCs.

CONCLUSION

Our data demonstrate that activation of cardiac fibroblast was inhibited by MSCs in a manner that was leptin-dependent. The mechanism may involve blocking TGF-β/Smad2 and MRTF-A signal pathways.

Myofibroblast differentiation: main features, biomedical relevance, and the role of reactive oxygen species

SIGNIFICANCE

Myofibroblasts are prototypical fibrotic cells, which are involved in a number of more or less pathological conditions, from foreign body reactions to scarring, from liver, kidney, or lung fibrosis to neoplastic phenomena. The differentiation of precursor cells (not only of fibroblastic nature) is characterized by a complex interplay between soluble factors (growth factors such as transforming growth factor β1, reactive oxygen species [ROS]) and material properties (matrix stiffness).

RECENT ADVANCES

The last 15 years have seen very significant advances in the identification of appropriate differentiation markers, in the understanding of the differentiation mechanism, and above all, the involvement of ROS as causative and persistence factors.

CRITICAL ISSUES

The specific mechanisms of action of ROS remain largely unknown, although evidence suggests that both intracellular and extracellular phenomena play a role.

FUTURE DIRECTIONS

Approaches based on antioxidant (ROS-scavenging) principles and on the potentiation of nitric oxide signaling hold much promise in view of a pharmacological therapy of fibrotic phenomena. However, how to make the active principles available at the target sites is yet a largely neglected issue.

Redox signaling as a therapeutic target to inhibit myofibroblast activation in degenerative fibrotic disease

Degenerative fibrotic diseases encompass numerous systemic and organ-specific disorders. Despite their associated significant morbidity and mortality, there is currently no effective antifibrotic treatment. Fibrosis is characterized by the development and persistence of myofibroblasts, whose unregulated deposition of extracellular matrix components disrupts signaling cascades and normal tissue architecture leading to organ failure and death. The profibrotic cytokine transforming growth factor beta (TGFβ) is considered the foremost inducer of fibrosis, driving myofibroblast differentiation in diverse tissues. This review summarizes recent in vitro and in vivo data demonstrating that TGF β-induced myofibroblast differentiation is driven by a prooxidant shift in redox homeostasis. Elevated NADPH oxidase 4 (NOX4)-derived hydrogen peroxide (H2O2) supported by concomitant decreases in nitric oxide (NO) signaling and reactive oxygen species scavengers are central factors in the molecular pathogenesis of fibrosis in numerous tissues and organs. Moreover, complex interplay between NOX4-derived H2O2 and NO signaling regulates myofibroblast differentiation. Restoring redox homeostasis via antioxidants or NOX4 inactivation as well as by enhancing NO signaling via activation of soluble guanylyl cyclases or inhibition of phosphodiesterases can inhibit and reverse myofibroblast differentiation. Thus, dysregulated redox signaling represents a potential therapeutic target for the treatment of wide variety of different degenerative fibrotic disorders.

The development of nasal polyp disease involves early nasal mucosal inflammation and remodelling

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by both a chronic inflammation and tissue remodelling; as indicated by extracellular matrix protein deposition, basement membrane thickening, goblet cell hyperplasia and subepithelial edema, with reduced vessels and glands. Although remodelling is generally considered to be consequence of persistent inflammation, the chronological order and relationship between inflammation and remodelling in polyp development is still not clear. The aim of our study was therefore to investigate the pathological features prevalent in the development of nasal polyps and to elucidate the chronological order and relationship between inflammation and remodelling, by comparing specific markers of inflammation and remodelling in early stage nasal polyps confined to the middle turbinate (refer to as middle turbinate CRSwNP) obtained from 5 CRSwNP patients with bilateral polyposis, mature ethmoidal polyps from 6 CRSwNP patients, and normal nasal mucosal tissue from 6 control subjects. Middle turbinate CRSwNP demonstrated significantly more severe epithelial loss compared to mature ethmoidal polyps and normal nasal mucosa. The epithelial cell junction molecules E-cadherin, ZO-1 and occludin were also expressed in significantly lower amounts in mature ethmoidal polyps compared to healthy mucosa. Middle turbinate CRSwNP were further characterized by significantly increased numbers of subepithelial eosinophils and M2 type macrophages, with a distinct lack of collagen and deposition of fibronectin in polyp part. In contrast, the turbinate area of the middle turbinate CRSwNP was characterized by an increase in TGF-β activated myofibroblasts expressing α-SMA and vimentin, an increase in the number of pSmad2 positive cells, as well as increased deposition of collagen. These findings suggest a complex network of processes in the formation of CRSwNP; including gross epithelial damage and repair reactions, eosinophil and macrophage cell infiltration, and tissue remodelling. Furthermore, remodelling appears to occur in parallel, rather than subsequent to inflammation.