ALOX15+ M2 macrophages contribute to epithelial remodeling in eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Epithelial remodeling is a prominent feature of eosinophilic chronic rhinosinusitis with nasal polyps (eCRSwNP), and infiltration of M2 macrophages plays a pivotal role in the pathogenesis of eCRSwNP, but the underlying mechanisms remain undefined.

OBJECTIVE

We aimed to investigate the role of ALOX15+ M2 macrophages in the epithelial remodeling of eCRSwNP.

METHODS

Digital spatial transcriptome and single-cell sequencing analyses were used to characterize the epithelial remodeling and cellular infiltrate in eCRSwNP. Hematoxylin and eosin staining, immunohistochemical and immunofluorescent staining were used to explore the relationship between ALOX15+ M2 (CD68+CD163+) macrophages and epithelial remodeling. A co-culture system of primary human nasal epithelial cells (hNECs) and the macrophage cell line THP-1 was used to determine the underlying mechanisms.

RESULTS

Spatial transcriptomics analysis showed that upregulation of epithelial remodeling-related genes, such as VIM and MMP10, and enrichment of epithelial-mesenchymal transition (EMT)-related pathways, in the epithelial areas in eCRSwNP, with more abundance of epithelial basal, goblet and glandular cells. Single-cell analysis identified ALOX15+, rather ALOX15-, M2 macrophages were specifically highly expressed in eCRSwNP. CRSwNP with high ALOX15+ M2THP-1-IL-4+IL-13 macrophages had more obvious epithelial remodeling features and increased genes associated with epithelial remodeling and integrity of epithelial morphology versus that with low ALOX15+ M2THP-1-IL-4+IL-13 macrophages. IL-4/13-polarized M2THP-1-IL-4+IL-13 macrophages upregulated expressions of EMT-related genes in hNECs, including VIM, TWIST1, Snail, and ZEB1. ALOX15 inhibition in M2THP-1-IL-4+IL-13 macrophages resulted in reduction of the EMT-related transcripts in hNECs. Blocking CCL13 signaling inhibited M2THP-1-IL-4+IL-13 macrophage-induced EMT alteration in hNECs.

CONCLUSION

ALOX15+ M2 macrophages are specifically increased in eCRSwNP and may contribute to the pathogenesis of epithelial remodeling via production of CCL13.

Anti-diabetic and anti-inflammatory bioactive hits from Coriaria intermedia Matsum. stem and Dracontomelon dao (Blanco) Merr. & Rolfe bark through bioassay-guided fractionation and liquid chromatography-tandem mass spectrometry

Women have been found to be at a higher risk of morbidity and mortality from type 2 diabetes mellitus (T2DM) and asthma. α-Glucosidase inhibitors have been used to treat T2DM, and arachidonic acid 15-lipoxygenase (ALOX15) inhibitors have been suggested to be used as treatments for asthma and T2DM. Compounds that inhibit both enzymes may be studied as potential treatments for people with both T2DM and asthma. This study aimed to determine potential anti-diabetic and anti-inflammatory bioactive hits from Coriaria intermedia Matsum. stem and Dracontomelon dao (Blanco) Merr. & Rolfe bark. A bioassay-guided fractionation framework was used to generate bioactive fractions from C. intermedia stem and D. dao bark. Subsequently, dereplication through ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and database searching was performed to putatively identify the components of one bioactive fraction from each plant. Seven compounds were putatively identified from the C. intermedia stem active fraction, and six of these compounds were putatively identified from this plant for the first time. Nine compounds were putatively identified from the D. dao bark active fraction, and seven of these compounds were putatively identified from this plant for the first time. One putative compound from the C. intermedia stem active fraction (corilagin) has been previously reported to have inhibitory activity against both α-glucosidase and 15-lipoxygenase-1. It is suggested that further studies on the potential of corilagin as an anti-diabetic and anti-inflammatory treatment should be pursued based on its several beneficial pharmacological activities and its low reported toxicity.

Cannabidiol acts as molecular switch in innate immune cells to promote the biosynthesis of inflammation-resolving lipid mediators

Cannabinoids are phytochemicals from cannabis with anti-inflammatory actions in immune cells. Lipid mediators (LM), produced from polyunsaturated fatty acids (PUFA), are potent regulators of the immune response and impact all stages of inflammation. How cannabinoids influence LM biosynthetic networks is unknown. Here, we reveal cannabidiol (CBD) as a potent LM class-switching agent that stimulates the production of specialized pro-resolving mediators (SPMs) but suppresses pro-inflammatory eicosanoid biosynthesis. Detailed metabololipidomics analysis in human monocyte-derived macrophages showed that CBD (i) upregulates exotoxin-stimulated generation of SPMs, (ii) suppresses 5-lipoxygenase (LOX)-mediated leukotriene production, and (iii) strongly induces SPM and 12/15-LOX product formation in resting cells by stimulation of phospholipase A2-dependent PUFA release and through Ca2+-independent, allosteric 15-LOX-1 activation. Finally, in zymosan-induced murine peritonitis, CBD increased SPM and 12/15-LOX products and suppressed pro-inflammatory eicosanoid levels in vivo. Switching eicosanoid to SPM production is a plausible mode of action of CBD and a promising inflammation-resolving strategy.

Functional and pathological role of 15-Lipoxygenase and its metabolites in pregnancy and pregnancy-associated complications

Maternal lipid metabolism status during pregnancy may have pivotal effects on a healthy pregnancy, the progression of labor, and childbirth. Based on evidence, changes in maternal lipid profile and metabolism is related to various alterations in fetal metabolic status, fat mass, birth weight and can result in serious maternal and fetal complications. 15-lipoxygenase accounts as a key enzyme in metabolizing polyunsaturated fatty acids that generate various inflammatory lipid metabolites. The possible involvement of 15- lipoxygenase and its metabolites in the inflammatory process, cell proliferation and death, and immune response has been postulated. The indicative role of the 15- lipoxygenase enzymatic pathway in the implantation process, stages of pregnancy, embryogenesis, organogenesis, progression of labor, pregnancy period, and pregnancy-associated complications is remarkable. Accordingly, this study will review the research conducted on the role of 15- lipoxygenase in different reproductive tissues, and its pathological role in pregnancy-related diseases to provide more insight regarding the emerging role of 15-lipoxygenase in normal pregnancy.

15-Lipoxygenase and its metabolites in the pathogenesis of breast cancer: A double-edged sword

15-lipoxygenase is one of the key enzymes for the metabolism of unsaturated fatty acids that its manipulation has been proposed recently as a new molecular target for regulating cancer cell growth. Aberrant expression of 15-lipoxygenase enzyme seems to play an indicative role in the pathology of different cancer types, tumor progression, metastasis, or apoptosis. Based on the fact that breast cancer is one of the most common cancers that imposes a burden of mortality in women also, on the other hand, evidence in experimental models and human studies indicate the emerging role of the 15-lipoxygenase pathway in breast cancer pathogenesis, we present a review of recent findings related to the role of 15- lipoxygenase enzyme and metabolites in breast cancer growth, apoptosis, metastasis, and invasion as well as their local and circulating expression pattern in patients with breast cancer. Our review supports the emerging role of 15- lipoxygenase in molecular and cellular processes regulating breast tumor cell fate with both positive and negative effects.

Replacement of an Indole Scaffold Targeting Human 15-Lipoxygenase-1 Using Combinatorial Chemistry

Human 15-lipoxygenase-1 (15-LOX-1) belongs to the class of lipoxygenases, which catalyze oxygenation of polyunsaturated fatty acids, such as arachidonic and linoleic acid. Recent studies have shown that 15-LOX-1 plays an important role in physiological processes linked to several diseases such as airway inflammation disease, coronary artery disease, and several types of cancer such as rectal, colon, breast and prostate cancer. In this study, we aimed to extend the structural diversity of 15-LOX-1 inhibitors, starting from the recently identified indolyl core. In order to find new scaffolds, we employed a combinatorial approach using various aromatic aldehydes and an aliphatic hydrazide tail. This scaffold-hopping study resulted in the identification of the 3-pyridylring as a suitable replacement of the indolyl core with an inhibitory activity in the micromolar range (IC 50=16±6 μm) and a rapid and efficient structure-activity relationship investigation.

Expression of 15-lipoxygenase-1 in Merkel cell carcinoma is linked to advanced disease

BACKGROUND

The purpose of this study was to determine whether the expression of 15-lipoxygenase-1 (ALOX15) in primary tumour specimens predicts lymph node metastasis and subsequently clinical outcome in Merkel cell carcinoma (MCC) patients.

METHODS

A retrospective medical chart review of 33 patients was performed between 1994 and 2014. Eleven out of 33 (33%) Patients with primary MCC stages I and II were categorised as group I. Twenty two out of 33 (67%) Patients with regional lymph node metastases and/or distant metastases were defined as group II. All available tumour samples were immunostained for ALOX15, Podoplanin and MCPyV large T-protein antibody.

RESULTS

ALOX15 expression was observed in 19/23 (83%) primary tumour samples and in all lymph node metastasis. Primary tumours in patients with stage III and IV disease showed a higher expression rate of ALOX15 compared to patients with early stage disease (11/12 (92%) and 8/11 (73%), respectively). In group I, five patients (45%) were MCPyV positive, whereas in group II, 15 patients (68%) were MCPyV positive. The median lymphatic vessel density in ALOX15 negative group I primary tumour samples was lower compared to the median lymphatic vessel density in ALOX15 positive group I primary tumour probes (2.7 range, 1-4.3 vs 4.7 range, 4.0-7.3). Furthermore, all 17 samples of MCC metastases showed ALOX15 expression with a median lymphatic vessel density (not lymph node metastases) of 5.3 (range 2.0-7.3).

CONCLUSION

In the current study, we were able to show ALOX15 expression in the primary MCC sample and the metastasis sample. Based on the findings of the current study, expression rate of ALOX15 in primary MCC and metastases is possibly linked to an increased lymphatic vessel density.

Preferential Generation of 15-HETE-PE Induced by IL-13 Regulates Goblet Cell Differentiation in Human Airway Epithelial Cells

Type 2-associated goblet cell hyperplasia and mucus hypersecretion are well known features of asthma. 15-Lipoxygenase-1 (15LO1) is induced by the type 2 cytokine IL-13 in human airway epithelial cells (HAECs) in vitro and is increased in fresh asthmatic HAECs ex vivo. 15LO1 generates a variety of products, including 15-hydroxyeicosatetraenoic acid (15-HETE), 15-HETE-phosphatidylethanolamine (15-HETE-PE), and 13-hydroxyoctadecadienoic acid (13-HODE). In this study, we investigated the 15LO1 metabolite profile at baseline and after IL-13 treatment, as well as its influence on goblet cell differentiation in HAECs. Primary HAECs obtained from bronchial brushings of asthmatic and healthy subjects were cultured under air-liquid interface culture supplemented with arachidonic acid and linoleic acid (10 μM each) and exposed to IL-13 for 7 days. Short interfering RNA transfection and 15LO1 inhibition were applied to suppress 15LO1 expression and activity. IL-13 stimulation induced expression of 15LO1 and preferentially generated 15-HETE-PE in vitro, both of which persisted after removal of IL-13. 15LO1 inhibition (by short interfering RNA and chemical inhibitor) decreased IL-13-induced forkhead box protein A3 (FOXA3) expression and enhanced FOXA2 expression. These changes were associated with reductions in both mucin 5AC and periostin. Exogenous 15-HETE-PE stimulation (alone) recapitulated IL-13-induced FOXA3, mucin 5AC, and periostin expression. The results of this study confirm the central importance of 15LO1 and its primary product, 15-HETE-PE, for epithelial cell remodeling in HAECs.

Mechanistic contribution of ubiquitous 15-lipoxygenase-1 expression loss in cancer cells to terminal cell differentiation evasion

Loss of terminal cell differentiation promotes tumorigenesis. 15-Lipoxygenase-1 (15-LOX-1) contributes to terminal cell differentiation in normal cells. The mechanistic significance of 15-LOX-1 expression loss in human cancers to terminal cell differentiation suppression is unknown. In a screen of 128 cancer cell lines representing more than 20 types of human cancer, we found that 15-LOX-1 mRNA expression levels were markedly lower than levels in terminally differentiated cells. Relative expression levels of 15-LOX-1 (relative to the level in terminally differentiated primary normal human-derived bronchial epithelial cells) were lower in 79% of the screened cancer cell lines than relative expression levels of p16 (INK4A), which promotes terminal cell differentiation and is considered one of the most commonly lost tumor suppressor genes in cancer cells. 15-LOX-1 was expressed during terminal differentiation in three-dimensional air-liquid interface cultures, and 15-LOX-1 expression and terminal differentiation occurred in immortalized nontransformed bronchial epithelial but not in lung cancer cell lines. 15-LOX-1 expression levels were lower in human tumors than in paired normal lung epithelia. Short hairpin RNA-mediated downregulation of 15-LOX-1 in Caco-2 cells blocked enterocyte-like differentiation, disrupted tight junction formation, and blocked E-cadherin and ZO-1 localization to the cell wall membrane. 15-LOX-1 episomal expression in Caco-2 and HT-29 colon cancer cells induced differentiation. Our findings indicate that 15-LOX-1 downregulation in cancer cells is an important mechanism for terminal cell differentiation dysregulation and support the potential therapeutic utility of 15-LOX-1 reexpression to inhibit tumorigenesis.

Interleukin-13-induced MUC5AC is regulated by 15-lipoxygenase 1 pathway in human bronchial epithelial cells

RATIONALE

15-Lipoxygenase-1 (15LO1) and MUC5AC are highly expressed in asthmatic epithelial cells. IL-13 is known to induce 15LO1 and MUC5AC in human airway epithelial cells in vitro. Whether 15LO1 and/or its product 15-HETE modulate MUC5AC expression is unknown.

OBJECTIVES

To determine the expression of 15LO1 in freshly harvested epithelial cells from subjects with asthma and normal control subjects and to determine whether IL-13-induced 15LO1 expression and activation regulate MUC5AC expression in human bronchial epithelial cells in vitro.

METHODS

Human airway epithelial cells from subjects with asthma and normal subjects were evaluated ex vivo for 15LO1 and MUC5AC expression. The impact of 15LO1 on MUC5AC expression in vitro was analyzed by inhibiting 15LO1 through pharmacologic (PD146176) and siRNA approaches in human bronchial epithelial cells cultured under air-liquid interface. We analyzed 15 hydroxyeicosatetraenoic acid (15-HETE) by liquid chromatography/UV/mass spectrometry. MUC5AC and 15LO1 were analyzed by real-time RT-PCR, immunofluoresence, and Western blot.

MEASUREMENTS AND MAIN RESULTS

Epithelial 15LO1 expression increased with asthma severity (P < 0.0001). 15LO1 significantly correlated with MUC5AC ex vivo and in vitro. IL-13 increased 15LO1 expression and stimulated formation of two molecular species of 15-HETE esterified to phosphotidylethanolamine (15-HETE-PE). Inhibition of 15LO1 suppressed 15-HETE-PE and decreased MUC5AC expression in the presence of IL-13 stimulation. The addition of exogenous 15-HETE partially restored MUC5AC expression.

CONCLUSIONS

Epithelial 15LO1 expression increases with increasing asthma severity. IL-13 induction of 15-HETE-PE enhances MUC5AC expression in human airway epithelial cells. High levels of 15LO1 activity could contribute to the increases of MUC5AC observed in asthma.

15-lipoxygenase-1 production is lost in pancreatic cancer and overexpression of the gene inhibits tumor cell growth. Neoplasia. 2007;9:917-926. [PMID: 18030360 DOI: 10.1593/neo.07565]

Pancreatic cancer patients have an abysmal prognosis because of late diagnosis and lack of therapeutic options. Pancreatic intraepithelial neoplasias (PanINs), the precursor lesions, are a potential target for chemoprevention. Targeting eicosanoid pathways is an obvious choice because 5-lipoxygenase (5-LOX) has been suggested as a tumor promoter in pancreatic carcinogenesis. Here we provide evidence that 15-lipoxygenase-1 (15-LOX-1) expression and activity may exert antitumorigenic effects in pancreatic cancer. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis showed absence or very weak expression of 15-LOX-1 in all pancreatic cancer cell lines tested. 15-LOX-1 was strongly stained in normal ductal cells, tubular complexes, and centroacinar cells, but no staining was seen in islets, cancer cells, PanIN lesions, or in tumor cells in lymph node metastases, indicating that 15-LOX-1 expression is lost during tumor development in human pancreas. Overexpression of 15-LOX-1 in pancreatic tumor cells or treatment with its arachidonic acid-derived metabolite resulted in decreased cell growth. These findings provide evidence that loss of 15-LOX-1 may play an important role in pancreatic carcinogenesis, possibly as a tumor suppressor gene. Thus, induction of 15-LOX-1 expression may be an attractive option for the prevention and treatment of pancreatic cancer.

Prostate tumor growth and recurrence can be modulated by the omega-6:omega-3 ratio in diet: athymic mouse xenograft model simulating radical prostatectomy

Evidence indicates that a diet rich in omega (omega)-6 polyunsaturated fatty acids (PUFAs) [e.g., linoleic acid (LA)] increases prostate cancer (PCa) risk, whereas a diet rich in omega-3 decreases risk. Precisely how these PUFAs affect disease development remains unclear. So we examined the roles that PUFAs play in PCa, and we determined if increased omega-3 consumption can impede tumor growth. We previously demonstrated an increased expression of an omega-6 LA-metabolizing enzyme, 15-lipoxygenase-1 (15-LO-1, ALOX15), in prostate tumor tissue compared with normal adjacent prostate tissue, and that elevated 15-LO-1 activity in PCa cells has a protumorigenic effect. A PCa cell line, Los Angeles Prostate Cancer-4 (LAPC-4), expresses prostate-specific antigen (PSA) as well an active 15-LO-1 enzyme. Therefore, to study whether or not the protumorigenic role of 15-LO-1 and dietary omega-6 LA can be modulated by altering omega-3 levels through diet, we surgically removed tumors caused by LAPC-4 cells (mouse model to simulate radical prostatectomy). Mice were then randomly divided into three different diet groups-namely, high omega-6 LA, high omega-3 stearidonic acid (SDA), and no fat-and examined the effects of omega-6 and omega-3 fatty acids in diet on LAPC-4 tumor recurrence by monitoring for PSA. Mice in these diet groups were monitored for food consumption, body weight, and serum PSA indicative of the presence of LAPC-4 cells. Fatty acid methyl esters from erythrocyte membranes were examined for omega-6 and omega-3 levels to reflect long-term dietary intake. Our results provide evidence that prostate tumors can be modulated by the manipulation of omega-6:omega-3 ratios through diet and that the omega-3 fatty acid SDA [precursor of eicosapentaenoic acid (EPA)] promotes apoptosis and decreases proliferation in cancer cells, causing decreased PSA doubling time, compared to omega-6 LA fatty acid, likely by competing with the enzymes of LA and AA pathways, namely, 15-LO-1 and cyclooxygenases (COXs). Thus, EPA and DHA (major components of fish oil) could potentially be promising dietary intervention agents in PCa prevention aimed at 15-LO-1 and COX-2 as molecular targets. These observations also provide clues as to its mechanisms of action.