Stimulation of iNOS expression and apoptosis resistance in B-cell chronic lymphocytic leukemia (B-CLL) cells through engagement of Toll-like receptor 7 (TLR-7) and NF-kappaB activation

Exploring TLR signaling pathways as promising targets in cervical cancer: The road less traveled

Cervical cancer is the leading cause of cancer-related deaths for women globally. Despite notable advancements in prevention and treatment, the identification of novel therapeutic targets remains crucial for cervical cancer. Toll-like receptors (TLRs) play an essential role in innate immunity as pattern-recognition receptors. There are several types of pathogen-associated molecular patterns (PAMPs), including those present in cervical cancer cells, which have the ability to activate toll-like receptors (TLRs). Recent studies have revealed dysregulated toll-like receptor (TLR) signaling pathways in cervical cancer, leading to the production of inflammatory cytokines and chemokines that can facilitate tumor growth and metastasis. Consequently, TLRs hold significant promise as potential targets for innovative therapeutic agents against cervical cancer. This book chapter explores the role of TLR signaling pathways in cervical cancer, highlighting their potential for targeted therapy while addressing challenges such as tumor heterogeneity and off-target effects. Despite these obstacles, targeting TLR signaling pathways presents a promising approach for the development of novel and effective treatments for cervical cancer.

The Role of TRL7/8 Agonists in Cancer Therapy, with Special Emphasis on Hematologic Malignancies

Toll-like receptors (TLR) belong to the pattern recognition receptors (PRR). TLR7 and the closely correlated TLR8 affiliate with toll-like receptors family, are located in endosomes. They recognize single-stranded ribonucleic acid (RNA) molecules and synthetic deoxyribonucleic acid (DNA)/RNA analogs-oligoribonucleotides. TLRs are primarily expressed in hematopoietic cells. There is compiling evidence implying that TLRs also direct the formation of blood cellular components and make a contribution to the pathogenesis of certain hematopoietic malignancies. The latest research shows a positive effect of therapy with TRL agonists on the course of hemato-oncological diseases. Ligands impact activation of antigen-presenting cells which results in production of cytokines, transfer of mentioned cells to the lymphoid tissue and co-stimulatory surface molecules expression required for T-cell activation. Toll-like receptor agonists have already been used in oncology especially in the treatment of dermatological neoplastic lesions. The usage of these substances in the treatment of solid tumors is being investigated. The present review discusses the direct and indirect influence that TLR7/8 agonists, such as imiquimod, imidazoquinolines and resiquimod have on neoplastic cells and their promising role as adjuvants in anticancer vaccines.

The toxicity of cooking oil fumes on human bronchial epithelial cells through ROS-mediated MAPK, NF-κB signaling pathways and NLRP3 inflammasome

Cooking oil fumes (COFs) are the main pollutants in kitchen and indoor air, which threaten human health. Exposure to COFs may lead to respiratory diseases and impair pulmonary function. To investigate the toxicity of COFs on human bronchial epithelial cells (Beas-2B) and explore the underlying mechanisms, MTT assay was conducted to detect the viability of Beas-2B. Intracellular reactive oxygen species (ROS) levels and nitric oxide (NO) levels were determined with DCFH-DA assay and DAF-FM assay. The expression of genes involved in inflammation were measured with quantitative real-time PCR (qRT-PCR). The phosphorylation and the expression of proteins related to Mitogen-activated protein kinase (MAPK), NF-κB signaling pathways were measured with western blot. Our results revealed that COFs decreased cell viability, increased the ROS levels and NO levels and induced apoptosis in Beas-2B cells. The results of qRT-PCR and western blot showed that the expression of NLRP3, p65, iNOS, IL-1β, and the factors related to oxidative stress and inflammation increased, NF-κB signaling pathway and MAPK signaling pathway were activated. This study provided some useful information to evaluate the toxicity of COFs and revealed the possible mechanism for the damage on respiratory system induced by COFs.

An Assessment on Impact of COVID-19 Infection in a Gender Specific Manner

Coronavirus disease 2019 (COVID-19) is caused by novel coronavirus Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first time reported in December 2019 in Wuhan, China and thereafter quickly spread across the globe. Till September 19, 2020, COVID-19 has spread to 216 countries and territories. Severe infection of SARS-CoV-2 cause extreme increase in inflammatory chemokines and cytokines that may lead to multi-organ damage and respiratory failure. Currently, no specific treatment and authorized vaccines are available for its treatment. Renin angiotensin system holds a promising role in human physiological system specifically in regulation of blood pressure and electrolyte and fluid balance. SARS-CoV-2 interacts with Renin angiotensin system by utilizing angiotensin-converting enzyme 2 (ACE2) as a receptor for its cellular entry. This interaction hampers the protective action of ACE2 in the cells and causes injuries to organs due to persistent angiotensin II (Ang-II) level. Patients with certain comorbidities like hypertension, diabetes, and cardiovascular disease are under the high risk of COVID-19 infection and mortality. Moreover, evidence obtained from several reports also suggests higher susceptibility of male patients for COVID-19 mortality and other acute viral infections compared to females. Analysis of severe acute respiratory syndrome coronavirus (SARS) and Middle East respiratory syndrome coronavirus (MERS) epidemiological data also indicate a gender-based preference in disease consequences. The current review addresses the possible mechanisms responsible for higher COVID-19 mortality among male patients. The major underlying aspects that was looked into includes smoking, genetic factors, and the impact of reproductive hormones on immune systems and inflammatory responses. Detailed investigations of this gender disparity could provide insight into the development of patient tailored therapeutic approach which would be helpful in improving the poor outcomes of COVID-19. Graphical abstract.

Immunobiology of Inherited Muscular Dystrophies

The immune response to acute muscle damage is important for normal repair. However, in chronic diseases such as many muscular dystrophies, the immune response can amplify pathology and play a major role in determining disease severity. Muscular dystrophies are inheritable diseases that vary tremendously in severity, but share the progressive loss of muscle mass and function that can be debilitating and lethal. Mutations in diverse genes cause muscular dystrophy, including genes that encode proteins that maintain membrane strength, participate in membrane repair, or are components of the extracellular matrix or the nuclear envelope. In this article, we explore the hypothesis that an important feature of many muscular dystrophies is an immune response adapted to acute, infrequent muscle damage that is misapplied in the context of chronic injury. We discuss the involvement of the immune system in the most common muscular dystrophy, Duchenne muscular dystrophy, and show that the immune system influences muscle death and fibrosis as disease progresses. We then present information on immune cell function in other muscular dystrophies and show that for many muscular dystrophies, release of cytosolic proteins into the extracellular space may provide an initial signal, leading to an immune response that is typically dominated by macrophages, neutrophils, helper T-lymphocytes, and cytotoxic T-lymphocytes. Although those features are similar in many muscular dystrophies, each muscular dystrophy shows distinguishing features in the magnitude and type of inflammatory response. These differences indicate that there are disease-specific immunomodulatory molecules that determine response to muscle cell damage caused by diverse genetic mutations. © 2018 American Physiological Society. Compr Physiol 8:1313-1356, 2018.

Toll-like receptor-9 in hypoxic nasopharyngeal carcinoma cells and its correlation with cell proliferation and apoptosis

The purpose of this study was to investigate the correlation between the expression of Toll-like receptor-9 (TLR-9) and cell proliferation and apoptosis in hypoxic nasopharyngeal carcinoma cells. Human nasopharyngeal carcinoma cell line HNE-1 (EBV positive) and CNE-1 (EBV negative) were used. Cells were divided into normal control group, hypoxia group and hyperoxia group. Hypoxic conditions were 5% CO₂ and 0.01% partial pressure of oxygen, hyperoxia conditions were 5% CO₂ and 10% partial pressure of oxygen. Reverse transcription-PCR (RT-PCR) and western blot analysis were used to detect the expression of TLR-9 mRNA and protein at 6, 12 and 24 h after the beginning of cell culture. MTT assay was used to detect the cell proliferation rate and flow cytometry was used to detect cell apoptosis rate. Expression levels of TLR-9 mRNA and protein in hypoxia group reached the peak at 12 h after the beginning of cell culture, and were significantly higher than those of hyperoxia group at all time-points, expression levels of TLR-9 mRNA and protein of control group were the lowest, difference between groups were all statistically significant (P<0.05). No significant changes in expression levels of TLR-9 mRNA and protein were found in control group and hyperoxia group between different time-points (P>0.05). Compared with the other two groups, cell proliferation rate was gradually decreased and apoptotic rate was gradually decreased in hypoxia group, significant differences were found between hypoxia group, and control group and hyperoxia group (P<0.05), no significant differences were found between control group and hyperoxia group (P>0.05). In conclusion, TLR-9 was highly expressed in hypoxic nasopharyngeal carcinoma cells regulating cell proliferation and apoptosis, which may be an important mechanism of tumorigenesis and a potential target for intervention therapy.

Involvement of the Toll-Like Receptor/Nitric Oxide Signaling Pathway in the Pathogenesis of Cervical Cancer Caused by High-Risk Human Papillomavirus Infection

Human papillomavirus (HPV) can activate Toll-like receptor (TLR)/nitric oxide (NO) signaling pathways; however, whether the TLR/NO pathway is involved in cervical cancer caused by high-risk HPV (HR-HPV) remains unclear. In this study, 43 HR-HPV-positive patients with cervical cancer (CC group), 39 HR-HPV-positive patients with a healthy cervix (HR-HPV group), and 33 HR-HPV-negative controls were recruited. NO concentration in cervical canal and expression of inducible NO synthase (iNOS) in cervical tissues were detected. Expressions of key TLR/NO pathway genes (TLR3/4/7/8, NF-κB p65, and iNOS) in cervical epithelial cells were detected by quantitative reverse transcription PCR. Expressions of TLR4, NF-κB p65, and iNOS in CaSki, HeLa, and C33a cells were determined by Western blot. NO concentration in cervical canal of CC group was significantly higher than in other groups (P < 0.05). Positive rates of iNOS in cervical tissues were 72.1%, 28.2%, and 3.1% in the CC group, HR-HPV group, and controls, respectively (P < 0.05). Levels of TLR3, TLR4, TLR7, TLR8, NF-κB p65, and iNOS in cervical epithelial cells were higher in CC group than in other groups (P < 0.05). Both mRNA and protein levels of TLR4, NF-κB p65, and iNOS were higher in HPV-positive HeLa and CaSki cells than in HPV-negative C33a cells (P < 0.05). Together, these results suggest that TLR/NO signaling pathway may be involved in pathogenesis of cervical cancer caused by HR-HPV.

Mucosal Inducible NO Synthase-Producing IgA+ Plasma Cells in Helicobacter pylori-Infected Patients

The mucosal immune system is relevant for homeostasis, immunity, and also pathological conditions in the gastrointestinal tract. Inducible NO synthase (iNOS)-dependent production of NO is one of the factors linked to both antimicrobial immunity and pathological conditions. Upregulation of iNOS has been observed in human Helicobacter pylori infection, but the cellular sources of iNOS are ill defined. Key differences in regulation of iNOS expression impair the translation from mouse models to human medicine. To characterize mucosal iNOS-producing leukocytes, biopsy specimens from H. pylori-infected patients, controls, and participants of a vaccination trial were analyzed by immunohistochemistry, along with flow cytometric analyses of lymphocytes for iNOS expression and activity. We newly identified mucosal IgA-producing plasma cells (PCs) as one major iNOS(+) cell population in H. pylori-infected patients and confirmed intracellular NO production. Because we did not detect iNOS(+) PCs in three distinct infectious diseases, this is not a general feature of mucosal PCs under conditions of infection. Furthermore, numbers of mucosal iNOS(+) PCs were elevated in individuals who had cleared experimental H. pylori infection compared with those who had not. Thus, IgA(+) PCs expressing iNOS are described for the first time, to our knowledge, in humans. iNOS(+) PCs are induced in the course of human H. pylori infection, and their abundance seems to correlate with the clinical course of the infection.

Activation of Toll-like receptor 7 inhibits the proliferation and migration, and induces the apoptosis of pancreatic cancer cells

Pancreatic cancer is one of the most malignant types of tumor and has a poor prognosis. Toll‑like receptor 7 (TLR7) has been found to be present and have different roles in different types of cancer cells. In the present study, the roles of TLR7 in BxPC‑3 cells, a human pancreatic adenocarcinoma cell line, were investigated. The cells were treated with gardiquimod, an agonist of TLR7, following which the properties of the cells, including proliferation, migration, cell cycle and apoptosis, were analyzed. It was revealed that activation of TLR7 by gardiquimod inhibited cell proliferation and migration, and induced apoptosis of the cells. In addition, gardiquimod downregulated the expression levels of cyclin B1, cyclin E and B‑cell lymphoma 2, while upregulating the expression of B‑cell‑associated X protein. These results suggested that the activation of TLR7 suppresses the progression of pancreatic cancer.

Targeting apoptosis pathways in cancer and perspectives with natural compounds from mother nature

Although the incidences are increasing day after day, scientists and researchers taken individually or by research group are trying to fight against cancer by several ways and also by different approaches and techniques. Sesquiterpenes, flavonoids, alkaloids, diterpenoids, and polyphenolic represent a large and diverse group of naturally occurring compounds found in a variety of fruits, vegetables, and medicinal plants with various anticancer properties. In this review, our aim is to give our perspective on the current status of the natural compounds belonging to these groups and discuss their natural sources, their anticancer activity, their molecular targets, and their mechanism of actions with specific emphasis on apoptosis pathways, which may help the further design and conduct of preclinical and clinical trials. Unlike pharmaceutical drugs, the selected natural compounds induce apoptosis by targeting multiple cellular signaling pathways including transcription factors, growth factors, tumor cell survival factors, inflammatory cytokines, protein kinases, and angiogenesis that are frequently deregulated in cancers and suggest that their simultaneous targeting by these compounds could result in efficacious and selective killing of cancer cells. This review suggests that they provide a novel opportunity for treatment of cancer, but clinical trials are still required to further validate them in cancer chemotherapy.

Inducible nitric oxide synthase drives mTOR pathway activation and proliferation of human melanoma by reversible nitrosylation of TSC2

Melanoma is one of the cancers of fastest-rising incidence in the world. Inducible nitric oxide synthase (iNOS) is overexpressed in melanoma and other cancers, and previous data suggest that iNOS and nitric oxide (NO) drive survival and proliferation of human melanoma cells. However, specific mechanisms through which this occurs are poorly defined. One candidate is the PI3K-AKT-mTOR pathway, which plays a major role in proliferation, angiogenesis, and metastasis of melanoma and other cancers. We used the chick embryo chorioallantoic membrane (CAM) assay to test the hypothesis that melanoma growth is regulated by iNOS-dependent mTOR pathway activation. Both pharmacologic inhibition and siRNA-mediated gene silencing of iNOS suppressed melanoma proliferation and in vivo growth on the CAM in human melanoma models. This was associated with strong downregulation of mTOR pathway activation by Western blot analysis of p-mTOR, p70 ribosomal S6 kinase (p-P70S6K), p-S6RP, and p-4EBP1. iNOS expression and NO were associated with reversible nitrosylation of tuberous sclerosis complex (TSC) 2, and inhibited dimerization of TSC2 with its inhibitory partner TSC1, enhancing GTPase activity of its target Ras homolog enriched in brain (Rheb), a critical activator of mTOR signaling. Immunohistochemical analysis of tumor specimens from stage III melanoma patients showed a significant correlation between iNOS expression levels and expression of the mTOR pathway members. Exogenously supplied NO was also sufficient to reverse the mTOR pathway inhibition by the B-Raf inhibitor vemurafenib. In summary, covalent modification of TSC2 by iNOS-derived NO is associated with impaired TSC2/TSC1 dimerization, mTOR pathway activation, and proliferation of human melanoma. This model is consistent with the known association of iNOS overexpression and poor prognosis in melanoma and other cancers.

NPM-ALK up-regulates iNOS expression through a STAT3/microRNA-26a-dependent mechanism

NPM-ALK chimeric oncogene is aberrantly expressed in an aggressive subset of T-cell lymphomas that frequently occurs in children and young adults. The mechanisms underlying the oncogenic effects of NPM-ALK are not completely elucidated. Inducible nitric oxide synthase (iNOS) promotes the survival and maintains the malignant phenotype of cancer cells by generating NO, a highly active free radical. We tested the hypothesis that iNOS is deregulated in NPM-ALK(+) T-cell lymphoma and promotes the survival of this lymphoma. In line with this possibility, an iNOS inhibitor and NO scavenger decreased the viability, adhesion, and migration of NPM-ALK(+) T-cell lymphoma cells, and an NO donor reversed these effects. Moreover, the NO donor salvaged the viability of lymphoma cells treated with ALK inhibitors. In further support of an important role of iNOS, we found iNOS protein to be highly expressed in NPM-ALK(+) T-cell lymphoma cell lines and in 79% of primary tumours but not in human T lymphocytes. Although expression of iNOS mRNA was identified in NPM-ALK(+) T-cell lymphoma cell lines and tumours, iNOS mRNA was remarkably elevated in T lymphocytes, suggesting post-transcriptional regulation. Consistently, we found that miR-26a contains potential binding sites and interacts with the 3'-UTR of iNOS. In addition, miR-26a was significantly decreased in NPM-ALK(+) T-cell lymphoma cell lines and tumours compared with T lymphocytes and reactive lymph nodes. Restoration of miR-26a in lymphoma cells abrogated iNOS protein expression and decreased NO production and cell viability, adhesion, and migration. Importantly, the effects of miR-26a were substantially attenuated when the NO donor was simultaneously used to treat lymphoma cells. Our investigation of the mechanisms underlying the decrease in miR-26a in this lymphoma revealed novel evidence that STAT3, a major downstream substrate of NPM-ALK tyrosine kinase activity, suppresses MIR26A1 gene expression.

B cell receptor and antigens in CLL

Nowadays, chronic lymphocytic leukemia (CLL) is considered as a prototypic antigen-driven lymphoma, with antigenic stimuli from the microenvironment promoting tumor outgrowth. Antigen recognition is a function of both the clonotypic B cell receptor immunoglobulin (BcR IG) and various other immune sensors, e.g., the Toll-like receptors. The critical role of BcR IG-mediated signaling in CLL development and evolution is underscored by the following: the disease-biased IG gene repertoire; the subdivision of CLL based on the somatic hypermutation load of the BcR IG into two broad categories with vastly different prognosis and eventual outcome; the existence of subsets of cases with distinct, quasi-identical (stereotyped) BcR IGs; and the clinical efficacy of novel therapeutics inhibiting BcR signaling. Here, we trace the immunogenetic evidence for antigen selection in CLL and also consider the types of implicated antigens as well as the immune signaling pathways relevant for CLL ontogeny and clonal progression.

Toll-like receptor signaling pathway in chronic lymphocytic leukemia: distinct gene expression profiles of potential pathogenic significance in specific subsets of patients

BACKGROUND

Signaling through the B-cell receptor appears to be a major contributor to the pathogenesis of chronic lymphocytic leukemia. Toll-like receptors bridge the innate and adaptive immune responses by acting as co-stimulatory signals for B cells. The available data on the expression of Toll-like receptors in chronic lymphocytic leukemia are limited and derive from small series of patients.

DESIGN AND METHODS

We profiled the expression of genes associated with Toll-like receptor signaling pathways in 192 cases of chronic lymphocytic leukemia and explored potential associations with molecular features of the clonotypic B-cell receptors.

RESULTS

Chronic lymphocytic leukemia cells express all Toll-like receptors expressed by normal activated B cells, with high expression of TLR7 and CD180, intermediate expression of TLR1, TLR6, TLR10 and low expression of TLR2 and TLR9. The vast majority of adaptors, effectors and members of the NFKB, JNK/p38, NF/IL6 and IRF pathways are intermediately-to-highly expressed, while inhibitors of Toll-like receptor activity are generally low-to-undetectable, indicating that the Toll-like receptor-signaling framework is competent in chronic lymphocytic leukemia. Significant differences were identified for selected genes between cases carrying mutated or unmutated IGHV genes or assigned to different subsets with stereotyped B-cell receptors. The differentially expressed molecules include receptors, NFκB/MAPK signaling molecules and final targets of the cascade.

CONCLUSIONS

The observed variations are suggestive of distinctive activation patterns of the Toll-like receptor signaling pathway in subgroups of cases of chronic lymphocytic leukemia defined by the molecular features of B-cell receptors. Additionally, they indicate that different or concomitant signals acting through receptors other than the B-cell receptor can affect the behavior of the malignant clone.

STAT-3 activates NF-kappaB in chronic lymphocytic leukemia cells

NF-κB plays a major role in the pathogenesis of B-cell neoplasms. A broad array of mostly extracellular stimuli has been reported to activate NF-κB, to various degrees, in chronic lymphocytic leukemia (CLL) cells. Because CLL cells harbor high levels of unphosphorylated STAT-3 (USTAT-3) and USTAT-3 was reported to activate NF-κB, we sought to determine whether USTAT-3 activates NF-κB in CLL. Using the electrophoretic mobility shift assay (EMSA), we studied peripheral blood low-density cells from 15 patients with CLL and found that CLL cell nuclear extracts from all the samples bound to an NF-κB DNA probe, suggesting that NF-κB is constitutively activated in CLL. Immunoprecipitation studies showed that STAT-3 bound NF-κB p65, and confocal microscopy studies detected USTAT-3/NF-κB complexes in the nuclei of CLL cells, thereby confirming these findings. Furthermore, infection of CLL cells with retroviral STAT-3-short hairpin RNA attenuated the binding of NF-κB to DNA, as assessed by EMSA, and downregulated mRNA levels of NF-κB-regulated genes, as assessed by quantitative PCR. Taken together, our data suggest that USTAT-3 binds to the NF-κB p50/p65 dimers and that the USTAT-3/NF-κB complexes bind to DNA and activate NF-κB-regulated genes in CLL cells.

Toll-like receptor 7 agonists are potent and rapid bronchodilators in guinea pigs

BACKGROUND

Respiratory tract viral infections result in asthma exacerbations. Toll-like receptor (TLR) 7 is a receptor for viral single-stranded RNA and is expressed at high levels in the lungs.

OBJECTIVE

Because TLR7 polymorphisms are associated with asthma, we examined the effects of TLR7 agonists in guinea pig airways.

METHODS

We induced bronchoconstriction in guinea pigs in vivo by means of electrical stimulation of the vagus nerve or intravenous administration of acetylcholine and measured the effect of a TLR7 agonist administered intravenously. We induced contraction of airway smooth muscle in segments of isolated guinea pig tracheas in vitro and measured the effect of TLR7 agonists, antagonists, and pharmacologic inhibitors of associated signaling pathways administered directly to the bath.

RESULTS

TLR7 agonists acutely inhibited bronchoconstriction in vivo and relaxed contraction of airway smooth muscle in vitro within minutes of administration. Airway relaxation induced by the TLR7 agonist R837 (imiquimod) was partially blocked with a TLR7 antagonist and was also blocked by inhibitors of large-conductance, calcium-activated potassium channels; prostaglandin synthesis; and nitric oxide generation. Another TLR7 agonist, 21-mer single-stranded phosphorothioated polyuridylic acid (PolyUs), mediated relaxation that was completely blocked by a TLR7 antagonist.

CONCLUSIONS

These data demonstrate a novel protective mechanism to limit bronchoconstriction and maintain airflow during respiratory tract viral infections. The fast time frame is inconsistent with canonical TLR7 signaling. R837 mediates bronchodilation by means of TLR7-dependent and TLR7-independent mechanisms, whereas PolyUs does so through only the TLR7-dependent mechanism. TLR7-independent mechanisms involve prostaglandins and large-conductance, calcium-activated potassium channels, whereas TLR7-dependent mechanisms involve nitric oxide. TLR7 is an attractive therapeutic target for its ability to reverse bronchoconstriction within minutes.

Toll-like receptors in innate immunity and infectious diseases

The protective ability of host defense system is largely dependent on germ-line encoded pattern-recognition receptors (PRRs). These PRRs respond to a variety of exogenous pathogens or endogenous danger signals, by recognizing some highly conserved structures such as pathogen-associated molecular patterns (PAMPs) and danger/damage associated molecular patterns (DAMPs). The most studied PRRs are Toll-like receptors (TLRs). Activation of TLRs triggers production of inflammatory cytokines and type I interferons (IFNs) via myeloid differentiation primary response gene 88 (MyD88)-dependent or -independent signaling respectively, thereby modulating innate and adaptive immunity, as well as inflammatory responses. This review introduces the classification, structure, and specific ligands of TLRs, and focuses on their signal pathways and biological activities, as well as clinical relevance. These studies of TLRs in the innate immune system have implications for the prevention and treatment of a variety of infectious diseases, including tuberculosis (TB), microbial keratitis, and hepatitis B and C.