Janus kinase-signal transducer and activator of transcription mediates phosphatidic acid-induced interleukin (IL)-1beta and IL-6 production

Inhibition of STAT-mediated cytokine responses to chemically-induced colitis prevents inflammation-associated neurobehavioral impairments

Depression can be associated with chronic systemic inflammation, and production of peripheral proinflammatory cytokines and upregulation of the kynurenine pathway have been implicated in pathogenesis of depression. However, the mechanistic bases for these comorbidities are not yet well understood. As tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO), which convert tryptophan to kynurenine, are rate-limiting enzymes of the kynurenine pathway, we screened TDO or IDO inhibitors for effects on the production of proinflammatory cytokines in a mouse macrophage cell line. The TDO inhibitor 680C91 attenuated LPS-induced pro-inflammatory cytokines including IL-1β and IL-6. Surprisingly, this effect was TDO-independent, as it occurred even in peritoneal macrophages from TDO knockout mice. Instead, the anti-inflammatory effects of 680C91 were mediated through the suppression of signal transducer and activator of transcription(STAT) signaling. Furthermore, 680C91 suppressed production of proinflammatory cytokines and STAT signaling in an animal model of inflammatory bowel disease. Specifically, 680C91 effectively attenuated acute phase colon cytokine responses in male mice subjected to dextran sulfate sodium (DSS)-induced colitis. Interestingly, this treatment also prevented the development of anxiodepressive-like neurobehaviors in DSS-treated mice during the recovery phase. The ability of 680C91 to prevent anxiodepressive-like behavior in response to chemically-induced colitis appeared to be due to rescue of attenuated dopamine responses in the nucleus accumbens. Thus, inhibition of STAT-mediated, but TDO-independent proinflammatory cytokines in macrophages can prevent inflammation-associated anxiety and depression. Identification of molecular mechanisms involved may facilitate the development of new treatments for gastrointestinal-neuropsychiatric comorbidity.

Hepcidin and its multiple partners: Complex regulation of iron metabolism in health and disease

The peptide hormone hepcidin is central to the regulation of iron metabolism, influencing the movement of iron into the circulation and determining total body iron stores. Its effect on a cellular level involves binding ferroportin, the main iron export protein, preventing iron egress and leading to iron sequestration within ferroportin-expressing cells. Hepcidin expression is enhanced by iron loading and inflammation and suppressed by erythropoietic stimulation. Aberrantly increased hepcidin leads to systemic iron deficiency and/or iron restricted erythropoiesis as occurs in anemia of chronic inflammation. Furthermore, insufficiently elevated hepcidin occurs in multiple diseases associated with iron overload such as hereditary hemochromatosis and iron loading anemias. Abnormal iron metabolism as a consequence of hepcidin dysregulation is an underlying factor resulting in pathophysiology of multiple diseases and several agents aimed at manipulating this pathway have been designed, with some already in clinical trials. In this chapter, we assess the complex regulation of hepcidin, delineate the many binding partners involved in its regulation, and present an update on the development of hepcidin agonists and antagonists in various clinical scenarios.

Hepcidin mimetics in polycythemia vera: resolving the irony of iron deficiency and erythrocytosis

PURPOSE OF REVIEW

Development of hepcidin therapeutics has been a ground-breaking discovery in restoring iron homeostasis in several haematological disorders. The hepcidin mimetic, rusfertide, is in late-stage clinical development for treating polycythemia vera patients with a global phase 3 trial [NCT05210790] currently underway. Rusfertide serves as the first possible noncytoreductive therapeutic option to maintain haematocrit control and avoid phlebotomy in polycythemia vera patients. In this comprehensive review, we discuss the pathobiology of dysregulated iron metabolism in polycythemia vera, provide the rationale for targeting the hepcidin-ferroportin axis and elaborate on the preclinical and clinical trial evidence supporting the role of hepcidin mimetics in polycythemia vera.

RECENT FINDINGS

Recently, updated results from two phase 2 clinical trials [NCT04057040 & NCT04767802] of rusfertide (PTG300) demonstrate that the drug is highly effective in eliminating the need for therapeutic phlebotomies, normalizing haematological parameters, repleting iron stores and relieving constitutional symptoms in patients with polycythemia vera. In light of these findings, additional hepcidin mimetic agents are also being evaluated in polycythemia vera patients.

SUMMARY

Hepcidin agonists essentially serve as a 'chemical phlebotomy' and are poised to vastly improve the quality of life for phlebotomy requiring polycythemia vera patients.

Clinical assessment of endothelial function in convalescent COVID-19 patients: a meta-analysis with meta-regressions

BACKGROUND

Endothelial dysfunction has been proposed to play a key role in the pathogenesis of coronavirus disease 2019 (COVID-19) and its post-acute sequelae. Flow-mediated dilation (FMD) is recognized as an accurate clinical method to assess endothelial function. Thus, we performed a meta-analysis of the studies evaluating FMD in convalescent COVID-19 patients and controls with no history of COVID-19.

METHODS

A systematic literature search was conducted in the main scientific databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Using the random effects method, differences between cases and controls were expressed as mean difference (MD) with 95% confidence intervals (95% CI). The protocol was registered on PROSPERO with reference number CRD42021289684.

RESULTS

Twelve studies were included in the final analysis. A total of 644 convalescent COVID-19 patients showed significantly lower FMD values as compared to 662 controls (MD: -2.31%; 95% CI: -3.19, -1.44; p < 0.0001). Similar results were obtained in the sensitivity analysis of the studies that involved participants in either group with no cardiovascular risk factors or history of coronary artery disease (MD: -1.73%; 95% CI: -3.04, -0.41; p = 0.010). Interestingly, when considering studies separately based on enrolment within or after 3 months of symptom onset, results were further confirmed in both short- (MD: -2.20%; 95% CI: -3.35, -1.05; p < 0.0001) and long-term follow-up (MD: -2.53%; 95% CI: -4.19, -0.86; p = 0.003). Meta-regression models showed that an increasing prevalence of post-acute sequelae of COVID-19 was linked to a higher difference in FMD between cases and controls (Z-score: -2.09; p = 0.037).

CONCLUSIONS

Impaired endothelial function can be documented in convalescent COVID-19 patients, especially when residual clinical manifestations persist. Targeting endothelial dysfunction through pharmacological and rehabilitation strategies may represent an attractive therapeutic option.Key messagesThe mechanisms underlying the post-acute sequelae of coronavirus disease 2019 (COVID-19) have not been fully elucidated.Impaired endothelial function can be documented in convalescent COVID-19 patients for up to 1 year after infection, especially when residual clinical manifestations persist.Targeting endothelial dysfunction may represent an attractive therapeutic option in the post-acute phase of COVID-19.

Lactoferrin: from the structure to the functional orchestration of iron homeostasis

Iron is by far the most widespread and essential transition metal, possessing crucial biological functions for living systems. Despite chemical advantages, iron biology has forced organisms to face with some issues: ferric iron insolubility and ferrous-driven formation of toxic radicals. For these reasons, acquisition and transport of iron constitutes a formidable challenge for cells and organisms, which need to maintain adequate iron concentrations within a narrow range, allowing biological processes without triggering toxic effects. Higher organisms have evolved extracellular carrier proteins to acquire, transport and manage iron. In recent years, a renewed interest in iron biology has highlighted the role of iron-proteins dysregulation in the onset and/or exacerbation of different pathological conditions. However, to date, no resolutive therapy for iron disorders has been found. In this review, we outline the efficacy of Lactoferrin, a member of the transferrin family mainly secreted by exocrine glands and neutrophils, as a new emerging orchestrator of iron metabolism and homeostasis, able to counteract iron disorders associated to different pathologies, including iron deficiency and anemia of inflammation in blood, Parkinson and Alzheimer diseases in the brain and cystic fibrosis in the lung.

Cytokines and microRNAs in SARS-CoV-2: What do we know?

The coronavirus disease 2019 (COVID-19) pandemic constitutes a global health emergency. Currently, there are no completely effective therapeutic medications for the management of this outbreak. The cytokine storm is a hyperinflammatory medical condition due to excessive and uncontrolled release of pro-inflammatory cytokines in patients suffering from severe COVID-19, leading to the development of acute respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS) and even mortality. Understanding the pathophysiology of COVID-19 can be helpful for the treatment of patients. Evidence suggests that the levels of tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1 and IL-6 are dramatically different between mild and severe patients, so they may be important contributors to the cytokine storm. Several serum markers can be predictors for the cytokine storm. This review discusses the cytokines involved in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, focusing on interferons (IFNs) and ILs, and whether they can be used in COVID-19 treatment. Moreover, we highlight several microRNAs that are involved in these cytokines and their role in the cytokine storm caused by COVID-19.

COVID-19 pandemic: Insights into genetic susceptibility to SARS-CoV-2 and host genes implications on virus spread, disease severity and outcomes

The outbreak of the newly emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) all over the world has caused global public health emergencies, international concern and economic crises. The systemic SARS-CoV-2 disease (COVID-19) can lead to death through causing unrestrained cytokines-storm and subsequent pulmonary shutdown among the elderly and patients with pre-existing comorbidities. Additionally, in comparison with poor nations without primary health care services, in developed countries with advanced healthcare system we can witness higher number of infections per one million people. In this review, we summarize the latest studies on genes associated with SARS-CoV-2 pathogenesis and propose possible mechanisms of the virus replication cycle and its triggered signaling pathways to encourage researchers to investigate genetic and immune profiles of the disease and try strategies for its treatment. Our review shows that immune response in people with different genetic background might vary as African and then Asian populations have lowest number of affected cases compared with European and American nations. Considering SARS-CoV-2 pathogenesis, we put forward some potentially important genetic gateways to COVID-19 infection including genes involved in the entry and replication of SARS-CoV-2 and the regulation of host immune response which might represent explanation for its spread, severity, and morality. Finally, we suggest that genetic alterations within these gateways could be critical factors in influencing geographical discrepancies of the virus, so it is essential to fully study them and design appropriated and reliable therapeutic agents against COVID-19.

Fat of the Gut: Epithelial Phospholipids in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) comprise a distinct set of clinical symptoms resulting from chronic inflammation within the gastrointestinal (GI) tract. Despite the significant progress in understanding the etiology and development of treatment strategies, IBD remain incurable for thousands of patients. Metabolic deregulation is indicative of IBD, including substantial shifts in lipid metabolism. Recent data showed that changes in some phospholipids are very common in IBD patients. For instance, phosphatidylcholine (PC)/phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC)/PC ratios are associated with the severity of the inflammatory process. Composition of phospholipids also changes upon IBD towards an increase in arachidonic acid and a decrease in linoleic and a-linolenic acid levels. Moreover, an increase in certain phospholipid metabolites, such as lysophosphatidylcholine, sphingosine-1-phosphate and ceramide, can result in enhanced intestinal inflammation, malignancy, apoptosis or necroptosis. Because some phospholipids are associated with pathogenesis of IBD, they may provide a basis for new strategies to treat IBD. Current attempts are aimed at controlling phospholipid and fatty acid levels through the diet or via pharmacological manipulation of lipid metabolism.

SARS-CoV-2 Disrupts Proximal Elements in the JAK-STAT Pathway

SARS-CoV-2 can infect multiple organs, including lung, intestine, kidney, heart, liver, and brain. The molecular details of how the virus navigates through diverse cellular environments and establishes replication are poorly defined. Here, we generated a panel of phenotypically diverse, SARS-CoV-2-infectible human cell lines representing different body organs and performed longitudinal survey of cellular proteins and pathways broadly affected by the virus. This revealed universal inhibition of interferon signaling across cell types following SARS-CoV-2 infection. We performed systematic analyses of the JAK-STAT pathway in a broad range of cellular systems, including immortalized cells and primary-like cardiomyocytes, and found that SARS-CoV-2 targeted the proximal pathway components, including Janus kinase 1 (JAK1), tyrosine kinase 2 (Tyk2), and the interferon receptor subunit 1 (IFNAR1), resulting in cellular desensitization to type I IFN. Detailed mechanistic investigation of IFNAR1 showed that the protein underwent ubiquitination upon SARS-CoV-2 infection. Furthermore, chemical inhibition of JAK kinases enhanced infection of stem cell-derived cultures, indicating that the virus benefits from inhibiting the JAK-STAT pathway. These findings suggest that the suppression of interferon signaling is a mechanism widely used by the virus to evade antiviral innate immunity, and that targeting the viral mediators of immune evasion may help block virus replication in patients with COVID-19. IMPORTANCE SARS-CoV-2 can infect various organs in the human body, but the molecular interface between the virus and these organs remains unexplored. In this study, we generated a panel of highly infectible human cell lines originating from various body organs and employed these cells to identify cellular processes commonly or distinctly disrupted by SARS-CoV-2 in different cell types. One among the universally impaired processes was interferon signaling. Systematic analysis of this pathway in diverse culture systems showed that SARS-CoV-2 targets the proximal JAK-STAT pathway components, destabilizes the type I interferon receptor though ubiquitination, and consequently renders the infected cells resistant to type I interferon. These findings illuminate how SARS-CoV-2 can continue to propagate in different tissues even in the presence of a disseminated innate immune response.

Study on the Mechanism of Lianpu Drink for the Treatment of Chronic Gastritis Based on Network Pharmacology

Chronic gastritis (CG) places a considerable burden on the healthcare system worldwide. Traditional Chinese Medicine (TCM) formulas characterized by multicompounds and multitargets have been acknowledged with striking effects in the treatment of CG in China's history. Nevertheless, their accurate mechanisms of action are still ambiguous. In this study, we analyzed the effective compounds, potential targets, and related biological pathway of Lianpu Drink (LPD), a TCM formula which has been reported to have a therapeutic effect on CG, by contrasting a “compound-target-disease” network. According to the results, 92 compounds and 5762 putative targets of LPD were screened; among them, 8 compounds derived from different herbs in LPD and 30 common targets related to LPD and CG were selected as candidate compounds and precision targets, respectively. Meanwhile, the predicted common targets were verified by Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis and pharmacological experiments. The results demonstrated that quercetin, ephedrine, trigonelline, crocetin, and β-sitosterol were major effective compounds of LPD responsible for the CG treatment by inhibiting the activation of the JAK 2-STAT 3 signaling pathway to reduce the expressions of cyclin D1 and Bcl-2 proteins. The study provides evidence for the mechanism of understanding of LPD for the treatment of CG.

Immune response scenario and vaccine development for SARS-CoV-2 infection

COVID-19 pandemic has started in December 2019 in China and quickly extended to become a worldwide health and economic emergency issue. It is caused by the novel coronavirus; SARS-CoV-2. COVID-19 patients’ clinical presentations vary from asymptomatic infection or flu like symptoms to serious pneumonia which could be associated with multiple organ failure possibly leading to death. It is understood that the immune response to SARS-CoV-2 includes all elements of the immune system which could altogether succeed in viral elimination and complete cure. Meanwhile, this immune response may also lead to disease progression and could be responsible for the patient’s death. Many trials have been done recently to create therapies and vaccines against human coronavirus infections such as MERS or SARS, however, till now, there is some controversy about the effectiveness and safety of antiviral drugs and vaccines which have been developed to treat and prevent this disease and its management depends mainly on supportive care. The spike glycoprotein or protein S of SARS-CoV-2 is the main promoter that induces development of neutralizing antibodies; hence, many attempts of vaccines and antiviral drugs development have been designed to be directed specifically against this protein. While some of these attempts have been proved to be efficient in in vitro settings, only few of them have been proceeded to randomized animal trials and human studies which makes COVID-19 prevention an ongoing challenge.

This review describes the natural immune response scenario during COVID-19 and the vaccines development trials to create efficient vaccines thus helping to build more effective approaches for prophylaxis and management.

COVID-19: High-JAKing of the Inflammatory "Flight" by Ruxolitinib to Avoid the Cytokine Storm

Since SARS-CoV-2 outbreak in December 2019, world health-system has been severely impacted with increased hospitalization, Intensive-Care-Unit (ICU) access and high mortality rates, mostly due to severe acute respiratory failure and multi-organ failure. Excessive and uncontrolled release of proinflammatory cytokines (cytokine release/storm syndrome, CRS) have been linked to the development of these events. The recent advancements of immunotherapy for the treatment of hematologic and solid tumors shed light on many of the molecular mechanisms underlying this phenomenon, thus rendering desirable a multidisciplinary approach to improve COVID-19 patients' outcome. Indeed, currently available therapeutic-strategies to overcome CRS, should be urgently evaluated for their capability of reducing COVID-19 mortality. Notably, COVID-19 shares different pathogenic aspects with acute graft-versus-host-disease (aGVHD), hemophagocytic-lymphohistiocytosis (HLH), myelofibrosis, and CAR-T-associated CRS. Specifically, similarly to aGVHD, an induced tissue damage (caused by the virus) leads to increased cytokine release (TNFα and IL-6) which in turn leads to exaggerated dendritic cells, macrophages (like in HLH) and lymphocytes (as in CAR-T) activation, immune-cells migration, and tissue-damage (including late-stage fibrosis, similar to myelofibrosis). Janus Kinase (JAK) signaling represents a molecular hub linking all these events, rendering JAK-inhibitors suitable to limit deleterious effects of an overwhelming inflammatory-response. Accordingly, ruxolitinib is the only selective JAK1 and JAK2-inhibitor approved for the treatment of myelofibrosis and aGVHD. Here, we discuss, from a molecular and hematological point of view, the rationale for targeting JAK signaling in the management of COVID-19 patients and report the clinical results of a patient admitted to ICU among the firsts to be treated with ruxolitinib in Italy.

Differential gene expression profiles of periodontal soft tissue from rat teeth after immediate and delayed replantation: a pilot study

Purpose

In dental avulsion, delayed replantation usually has an uncertain prognosis. After tooth replantation, complex inflammatory responses promote a return to periodontal tissue homeostasis. Various types of cytokines are produced in the inflammatory microenvironment, and these cytokines determine the periodontal tissue response. This study aimed to identify the gene expression profiles of replanted teeth and evaluate the functional differences between immediate and delayed replantation.

Methods

Maxillary molars from Sprague-Dawley rats were extracted, exposed to a dry environment, and then replanted. The animals were divided into 2 groups according to the extra-oral time: immediate replantation (dry for 5 minutes) and delayed replantation (dry for 60 minutes). Either 3 or 7 days after replantation, the animals were sacrificed. Periodontal soft tissues were harvested for mRNA sequencing. Hallmark gene set enrichment analysis was performed to predict the function of gene-gene interactions. The normalized enrichment score (NES) was calculated to determine functional differences.

Results

The hallmark gene sets enriched in delayed replantation at 3 days were oxidative phosphorylation (NES=2.82, Q<0.001) and tumor necrosis factor-alpha (TNF-α) signaling via the nuclear factor kappa light chain enhancer of activated B cells (NF-κB) pathway (NES=1.52, Q=0.034). At 7 days after delayed replantation, TNF-α signaling via the NF-κB pathway (NES=–1.82, Q=0.002), angiogenesis (NES=–1.66, Q=0.01), and the transforming growth factor-beta signaling pathway (NES=–1.46, Q=0.051) were negatively highlighted.

Conclusions

Differentially expressed gene profiles were significantly different between immediate and delayed replantation. TNF-α signaling via the NF-κB pathway was marked during the healing process. However, the enrichment score of this pathway changed in a time-dependent manner between immediate and delayed replantation.

SARS-CoV-2 desensitizes host cells to interferon through inhibition of the JAK-STAT pathway

SARS-CoV-2 can infect multiple organs, including lung, intestine, kidney, heart, liver, and brain. The molecular details of how the virus navigates through diverse cellular environments and establishes replication are poorly defined. Here, we performed global proteomic analysis of the virus-host interface in a newly established panel of phenotypically diverse, SARS-CoV-2-infectable human cell lines representing different body organs. This revealed universal inhibition of interferon signaling across cell types following SARS-CoV-2 infection. We performed systematic analyses of the JAK-STAT pathway in a broad range of cellular systems, including immortalized cell lines and primary-like cardiomyocytes, and found that several pathway components were targeted by SARS-CoV-2 leading to cellular desensitization to interferon. These findings indicate that the suppression of interferon signaling is a mechanism widely used by SARS-CoV-2 in diverse tissues to evade antiviral innate immunity, and that targeting the viral mediators of immune evasion may help block virus replication in patients with COVID-19.

Immune Dysfunction and Multiple Treatment Modalities for the SARS-CoV-2 Pandemic: Races of Uncontrolled Running Sweat?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic threat with more than 11.8 million confirmed cases and more than 0.5 million deaths as of 3 July 2020. Given the lack of definitive pharmaceutical interventions against SARS-CoV-2, multiple therapeutic strategies and personal protective applications are being used to reduce the risk of high mortality and community spread of this infection. Currently, more than a hundred vaccines and/or alternative therapeutic regimens are in clinical trials, and some of them have shown promising results in improving the immune cell environment and controlling the infection. In this review, we discussed high-performance multi-directory strategies describing the uncontrolled deregulation of the host immune landscape associated with coronavirus disease (COVID-19) and treatment strategies using an anti-neoplastic regimen. We also followed selected current treatment plans and the most important on-going clinical trials and their respective outcomes for blocking SARS-CoV-2 pathogenesis through regenerative medicine, such as stem cell therapy, chimeric antigen receptors, natural killer (NK) cells, extracellular vesicular-based therapy, and others including immunomodulatory regimens, anti-neoplastic therapy, and current clinical vaccine therapy.

Inhibition of Inflammatory Responses by Centella asiatica via Suppression of IRAK1-TAK1 in Mouse Macrophages

Centella asiatica (L.) Urb. (C. asiatica) has been widely treated for inflammation-related diseases in China for thousands of years. While C. asiatica showed relevant effects as traditional medicine, the mechanism of C. asiatica suppressing inflammation has not been thoroughly investigated. Therefore, this study was conducted to reveal the anti-inflammatory mechanism of methanol fraction from C. asiatica (MCA) at the molecular level in murine macrophages. Levels of inflammation-related mediators were observed with treatment of MCA. MCA significantly suppressed nitric oxide production and iNOS expression in RAW 264.7 macrophages. Prostaglandin E₂ production was alleviated by MCA via the downregulation of cyclooxygenase-2. MCA treatment also reduced pro-inflammatory tumor necrosis factor-[Formula: see text] and interleukin (IL)-6 levels. LPS/D-GalN-induced acute hepatitis in mouse was alleviated by MCA treatment. In addition, MCA decreased the phosphorylation of inhibitory [Formula: see text]B[Formula: see text] (I[Formula: see text]B[Formula: see text]) at Ser32/36 and thereby blocked I[Formula: see text]B[Formula: see text] degradation. TXY motif phosphorylation in the activation loops of mitogen-activated protein kinases (MAPKs) was also suppressed by MCA treatment. Further investigation revealed that MCA inhibited transforming growth factor-[Formula: see text]-activated kinase 1 (TAK1) phosphorylation and IL-1 receptor-associated kinase (IRAK1) degradation, the upstream kinases activating nuclear factor [Formula: see text]B and MAPKs. Taken together, MCA exhibited anti-inflammatory properties via the downregulation of IRAK1-TAK1 signaling pathways.

Immune response in COVID-19: addressing a pharmacological challenge by targeting pathways triggered by SARS-CoV-2

To date, no vaccines or effective drugs have been approved to prevent or treat COVID-19 and the current standard care relies on supportive treatments. Therefore, based on the fast and global spread of the virus, urgent investigations are warranted in order to develop preventive and therapeutic drugs. In this regard, treatments addressing the immunopathology of SARS-CoV-2 infection have become a major focus. Notably, while a rapid and well-coordinated immune response represents the first line of defense against viral infection, excessive inflammatory innate response and impaired adaptive host immune defense may lead to tissue damage both at the site of virus entry and at systemic level. Several studies highlight relevant changes occurring both in innate and adaptive immune system in COVID-19 patients. In particular, the massive cytokine and chemokine release, the so-called "cytokine storm", clearly reflects a widespread uncontrolled dysregulation of the host immune defense. Although the prospective of counteracting cytokine storm is compelling, a major limitation relies on the limited understanding of the immune signaling pathways triggered by SARS-CoV-2 infection. The identification of signaling pathways altered during viral infections may help to unravel the most relevant molecular cascades implicated in biological processes mediating viral infections and to unveil key molecular players that may be targeted. Thus, given the key role of the immune system in COVID-19, a deeper understanding of the mechanism behind the immune dysregulation might give us clues for the clinical management of the severe cases and for preventing the transition from mild to severe stages.

Anti-Inflammatory and Anti-Oxidative Effects of luteolin-7-O-glucuronide in LPS-Stimulated Murine Macrophages through TAK1 Inhibition and Nrf2 Activation

Various herbal extracts containing luteolin-7-O-glucuronide (L7Gn) have been traditionally used to treat inflammatory diseases. However, systemic studies aimed at elucidating the anti-inflammatory and anti-oxidative mechanisms of L7Gn in macrophages are insufficient. Herein, the anti-inflammatory and anti-oxidative effects of L7Gn and their underlying mechanisms of action in macrophages were explored. L7Gn inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages by transcriptional regulation of inducible NO synthase (iNOS) in a dose-dependent manner. The mRNA expression of inflammatory mediators, including cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α), was inhibited by L7Gn treatment. This suppression was mediated through transforming growth factor beta-activated kinase 1 (TAK1) inhibition that leads to reduced activation of nuclear factor-κB (NF-κB), p38, and c-Jun N-terminal kinase (JNK). L7Gn also enhanced the radical scavenging effect and increased the expression of anti-oxidative regulators, including heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and NAD(P)H quinone oxidoreductase 1 (NQO1), by nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) activation. These results indicate that L7Gn exhibits anti-inflammatory and anti-oxidative properties in LPS-stimulated murine macrophages, suggesting that L7Gn may be a suitable candidate to treat severe inflammation and oxidative stress.

Pyruvate Protects Against Intestinal Injury by Inhibiting the JAK/STAT Signaling Pathway in Rats With Hemorrhagic Shock

BACKGROUND

This study aimed to investigate the role of Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway in protection by peritoneal resuscitation (PR) using pyruvate-peritoneal dialysis solution (PY-PDS) against intestinal injury from hemorrhagic shock (HS) in rats.

MATERIALS AND METHODS

Sixty-four rats were assigned to eight groups: group SHAM; group intravenous resuscitation (VR); groups NS, LA, and PY in which the rats were subjected to HS and PR with normal saline (NS), lactate-peritoneal dialysis solution (LA-PDS), and PY-PDS, respectively, combined with VR; and groups DMSO, RPM, and AG490 in which the rats were subjected to HS and VR with pretreatment of dimethyl sulfoxide (DMSO), rapamycin (RPM), and tyrphostin B42 (AG490).

RESULTS

At 2 h after HS and resuscitation, the levels of diamine oxidase, 15-F_2t-isoprostane, thromboxane B₂, and endothelin-1, in the blood and the intestinal mucosal apoptotic index and caspase-3 were lower in groups PY, RPM, and AG490 than in groups VR, NS, LA, and DMSO. Group PY showed lower levels of malondialdehyde and myeloperoxidase and a higher level of superoxide dismutase than groups VR, NS, and LA. Phosphorylated JAK2 and phosphorylated STAT3 levels were lower in groups PY, RPM, AG490, and LA than in groups VR, NS, and DMSO.

CONCLUSIONS

The protection mechanism of PR with PY-PDS combined with VR was related to the inhibition of the JAK/STAT signaling pathway during HS and resuscitation. The process might include suppression of oxidative stress, reduction of neutrophil infiltration, regulation of microcirculation, and inhibition of apoptosis.

Role and mechanism of nursing cooperation and tetramethylpyrazine application in post-operative pain in patients undergoing total knee arthroplasty

The aim of the present study was to investigate the effect of nursing cooperation on the post-operative complication of pain following total knee arthroplasty (TKA) and to explore the effects of tetramethylpyrazine (TMP) application on post-TKA pain. A total of 26 patients who received TKA between June 2014 and March 2016 were enrolled in this study. Nursing cooperation was provided to the patients during the TKA surgery, and pain was evaluated based on the visual analog scale (VAS). In addition, 40 male Sprague Dawley rats were used for the TKA model construction. The rats were randomly separated into 4 groups (sham, TKA, TKA+TMP and TKA+TMP+Interferon γ). Pain tolerance in rats was evaluated by mechanical stimulation. Inflammatory cytokine levels in TKA rat tissue were detected using ELISA. mRNA and protein expression of Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) was detected using reverse transcription-polymerase chain reaction and western blot analysis, respectively. The results indicated that nursing cooperation serves a critical function during TKA and was associated with a lower level of pain compared with the control (P<0.05). Furthermore, TMP treatment reduced the level of inflammatory cytokines in the rat tissues, including interleukin (IL)-6, IL-10 and tumor necrosis factor-α in post-TKA (P<0.01). TMP was indicated to alleviate pain in post-TKA through suppressing the JAK/STAT3 signaling pathway. The results of the present study suggest that nursing cooperation is critical to TKA, and TMP may alleviate post-TKA pain through inhibiting the JAK/STAT3 signaling pathway.

Hepcidin-ferroportin axis in health and disease

Hepcidin is central to regulation of iron metabolism. Its effect on a cellular level involves binding ferroportin, the main iron export protein, resulting in its internalization and degradation and leading to iron sequestration within ferroportin-expressing cells. Aberrantly increased hepcidin leads to systemic iron deficiency and/or iron restricted erythropoiesis. Furthermore, insufficiently elevated hepcidin occurs in multiple diseases associated with iron overload. Abnormal iron metabolism as a consequence of hepcidin dysregulation is an underlying factor resulting in pathophysiology of multiple diseases and several agents aimed at manipulating this pathway have been designed, with some already in clinical trials. In this chapter, we present an overview of and rationale for exploring the development of hepcidin agonists and antagonists in various clinical scenarios.

Inhibition of microRNA-132 attenuates inflammatory response and detrusor fibrosis in rats with interstitial cystitis via the JAK-STAT signaling pathway

Interstitial cystitis (IC) is a heterogeneous syndrome with unknown etiology, and microRNAs (miRs) were found to be involved in IC. In our study, we aim to explore the role of miR-132 in the inflammatory response and detrusor fibrosis in IC through the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway in rat models. A rat model of IC was established and treated with the miR-132 mimic, miR-132 inhibitor, and/or JAK-STAT signaling pathway inhibitor AG490. Enzyme-linked immunosorbent assay was applied to measure the expression of interleukin (IL)-6, IL-10, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α), and intercellular adhesion molecule-1 (ICAM-1). The urodynamic test was performed to assess urodynamic parameters, and reverse transcription quantitative polymerase chain reaction and Western blot analysis for the expression of miR-132, STAT4, suppressors of cytokine signaling 3 (SOCS3), JAK2, vascular endothelial growth factor (VEGF), IFN-γ, and TNF-α. IC rats treated with miR-132 inhibitor and AG490 had decreased collagen fiber, inflammatory cell infiltration, and mast cells, lower expression of IL-6, IL-10, IFN-γ, TNF-α, ICAM-1, collagens I and III, and alleviated urodynamic parameters and decreased expression of STAT4, VEGF, JAK2, IFN-γ, TNF-α, and increased expression of SOCS3. Taken together, our data indicate that downregulation of miR-132 alleviates inflammatory response and detrusor fibrosis in IC via the inhibition of the JAK-STAT signaling pathway.

Dysregulated iron metabolism in polycythemia vera: etiology and consequences

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm. Virtually all PV patients are iron deficient at presentation and/or during the course of their disease. The co-existence of iron deficiency and polycythemia presents a physiological disconnect. Hepcidin, the master regulator of iron metabolism, is regulated by circulating iron levels, erythroblast secretion of erythroferrone, and inflammation. Both decreased circulating iron and increased erythroferrone levels, which occur as a consequence of erythroid hyperplasia in PV, are anticipated to suppress hepcidin and enable recovery from iron deficiency. Inflammation which accompanies PV is likely to counteract hepcidin suppression, but the relatively low serum ferritin levels observed suggest that inflammation is not a major contributor to the dysregulated iron metabolism. Furthermore, potential defects in iron absorption, aberrant hypoxia sensing and signaling, and frequency of bleeding to account for iron deficiency in PV patients have not been fully elucidated. Insufficiently suppressed hepcidin given the degree of iron deficiency in PV patients strongly suggests that disordered iron metabolism is an important component of the pathobiology of PV. Normalization of hematocrit levels using therapeutic phlebotomy is the most common approach for reducing the incidence of thrombotic complications, a therapy which exacerbates iron deficiency, contributing to a variety of non-hematological symptoms. The use of cytoreductive therapy in high-risk PV patients frequently works more effectively to reverse PV-associated symptoms in iron-deficient relative to iron-replete patients. Lastly, differences in iron-related parameters between PV patients and mice with JAK2 V617F and JAK2 exon 12 mutations suggest that specific regions in JAK2 may influence iron metabolism by nuanced changes of erythropoietin receptor signaling. In this review, we comprehensively discuss the clinical consequences of iron deficiency in PV, provide a framework for understanding the potential dysregulation of iron metabolism, and present a rationale for additional therapeutic options for iron-deficient PV patients.

Role of ALDH1 in the prognosis of esophageal cancer and its relationship with tumor microenvironment

Aldehyde dehydrogenase 1 (ALDH1) is associated with tumorigenesis, and significantly increased in cancer stem-like cells. In the present study, the role of ALDH1 in esophageal squamous cell carcinoma (ESCC) was investigated. We retrospectively analyzed the clinical outcomes of 148 ESCC and examined its correlation with ALDH1 levels. Furthermore, we preformed cellular and animal experiments to investigate the role of ALDH1 in tumor progression and microenvironment. Our data revealed that ALDH1 staining was positively linked to a higher clinical stage, higher loco-regional failure rate, and shorter survival time. Furthermore, there was a positive link between ALDH1 expression and IL-6 signaling according to the data of clinical specimens and cellular experiments. Using animal model, ALDH1-positive tumors were associated with aggressive tumor growth, increased IL-6, augmented epithelial-mesenchymal transition (EMT), and activation of myeloid-derived suppressor cells (MDSCs). Blockade of COX-2 attenuated the aggressive tumor growth of ALDH1-positive cancer cells. In conclusion, our findings suggested that ALDH1 played an important role in tumor aggressiveness and associated with a tumor-promoting microenvironment in esophageal cancer. Directly targeting ALDH1 or using a COX-2 inhibitor could be a promising strategy for the treatment of ESCC.

Macrophage JAK2 deficiency protects against high-fat diet-induced inflammation

During obesity, macrophages can infiltrate metabolic tissues, and contribute to chronic low-grade inflammation, and mediate insulin resistance and diabetes. Recent studies have elucidated the metabolic role of JAK2, a key mediator downstream of various cytokines and growth factors. Our study addresses the essential role of macrophage JAK2 in the pathogenesis to obesity-associated inflammation and insulin resistance. During high-fat diet (HFD) feeding, macrophage-specific JAK2 knockout (M-JAK2^−/−) mice gained less body weight compared to wildtype littermate control (M-JAK2^+/+) mice and were protected from HFD-induced systemic insulin resistance. Histological analysis revealed smaller adipocytes and qPCR analysis showed upregulated expression of some adipogenesis markers in visceral adipose tissue (VAT) of HFD-fed M-JAK2^−/− mice. There were decreased crown-like structures in VAT along with reduced mRNA expression of some macrophage markers and chemokines in liver and VAT of HFD-fed M-JAK2^−/− mice. Peritoneal macrophages from M-JAK2^−/− mice and Jak2 knockdown in macrophage cell line RAW 264.7 also showed lower levels of chemokine expression and reduced phosphorylated STAT3. However, leptin-dependent effects on augmenting chemokine expression in RAW 264.7 cells did not require JAK2. Collectively, our findings show that macrophage JAK2 deficiency improves systemic insulin sensitivity and reduces inflammation in VAT and liver in response to metabolic stress.

Obesity and neuroinflammatory phenotype in mice lacking endothelial megalin

BACKGROUND

The multiligand receptor megalin controls the brain uptake of a number of ligands, including insulin and leptin. Despite the role of megalin in the transport of these metabolically relevant hormones, the role of megalin at the blood-brain-barrier (BBB) has not yet been explored in the context of metabolic regulation.

METHODS

Here we investigate the role of brain endothelial megalin in energy metabolism and leptin signaling using an endothelial cell-specific megalin deficient (EMD) mouse model.

RESULTS

We found megalin is important to protect mice from developing obesity and metabolic syndrome when mice are fed a normal chow diet. EMD mice developed neuroinflammation, by triggering several pro-inflammatory cytokines, displayed reduced neurogenesis and mitochondrial deregulation.

CONCLUSIONS

These results implicate brain endothelial megalin expression in obesity-related metabolic changes through the leptin signaling pathway proposing a potential link between obesity and neurodegeneration.

High mobility group box 1 induces the activation of the Janus kinase 2 and signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in pancreatic acinar cells in rats, while AG490 and rapamycin inhibit their activation

The pathogenesis of severe acute pancreatitis (SAP) remains unclear. The Janus kinase and signal transducer and activator of transcription (JAK/STAT) pathway is important for various cytokines and growth factors. This study investigated the effect of the late inflammatory factor high mobility group box 1 (HMGB1) on the activation of JAK2/STAT3 in pancreatic acinar cells and the inhibitory effects of AG490 (a JAK2 inhibitor) and rapamycin (a STAT3 inhibitor) on this pathway. Rat pancreatic acinar cells were randomly divided into the control, HMGB1, AG490, and rapamycin groups. The mRNA levels of JAK2 and STAT3 at 10, 30, 60, and 120 minutes were detected using reverse transcription polymerase chain reaction (RT-PCR). The protein levels of JAK2 and STAT3 at 60 and 120 minutes were observed using Western blotting. Compared with the control group, the HMGB1 group exhibited significantly increased levels of JAK2 mRNA at each time point; STAT3 mRNA at 30, 60, and 120 minutes; and JAK2 and STAT3 proteins at 60 and 120 minutes (p < 0.01). Compared with the HMGB1 group, the AG490 and rapamycin groups both exhibited significantly decreased levels of JAK2 mRNA at each time point (p < 0.05); STAT3 mRNA at 30, 60, and 120 minutes (p < 0.01); and JAK2 and STAT3 proteins at 60 and 120 minutes (p < 0.01). HMGB1 induces the activation of the JAK2/STAT3 signaling pathway in rat pancreatic acinar cells, and this activation can be inhibited by AG490 and rapamycin. The results of this study may provide new insights for the treatment of SAP.

Effect of N-Feruloylserotonin and Methotrexate on Severity of Experimental Arthritis and on Messenger RNA Expression of Key Proinflammatory Markers in Liver

Rheumatoid arthritis (RA) is a chronic inflammatory disease, leading to progressive destruction of joints and extra-articular tissues, including organs such as liver and spleen. The purpose of this study was to compare the effects of a potential immunomodulator, natural polyphenol N-feruloylserotonin (N-f-5HT), with methotrexate (MTX), the standard in RA therapy, in the chronic phase of adjuvant-induced arthritis (AA) in male Lewis rats. The experiment included healthy controls (CO), arthritic animals (AA), AA given N-f-5HT (AA-N-f-5HT), and AA given MTX (AA-MTX). N-f-5HT did not affect the body weight change and clinical parameters until the 14th experimental day. Its positive effect was rising during the 28-day experiment, indicating a delayed onset of N-f-5HT action. Administration of either N-f-5HT or MTX caused reduction of inflammation measured as the level of CRP in plasma and the activity of LOX in the liver. mRNA transcription of TNF-α and iNOS in the liver was significantly attenuated in both MTX and N-f-5HT treated groups of arthritic rats. Interestingly, in contrast to MTX, N-f-5HT significantly lowered the level of IL-1β in plasma and IL-1β mRNA expression in the liver and spleen of arthritic rats. This speaks for future investigations of N-f-5HT as an agent in the treatment of RA in combination therapy with MTX.

Inhibitory effect of baicalin on allergic response in ovalbumin-induced allergic rhinitis guinea pigs and lipopolysaccharide-stimulated human mast cells

OBJECTIVE

Baicalin, a flavonoid compound purified from the dry roots of Scutellaria baicalensis Georgi, has generally been used for the treatment of various allergic diseases. However, there is little information about the anti-inflammatory effects of baicalin for allergic rhinitis. This study aims to investigate the anti-allergic effect of baicalin on allergic response in ovalbumin (OVA)-induced allergic rhinitis guinea pigs and lipopolysaccharide (LPS)-stimulated human mast cells.

METHODS

Using in vivo models, we evaluated the effect of baicalin on allergic rhinitis symptoms via recording the number of nasal rubs and sneezes. The levels of histamine, OVA-specific immunoglobulin E(IgE), eosinophil cationic protein (ECP) and inflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The histological changes of nasal mucosa were observed by light microscope after HE staining. In vitro, the release of histamine and β-hexosaminidase of compound 48/80-induced human mast cells were measured by ELISA and PNP-NAG colorimetry, respectively. The productions of inflammatory cytokines of LPS-stimulated human mast cells were determined using ELISA. Western blot was used to test the protein expression of JAK2, p-JAK2, STAT5, p-STAT5, IKKβ, p-IKKβ, IκBα, p-IκBα and NF-κB (p65) of LPS-stimulated human mast cells.

RESULTS

The oral administration of baicalin at doses of 50 and 200 mg/kg improved allergic rhinitis symptoms and the histological changes of nasal mucosa and decreased the serum levels of histamine, ECP, interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α and OVA-specific IgE in OVA-induced allergic rhinitis guinea pigs. In vitro, baicalin suppressed the release of histamine and β-hexosaminidase in compound 48/80-induced human mast cells. In addition, baicalin also inhibited the productions of inflammatory cytokines such as IL-1β, IL-6, IL-8 and TNF-α and suppressed the phosphorylation of JAK2, STAT5, IKKβ, IκBα and the nuclear translocation of NF-κB (p65) subunit in LPS-stimulated human mast cells.

CONCLUSIONS

These results suggest that baicalin can effectively prevent allergic response in OVA-induced allergic rhinitis guinea pigs and inhibit inflammatory response via blocking JAK2-STAT5 and NF-κB signaling pathways in LPS-stimulated human mast cells. Considered together,the results show that baicalin may be a useful drug in the treatment of allergic rhinitis.

c-Jun N-terminal kinase-mediated anti-inflammatory effects of Garcinia subelliptica in macrophages

Garcinia plants have been traditionally used to treat inflammatory diseases, such as skin infections and pain, in many regions including South‑East Asia. Garcinia subelliptica, a plant of the Garcinia species widely distributed from Japan to Thailand, has been reported to contain components similar to other Garcinia plants that exhibit anti‑inflammatory effects. The present study aimed to explore the anti‑inflammatory effects of ethanol extracts of Garcinia subelliptica (EGS) in macrophages, as there are no previous systemic studies that have investigated the effects of Garcinia subelliptica on inflammation. Non‑cytotoxic concentrations of EGS (≤200 µg/ml) were observed to reduce nitric oxide production by modulating iNOS expression in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. The expression of cyclooxygenase‑2, the enzyme responsible for the production of prostaglandin E2, was notably reduced by EGS. EGS treatment inhibited the production of pro‑inflammatory cytokines, including IL‑6 and IL‑1β, however, not TNF‑α. Reduced production of inflammatory mediators by EGS was followed by reduced phosphorylation of c‑Jun N‑terminal kinase (JNK) however, not of other mitogen‑activated protein kinases and nuclear factor‑κB. These results indicate that EGS selectively inhibits the excessive production of inflammatory mediators in LPS‑stimulated murine macrophages by reducing the activation of JNK, suggesting that EGS is a candidate for modulating severe inflammation.

Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms

The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34⁺ cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34⁺ cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs.

Interdependent and independent roles of type I interferons and IL-6 in innate immune, neuroinflammatory and sickness behaviour responses to systemic poly I:C

Type I interferons (IFN-I) are expressed in the brain during many inflammatory and neurodegenerative conditions and have multiple effects on CNS function. IFN-I is readily induced in the brain by systemic administration of the viral mimetic, poly I:C (synthetic double-stranded RNA). We hypothesised that IFN-I contributes to systemically administered poly I:C-induced sickness behaviour, metabolic and neuroinflammatory changes. IFN-I receptor 1 deficient mice (IFNAR1(-/-)) displayed significantly attenuated poly I:C-induced hypothermia, hypoactivity and weight loss compared to WT C57BL/6 mice. This amelioration of sickness was associated with equivalent IL-1β and TNF-α responses but much reduced IL-6 responses in plasma, hypothalamus and hippocampus of IFNAR1(-/-) mice. IFN-β injection induced trivial IL-6 production and limited behavioural change and the poly I:C-induced IFN-β response did not preceed, and would not appear to mediate, IL-6 induction. Rather, IFNAR1(-/-) mice lack basal IFN-I activity, have lower STAT1 levels and show significantly lower levels of several inflammatory transcripts, including stat1. Basal IFN-I activity appears to play a facilitatory role in the full expression of the IL-6 response and activation of the tryptophan-kynurenine metabolism pathway. The deficient IL-6 response in IFNAR1(-/-) mice partially explains the observed incomplete sickness behaviour response. Reconstitution of circulating IL-6 revealed that the role of IFNAR in burrowing activity is mediated via IL-6, while IFN-I and IL-6 have additive effects on hypoactivity, but the role of IFN-I in anorexia is independent of IL-6. Hence, we have demonstrated both interdependent and independent roles for IFN-I and IL-6 in systemic inflammation-induced changes in brain function.

The metastatic tumor antigen 1-transglutaminase-2 pathway is involved in self-limitation of monosodium urate crystal-induced inflammation by upregulating TGF-β1

INTRODUCTION

Transglutaminase 2 (TG2), a protein crosslinking enzyme with multiple biochemical functions, has been connected to various inflammatory processes. In this study, the involvement of TG2 in monosodium urate (MSU) crystal-induced inflammation was studied.

METHODS

Immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR) were performed to detect TG2 expression in synovial fluid mononuclear cells (SFMCs) and synovial tissue from patients with gouty arthritis. MSU crystal-exposed RAW264.7 mouse macrophages were analyzed for interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), transforming growth factor β1 (TGF-β1) and TG2 expression by RT-PCR and enzyme-linked immunosorbent assay (ELISA). TG2 small interfering (si)-RNA-mediated silencing and overexpression in RAW264.7 cells were used to evaluate the involvement of TG2 in resolving MSU crystal-induced inflammation. The role of metastatic tumor antigen 1 (MTA1), a master chromatin modifier, was investigated by MTA1 si-RNA-mediated knockdown. In addition, the inflammatory responses were followed in wild type and TG2 null mice after being challenged with MSU crystals in an in vivo peritonitis model.

RESULTS

TG2 expression was up-regulated in the synovium tissue and SFMCs from patients with gouty arthritis. The levels of MTA1, TG2, TGF-β1, IL-1β and TNF-α mRNAs were consistently increased in MSU crystal-stimulated RAW264.7 cells. si-MTA1 impaired the basal, as well as the MSU crystal-induced expression of TG2 and TGF-β1, but increased that of IL-1β and TNF-α. TG2 overexpression dramatically suppressed MSU crystal-induced IL-1β and TNF-α, but significantly enhanced the TGF-β1 production. Neutralizing TGF-β antibodies or inhibition of the crosslinking activity of TG2 attenuated these effects. On the contrary, loss of TG2 resulted in a reduced TGF-β, but in an increased IL-1β and TNF-α production in MSU crystal-stimulated RAW264.7 cells and mouse embryonic fibroblasts (MEFs). MSU crystal-stimulated IL-1β production was Janus kinase 2 (JAK2)-signaling dependent and TG2-induced TGF-β suppressed the activity of it. Finally, TG2-deficient mice exhibited hyper inflammatory responses after being challenged with MSU crystals in an in vivo peritonitis model.

CONCLUSIONS

These findings reveal an inherent regulatory role of the MTA1-TG2 pathway in the self-limitation of MSU crystal-induced inflammation via positively regulating the levels of active TGF-β1 in macrophages that opposes the MSU crystal-induced JAK2-dependent pro-inflammatory cytokine formation.

Anti-inflammatory effects of Crataeva nurvala Buch. Ham. are mediated via inactivation of ERK but not NF-κB

ETHNOPHARMACOLOGICAL RELEVANCE

Crataeva nurvala Buch. Ham. is an important medicinal plant in India, and its extracts and components were used to treat various inflammatory diseases, such as urinary tract infection, rheumatoid arthritis, and colitis. However, no systemic studies about anti-inflammatory effects of Crataeva nurvala Buch. Ham. and its underlying mechanisms of action have been reported. This study aimed to explore the anti-inflammatory effects of ethanol extracts of Crataeva nurvala Buch. Ham. (ECN).

MATERIALS AND METHODS

The non-cytotoxic and maximal effective concentration of ECN was determined by measuring the formation of formazan from water-soluble tetrazolium salt in living cells. The inhibitory effect of ECN on nitric oxide (NO) synthesis was measured using Griess reagent, and Enzyme-linked immunosorbent assay (ELISA) was used to measure secreted tumor necrosis factor (TNF)-α and interleukin (IL)-6 protein levels. Furthermore, reverse transcription polymerase chain reaction (RT-PCR) and Western blotting analysis were used to assess the mRNA and protein expression of each inflammatory mediator or relating signaling protein, respectively.

RESULTS

A non-cytotoxic concentration of ECN (≤200 μg/ml) significantly reduced the production of NO and IL-6, but not TNF-α, in lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. Decreased production of NO by ECN was correlated with reduced expression of iNOS at the mRNA and protein levels. However, cyclooxygenase (COX)-2 expressions at mRNA and protein level were not regulated by ECN. The mRNA expression of IL-6 and IL-1β, but not TNF-α, was also inhibited by ECN treatment in LPS-stimulated RAW 264.7 macrophages. Reduced production of inflammatory mediators by ECN was followed by decreased activity of mitogen-activated protein kinases (MAPKs), especially extracellular signal-regulated kinase (ERK), but not nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB).

CONCLUSIONS

These results indicate that ECN inhibits LPS-induced inflammatory responses via negative regulation of ERK in murine macrophages, suggesting that ECN is a candidate for alleviating severe inflammation.

Methanol extracts of Euphorbia cooperi inhibit the production of inflammatory mediators by inhibiting the activation of c‑Jun N‑terminal kinase and p38 in murine macrophages

Numerous Euphorbiaceae plants have been used for the treatment of diseases, including liver diseases, asthma and rheumatism. The present study evaluated the effect of methanol extracts from Euphorbia cooperi (MEC), a member of the Euphorbiaceae plant family, on the production of inflammatory cytokines interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α, nitric oxide (NO) as well as the activation of mitogen‑activated protein kinase and nuclear factor (NF)‑κB signaling. Non‑cytotoxic concentrations of MEC significantly reduced the production of NO and IL‑6, but not TNF‑α, in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. The decreased production of NO by MEC was due to alleviated expression of inducible NO synthase. Reporter assays with cells treated with MEC demonstrated reduced activator protein‑1 (AP-1) activity, while NF‑κB activity was not reduced. Furthermore, the phosphorylation levels of c‑Jun N‑terminal kinase (JNK) and p38 were suppressed by MEC while phosphorylation levels of inhibitor of κB were not reduced by MEC, suggesting that MEC‑mediated inactivation of JNK and p38 is the underlying regulatory mechanism for inflammatory mediators in LPS‑stimulated RAW 264.7 macrophages.

Cyclovirobuxinum D suppresses lipopolysaccharide-induced inflammatory responses in murine macrophages in vitro by blocking JAK-STAT signaling pathway

AIM

Cyclovirobuxinum D (CVB-D), an alkaloid isolated from the Chinese medicinal plant Buxus microphylla, has been found to be effective to treat cardiac insufficiency, arrhythmias and coronary heart disease. In the present study, we investigated the effects of CVB-D on the inflammatory responses in lipopolysaccharide (LPS)-stimulated murine macrophages in vitro and the underlying mechanisms.

METHODS

Murine macrophage cell line RAW264.7 cells were incubated in the presence of LPS (0.1 μg/mL) for 24 h. The cell viability was measured using MTT assay. The release of NO and cytokines were detected using the Griess test and ELISA, respectively. The mRNA and protein levels were determined using RT-PCR and Western blot, respectively. Reporter gene assays were used to analyze the transcriptional activity of NF-κB.

RESULTS

Treatment of RAW264.7 cells with CVB-D (25-300 μmol/L) did not affect the cell viability. Pretreatment with CVB-D (50, 100 and 200 μmol/L) concentration-dependently decreased NO release and iNOS expression in LPS-treated RAW264.7 cells (its IC50 value in inhibition of NO production was 144 μmol/L). CVB-D also concentration-dependently inhibited the secretion and mRNA expression of IL-1β and IL-6 in LPS-treated RAW264.7 cells. Furthermore, CVB-D remarkably inhibited the phosphorylation of STAT1 and STAT3, as well as JAK2 in LPS-treated RAW264.7 cells, but did not affect the activation of NF-κB and MAPKs pathways. Pretreatment with the JAK2 specific inhibitor AG490 (30 μmol/L) produced similar effects on NO release and iNOS expression in LPS-treated RAW264.7 cells.

CONCLUSION

CVB-D exerts anti-inflammatory effects in LPS-stimulated murine macrophages in vitro at least in part by blocking the JAK-STAT signaling pathway. The anti-inflammatory actions of CVB-D may contribute to its cardioprotection.

Lysimachia clethroides Duby extract attenuates inflammatory response in Raw 264.7 macrophages stimulated with lipopolysaccharide and in acute lung injury mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Lysimachia clethroides Duby (LC) is a traditional medicinal herb used to treat edema, hepatitis and inflammatory diseases in China and other Asian countries. In this study, the anti-inflammatory effects of LC extract and the mechanisms underlying were explored in both in vitro cell lines and acute lung injury (ALI) animal model of inflammation in vivo.

MATERIALS AND METHODS

Lipopolysaccharide (LPS)-stimulated Raw 264.7 murine macrophages were used to study the regulatory effects of LC extract on inflammatory mediators such as nitric oxide (NO) and proinflammatory cytokine expression. Western blotting or ELISA techniques were employed to estimate protein levels. RT-PCR was used for analyzing the interferon (IFN)-β production. LPS-induced ALI mouse model in vivo was employed to study the effect of LC extract. Further high-performance liquid chromatography (HPLC) fingerprinting technique was used to evaluate the active constituents present in LC extract, compared with reference standards.

RESULTS

Pre-treatment with LC extract inhibited the LPS-stimulated NO release, interleukin (IL)-1β and IL-6 production in Raw 264.7 cells dose dependently. LC extract inhibited the LPS-stimulated IRF3 and STAT1 phosphorylation. Further, in vivo experiments revealed that LC extract suppressed the infiltration of immune cells into the lung and proinflammatory cytokine production in broncho-alveolar lavage fluid (BALF) in the LPS-induced ALI mouse model.

CONCLUSIONS

Our results indicate that LC extract attenuates LPS-stimulated inflammatory responses in macrophages via regulating the key inflammatory mechanisms, providing a scientific support for its traditional use in treating various inflammatory diseases.

A plant kavalactone desmethoxyyangonin prevents inflammation and fulminant hepatitis in mice

Alpinia pricei Hayata is a Formosan plant which has been popularly used as nutraceutical or folk medicine for inflammation and various disorders. An active compound of the plant rhizomes, desmethoxyyangonin (DMY), was identified in this study for its novel effect against endotoxin lipopolysaccharide (LPS)-stimulated inflammation in murine macrophages and LPS/D-galactosamine (LPS/D-GalN)-induced fulminant hepatitis in mice. DMY was observed to significantly inhibit proliferation and activation of T cells ex vivo and the activity of several pro-inflammatory mediators in vitro. DMY also protected LPS/D-GalN−induced acute hepatic damages in mice through inhibiting aminotransferases activities and infiltrations of inflammatory macrophages, neutrophils and pathogenic T cells into the liver tissues. In addition, pretreatment with DMY significantly improved the survival rate of LPS/D-GalN−treated mice to 90% (9/10), compared to LPS/D-GalN−treated group (40%, 4/10). UPLC/MS platform-based comparative metabolomics approach was used to explore the serum metabolic profile in fulminant hepatic failure (FHF) mice with or without the DMY pretreatment. The results showed that LPS/D-GalN−induced hepatic damage is likely through perturbing amino acid metabolism, which leads to decreased pyruvate formation via catalysis of aminotransferases, and DMY treatment can prevent to a certain degree of these alterations in metabolic network in mouse caused by LPS/D-GalN. Mechanistic investigation demonstrated that DMY protects LPS or LPS/D-GalN−induced damages in cell or liver tissues mainly through de-regulating IKK/NFκB and Jak2/STAT3 signaling pathways. This report provides evidence-based knowledge to support the rationale for the use of A. pricei root extract in anti-inflammation and also its new function as hepatoprotetive agent against fulminant hepatitis.

MicroRNA-124 mediates the cholinergic anti-inflammatory action through inhibiting the production of pro-inflammatory cytokines

The vagus nerve can control inflammatory response through a 'cholinergic anti-inflammatory pathway', which is mediated by the α7-nicotinic acetylcholine receptor (α7nAChR) on macrophages. However, the intracellular mechanisms that link α7nAChR activation and pro-inflammatory cytokine production remain not well understood. In this study, we found that miR-124 is upregulated by cholinergic agonists in LPS-exposed cells and mice. Utilizing miR-124 mimic and siRNA knockdown, we demonstrated that miR-124 is a critical mediator for the cholinergic anti-inflammatory action. Furthermore, our data indicated that miR-124 modulates LPS-induced cytokine production by targeting signal transducer and activator of transcription 3 (STAT3) to decrease IL-6 production and TNF-α converting enzyme (TACE) to reduce TNF-α release. These results also indicate that miR-124 is a potential therapeutic target for the treatment of inflammatory diseases.

Mollugin inhibits the inflammatory response in lipopolysaccharide-stimulated RAW264.7 macrophages by blocking the Janus kinase-signal transducers and activators of transcription signaling pathway

Mollugin, a kind of naphthohydroquinone, is a major constituent isolated from Rubia cordifolia L. and demonstrated to possess anti-inflammatory activity in recent reports. However, the effects and mechanism of action of mollugin in inflammation have not been fully defined. The present study was therefore designed to investigate whether mollugin suppresses the inflammatory response in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Mollugin attenuated the LPS-induced expression of nitric oxide (NO), inducible nitric oxide synthase (iNOS), interleukin (IL)-1β and IL-6 but augmented the expression of tumor necrosis factor (TNF)-α. Mollugin did not inhibit the degradation of inhibitory kappa B (IκB)-α or the nuclear translocation of p65 nuclear factor-kappa B (NF-κB) but rather enhanced the phosphorylation of p65 subunits evoked by LPS. Mollugin did not inhibit the phosphorylation of extracellular-signal-related kinase (ERK) 1/2, p38, and c-Jun N-terminal kinase (JNK) 1/2 either. Mollugin significantly reduced the LPS-mediated phosphorylation of Janus kinase (JAK) 2, signal transducers and activators of transcription (STAT) 1 and STAT3. Molecular docking analysis showed that mollugin binds to JAK2 in a manner similar to that of AG490, a specific JAK2 inhibitor. We conclude that mollugin may be a JAK2 inhibitor and inhibits LPS-induced inflammatory responses by blocking the activation of the JAK-STAT pathway.

Inducible microRNA-223 down-regulation promotes TLR-triggered IL-6 and IL-1β production in macrophages by targeting STAT3

MicroRNAs are small non-coding RNA molecules that regulate gene expression by either translational inhibition or mRNA degradation. MicroRNAs play pivotal roles in the regulation of both innate and adaptive immune responses, including TLR-triggered inflammatory response. Here we reported that the expression of microRNA-223 (miR-223) was significantly decreased in murine macrophages during activation by lipopolysaccharide (LPS) or poly (I∶C) stimulation. The inducible miR-223 down-regulation resulted in the activation of signal transducer and activator of transcription 3 (STAT3), which is directly targeted by miR-223, thus promoting the production of pro-inflammatory cytokines IL-6 and IL-1β, but not TNF-α. Interestingly, IL-6 was found to be a main factor in inducing the decrease in miR-223 expression after LPS stimulation, which formed a positive feedback loop to regulate IL-6 and IL-1β. Herein, our findings provide a new explanation characterizing the molecular mechanism responsible for the regulation of IL-6 production after TLR-triggered macrophage activation.

Nicotinic acetylcholine receptor α7 subunit: a novel therapeutic target for cardiovascular diseases

Inflammation is important in the pathogenesis and development of cardiovascular diseases. Recent studies show that vagus nerve stimulation inhibits pro-inflammatory cytokine production through "the cholinergic anti-inflammatory pathway," more specifically via the α7 nicotinic acetylcholine receptor (α7nAChR). In the current study, the role of the cholinergic anti-inflammatory pathway during septic shock, hypertension, and myocardial infarction is reviewed, and its possible clinical implications in cardiovascular diseases are discussed.

Regulation of carcinoembryonic antigen release from colorectal cancer cells

Clinical and experimental evidence suggest that circulating carcinoembryonic antigen (CEA) released from tumor cells has an instrumental role in colorectal cancer-liver metastasis. However, the precise mechanism of the regulation of the CEA release from cancer cells is not known. We investigated if the rate of CEA and another GPI-anchored protein, alkaline phosphatase (AP) release is correlated with cellular glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) expression. We also evaluated the effects of phosphatidic acid (PA), a compound known to inhibit GPI-PLD activity, on the CEA and AP release from colon cancer cells. The expression of CEA, GPI-PLD, and AP in five colon carcinoma cells (LS180, Caco2, SW742, SW1116, and HT29/219) was verified by immunoblot and real-time RT-PCR analysis. The amounts of CEA and AP released into cell culture media were determined using ELISA and a colorimetric assay, respectively. We examined the effects of PA (20-100 μM) on CEA and AP release from LS180 cells. All five cancer cell lines analyzed expressed GPI-PLD protein. While there was a positive relationship between AP release and the levels of GPI-PLD transcript expression, we found no direct correlation between CEA released from cancer cells and the GPI-PLD mRNA expression level. However, the rate of CEA release was positively associated with the level of CEA transcript expression. In comparison to controls, the release of GPI-anchored CEA and AP, but not CA19-9 was inhibited significantly by both crude and pure phosphatidic acid (by 56 and 54.5%, respectively). Using PA for inhibiting CEA release from cancer cells may have therapeutic application in preventing CRC-liver metastasis.