Involvement of p38 MAPK in haemozoin-dependent MMP-9 enhancement in human monocytes

Circadian Control of the Response of Macrophages to Plasmodium Spp.-Infected Red Blood Cells

Malaria is a serious vector-borne disease characterized by periodic episodes of high fever and strong immune responses that are coordinated with the daily synchronized parasite replication cycle inside RBCs. As immune cells harbor an autonomous circadian clock that controls various aspects of the immune response, we sought to determine whether the intensity of the immune response to Plasmodium spp., the parasite causing malaria, depends on time of infection. To do this, we developed a culture model in which mouse bone marrow-derived macrophages are stimulated with RBCs infected with Plasmodium berghei ANKA (iRBCs). Lysed iRBCs, but not intact iRBCs or uninfected RBCs, triggered an inflammatory immune response in bone marrow-derived macrophages. By stimulating at four different circadian time points (16, 22, 28, or 34 h postsynchronization of the cells' clock), 24-h rhythms in reactive oxygen species and cytokines/chemokines were found. Furthermore, the analysis of the macrophage proteome and phosphoproteome revealed global changes in response to iRBCs that varied according to circadian time. This included many proteins and signaling pathways known to be involved in the response to Plasmodium infection. In summary, our findings show that the circadian clock within macrophages determines the magnitude of the inflammatory response upon stimulation with ruptured iRBCs, along with changes of the cell proteome and phosphoproteome.

Plasmodium curtails autoimmune nephritis via lasting bone marrow alterations, independent of hemozoin accumulation

The host response against infection with Plasmodium commonly raises self-reactivity as a side effect, and antibody deposition in kidney has been cited as a possible cause of kidney injury during severe malaria. In contrast, animal models show that infection with the parasite confers long-term protection from lethal lupus nephritis initiated by autoantibody deposition in kidney. We have limited knowledge of the factors that make parasite infection more likely to induce kidney damage in humans, or the mechanisms underlying protection from autoimmune nephritis in animal models. Our experiments with the autoimmune-prone FcγR2B[KO] mice have shown that a prior infection with P. yoelii 17XNL protects from end-stage nephritis for a year, even when overall autoreactivity and systemic inflammation are maintained at high levels. In this report we evaluate post-infection alterations, such as hemozoin accumulation and compensatory changes in immune cells, and their potential role in the kidney-specific protective effect by Plasmodium. We ruled out the role of pigment accumulation with the use of a hemozoin-restricted P. berghei ANKA parasite, which induced a self-resolved infection that protected from autoimmune nephritis with the same mechanism as parasitic infections that accumulated normal levels of hemozoin. In contrast, adoptive transfer experiments revealed that bone marrow cells were altered by the infection and could transmit the kidney protective effect to a new host. While changes in the frequency of bone marrow cell populations after infection were variable and unique to a particular parasite strain, we detected a sustained bias in cytokine/chemokine expression that suggested lower fibrotic potential and higher Th1 bias likely affecting multiple cell populations. Sustained changes in bone marrow cell activation profile could have repercussions in immune responses long after the infection was cleared.

Ginsenoside Rb1 from Panax notoginseng Suppressed TNF-α-Induced Matrix Metalloproteinase-9 via the Suppression of Double-Strand RNA-Dependent Protein Kinase (PKR)/NF-κB Pathway

Chronic inflammation is commonly accompanied by the stimulation of matrix metalloproteinases (MMPs) production and the degradation of the extracellular matrix. The overexpression of MMP-9 (Gelatinase B) highly participates in the progression of pathetic cardiac remodeling and liver cancer metastasis. Panax notoginseng (Burkill) F. H. Chen (Sanqi), a widely used traditional Chinese medicinal herb, shows myocardial protective and anti-tumor effects. In this study, we examined the inhibitory effect of different PNG extracts on tumor necrosis factor (TNF)-α-induced MMP-9 expression in cardiac myoblast H9c2 cells. Using a bioassay-guided fractionation scheme, the most active extract was fractionated by silica gel column chromatography and high-performance liquid chromatography until an active compound was obtained. The compound was identified as Ginsenoside Rb1 by nuclear magnetic resonance. Ginsenoside Rb1 inhibited TNF-α-induced MMP-9 production in both H9c2 and liver carcinoma HepG-2 cells. Interestingly, it did not affect the MMP-2 (Gelatinase A) level and the cell proliferation of the two cell lines. The inhibitory effects of Ginsenoside Rb1 may be due to its modulation of double-strand RNA-dependent protein kinase and nuclear factor kappa B signaling pathways. The results reveal the potential use of Ginsenoside Rb1 for the treatment of inflammatory and MMP-9-related cardiac remodeling and metastasis of hepatocellular carcinomas.

Fangchinoline, a Bisbenzylisoquinoline Alkaloid can Modulate Cytokine-Impelled Apoptosis via the Dual Regulation of NF-κB and AP-1 Pathways

Fangchinoline (FCN) derived from Stephaniae tetrandrine S. Moore can be employed to treat fever, inflammation, rheumatism arthralgia, edema, dysuria, athlete’s foot, and swollen wet sores. FCN can exhibit a plethora of anti-neoplastic effects although its precise mode of action still remains to be deciphered. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) can closely regulate carcinogenesis and thus we analyzed the possible action of FCN may have on these two signaling cascades in tumor cells. The effect of FCN on NF-κB and AP-1 signaling cascades and its downstream functions was deciphered using diverse assays in both human chronic myeloid leukemia (KBM5) and multiple myeloma (U266). FCN attenuated growth of both leukemic and multiple myeloma cells and repressed NF-κB, and AP-1 activation through diverse mechanisms, including attenuation of phosphorylation of IκB kinase (IKK) and p65. Furthermore, FCN could also cause significant enhancement in TNFα-driven apoptosis as studied by various molecular techniques. Thus, FCN may exhibit potent anti-neoplastic effects by affecting diverse oncogenic pathways and may be employed as pro-apoptotic agent against various malignancies.

Formononetin Regulates Multiple Oncogenic Signaling Cascades and Enhances Sensitivity to Bortezomib in a Multiple Myeloma Mouse Model

Here, we determined the anti-neoplastic actions of formononetin (FT) against multiple myeloma (MM) and elucidated its possible mode of action. It was observed that FT enhanced the apoptosis caused by bortezomib (Bor) and mitigated proliferation in MM cells, and these events are regulated by nuclear factor-κB (NF-κB), phosphatidylinositol 3-kinase (PI3K)/AKT, and activator protein-1 (AP-1) activation. We further noted that FT treatment reduced the levels of diverse tumorigenic proteins involved in myeloma progression and survival. Interestingly, we observed that FT also blocked persistent NF-κB, PI3K/AKT, and AP-1 activation in myeloma cells. FT suppressed the activation of these oncogenic cascades by affecting a number of signaling molecules involved in their cellular regulation. In addition, FT augmented tumor growth-inhibitory potential of Bor in MM preclinical mouse model. Thus, FT can be employed with proteasomal inhibitors for myeloma therapy by regulating the activation of diverse oncogenic transcription factors involved in myeloma growth.

The Rough Guide to Monocytes in Malaria Infection

While half of the world's population is at risk of malaria, the most vulnerable are still children under five, pregnant women and returning travelers. Anopheles mosquitoes transmit malaria parasites to the human host; but how Plasmodium interact with the innate immune system remains largely unexplored. The most recent advances prove that monocytes are a key component to control parasite burden and to protect host from disease. Monocytes' protective roles include phagocytosis, cytokine production and antigen presentation. However, monocytes can be involved in pathogenesis and drive inflammation and sequestration of infected red blood cells in organs such as the brain, placenta or lungs by secreting cytokines that upregulate expression of endothelial adhesion receptors. Plasmodium DNA, hemozoin or extracellular vesicles can impair the function of monocytes. With time, reinfections with Plasmodium change the relative proportion of monocyte subsets and their physical properties. These changes relate to clinical outcomes and might constitute informative biomarkers of immunity. More importantly, at the molecular level, transcriptional, metabolic or epigenetic changes can “prime” monocytes to alter their responses in future encounters with Plasmodium. This mechanism, known as trained immunity, challenges the traditional view of monocytes as a component of the immune system that lacks memory. Overall, this rough guide serves as an update reviewing the advances made during the past 5 years on understanding the role of monocytes in innate immunity to malaria.

Ophiopogonin D modulates multiple oncogenic signaling pathways, leading to suppression of proliferation and chemosensitization of human lung cancer cells

BACKGROUND

Ophiopogonin D (OP-D), a steroidal glycoside obtained from the Chinese medicinal plant Ophiopogonin japonicas (the root portion), has been traditionally used to treat fever, inflammation, cough, sputum etc. However, the detailed molecular mechanism(s) underlying its therapeutic actions is still unknown.

HYPOTHESIS

Because nuclear factor-κB (NF-κB), PI3K/AKT, and activator protein-1 (AP-1) signaling cascades have significant functions in cell proliferation, inflammation, and angiogenesis in tumor cells, we hypothesized that OP-D may disrupt these signaling cascades to exert its anticancer effects in human lung-cancer cells.

METHODS

We evaluated the effect of OP-D on multiple signaling cascades and its regulated functional responses in lung cancer cells.

RESULTS

OP-D blocked both basal and cytokine-induced proliferation of human lung-cancer cells and caused down-regulation of the expression of diverse oncogenic gene products through the suppression of NF-κB, PI3K/AKT, and AP-1 pathways; but did not affect JNK, p38 and ERK MAP kinases. Interestingly, OP-D suppressed constitutive NF-κB activation in lung cancer cells via interfering with the IκB kinase activation, which inhibited phosphorylation and caused degradation of IκB-α. OP-D also blocked phosphorylation and the nuclear translocation of p65, thereby suppressing NF-κB reporter activity in lung cancer cells. Besides, OP-D could augment cell death induced by paclitaxel in lung-cancer cells.

CONCLUSION

Overall, the data indicates that OP-D may abrogate diverse signaling cascades linked to tumorigenesis, and can be used in combination with chemotherapeutic agents for cancer therapy.

Malaria pigment stimulates chemokine production by human microvascular endothelium

Severe falciparum malaria is characterized by the sequestration of infected erythrocytes and leukocyte recruitment in the microvasculature, resulting in impaired blood flow and metabolic disturbances. Which parasite products cause chemokine production, thus contributing to the strong host inflammatory response and cellular recruitment are not well characterized. Here, we studied haemozoin (Hz), the end-product of haem, a ferriprotoporphyrin-IX crystal bound to host and parasite lipids, DNA, and proteins. We found that natural Hz isolated from Plasmodium falciparum cultures induces CXCL8 and CCL5 production in human dermal microvascular endothelial cells (HMEC-1) in a time-dependent manner. This up-regulation is not caused by haem but rather by Hz-generated lipoperoxidation products (15-HETE) and fibrinogen associated to Hz, and is, at least in part, triggered by the activation of NF-κB, as it was significantly inhibited by artemisinin and other NF-κB pathway inhibitors.

Host-pathogen interactions in malaria: cross-kingdom signaling and mitochondrial regulation

Malaria parasite-host interactions are complex and have confounded available drugs and the development of vaccines. Further, we now appreciate that interventions for malaria elimination and eradication must include therapeutics with intrinsic transmission blocking activity to treat the patient and prevent disease spread. Studies over the past 15 years have revealed significant conservation in the response to infection in mosquito and human hosts. More recently, we have recognized that conserved cell signaling cascades in mosquitoes and humans dictate infection outcome through the regulation of mitochondrial function and biogenesis, which feed back to host immunity, basic intermediary metabolism, and stress responses. These responses - reflected clearly in the primeval insect host - provide fertile ground for innovative strategies for both treatment and transmission blocking.

Autoantibody profile of patients infected with knowlesi malaria

BACKGROUND

Autoantibodies or antibodies against self-antigens are produced either during physiological processes to maintain homeostasis or pathological process such as trauma and infection. Infection with parasites including Plasmodium has been shown to generally induce elevated self-antibody (autoantibody) levels. Plasmodium knowlesi is increasingly recognized as one of the most important emerging human malaria in Southeast Asia that can cause severe infection leading to mortality. Autoimmune-like phenomena have been hypothesized to play a role in the protective immune responses in malaria infection.

METHODS

We studied the autoantibody profile from serum of eleven patients diagnosed with P. knowlesi. Autoantigen arrays were used to elucidate the autoantibody repertoire of P. knowlesi infected patients. The patented OGT Discovery Array with 1636 correctly folded antigen was employed.

RESULTS

Analysis of the patient versus control sera gave us 24 antigens with high reactivity with serum antibodies.

CONCLUSIONS

Understanding the autoantibody profile of malarious patients infected with P. knowlesi would help to further understand the host-parasite interaction, host immune response and disease pathogenesis. These reactive antigens may serve as potential biomarkers for cases of asymptomatic malaria and mild malaria or predictive markers for severe malaria.

Ophiopogonin-D suppresses MDA-MB-435 cell adhesion and invasion by inhibiting matrix metalloproteinase-9

Ophiopogonin-D is one of steroidal saponins isolated from the root of the Chinese medicinal plant Ophiopogon japonicas. It has been claimed to possess anti-inflammatory and anti-oxidant properties. The present study was the first to examine the anti-tumor metastasis properties of ophiopogonin-D. An MTT assay showed that ophiopogonin-D inhibited the proliferation of MDA-MB-435 melanoma cells, and decreased invasion was demonstrated using a Transwell invasion assay. Furthermore, adhesion of MDA-MB-435 cells to human umbilical vascular endothelial cells and to fibronectin was inhibited by ophiopogonin-D. Gelatin zymography and western blot analysis showed that ophiopogonin-D inhibited the expression and secretion of matrix metalloproteinase-9 (MMP-9), but not that of MMP-2. Inhibition of phosphorylation of p38 by ophiopogonin-D indicated its inhibition of the mitogen-activated protein kinase pathway. Overall, the results suggested that ophiopogonin-D may be considered as a candidate drug for treating or preventing tumor metastasis.

Oxygen-Loaded Nanodroplets Effectively Abrogate Hypoxia Dysregulating Effects on Secretion of MMP-9 and TIMP-1 by Human Monocytes

Monocytes play a key role in the inflammatory stage of the healing process. To allow monocyte migration to injured tissues, the balances between secreted matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) must be finely modulated. However, a reduction of blood supply and local oxygen tension can modify the phenotype of immune cells. Intriguingly, hypoxia might be targeted by new effective oxygenating devices such as 2H,3H-decafluoropentane- (DFP-) based oxygen-loaded nanodroplets (OLNs). Here, hypoxia effects on gelatinase/TIMP release from human peripheral monocytes were investigated, and the therapeutic potential of dextran-shelled OLNs was evaluated. Normoxic monocytes constitutively released ~500 ng/mL MMP-9, ~1.3 ng/mL TIMP-1, and ~0.6 ng/mL TIMP-2 proteins. MMP-2 was not detected. After 24 hours, hypoxia significantly altered MMP-9/TIMP-1 balance by reducing MMP-9 and increasing TIMP-1, without affecting TIMP-2 secretion. Interestingly OLNs, not displaying toxicity to human monocytes after cell internalization, effectively counteracted hypoxia, restoring a normoxia-like MMP-9/TIMP-1 ratio. The action of OLNs was specifically dependent on time-sustained oxygen diffusion up to 24 h from their DFP-based core. Therefore, OLNs appear as innovative, nonconventional, cost-effective, and nontoxic therapeutic tools, to be potentially employed to restore the physiological invasive phenotype of immune cells in hypoxia-associated inflammation.

Inhibition of metalloproteinase-9 secretion and gene expression by artemisinin derivatives

Malaria remains one of the world's most common infectious diseases, being responsible for more deaths than any other communicable disease except tuberculosis. There is strong evidence that tumour necrosis factor α and interleukin-1β are important contributors to the systemic disease caused by the infection with Plasmodium falciparum. Circulating levels of TNFα are increased after infection, as a consequence of stimulation of monocyte-macrophages by infected red blood cells or parasite products, as shown in vitro for the malaria pigment haemozoin. TNFα in turn enhances the synthesis of metalloproteinase-9 in monocytes and macrophages. Metalloproteinase-9 acts on the extracellular matrix but also on non-traditional substrates, including precursors of inflammatory cytokines, which are proteolytically activated and contribute to the amplification of the inflammatory response. The aim of the present work was to establish whether artemisinin and its derivatives artemisone, artesunate and dihydroartemisinin possess immuno-modulatory properties. In particular, it is necessary to evaluate their effects on mRNA levels and secretion of MMP-9 by the human monocytic cell line (THP-1 cells) stimulated by hemozoin or TNFα. 5μM of each derivative, although not artemisinin itself, induced significantly inhibited TNFα production. Artesunate, artemisone and DHA antagonized haemozoin-induced MMP-9 secretion by 25%, 24% and 50%, respectively. mRNA levels were also depressed by 14%, 20% and 27%, respectively, thus reflecting in part the effect observed on protein production. The derivatives significantly inhibited both TNFα-induced MMP-9 secretion and mRNA levels to a greater extent than haemozoin itself. Both haemozoin and TNFα increased NF-κB driven transcription by 11 and 7.7 fold, respectively. Artesunate, artemisone and DHA inhibited haemozoin-induced NF-κB driven transcription by 28%, 34%, and 49%, respectively. Similarly the derivatives, but not artemisinin, prevented TNFα-induced NF-κB driven transcription by 47-51%. The study indicates that artemisinins may attenuate the inflammatory potential of monocytes in vivo. Thus, in addition to direct anti-parasitic activities, the beneficial clinical effects of artemisinins for the treatment of malaria include the apparent ability to attenuate the inflammatory response, thus limiting the risk of progression to the more severe form of the disease, including the onset of cerebral malaria.

Hemozoin induces hepatic inflammation in mice and is differentially associated with liver pathology depending on the Plasmodium strain

Malaria is a global disease that clinically affects more than two hundred million people annually. Despite the availability of effective antimalarials, mortality rates associated with severe complications are high. Hepatopathy is frequently observed in patients with severe malarial disease and its pathogenesis is poorly understood. Previously, we observed high amounts of hemozoin or malaria pigment in livers from infected mice. In this study, we investigated whether hemozoin is associated with liver injury in different mouse malaria models. C57BL/6J mice infected with the rodent parasites Plasmodium berghei ANKA, P. berghei NK65 or P. chabaudi AS had elevated serum liver enzymes without severe histological changes in the liver, in line with the observations in most patients. Furthermore, liver enzymes were significantly higher in serum of P. chabaudi AS-infected mice compared to mice infected with the P. berghei parasite strains and a strong positive correlation was found between hepatic hemozoin levels, hepatocyte damage and inflammation in the liver with P. chabaudi AS. The observed liver injury was only marginally influenced by the genetic background of the host, since similar serum liver enzyme levels were measured in infected C57BL/6J and BALB/c mice. Intravenous injection of P. falciparum-derived hemozoin in malaria-free C57BL/6J mice induced inflammatory gene transcription in the liver, suggesting that hemozoin may be involved in the pathogenesis of malaria hepatopathy by inducing inflammation.

Host matrix metalloproteinases in cerebral malaria: new kids on the block against blood-brain barrier integrity?

Cerebral malaria (CM) is a life-threatening complication of falciparum malaria, associated with high mortality rates, as well as neurological impairment in surviving patients. Despite disease severity, the etiology of CM remains elusive. Interestingly, although the Plasmodium parasite is sequestered in cerebral microvessels, it does not enter the brain parenchyma: so how does Plasmodium induce neuronal dysfunction? Several independent research groups have suggested a mechanism in which increased blood–brain barrier (BBB) permeability might allow toxic molecules from the parasite or the host to enter the brain. However, the reported severity of BBB damage in CM is variable depending on the model system, ranging from mild impairment to full BBB breakdown. Moreover, the factors responsible for increased BBB permeability are still unknown. Here we review the prevailing theories on CM pathophysiology and discuss new evidence from animal and human CM models implicating BBB damage. Finally, we will review the newly-described role of matrix metalloproteinases (MMPs) and BBB integrity. MMPs comprise a family of proteolytic enzymes involved in modulating inflammatory response, disrupting tight junctions, and degrading sub-endothelial basal lamina. As such, MMPs represent potential innovative drug targets for CM.

Natural haemozoin induces expression and release of human monocyte tissue inhibitor of metalloproteinase-1

Recently matrix metalloproteinase-9 (MMP-9) and its endogenous inhibitor (tissue inhibitor of metalloproteinase-1, TIMP-1) have been implicated in complicated malaria. In vivo, mice with cerebral malaria (CM) display high levels of both MMP-9 and TIMP-1, and in human patients TIMP-1 serum levels directly correlate with disease severity. In vitro, natural haemozoin (nHZ, malarial pigment) enhances monocyte MMP-9 expression and release. The present study analyses the effects of nHZ on TIMP-1 regulation in human adherent monocytes. nHZ induced TIMP-1 mRNA expression and protein release, and promoted TNF-α, IL-1β, and MIP-1α/CCL3 production. Blocking antibodies or recombinant cytokines abrogated or mimicked nHZ effects on TIMP-1, respectively. p38 MAPK and NF-κB inhibitors blocked all nHZ effects on TIMP-1 and pro-inflammatory molecules. Still, total gelatinolytic activity was enhanced by nHZ despite TIMP-1 induction. Collectively, these data indicate that nHZ induces inflammation-mediated expression and release of human monocyte TIMP-1 through p38 MAPK- and NF-κB-dependent mechanisms. However, TIMP-1 induction is not sufficient to counterbalance nHZ-dependent MMP-9 enhancement. Future investigation on proteinase-independent functions of TIMP-1 (i.e. cell survival promotion and growth/differentiation inhibition) is needed to clarify the role of TIMP-1 in malaria pathogenesis.