Survival, bacterial clearance and thrombocytopenia are improved in polymicrobial sepsis by targeting nuclear transport shuttles

Anti-inflammatory control of human skin keratinocytes by targeting nuclear transport checkpoint

Background

In the two common inflammatory skin diseases, Atopic Dermatitis (AD) and Psoriasis (Ps), keratinocytes (KCs) respond to immune insults through activation of proinflammatory transcription factors (TFs) and their translocation to the cell's nucleus. Therein, the TFs induce expression of genes encoding mediators of skin inflammation. The Nuclear Transport Checkpoint Inhibitors (NTCIs) were developed to regulate nuclear translocation of activated TFs, the essential step of inflammatory response. This new class of cell-penetrating peptide therapeutics controls inflammation caused by allergic, autoimmune, metabolic, and microbial insults. In preclinical model of AD, the treatment with NTCI, cSN50.1 peptide, suppressed the expression of Thymic Stromal Lymphopoietin (TSLP), the key gene in the development of allergic inflammation, among the 15 genes silenced by the NTCI. Here, we report the mechanism of anti-inflammatory action of NTCI in human skin-derived KCs.

Objectives

We aimed to determine whether the NTCI treatment can protect human KCs from harmful inflammatory insults.

Methods

Human primary KCs were pretreated with NTCI and challenged with the mix of cytokines Tumour Necrosis Factor alpha (TNF-α) and Interleukin (IL)-17A, or with Phorbol 12-Myristate 13-Acetate (PMA), and analysed for nuclear content of TFs and the expression of genes encoding mediators of inflammation.

Results

The nuclear import of TFs, Nuclear Factor ĸB (NF-ĸB) and Signal Transduction and Activator of Transcription 3 (STAT3), was inhibited in cells treated with NTCI. The expression of TSLP, along with genes encoding the core mediators of inflammation (TNF, IL1B, and IL6) was suppressed by NTCI. Noteworthy, NTCI silenced genes encoding Granulocyte-Macrophage Colony-Stimulating Factor (CSF2), and chemokine IL-8 (CXCL8), responsible for skin infiltration by the eosinophils and other myelomonocytic cells.

Conclusion

The control of inflammatory response in human KCs by NTCI is attributed to the inhibition of nuclear import of proinflammatory TFs. The protection of human KCs by NTCI, adds new perspectives to the completed Phase two clinical trial of the NTCI (AMTX-100 CF) for AD (NCT04313400).

Ivermectin ameliorates acute myocarditis via the inhibition of importin-mediated nuclear translocation of NF-κB/p65

BACKGROUND

Myocarditis is an important clinical issue which lacks specific treatment by now. Ivermectin (IVM) is an inhibitor of importin α/β-mediated nuclear translocation. This study aimed to explore the therapeutic effects of IVM on acute myocarditis.

METHODS

Mouse models of coxsackie B3 virus (CVB3) infection-induced myocarditis and experimental autoimmune myocarditis (EAM) were established to evaluate the effects of IVM. Cardiac functions were evaluated by echocardiography and Millar catheter. Cardiac inflammatory infiltration was assessed by histological staining. Cytometric bead array and quantitative real-time PCR were used to detect the levels of pro-inflammatory cytokines. The macrophages and their M1/M2 polarization were analyzed via flow cytometry. Protein expression and binding were detected by co-immunoprecipitation, Western blotting and histological staining. The underlying mechanism was verified in vitro using CVB3-infected RAW264.7 macrophages. Cyclic polypeptide (cTN50) was synthesized to selectively inhibit the nuclear translocation of NF-κB/p65, and CVB3-infected RAW264.7 cells were treated with cTN50.

RESULTS

Increased expression of importin β was observed in both models. IVM treatment improved cardiac functions and reduced the cardiac inflammation associated with CVB3-myocarditis and EAM. Furthermore, the pro-inflammatory cytokine (IL-1β/IL-6/TNF-α) levels were downregulated via the inhibition of the nuclear translocation of NF-κB/p65 in macrophages. IVM and cTN50 treatment also inhibited the nuclear translocation of NF-κB/p65 and downregulated the expression of pro-inflammatory cytokines in RAW264.7 macrophages.

CONCLUSIONS

Ivermectin inhibits the nuclear translocation of NF-κB/p65 and the expression of major pro-inflammatory cytokines in myocarditis. The therapeutic effects of IVM on viral and non-viral myocarditis models suggest its potential application in the treatment of acute myocarditis.

Activation of thousands of genes in the lungs and kidneys by sepsis is countered by the selective nuclear blockade

The steady rise of sepsis globally has reached almost 49 million cases in 2017, and 11 million sepsis-related deaths. The genomic response to sepsis comprising multi-system stage of raging microbial inflammation has been reported in the whole blood, while effective treatment is lacking besides anti-microbial therapy and supportive measures. Here we show that, astoundingly, 6,237 significantly expressed genes in sepsis are increased or decreased in the lungs, the site of acute respiratory distress syndrome (ARDS). Moreover, 5,483 significantly expressed genes in sepsis are increased or decreased in the kidneys, the site of acute injury (AKI). This massive genomic response to polymicrobial sepsis is countered by the selective nuclear blockade with the cell-penetrating Nuclear Transport Checkpoint Inhibitor (NTCI). It controlled 3,735 sepsis-induced genes in the lungs and 1,951 sepsis-induced genes in the kidneys. The NTCI also reduced without antimicrobial therapy the bacterial dissemination: 18-fold in the blood, 11-fold in the lungs, and 9-fold in the spleen. This enhancement of bacterial clearance was not significant in the kidneys. Cumulatively, identification of the sepsis-responsive host's genes and their control by the selective nuclear blockade advances a better understanding of the multi-system mechanism of sepsis. Moreover, it spurs much-needed new diagnostic, therapeutic, and preventive approaches.

Hyperlipidemic hypersensitivity to lethal microbial inflammation and its reversal by selective targeting of nuclear transport shuttles

Hyperlipidemia, the hallmark of Metabolic Syndrome that afflicts millions of people worldwide, exacerbates life-threatening infections. We present a new evidence for the mechanism of hyperlipidemic hypersensitivity to microbial inflammation caused by pathogen-derived inducer, LPS. We demonstrate that hyperlipidemic animals succumbed to a non-lethal dose of LPS whereas normolipidemic controls survived. Strikingly, survival of hyperlipidemic animals was restored when the nuclear import of stress-responsive transcription factors (SRTFs), Sterol Regulatory Element-Binding Proteins (SREBPs), and Carbohydrate-Responsive Element-Binding Proteins (ChREBPs) was impeded by targeting the nuclear transport checkpoint with cell-penetrating, biselective nuclear transport modifier (NTM) peptide. Furthermore, the burst of proinflammatory cytokines and chemokines, microvascular endothelial injury in the liver, lungs, heart, and kidneys, and trafficking of inflammatory cells were also suppressed. To dissect the role of nuclear transport signaling pathways we designed and developed importin-selective NTM peptides. Selective targeting of the importin α5, ferrying SRTFs and ChREBPs, protected 70-100% hyperlipidemic animals. Targeting importin β1, that transports SREBPs, was only effective after 3-week treatment that lowered blood triglycerides, cholesterol, glucose, and averted fatty liver. Thus, the mechanism of hyperlipidemic hypersensitivity to lethal microbial inflammation depends on metabolic and proinflammatory transcription factors mobilization, which can be counteracted by targeting the nuclear transport checkpoint.

Protection from Endotoxin Shock by Selective Targeting of Proinflammatory Signaling to the Nucleus Mediated by Importin Alpha 5

Endotoxin shock is induced by LPS, one of the most potent virulence factors of the Gram-negative bacteria that cause sepsis. It remains unknown if either proinflammatory stress-responsive transcription factors (SRTFs), ferried to nucleus by importin α5, or lipid-regulating sterol regulatory element binding proteins (SREBPs), transported to the nucleus by importin β1, mediate endotoxin shock. A novel cell-penetrating peptide targeting importin α5 while sparing importin β1 protected 80% of animals from death in response to a high dose of LPS. This peptide suppresses inflammatory mediators, liver glycogen depletion, endothelial injury, neutrophil trafficking, and apoptosis caused by LPS. In d-galactosamine-pretreated mice challenged by 700-times lower dose of LPS, rapid death through massive apoptosis and hemorrhagic necrosis of the liver was also averted by the importin α5–selective peptide. Thus, using a new tool for selective suppression of nuclear transport, we demonstrate that SRTFs, rather than SREBPs, mediate endotoxin shock.

Decoding inflammation, its causes, genomic responses, and emerging countermeasures

Inflammation is the mechanism of diseases caused by microbial, autoimmune, allergic, metabolic and physical insults that produce distinct types of inflammatory responses. This aetiologic view of inflammation informs its classification based on a cause‐dependent mechanism as well as a cause‐directed therapy and prevention. The genomic era ushered in a new understanding of inflammation by highlighting the cell's nucleus as the centre of the inflammatory response. Exogenous or endogenous inflammatory insults evoke genomic responses in immune and non‐immune cells. These genomic responses depend on transcription factors, which switch on and off a myriad of inflammatory genes through their regulatory networks. We discuss the transcriptional paradigm of inflammation based on denying transcription factors’ access to the nucleus. We present two approaches that control proinflammatory signalling to the nucleus. The first approach constitutes a novel intracellular protein therapy with bioengineered physiologic suppressors of cytokine signalling. The second approach entails control of proinflammatory transcriptional cascades by targeting nuclear transport with a cell‐penetrating peptide that inhibits the expression of 23 out of the 26 mediators of inflammation along with the nine genes required for metabolic responses. We compare these emerging anti‐inflammatory countermeasures to current therapies. The transcriptional paradigm of inflammation offers nucleocentric strategies for microbial, autoimmune, metabolic, physical and other types of inflammation afflicting millions of people worldwide.

Inhibitors of nuclear transport

Central to eukaryotic cell function, transport into and out of the nucleus is largely mediated by members of the Importin (IMP) superfamily of transporters of α- and β-types. The first inhibitor of nuclear transport, leptomycin B (LMB), was shown to be a specific inhibitor of the IMPβ homologue Exportin 1 (EXP1) almost 20 years ago, but it has only been in the last five or so years that new inhibitors of nuclear export as well as import have been identified and characterised. Of utility in biological research, these inhibitors include those that target-specific EXPs/IMPs, with accompanying toxicity profiles, as well as agents that specifically target particular nuclear import cargoes. Both types of inhibitors have begun to be tested in preclinical/clinical studies, with particular focus on limiting various types of cancer or treating viral infection, and the most advanced agent targeting EXP1 (Selinexor) has progressed successfully through >40 clinical trials for a range of high-grade cancers and is approaching FDA approval for a number of indications. Selectively inhibiting the nucleocytoplasmic trafficking of specific proteins of interest remains a challenge, but progress in the area of the host-pathogen interface holds promise for the future.

Controlling the Gatekeeper: Therapeutic Targeting of Nuclear Transport

Nuclear transport receptors of the karyopherin superfamily of proteins transport macromolecules from one compartment to the other and are critical for both cell physiology and pathophysiology. The nuclear transport machinery is tightly regulated and essential to a number of key cellular processes since the spatiotemporally expression of many proteins and the nuclear transporters themselves is crucial for cellular activities. Dysregulation of the nuclear transport machinery results in localization shifts of specific cargo proteins and associates with the pathogenesis of disease states such as cancer, inflammation, viral illness and neurodegenerative diseases. Therefore, inhibition of the nuclear transport system has future potential for therapeutic intervention and could contribute to the elucidation of disease mechanisms. In this review, we recapitulate clue findings in the pathophysiological significance of nuclear transport processes and describe the development of nuclear transport inhibitors. Finally, clinical implications and results of the first clinical trials are discussed for the most promising nuclear transport inhibitors.