Inhibition of Mitogen-Activated Protein Kinase (MAPK)-Activated Protein Kinase 2 (MK2) is Protective in Pulmonary Hypertension

CC chemokines Modulate Immune responses in Pulmonary Hypertension

BACKGROUND

Pulmonary hypertension (PH) represents a progressive condition characterized by the remodeling of pulmonary arteries, ultimately culminating in right heart failure and increased mortality rates. Substantial evidence has elucidated the pivotal role of perivascular inflammatory factors and immune dysregulation in the pathogenesis of PH. Chemokines, a class of small secreted proteins, exert precise control over immune cell recruitment and functionality, particularly with respect to their migration to sites of inflammation. Consequently, chemokines emerge as critical drivers facilitating immune cell infiltration into the pulmonary tissue during inflammatory responses. This review comprehensively examines the significant contributions of CC chemokines in the maintenance of immune cell homeostasis and their pivotal role in regulating inflammatory responses. The central focus of this discussion is directed towards elucidating the precise immunoregulatory actions of CC chemokines concerning various immune cell types, including neutrophils, monocytes, macrophages, lymphocytes, dendritic cells, mast cells, eosinophils, and basophils, particularly in the context of pH processes. Furthermore, this paper delves into an exploration of the underlying pathogenic mechanisms that underpin the development of PH. Specifically, it investigates processes such as cellular pyroptosis, examines the intricate crosstalk between bone morphogenetic protein receptor type 2 (BMPR2) mutations and the immune response, and sheds light on key signaling pathways involved in the inflammatory response. These aspects are deemed critical in enhancing our understanding of the complex pathophysiology of PH. Moreover, this review provides a comprehensive synthesis of findings from experimental investigations targeting immune cells and CC chemokines.

AIM OF REVIEW

In summary, the inquiry into the inflammatory responses mediated by CC chemokines and their corresponding receptors, and their potential in modulating immune reactions, holds promise as a prospective avenue for addressing PH. The potential inhibition of CC chemokines and their receptors stands as a viable strategy to attenuate the inflammatory cascade and ameliorate the pathological manifestations of PH. Nonetheless, it is essential to acknowledge the current state of clinical trials and the ensuing progress, which regrettably appears to be less than encouraging. Substantial hurdles exist in the successful translation of research findings into clinical applications. The intention is that such emphasis could potentially foster the advancement of potent therapeutic agents presently in the process of clinical evaluation. This, in turn, may further bolster the potential for effective management of PH.

Sex-biased TGFβ signalling in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare cardiovascular disorder leading to pulmonary hypertension and, often fatal, right heart failure. Sex differences in PAH are evident, which primarily presents with a female predominance and increased male severity. Disturbed signalling of the transforming growth factor-β (TGFβ) family and gene mutations in the bone morphogenetic protein receptor 2 (BMPR2) are risk factors for PAH development, but how sex-specific cues affect the TGFβ family signalling in PAH remains poorly understood. In this review, we aim to explore the sex bias in PAH by examining sex differences in the TGFβ signalling family through mechanistical and translational evidence. Sex hormones including oestrogens, progestogens, and androgens, can determine the expression of receptors (including BMPR2), ligands, and soluble antagonists within the TGFβ family in a tissue-specific manner. Furthermore, sex-related genetic processes, i.e. Y-chromosome expression and X-chromosome inactivation, can influence the TGFβ signalling family at multiple levels. Given the clinical and mechanistical similarities, we expect that the conclusions arising from this review may apply also to hereditary haemorrhagic telangiectasia (HHT), a rare vascular disorder affecting the TGFβ signalling family pathway. In summary, we anticipate that investigating the TGFβ signalling family in a sex-specific manner will contribute to further understand the underlying processes leading to PAH and likely HHT.

Role of histone lactylation interference RNA m6A modification and immune microenvironment homeostasis in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe disease resulting from progressive increases in pulmonary vascular resistance and pulmonary vascular remodeling, ultimately leading to right ventricular failure and even death. Hypoxia, inflammation, immune reactions, and epigenetic modifications all play significant contributory roles in the mechanism of PAH. Increasingly, epigenetic changes and their modifying factors involved in reprogramming through regulation of methylation or the immune microenvironment have been identified. Among them, histone lactylation is a new post-translational modification (PTM), which provides a novel visual angle on the functional mechanism of lactate and provides a promising diagnosis and treatment method for PAH. This review detailed introduces the function of lactate as an important molecule in PAH, and the effects of lactylation on N6-methyladenosine (m6A) and immune cells. It provides a new perspective to further explore the development of lactate regulation of pulmonary hypertension through histone lactylation modification.

MK2 drives progression of pancreas and colon cancers by suppressing CD8+ T cell cytotoxic function and is a potential immunotherapy target

Background

Immune cell composition is a critical and dynamic component of the tumor microenvironment, which has an impact on immunosuppression and progression of cancer. T cells, especially CD8+ T cells, are one of the major immune cell types responsible for tumor cell killing employing receptor-ligand mediated apoptosis and/or releasing lytic granules among others. Accumulating evidence highlighted that adoptive transfer of activated and/or modified immune cells can enhance anti-tumorigenic immune responses and serve as promising therapy approach for patients with cancers. The mitogen-activated protein kinase-activated protein kinase 2 (MK2) is a serine/threonine protein kinase, which controls production and secretion of numerous pro-inflammatory cytokines and chemokines involved in tumorigenesis. However, limited efforts have been made to learn how MK2 may affects CD8+ T cell action and function in the tumor microenvironment especially in gastrointestinal cancers.

Methods

To explore the therapeutic potential of MK2 in the immune response mediated by CD8+ T cells, RAG1 knockout mice with PK5L1940 and BRAF cells-derived allograft tumors were treated with WT or MK2 knockout CD8+ T cells. The phenotype of CD8+ T cells with MK2 depletion were evaluated in vitro. Immunofluorescence staining, real-time PCR and multiplex analysis were utilized to estimate the expression of apoptotic and lytic factors.

Results

Here, we show that CD8+ T cells with MK2 depletion prevent gastrointestinal cancer growth, which is accompanied by enhanced expression and secretion of factors related to apoptosis. Moreover, using in vitro and in vivo approaches, we found that depletion of MK2 lead to hyperactivation of CD8+ T cells and enhanced anti-tumor immunity.

Conclusion

Overall, we documented that MK2 drives the progression of gastrointestinal cancers and prevents immune response generated by CD8+ T cells suggesting potential implications of MK2 in the immunotherapy of gastrointestinal cancers.

Ormeloxifene, a selective estrogen receptor modulator, protects against pulmonary hypertension

PURPOSE

Protective effect of 17β-estradiol is well-known in pulmonary hypertension. However, estrogen-based therapy may potentially increase the risk of breast cancer, necessitating a search for novel drugs. This study, therefore, investigated the ameliorative effects of a selective estrogen receptor modulator, ormeloxifene, in pulmonary hypertension.

METHODS

Cardiomyocytes (H9C2) and human pulmonary arterial smooth muscle cells (HPASMCs) were exposed to hypoxia (1% O₂) for 42 and 96 h, respectively, with or without ormeloxifene pre-treatment (1 μM). Also, female (ovary-intact or ovariectomized) and male Sprague-Dawley rats received monocrotaline (60 mg/kg, once, subcutaneously), with or without ormeloxifene treatment (2.5 mg/kg, orally) for four weeks.

RESULTS

Hypoxia dysregulated 17β-hydroxysteroid dehydrogenase (17βHSD) 1 & 2 expressions, reducing 17β-estradiol production and estrogen receptors α and β in HPASMC but increasing estrone, proliferation, inflammation, oxidative stress, and mitochondrial dysfunction. Similarly, monocrotaline decreased plasma 17β-estradiol and uterine weight in ovary-intact rats. Further, monocrotaline altered 17βHSD1 & 2 expressions and reduced estrogen receptors α and β, increasing right ventricular pressure, proliferation, inflammation, oxidative stress, endothelial dysfunction, mitochondrial dysfunction, and vascular remodeling in female and male rats, with worsened conditions in ovariectomized rats. Ormeloxifene was less uterotrophic; however, it attenuated both hypoxia and monocrotaline effects by improving pulmonary 17β-estradiol synthesis. Furthermore, ormeloxifene decreased cardiac hypertrophy and right ventricular remodeling induced by hypoxia and monocrotaline.

CONCLUSION

This study demonstrates that ormeloxifene promoted pulmonary 17β-estradiol synthesis, alleviated inflammation, improved the NOX4/HO1/Nrf/PPARγ/PGC-1α axis, and attenuated pulmonary hypertension. It is evidently safe at tested concentrations and may be effectively repurposed for pulmonary hypertension treatment.

Inhibition of poly (ADP-ribose) Polymerase-1 (PARP-1) improves endothelial function in pulmonary hypertension

Endothelial dysfunction is critical in the pulmonary vasculature during pulmonary hypertension (PH). Moreover, in PH, increased inflammation and oxidative/nitrosative stress cause DNA damage, activating poly (ADP-ribose) polymerase-1 (PARP-1). Meloche et al. (2014) and our previous research have shown that inhibiting PARP-1 is protective in PH and associated RV hypertrophy. However, the role of PARP-1 in pulmonary arterial endothelial dysfunction has not been explored completely. Therefore, the current study aims to investigate the involvement of PARP-1 in endothelial dysfunction associated with PH. Hypoxia (1% O2) was used to induce a PH-like phenotype in human pulmonary artery endothelial cells (HPAECs), and PARP-1 inhibition was achieved via siRNA (60 nM). For the in vivo study, male Sprague Dawley rats were administered monocrotaline (MCT; 60 mg/kg, SC, once) to induce PH, and 1, 5-isoquinolinediol (ISO; 3 mg/kg) was administered daily intraperitoneally to inhibit PARP-1. PARP-1 inhibition decreased proliferation and inflammation, as well as improved mitochondrial dysfunction in hypoxic HPAECs. Furthermore, PARP-1 inhibition also promoted apoptosis by increasing DNA damage in hypoxic HPAECs. In addition, inhibition of PARP-1 reduced cell migration, VEGF expression, and tubule formation in hypoxic HPAECs. In in vivo studies, PARP-1 inhibition by ISO significantly decreased the RVP and RVH as well as improved endothelial function by increasing the pulmonary vascular reactivity and expression of p-eNOS in MCT-treated rats.

Inhibition of angiotensin II type 1 receptor partially prevents acute elevation of pulmonary arterial pressure induced by endovascular ethanol injection

This study aimed to examine whether the administration of losartan can prevent acute elevation of pulmonary arterial pressure (AEPAP) induced by endovascular ethanol injection and to assess its related mechanisms. Male swine were selected and performed with absolute ethanol endovascular injection. Saline was used as the negative control. Losartan was administered preoperatively. Pulmonary arterial pressure (PAP), femoral arterial pressure (FAP) and heart rate (HR) were monitored during operations. Venous plasma and pulmonary artery (PA) tissue were harvested for analyses. Protein level was detected by Western blotting and ELISA, whereas qRT-PCR was used in mRNA detection. H & E staining and immunohistochemistry were conducted to evaluate histopathology. Ethanol injection elevated PAP in swine. The concentration of RAS ligands was elevated in plasma (all P < 0.0001) but not in PA. The level of oxidative stress increased in both plasma and PA. MRNA level of AT1R (P < 0.01, 95% CI: 0.251-1.006), not AT2R increased in PA. Losartan failed to inhibit AEPAP after all sessions of ethanol injection, and partially reversed the ethanol-induced PA remodeling. The P38 MAPK was activated after ethanol injection and could be inhibited by losartan (P < 0.01, 95% CI: -0.391 to -0.164). Ethanol also promoted the translocation of the P40-PHOX/P47-PHOX/P67-PHOX complex and the activation of NOX, which was independent from RAS. Endovascular ethanol injection can induce AEPAP mainly by activating RAS and P38 MAPK signaling. Losartan can partially prevent AEPAP and vascular remodeling owing to the promotion of NOX activity by ethanol. Mechanism diagram of endovascular ethanol injection-induced acute elevation of pulmonary arterial pressure (AEPAP) partially prevented by losartan. RAS: Renin-angiotensin system; AGT: angiotensinogen; Ang I: angiotensin I; ACE: angiotensin I converting enzyme; Ang II: angiotensin II. AT1R: angiotensin II type 1 receptor. NOX2: NADPH oxidase 2. PA: pulmonary artery.

Comprehensive analysis and validation of novel immune and vascular remodeling related genes signature associated with drug interactions in pulmonary arterial hypertension

Background: Previous studies revealed that the gene signatures are associated with the modulation and pathogenesis of pulmonary arterial hypertension (PAH). However, identifying critical transcriptional signatures in the blood of PAH patients remains lacking.

Methods: The differentially expressed transcriptional signatures in the blood of PAH patients were identified by a meta-analysis from four microarray datasets. Then we investigated the enrichment of gene ontology and KEGG pathways and identified top hub genes. Besides, we investigated the correlation of crucial hub genes with immune infiltrations, hallmark gene sets, and blood vessel remodeling genes. Furthermore, we investigated the diagnostic efficacy of essential hub genes and their expression validation in an independent cohort of PAH, and we validate the expression level of hub genes in monocrotaline (MCT) induced PAH rats’ model. Finally, we have identified the FDA-approved drugs that target the hub genes and their molecular docking.

Results: We found 1,216 differentially expressed genes (DEGs), including 521 up-regulated and 695 down-regulated genes, in the blood of the PAH patients. The up-regulated DEGs are significantly associated with the enrichment of KEGG pathways mainly involved with immune regulation, cellular signaling, and metabolisms. We identified 13 master transcriptional regulators targeting the dysregulated genes in PAH. The STRING-based investigation identified the function of hub genes associated with multiple immune-related pathways in PAH. The expression levels of RPS27A, MAPK1, STAT1, RPS6, FBL, RPS3, RPS2, and GART are positively correlated with ssGSEA scores of various immune cells as positively correlated with the hallmark of oxidative stress. Besides, we found that these hub genes also regulate the vascular remodeling in PAH. Furthermore, the expression levels of identified hub genes showed good diagnostic efficacy in the blood of PAH, and we validated most of the hub genes are consistently dysregulated in an independent PAH cohort. Validation of hub genes expression level in the monocrotaline (MCT)-induced lung tissue of rats with PAH revealed that 5 screened hub genes (MAPK1, STAT1, TLR4, TLR2, GART) are significantly highly expressed in PAH rats, and 4 screened hub genes (RPS6, FBL, RPS3, and RPS2) are substantially lowly expressed in rats with PAH. Finally, we analyzed the interaction of hub proteins and FDA-approved drugs and revealed their molecular docking, and the results showed that MAPK1, TLR4, and GART interact with various drugs with appropriate binding affinity.

Conclusion: The identified blood-derived key transcriptional signatures significantly correlate with immune infiltrations, hypoxia, glycolysis, and blood vessel remodeling genes. These findings may provide new insight into the diagnosis and treatment of PAH patients.

Pyrroloquinoline quinone (PQQ) improves pulmonary hypertension by regulating mitochondrial and metabolic functions

Excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and endothelial cells (PAECs), inflammation, as well as mitochondrial and metabolic dysregulation, contributes to the development of pulmonary hypertension (PH). Pyrroloquinoline quinone (PQQ), a potent natural antioxidant with anti-diabetic, neuroprotective, and cardioprotective properties, is known to promote mitochondrial biogenesis. However, its effect on cellular proliferation, apoptosis resistance, mitochondrial and metabolic alterations associated with PH remains unexplored. The current study was designed to investigate the effect of PQQ in the treatment of PH. Human pulmonary artery smooth muscle cells (HPASMCs), endothelial cells (PAECs), and primary cultured cardiomyocytes were subjected to hypoxia to induce PH-like phenotype. Furthermore, Sprague Dawley (SD) rats injected with monocrotaline (MCT) (60 mg/kg, SC, once) progressively developed pulmonary hypertension. PQQ treatment (2 mg/kg, PO, for 35 days) attenuated cellular proliferation and promoted apoptosis via a mitochondrial-dependent pathway. Furthermore, PQQ treatment in HPASMCs prevented mitochondrial and metabolic dysfunctions, improved mitochondrial bioenergetics while preserving respiratory complexes, and reduced insulin resistance. In addition, PQQ treatment (preventive and curative) significantly attenuated the increase in right ventricle pressure and hypertrophy as well as reduced endothelial dysfunction and pulmonary artery remodeling in MCT-treated rats. PQQ also prevented cardiac fibrosis and improved cardiac functions as well as reduced inflammation in MCT-treated rats. Altogether, the above findings demonstrate that PQQ can attenuate mitochondrial as well as metabolic abnormalities in PASMCs and also prevent the development of PH in MCT treated rats; hence PQQ may act as a potential therapeutic agent for the treatment of PH.

Involvement of mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2) in endothelial dysfunction associated with pulmonary hypertension

AIMS

Increased proliferation, inflammation, and endothelial microparticle (EMP) generation in the pulmonary vasculature lead to endothelial dysfunction in pulmonary hypertension (PH). Interestingly, MK2, a downstream of p38MAPK, is a central regulator of inflammation, proliferation, and EMP generation in cardiovascular diseases. However, the role of MK2 in pulmonary endothelial dysfunction remains unexplored.

MAIN METHODS

The Human Pulmonary Artery Endothelial cells (HPAECs) were exposed to hypoxia (1% O₂) for 72 h, and MK2 inhibition was achieved by siRNA treatment. Western blotting, qualitative RT-PCR, immunocytochemistry, flow cytometry and enzyme-linked immunoassays were conducted to study pathological alterations and molecular mechanisms. Neoangiogenesis was studied using cell migration and tubule formation assays. For in vivo study, Male Sprague Dawley rats and MK2 knock-out mice with littermate control were treated with monocrotaline (MCT) 60 mg/kg and 600 mg/kg, respectively (s.c. once in rat and weekly in mice) to induce PH. MMI-0100 (40 μg/kg, i.p. daily for 35 days), was administered in rats to inhibit MK2.

KEY FINDINGS

MK2 inhibition significantly decreased inflammation, cell proliferation, apoptosis resistance, and improved mitochondrial functions in hypoxic HPAECs. Hypoxia promoted cell migration, VEGF expression, and angiogenesis in HPAECs, which were also reversed by MK2 siRNA. MK2 inhibition decreased EMP generation and increased the expression of p-eNOS in hypoxic HPAECs, a marker of endothelial function. Furthermore, MK2 deficiency and inhibition both reduced the EMP generation in mice and rats, respectively.

SIGNIFICANCE

These findings proved that MK2 is involved in endothelial dysfunction, and its inhibition may be beneficial for endothelial function in PH.