Decreased TGF-β1 and VEGF Release in Cystic Fibrosis Platelets: Further Evidence for Platelet Defects in Cystic Fibrosis

Microvascular significance of TGF-β axis activation in COVID-19

As 2023 approaches, the COVID-19 pandemic has killed millions. While vaccines have been a crucial intervention, only a few effective medications exist for prevention and treatment of COVID-19 in breakthrough cases or in unvaccinated or immunocompromised patients. SARS-CoV-2 displays early and unusual features of micro-thrombosis and immune dysregulation that target endothelial beds of the lungs, skin, and other organs. Notably, anticoagulation improves outcomes in some COVID-19 patients. The protein transforming growth factor-beta (TGF-β1) has constitutive roles in maintaining a healthy microvasculature through its roles in regulating inflammation, clotting, and wound healing. However, after infection (including viral infection) TGF-β1 activation may augment coagulation, cause immune dysregulation, and direct a path toward tissue fibrosis. Dysregulation of TGF-β signaling in immune cells and its localization in areas of microvascular injury are now well-described in COVID-19, and such events may contribute to the acute respiratory distress syndrome and skin micro-thrombosis outcomes frequently seen in severe COVID-19. The high concentration of TGF-β in platelets and in other cells within microvascular thrombi, its ability to activate the clotting cascade and dysregulate immune pathways, and its pro-fibrotic properties all contribute to a unique milieu in the COVID-19 microvasculature. This unique environment allows for propagation of microvascular clotting and immune dysregulation. In this review we summarize the physiological functions of TGF-β and detail the evidence for its effects on the microvasculature in COVID-19. In addition, we explore the potential role of existing TGF-β inhibitors for the prevention and treatment of COVID-19 associated microvascular thrombosis and immune dysregulation.

Association of Serum TGF-β1 Levels with Different Clinical Phenotypes of Cystic Fibrosis Exacerbation

PURPOSE

Cystic Fibrosis (CF) is a multi-organ genetic disorder and Transforming Growth Factor (TGF-β1) is a modifier gene which modulates lung pathology in CF. There is great phenotypic variability among CF patients who even have similar genotype. The aim of the present study was to associate the serum levels of TGF-β1 with several clinical phenotypes of CF.

METHODS

The diagnosed cases of CF were recruited and the blood sample was withdrawn at different time points: during exacerbation (n = 26), non-exacerbation (n = 9) and after antibiotic therapy (n = 11). The concentration of the total TGF-β1 in serum was measured with commercial ELISA kit. The ΔF508 mutation was assessed by the Amplification Refractory Mutation System (ARMS-PCR).

RESULTS

The levels of TGF-β1 were increased in exacerbation phase (119.89 ± 29.64 ng/mL), infection with P. aeruginosa (121.8 ± 28.83 ng/mL) and in subjects with ΔF508 mutation (139.2 ± 19.59 ng/mL). The levels of TGF-β1 in CF patients with Allergic Bronchopulmonary Aspergillosis (ABPA) (109.97 ± 27.71 ng/mL) were decreased as compared to CF patients without ABPA (123.55 ± 30.20 ng/mL). It was observed that the serum levels of TGF-β1 were decreased significantly after antibiotic therapy (p < 0.05).

CONCLUSIONS

The present study has determined that the serum levels of TGF-β1 vary with the type of infections, ΔF508 CFTR mutation, presence of ABPA and response to therapy.

Epithelial mesenchymal transition (EMT): a universal process in lung diseases with implications for cystic fibrosis pathophysiology

Cystic Fibrosis (CF) is a genetic disorder that arises due to mutations in the Cystic Fibrosis Transmembrane Conductance Regulator gene, which encodes for a protein responsible for ion transport out of epithelial cells. This leads to a disruption in transepithelial Cl-, Na + and HCO₃− ion transport and the subsequent dehydration of the airway epithelium, resulting in infection, inflammation and development of fibrotic tissue. Unlike in CF, fibrosis in other lung diseases including asthma, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis has been well characterised. One of the driving forces behind fibrosis is Epithelial Mesenchymal Transition (EMT), a process where epithelial cells lose epithelial proteins including E-Cadherin, which is responsible for tight junctions. The cell moves to a more mesenchymal phenotype as it gains mesenchymal markers such as N-Cadherin (providing the cells with migration potential), Vimentin and Fibronectin (proteins excreted to help form the extracellular matrix), and the fibroblast proliferation transcription factors Snail, Slug and Twist. This review paper explores the EMT process in a range of lung diseases, details the common links that these have to cystic fibrosis, and explores how understanding EMT in cystic fibrosis may open up novel methods of treating patients with cystic fibrosis.

NM23 proteins: innocent bystanders or local energy boosters for CFTR?

NM23 proteins NDPK-A and -B bind to the cystic fibrosis (CF) protein CFTR in different ways from kinases such as PKA, CK2 and AMPK or linkers to cell calcium such as calmodulin and annexins. NDPK-A (not -B) interacts with CFTR through reciprocal AMPK binding/control, whereas NDPK-B (not -A) binds directly to CFTR. NDPK-B can activate G proteins without ligand-receptor coupling, so perhaps NDPK-B's binding influences energy supply local to a nucleotide-binding site (NBD1) needed for CFTR to function. Curiously, CFTR (ABC-C7) is a member of the ATP-binding cassette (ABC) protein family that does not obey 'clan rules'; CFTR channels anions and is not a pump, regulates disparate processes, is itself regulated by multiple means and is so pleiotropic that it acts as a hub that orchestrates calcium signaling through its consorts such as calmodulin/annexins. Furthermore, its multiple partners make CFTR dance to different tunes in different cellular and subcellular locations as it recycles from the plasma membrane to endosomes. CFTR function in airway apical membranes is inhibited by smoking which has been dubbed 'acquired CF'. CFTR alone among family members possesses a trap for other proteins that it unfurls as a 'fish-net' and which bears consensus phosphorylation sites for many protein kinases, with PKA being the most canonical. Recently, the site of CFTR's commonest mutation has been proposed as a knock-in mutant that alters allosteric control of kinase CK2 by log orders of activity towards calmodulin and other substrates after CFTR fragmentation. This link from CK2 to calmodulin that binds the R region invokes molecular paths that control lumen formation, which is incomplete in the tracheas of some CF-affected babies. Thus, we are poised to understand the many roles of NDPK-A and -B in CFTR function and, especially lumen formation, which is defective in the gut and lungs of many CF babies.

Resolvin D1 drives establishment of Leishmania amazonensis infection

Previous studies have indicated that the balance between different eicosanoids reflect the intensity of the inflammatory profile in patients with tegumentary leishmaniasis. More recently, pro-resolution lipid mediators have been shown to play critical roles in dampening pathological inflammatory processes to reestablish homeostasis in a diverse range of experimental settings. Among these lipid mediator, resolvins from D series have been described as potent anti-inflammatory and immunomodulatory mediators, and its activities include inhibition of leukocyte chemotaxis and blockage production of proinflammatory cytokines, while increasing the expression of regulatory mediators. Whether resolvins play significant roles in establishment and persistence of Leishmania infection is currently unknown. We addressed this question in the current study by assessing circulating levels of D-series resolvins in tegumentary leishmaniasis patients presenting with localized or diffuse disease. We found heightened expression of resolvin D1 in diffuse cutaneous leishmaniasis which was correlated with expression profile of biomarkers associated with disease pathogenesis. Additional in vitro experiments using primary human macrophages indicated that resolvin D1 may promote intracellular Leishmania amazonensis replication through a mechanism associated with induction of heme oxygenase-1. These results suggest that targeting resolvin D1 could serve as potential strategy for host directed therapy in diffuse cutaneous leishmaniasis.

Cardio-Ankle Vascular Index (CAVI) and Plasma Transforming Growth Factor-β1 (TGF-β1) Level Correlate with Aortopathy in Adults with Repaired Tetralogy of Fallot

It is challenging to evaluate aortopathy in congenital heart disease using conventional investigations such as brachial-ankle pulse wave velocity (baPWV). Therefore, we evaluated the cardio-ankle vascular index (CAVI), a dimension of the ascending aorta and plasma transforming growth factor-β1 (TGF-β1) level, in order to find novel noninvasive parameters of aortopathy in adults with repaired tetralogy of Fallot (TOF). Prospectively, we enrolled 42 consecutive adults with TOF (28 patients with repaired TOF were not on ARB, 8 patients with repaired TOF on ARB, 6 patients with no repair or only palliative repair) and 20 age-matched healthy controls. We measured CAVI, baPWV, plasma TGF-β1 level and a diameter of the ascending aorta using echocardiography. The mean age of repaired TOF without ARB were 31.9 ± 9.1 years. An aortic diameter of the ascending aorta, CAVI, and plasma TGF-β1 level were significantly higher in repaired TOF without ARB than those in controls, whereas baPWV did not differ. On a univariate analysis, CAVI, plasma TGF-β1 level and Rastelli procedure were important factors for an aortic diameter of the ascending aorta (r = 0.56, P < 0.01, r = 0.59, P < 0.01, r = 0.39, P < 0.05, respectively) in this population. There was no significant correlation with age, baPWV, NT-pro brain natriuretic peptide (BNP), repair age, shunt duration, aortic regurgitation or right aortic arch. On the other hand, patients with unrepaired or palliative TOF, who had obvious volume overload, showed no significant correlation with CAVI, baPWV or plasma TGF-β1 level. CAVI and plasma TGF-β1 level, not baPWV, correlate to aortopathy in adults with repaired TOF.