With the global increase in life expectancy, there has been an alarming rise in the prevalence of age-related chronic diseases, including chronic obstructive pulmonary disease (COPD). COPD ranks among the leading causes of mortality worldwide and is associated with high morbidity, disability, and a relentless decline in quality of life (Divo et al., 2014; Skou et al., 2022; Agustí et al., 2023). The primary drivers of COPD progression are multifaceted, including the rampant smoking epidemic, the aging population, and, most critically, the absence of therapies that can halt or reverse the disease (Agustí et al., 2023; Huertas and Palange, 2011). Despite being both preventable and treatable, COPD remains incurable, representing a profound public health challenge (Agustí et al., 2023).

Chronic inflammation is a cornerstone of COPD pathophysiology. The initial inflammatory response could be triggered by prolonged exposure to noxious stimuli, such as cigarette smoke, the primary etiological factor in COPD. This exposure induces the migration of immune cells—neutrophils, macrophages, and lymphocytes—into the lung tissue (Huertas and Palange, 2011; Barnes, 2009; Wang et al., 2017; Wells et al., 2018). Yet, it is not solely the immune response that perpetuates this inflammatory state. Structural and resident cells of the lung, such as fibroblasts and epithelial cells, actively sustain the inflammatory cascade by producing pro-inflammatory mediators, exacerbating the chronic inflammatory response, and perpetuating it over time (Barnes, 2009).

The continuous cycle of inflammation and tissue damage in COPD results in the progressive destruction of lung parenchyma, manifesting in irreversible changes such as alveolar destruction and pulmonary emphysema (PE) (Huertas and Palange, 2011; Mannino and Buist, 2007; Cannon et al., 2016). PE is a debilitating chronic condition that imposes a substantial burden on global public health, and finding pharmacological solutions capable of reversing structural lung damage is an urgent need (Agustí et al., 2023). The imbalance between extracellular matrix synthesis and degradation impairs tissue repair, promoting unchecked lung remodeling. This cascade of events drives COPD into a state of unresolved chronic inflammation with far-reaching systemic consequences that severely deteriorate patient outcomes (Huertas and Palange, 2011; Wang et al., 2017; Wells et al., 2018; Cannon et al., 2016).

While cellular senescence is not the exclusive driver of PE and COPD progression, it plays a pivotal role in the chronic inflammatory process (Woldhuis et al., 2021; Muñoz-Espín and Serrano, 2014; Hamsanathan et al., 2019). In response to noxious stimuli and ongoing inflammation, cells undergo irreversible cell cycle arrest, entering a state of senescence (Hamsanathan et al., 2019; Tuder et al., 2012; Kheradmand et al., 2023). These senescent cells remain metabolically active, secreting a host of pro-inflammatory mediators and proteases—a phenomenon known as the senescence-associated secretory phenotype (SASP). This secretory profile amplifies inflammation through the activation of key intracellular pathways, including NF-κB, which is essential for regulating the inflammatory response (Hamsanathan et al., 2019; Tuder et al., 2012; Tsuji et al., 2006; Woldhuis et al., 2020).

Thus, in COPD, the failure to resolve inflammation induces both bronchitis and PE. In emphysema, the destruction of alveolar walls leads to reduced respiratory function, impairing gas exchange and causing air trapping, which results in lung hyperinflation (Agustí et al., 2023; Barnes, 2009; Barnes et al., 2019). This process increases respiratory effort and reduces oxygenation, contributing to systemic effects such as pulmonary hypertension and cardiovascular strain (Agustí et al., 2023). Additionally, aging exacerbates these effects, as tissue repair capacity and immune response become progressively less efficient, accelerating the structural and functional impairment of the lungs. Similarly, cigarette smoke exposure can accelerate lung aging, further worsening disease progression (Vij et al., 2018; MacNee, 2009; Ito and Barnes, 2009).

Current therapies for PE and COPD are primarily palliative, focusing on symptom management without addressing the underlying tissue damage or offering any potential for regeneration (Agustí et al., 2023). The urgent need for therapeutic strategies aimed at reversing lung damage, restoring lung architecture, and improving pulmonary function cannot be overstated. One emerging area of research that holds considerable promise is the renin-angiotensin system (RAS), specifically the axis formed by angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7) [Ang-(1-7)], and the Mas receptor (Gregório et al., 2021a; Santos et al., 2018). The considerable interest in this pathway arises from its demonstrated anti-inflammatory, anti-senescence, and pro-resolutive actions in preclinical studies (Gregório et al., 2021a; Santos et al., 2018; Magalhaes et al., 2020; Magalhães et al., 2019; Barroso et al., 2017; Bastos et al., 2020; Magalhães et al., 2015; Magalhães et al., 2020; Gregório et al., 2021b; Rodrigues-Machado et al., 2013; Magalhaes et al., 2018; Magalhães et al., 2021; Magalhães et al., 2016). Targeting the Ang-(1-7)/Mas receptor axis represents a compelling therapeutic strategy with the potential to reverse lung damage, restore pulmonary function, and arrest disease progression in PE and COPD.

In the present study, we explored the effects of an oral formulation of Ang-(1-7) on critical pathological features of PE and COPD, including senescence, inflammation, tissue remodeling, and regeneration, using an experimental model of elastase-induced pulmonary emphysema (EIPE). The findings from this investigation have the potential to drive translational clinical trials and promote a more robust collaboration between academia and industry, accelerating the development of innovative therapies to combat this debilitating disease.

PE is the main pathological feature of COPD that imposes a substantial burden on global public health, and finding pharmacological solutions capable of reversing structural lung damage is an urgent need (Agustí et al., 2023). This challenge is even more critical, as COPD is more prevalent in the elderly, where both the pulmonary and extrapulmonary effects of emphysema are worsened with age (MacNee, 2009; Ito and Barnes, 2009). Aging intensifies the deterioration of lung function, including reduced respiratory capacity and chronic hypoxemia, while extrapulmonary effects, such as pulmonary hypertension, right heart failure, and muscle wasting, also become more severe (Agustí et al., 2023; MacNee, 2009; Ito and Barnes, 2009; Wei et al., 2022). Additionally, exposure to harmful agents, such as cigarette smoke, induces lung aging, accelerating the decline in respiratory function and contributing to disease progression (Tuder et al., 2012; Vij et al., 2018; MacNee, 2009). PE is a key pathological component of COPD, contributing significantly to the disease’s morbidity, particularly in elderly individuals (Agustí et al., 2023; MacNee, 2009; Ito and Barnes, 2009; Wei et al., 2022). Aging exacerbates both pulmonary and systemic manifestations of emphysema, while exposure to harmful agents like cigarette smoke accelerates lung aging and disease progression (Tuder et al., 2012; Vij et al., 2018; MacNee, 2009; Ito and Barnes, 2009). Here we utilized a robust model of PE produced by elastase to investigate the therapeutic efficacy of the Ang-(1-7) peptide in treating this disease. The EIPE model was chosen for its ability to mimic the pathophysiology of advanced human emphysema, as elastase use results in more extensive and irreversible lung lesions than cigarette smoke exposure models (Oliveira et al., 2016). This choice is justified by elastase’s capacity to cause alveolar destruction, airspace enlargement, fibrosis, and persistent inflammation—characteristics that remain present for at least 5 weeks after the final elastase instillation, reinforcing the chronic and irreversible nature of this experimental disease (Bastos et al., 2020; Oliveira et al., 2016).

Either after one- or 5-weeks following elastase instillation, we observed that inflammatory markers (NLRP3, IL-1β), senescence markers (p53, p16, p21), and the NF-κB signaling pathway remained elevated in the EIPE group, indicating that the protocol results in irreversible injury within the evaluated time frame. These findings suggest that discontinuing the elastase challenge was insufficient to induce the resolution of inflammation or tissue repair, thus establishing a chronic pulmonary damage profile. In addition to molecular alterations, significant histological changes were observed, including airspace enlargement, reduced lung parenchyma, and increased collagen deposition, underscoring the severity of the lesions caused by the EIPE model, hallmark features of emphysema progression (Barnes, 2009; Woldhuis et al., 2021; Hamsanathan et al., 2019; Tuder et al., 2012; Barnes et al., 2019; Bastos et al., 2020; Oliveira et al., 2016). The structural damage induced by elastase, including elevated levels of VEGF, MMP-9, and collagen I and III, contributes to the tissue remodeling and alveolar destruction observed in this study and others (Wang et al., 2017; Wells et al., 2018; Voelkel et al., 2007). Moreover, we noted an increase in the expression of the klotho and Nrf2 genes, two cytoprotective proteins (Hu and Moe, 2014; Li et al., 2022) known for their roles in combating oxidative stress and regulating cellular aging. This increase was interpreted as a counter-regulatory response to the exacerbated inflammatory environment induced by elastase, as previously described in chronic inflammation models. Nrf2 is expressed in the lungs, where it plays a crucial role in regulating the cellular defense against oxidative stress and inflammation (Li et al., 2022). In previous studies, Nrf2 gene deletion in mice subjected to the EIPE protocol resulted in an even more exacerbated inflammatory response, demonstrating the critical role of Nrf2 as a modulator against oxidative and inflammatory damage (Ishii et al., 2005)

In this context of severe lung injury, the mice were treated with Ang-(1-7) formulated with hydroxypropyl-β-cyclodextrin (Magalhaes et al., 2018). The treatment was administered daily for 4 weeks, and our results demonstrated that the Ang-(1-7)-treated group exhibited remarkable improvements in lung architecture, with alveolar regeneration and a significant reduction in collagen deposition. Notably, the Ang-(1-7) treatment was initiated after the establishment of emphysema, highlighting its potential as an intervention after damage has occurred. This is a critical distinction, as experimental trials with emphysema models typically initiate treatment during the challenge period (Pan et al., 2018; Zhang et al., 2018). Although Bastos and collaborators (Santos et al., 2018) began treatment with Ang-(1-7) the day after the third elastase challenge, no characterization was performed at that time to identify lung damage before treatment (Bastos et al., 2020). Thus, we provided evidence indicating the ability of Ang-(1-7) to promote lung regeneration by reducing inflammation, which suggest this agent could be a good candidate for the treatment of chronic lung diseases, even when damage has already progressed. Our studies have helped strengthen the hypothesis that the Ang-(1-7)/Mas pathway induces counterbalancing mechanisms within the RAS to attenuate pulmonary inflammatory processes (Gregório et al., 2021a; Magalhães et al., 2015; Magalhães et al., 2020; Rodrigues-Machado et al., 2013; Magalhaes et al., 2018; Magalhães et al., 2021). Furthermore, impairment of the Ang-(1-7)/Mas pathway may exacerbate the pathophysiology of inflammatory processes by preventing the resolution of inflammation (Barroso et al., 2017; Gregório et al., 2021b; Magalhães et al., 2016). With aging, there is evidence that the balance of the RAS shifts, with a relative decrease in the protective arm mediated by Ang-(1-7) (Costa-Fraga et al., 2018; Valencia et al., 2022). This reduction in Ang-(1-7) levels with aging may contribute to age-related cardiovascular and respiratory diseases, including the progression of pulmonary conditions such as emphysema.

One of the novel findings of this study is the observed effects of Ang-(1-7) on senescence markers linked to PE. Previous studies have highlighted the role of cellular senescence in chronic lung diseases, with senescent cells contributing to chronic inflammation and tissue dysfunction (Woldhuis et al., 2021; Hamsanathan et al., 2019; Barnes et al., 2019). Therefore, Ang-(1-7) ability to inhibit NLRP3 inflammasome activation and IL-1β production, along with the suppression of senescence markers such as p53, p16, and p21, suggests that the peptide possesses both anti-inflammatory and anti-senescent properties. This dual action may be particularly valuable in treating diseases like PE and COPD, where senescence and inflammation perpetuate disease progression. Indeed, NLRP3 inflammasome activation is closely linked to the maintenance of chronic hyperinflammation states characteristic of aging-related diseases, such as atherosclerosis, diabetes mellitus (González-Moro et al., 2022; Zhang et al., 2021) and COPD (Zhang et al., 2021). Previous studies have also demonstrated that activation of the Ang-(1-7)/Mas receptor axis regulates NLRP3 activation in several inflammatory models, including hepatic fibrosis (Zhang et al., 2016), neuroinflammation (Duan et al., 2021), vascular senescence (Romero et al., 2019), and pulmonary inflammation (Zhang et al., 2016; Sun et al., 2017; Huang et al., 2020).

The increase in VEGF and MMP-9, along with the exacerbated expression of collagen I and III, plays a fundamental role in the tissue damage associated with PE. Overexpression of VEGF can induce pathological angiogenesis and contribute to inappropriate extracellular matrix remodeling in lung diseases (Wang et al., 2017; Voelkel et al., 2007). Excessive MMP-9 activity leads to the destruction of elastic fibers and the alveolar matrix (Wells et al., 2018), while increased collagen I and III deposition contributes to the progressive loss of respiratory function (Agustí et al., 2023; Barnes, 2009; Barnes et al., 2019). Therefore, attenuating these markers is critical to mitigating damage and restoring tissue balance. In this context, Ang-(1-7) emerges as a promising therapeutic agent. In experimental models of pulmonary inflammation, Ang-(1-7) has been shown to suppress the production of factors that promote proliferation and fibrosis, thereby fostering an environment conducive to the resolution of inflammation and the regeneration of damaged tissue (Barroso et al., 2017; Magalhães et al., 2015; Magalhães et al., 2020; Magalhaes et al., 2018; Xu et al., 2023). Therefore, Ang-(1-7) ability to attenuate VEGF, MMP-9, and collagen I/III expression may be therapeutically relevant in the context of PE. Indeed, by suppressing these mediators, Ang-(1-7) not only interrupts the cycle of tissue degradation and remodeling but also promotes alveolar repair and regeneration.

The Wnt/β-catenin pathway plays a fundamental role in the maintenance and proliferation of type 2 alveolar progenitor cells (AT2), which are essential for alveolar regeneration (Leeman et al., 2014; Nabhan et al., 2018). Previous studies have demonstrated that Wnt/β-catenin signaling is downregulated in COPD, contributing to impaired lung repair mechanisms (Conlon et al., 2020; Uhl et al., 2015). In our EIPE model, elastase administration resulted in a decrease in β-catenin expression, indicating suppression of this repair pathway. However, treatment with Ang-(1-7) restored β-catenin expression, suggesting the reactivation of regenerative mechanisms that may be responsible for the restoration of alveolar architecture observed at the end of the treatment. One study showed that Wnt/β-catenin activation could antagonize paracrine senescence in mesenchymal stem cells, disrupting pro-senescent cascades (Lehmann et al., 2022). However, there is controversy regarding the role of β-catenin in PE, with some studies suggesting that its activation may contribute to tissue dysfunction (Lehmann et al., 2020a; Lehmann et al., 2020b). This contrast highlights the complexity of this pathway and the need for further studies to fully understand its role in different stages of lung damage. Nonetheless, the possibility that Ang-(1-7) activates a tissue repair-related pathway is a promising mechanism by which the structural damage observed in our animals may have been reversed, particularly through the activation of AT2 progenitor cells to restore alveolar architecture.

Additionally, Ang-(1-7) suppressed NF-κB activation, a major driver of chronic inflammation in emphysema (Barnes, 2009; Zhang et al., 2018). Previous studies have shown that treatment with Ang-(1-7) via different routes, such as oral and intranasal, suppresses NF-κB activation, which is directly related to inflammation suppression and reduction of leukocyte survival, thus contributing to the resolution of the inflammatory process (Barroso et al., 2017; Magalhaes et al., 2018). The interaction between Wnt/β-catenin and NF-κB pathways is crucial in PE progression, as these pathways mutually regulate each other. NF-κB activation can inhibit β-catenin signaling, impairing lung regeneration, while β-catenin activation can suppress NF-κB activity, reducing inflammation (Conlon et al., 2020; Ma and Hottiger, 2016). Ang-(1-7) dual modulation of these pathways—activating β-catenin and suppressing NF-κB—highlights its ability to reduce inflammation and enhance lung repair, positioning it as a promising therapeutic agent.

We observed a downregulation of Klotho and Nrf2 genes after Ang-(1-7) treatment, contrasting with their elevation in the untreated EIPE group. Klotho and Nrf2 are cytoprotective proteins known for their roles in combating oxidative stress and cellular aging (Li et al., 2022; Romero et al., 2019). The reduction of their levels after treatment may reflect a return to pulmonary homeostasis, with inflammation suppression and promotion of tissue repair. As our analyses were performed at the end of the 4-week treatment period, it is possible that Klotho and Nrf2 were elevated at some intermediate point, but as the tissue environment became healthier, their levels decreased—contrasting with the untreated EIPE group, which remained in a state of exacerbated inflammation.

In conclusion, our findings reinforce the therapeutic potential of Ang-(1-7) in treating EIPE by modulating critical pathways such as Wnt/β-catenin and NF-κB, reducing inflammation, and promoting tissue repair. Ang-(1-7)’s ability to restore alveolar architecture after injury highlights its efficacy as a post-injury intervention (Figure 6). Although our results are promising, further studies are needed to elucidate the underlying mechanisms and investigate the role of β-catenin in different stages of tissue repair, as well as the interaction between the Ang-(1-7)/Mas axis and other anti-inflammatory and pro-resolving pathways. Additionally, with aging, the reduction of Ang-(1-7) may worsen tissue damage and hinder repair. Therefore, increasing pulmonary levels of Ang-(1-7) could be a promising alternative for the treatment of chronic inflammatory diseases, especially in elderly patients. These findings provide a solid foundation for translational and clinical advancements, positioning Ang-(1-7) as a potential multifaceted therapy for chronic lung diseases.