4. Discussion
Despite numerous proposed mechanisms, the pathophysiology of sepsis remains incompletely elucidated. Nevertheless, it is well established that a dysregulated host immune response to infection drives tissue injury. Immune cells recruited to sites of inflammation augment the synthesis and levels of pro-inflammatory cytokines, thereby precipitating cellular damage within organs [
28]. Pro-inflammatory cytokines promote the generation of reactive oxygen species (ROS), thereby inducing oxidative stress and consequent tissue injury. In sepsis, the lung is a primary target of this injury and one of the most frequently affected organs. Malondialdehyde (MDA), a lipid peroxidation product and a key biomarker of tissue-level oxidative stress, has been reported to increase in the lung following induction of sepsis [
29]. Reduced glutathione (GSH) is the cell’s foremost non-enzymatic antioxidant. Serving primarily as an electron donor for glutathione peroxidase (GPx), it detoxifies peroxides and helps neutralize superoxide and hydroxyl radicals [
30].
The documented antioxidant, anti-inflammatory, and immunomodulatory properties of statins have motivated their evaluation as adjunctive or alternative therapeutic strategies for chronic diseases. Rosuvastatin exhibits high affinity for the active site of HMG-CoA reductase and demonstrates superior in vitro potency in inhibiting enzymatic activity and cholesterol biosynthesis relative to other statins [
21].
In rat models of sepsis induced by CLP, it has been reported that MDA levels in lung tissue are significantly increased, whereas GSH levels are decreased. Various compounds have been shown to attenuate sepsis-induced pulmonary injury by decreasing MDA levels and increasing GSH levels [
4,
31,
32]. However, the potential effect of rosuvastatin on these oxidative stress parameters in lung tissue has not been clearly demonstrated in animal models of sepsis. In the present study, the elevated MDA levels and decreased GSH levels observed in the sepsis group were significantly reversed following rosuvastatin administration. These findings suggest that rosuvastatin exerts a protective effect against sepsis-induced oxidative damage in lung tissue.
In a study evaluating rosuvastatin’s antioxidant effects, rats were exposed to the toxicant fipronil to induce hepatic and renal oxidative injury. Abdel-Daim et al. administered rosuvastatin (10 mg/kg, oral, 15 days) and measured oxidative and antioxidant markers. Rosuvastatin significantly lowered fipronil-elevated MDA and restored depleted GSH in both organs. Fipronil also enhanced caspase-3 expression in hepatic and renal tissues; co-administration of oral rosuvastatin with vitamin E attenuated this apoptosis-associated upregulation [
33]. In a separate study conducted in myocardial tissue, azithromycin administration elevated malondialdehyde (MDA) levels, which were reduced by maintenance-dose rosuvastatin (2 mg/kg), while glutathione (GSH) levels increased. Concurrently, the azithromycin-induced upregulation of caspase-3 expression was attenuated by rosuvastatin [
34]. Consistent with these reports, rosuvastatin in our study conferred protection to lung tissue under heightened oxidative stress by reducing MDA levels and significantly increasing GSH. Thus, we confirm rosuvastatin’s antioxidant effect in sepsis-induced lung injury, extending prior evidence to pulmonary tissue.
In sepsis, NF-κB/p65 is central to TLR-mediated signaling: nuclear translocation of p65 triggers transcription of TNF-α, IL-1β, IL-6, and iNOS/COX-2. This program amplifies neutrophil recruitment, oxidative stress, and epithelial apoptosis, culminating in diffuse alveolar injury. Apoptosis of alveolar epithelial and capillary endothelial cells leads to barrier dysfunction, proteinaceous edema, and impaired gas exchange. Caspase-3, a principal executioner caspase, occupies a central position in the pathophysiology of sepsis. By integrating inputs from the intrinsic (caspase-9–dependent) and extrinsic (caspase-8–dependent) pathways, it orchestrates and carries out the terminal proteolytic events that execute the apoptotic program [
35,
36].
As one of the earliest organs affected during sepsis, the lung undergoes disruption of tissue integrity because of marked neutrophil infiltration within the pulmonary epithelium, leading to alveolar inflammation, interstitial inflammation, and vascular congestion. In addition, alveolar septal thickness is one of the histopathological features that is markedly altered and commonly evaluated in sepsis.[
27]. It has been reported that, in the CLP-induced sepsis group in which these histopathological features were analyzed, both the lung injury score (LDS) and alveolar septal thickness were significantly increased. [
24,
37]. Our histopathological analysis based on the scoring system of Matute-Bello et al., the lung injury score (LDS) was 0 (0–0.5) in the Sham group and 5 (4–7) in the CLP group. Following administration of rosuvastatin at 10 mg, this value decreased significantly to 0.5 (0–2), whereas treatment with 20 mg rosuvastatin reduced it to 1 (0–1). When the alveolar septal thickness ratio in the Sham group was accepted as 1, this ratio was determined to be 2.94 in the CLP group, 1.50 in the group treated with 10 mg rosuvastatin, and 1.60 in the group treated with 20 mg rosuvastatin. Our findings indicate that rosuvastatin exerts a protective effect against sepsis-induced acute lung injury (ALI); however, this effect appears to be dose-independent. Further studies are needed to validate and support these findings.
In a recently published study, increased expression of TNF-α and NF-κB in lung tissues of a rat sepsis model was reported [
4]. Consistent findings have also been documented in earlier studies evaluating various compounds [
31,
38]. In a murine model of sepsis, increased TNF-α expression in cortical tissues has been reported, and rosuvastatin was shown to significantly attenuate this elevation [
2]. Similarly, in the peritoneal lavage supernatants of the same model, elevated TNF-α levels were significantly reduced following rosuvastatin administration [
15]. Mărginean et al. compared the anti-inflammatory effects of rosuvastatin and simvastatin in a rat model of CLP. The statins were administered 18 and 3 hours before surgery, and serum levels of procalcitonin and cytokines (IL-1β, IL-6, and TNF-α) were measured. Both rosuvastatin and simvastatin demonstrated significant anti-inflammatory activity in this sepsis model [
39]. In another study, lung tissue samples from the CLP-induced sepsis group exhibited markedly elevated NF-κB/p65 expression, which was significantly reduced following fosfomycin administration [
24]. In our study, TNF-α and NF-κB/p65 levels were elevated in the sepsis group, whereas this increase was significantly attenuated in the rosuvastatin-treated group. These results further support the notion that rosuvastatin exerts modulatory effects on inflammatory pathways contributing to sepsis-induced lung injury.
8-OHdG is elevated in sepsis at both systemic (serum/urine) and pulmonary tissue levels, parallels indices of oxidative stress and lipid peroxidation (e.g., malondialdehyde, MDA), and correlates with disease severity and mortality. These findings support 8-OHdG as a reliable biomarker of oxidative DNA damage in sepsis and a useful pharmacodynamic readout for monitoring the impact of antioxidant or anti-inflammatory interventions [
40]. In a study using a CLP-induced sepsis/ALI model in rats, 8-OHdG levels were evaluated in lung tissue. The authors reported that 8-OHdG levels were elevated in the CLP group, whereas resveratrol treatment attenuated this elevation by 41%. Another study employing the same model, in which 8-OHdG immunopositivity was assessed, likewise reported increased 8-OHdG levels in the sepsis group and demonstrated that costunolide treatment reduced this marker [
41]. However, the effect of rosuvastatin on oxidative DNA damage in lung tissue has not previously been demonstrated. In our experimental groups, 8-OHdG levels were evaluated by immunohistochemical analysis. The increased positivity scores observed in the lung tissues of the sepsis group showed a statistically significant reduction following administration of rosuvastatin at doses of 10 mg and 20 mg. Nevertheless, no significant difference was detected between the two treatment doses. Our findings regarding 8-OHdG levels indicate that rosuvastatin also exerts a protective effect on the cellular pathways involved in oxidative DNA damage.
Rosuvastatin has been shown to inhibit apoptotic pathways in multiple tissues, including the liver, kidney, and myocardium [
33,
34]. Extending this evidence to the lung, we demonstrate an anti-apoptotic effect in the clinically relevant setting of sepsis, as evidenced by reduced caspase-3 expression. Caspase-3 levels, which were elevated in the CLP group, declined markedly after rosuvastatin treatment, without a discernible dose-dependent difference.
Our study had several limitations. First, sepsis is a systemic condition that affects not only the lungs but also the circulatory system and other organs, including the liver, kidneys, and spleen. Therefore, analysis of these organs would be necessary to comprehensively evaluate the overall effects of rosuvastatin. In addition, oxidative stress, inflammation, apoptosis, and oxidative DNA damage pathways were assessed using a limited number of biomarkers in the present study. Evaluation of additional key markers involved in these pathways would be required to further validate our findings. Moreover, tissue integrity was examined at the microscopic level; however, assessment of intercellular junction molecules at the molecular level could have provided more direct evidence regarding the effects of rosuvastatin. Rosuvastatin was administered exclusively as a prophylactic treatment, 4 hours before sepsis induction. Additional experimental designs incorporating post-sepsis treatment regimens would enhance the clinical relevance and translational value of our findings.