NPs preparation and characterization
The PDA NPs were synthesized through the oxidative polymerization of dopamine hydrochloride in an alkaline aqueous solution. This process was initiated by adjusting the pH with NaOH, followed by auto-oxidation under ambient air conditions, as illustrated in Scheme 1 (Scheme 1) [15]. Subsequently, following our previously established method [19,20,21], DNase-I and PEG were co-immobilized onto the surface of PDA NPs through a single-step procedure. This process exploits the reactivity of catechol and quinone groups on the PDA surface. The primary amine groups of DNase-I and the terminal amine groups of PEG formed covalent bonds with the PDA surface via Schiff base formation and Michael addition reactions, resulting in stable surface functionalization. Additionally, neutrophil-targeted Siv@PLGA NPs were prepared using a conventional emulsification method and subsequently conjugated with F(ab’)2 fragments of an antibody specific for neutrophils [22]. The morphology of the particles, as observed via SEM, was uniformly spherical (Fig. 1A). Additionally, the sizes of the PDA and DNase-I@PDA NPs, measured by DLS, were approximately 199 and 184 nm, respectively, with minimal size variation attributable to the binding of PEG and DNase-I to the surface (Fig. 1B). The sizes of PLGA and Siv@PLGA NPs were found to be 274 and 273 nm, respectively. This minimal difference in size indicates that the incorporation of Sivelestat into the PLGA nanoparticles did not significantly alter their dimensions. The zeta potentials of PLGA and Siv@PLGA NPs were −11.13 and − 11.87 mV, respectively, showing minimal variation (Fig. 1C). In contrast, PDA and DNase-I@PDA NPs exhibited zeta potentials of − 11.33 mV and − 17.92 mV, respectively, with DNase-I@PDA NPs displaying approximately 36% more negative charge. This increased negative charge is due to the binding of negatively charged DNase-I to the surface of PDA NPs [23, 24]. The release profile of Sivelestat from Siv@PLGA NPs was quantified over time using HPLC (Fig. 1D). The drug loading achieved was 163 µg of Sivelestat per mg of PLGA NPs, yielding an encapsulation efficiency of 54%. As shown in Fig 1D, Sivelestat demonstrated a sustained release from the PLGA NPs over a 24-h period. The DNA degradation enzymatic activity of DNase-I@PDA NPs were evaluated using agarose gel electrophoresis (Fig. S1). While 2 U of free DNase-I completely degraded 2 µg of DNA, DNase-I@PDA NPs achieved complete degradation of the same amount of DNA at concentrations above 5.0 µg. These results demonstrate that the DNase-I immobilized on the PDA NPs surface retains its effective DNA degradation capability.
Characterization of NPs. A SEM image (n = 3, Scale bar = 500 nm) B Size and C Zeta potential (n = 3) of PDA, DNase-I@PDA, PLGA, and Siv@PLGA NPs. D Drug release profile of Siv@PLGA NPs (n = 4). E In vitro targeting efficiency of Neutrophil targeted PLGA NPs (n = 5). Statistical analysis was performed using a two-tailed unpaired t-test. Data are presented as mean ± SEM. * P < 0.05, ** P < 0.01, *** P < 0.001, **** P < 0.0001 (v.s. LPS)
Neutrophil-targeted Siv@PLGA NPs were prepared by conjugating the F(ab’)2 fragment of the anti-Ly6g antibody, which targets neutrophils, to the Siv@PLGA NPs. To achieve this, the anti-Ly6g antibody is cleaved into F(ab’)2 and Fc fragments using the protease IdeS [17, 22]. The cleavage of the antibody was confirmed by non-reducing SDS–PAGE gel stained with Coomassie Brilliant Blue, where bands corresponding to F(ab’)2 and Fc were observed at 115 and 25 kDa, respectively (Fig. S2). After cleavage, the hinge region of the F(ab’)2 fragment is reduced with DTT to generate thiol groups, which then conjugate with the maleimide groups on the particle surface. The conjugation efficiency of the antibody to the particle surface was subsequently verified using a BCA assay. It was determined that 17.5 µg of antibody was bound per 1 mg of NPs, corresponding to 70% of the antibody used in the reaction being conjugated to the particle surface.
The targeting efficiency by the antibody conjugation to surface of PLGA NPs was assessed in vitro using flow cytometry with fluorescently labeled PLGA NPs in mouse splenocytes (Fig. 1E). The intensity shifts of DiD was compared between cells treated with DiD-loaded neutrophil-targeted PLGA NPs and cells treated with bare PLGA NPs, with untreated cells as baseline. In the case of target cells, neutrophils, the shift in DiD signal increased by 19% when treated with neutrophil-targeted PLGA NPs, which is approximately five times higher than that observed with DiD-loaded bare PLGA NPs. This indicates that the conjugation of antibodies to the surface of PLGA NPs enhances the targeting efficiency towards neutrophils. Additionally, to evaluate non-specific binding of the PLGA NPs, DiD signal shifts were examined in non-target cells, such as T cells and macrophages. The results showed that neutrophil-targeted PLGA NPs exhibited a slightly higher signal shift (approximately 2%) compared to bare PLGA NPs in both T cells and macrophages, indicating that non-specific binding of the neutrophil-targeted PLGA NPs is minimized.
Next, we analyzed time-dependent degradation of DNase-I@PDA NP in murine serum to evaluate its enzymatic persistence. The results showed that DNase-I levels peaked at 6 h post-treatment, suggesting that the nanoparticle formulation effectively maintained DNase-I activity during the early phase after administration. After reaching its peak, DNase-I levels steadily decreased. A significant drop was detected at 12 h post-treatment, which indicates continuous enzymatic degradation. By 24 h following treatment, DNase-I levels were no longer detectable within this timeframe. This observation demonstrates that the nanoparticle-conjugated DNase-I had undergone complete degradation. (Fig. S3).
These findings imply that DNase-I@PDA NPs remain active for a limited but sufficient duration to exert their enzymatic function before being naturally degraded, aligning with the expected pharmacokinetics of enzyme-based therapies. The observed degradation pattern suggests that DNase-I@PDA NPs provide a therapeutic window that allows for effective NET degradation while minimizing the risk of prolonged systemic exposure, which could potentially reduce off-target effects.
To assess the therapeutic potential of the nanoparticle formulations under inflammatory conditions resembling infection-induced lung injury, we established an in vitro transwell co-culture system that models the crosstalk between endothelial and alveolar compartments with a focus on neutrophil-mediated responses. Human endothelial cells (hy926) were seeded in the upper chamber, while human lung fibroblasts (MRC5) were placed in the lower chamber. LPS was applied to the entire system to induce a pro-inflammatory environment (Fig. S4 A). Following 12 h of LPS exposure, free DNase-I or DNase-I@PDA NPs were administered into the lower chamber to simulate alveolar delivery of therapeutics. One hour later, neutrophils were introduced into the upper chamber alongside either free Sivelestat or Siv@PLGA NPs, modeling systemic drug administration and neutrophil recruitment from circulation into inflamed lung tissue.
Under these conditions, neutrophils were anticipated to become activated and migrate toward the lower compartment in response to LPS-driven cues. Notably, treatment with nanoparticle formulations resulted in a measurable reduction in neutrophil infiltration (Fig. S4B), suggesting a potential role in tempering activation or migratory responsiveness. A concurrent decrease in cfDNA levels within the upper chamber supernatant over time (Fig. S4 C) further implied suppression of NET formation, which has been implicated in amplifying fibroblast activation through extracellular signaling. To better understand the functional consequence of this modulation, we examined the early fibrotic response in fibroblasts by measuring α-SMA levels in MRC5 lysates. Western blot analysis revealed that, in contrast to untreated conditions where α-SMA expression was elevated at early time points following LPS and neutrophil exposure, NP-treated groups did not exhibit this early induction (Fig. S4D). This early suppression may reflect a favorable alteration in the cellular microenvironment—potentially linked to reduced exposure to neutrophil-derived signals such as NETs or inflammatory proteases. Building on these in vitro findings, we proceeded to evaluate the therapeutic efficacy of the nanoparticle formulations in vivo to further validate their impact under physiologically relevant conditions.
Amelioration of acute immune responses in LPS-induced lung injury through early administration of DNase-I
In previous study, we demonstrated that the activity of DNase-I may decrease in the immediate aftermath of COVID-19 infection, potentially contributing the complications such as the formation of NETs and eventual increase of disease severity [19]. Based on these observations, we hypothesized that early intratracheal administration of DNase-I@PDA NPs could compensate for reduced DNase-I activity and attenuate the rapid accumulation of NET-derived DNA within the pulmonary system. This strategy was anticipated to prevent excessive inflammatory responses that contribute to acute lung injury. Additionally, intravenous administration of Siv@PLGA NPs, by inhibiting NE activity, was designed to suppress peripheral neutrophil hyperactivation, thereby preventing the sustained inflammatory escalation despite neutrophil infiltration into lung tissue (Fig. 2A).
Early administration of DNase-I ameliorates acute immune response in the case of COVID-19 infection. A Schematic of DNase-I@PDA NPs and Siv@PLGA NPs administration. B Schematic of LPS injection and sacrifice schedule. Mice were intratracheally (i.t.) administered three times with LPS (3 mg/kg) and sacrificed at every 24 h interval. C Schematic of LPS injection and treatment schedule. Mice were intratracheally (i.t.) administered three times with LPS (3 mg/kg) and were intratracheally (i.t.) administered twice with free DNase-I (D group) or DNase-I @NP (D@P group) at 24 h after the third injection of LPS. Mice were sacrificed at 12 h after the final administration of free DNase-I or DNase-I@NP at every 24 h interval. D Concentration of DNase-I in blood and BALF. E Neutrophil count in blood and BALF. F Immune cell populations in BALF at 72 h post-administration. G Immune cell populations in BALF at 96 h post-administration. Statistical analysis was performed using a two-tailed unpaired t-test. Data are presented as mean ± SEM. * P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 (v.s. LPS), ##P < 0.01, ###P < 0.001 (v.s. D + S)
To confirm the validity, we performed an investigation to determine whether aerosol injection of free DNase-I (D group) or DNase-I@PDA NPs (D@P group) decrease activation of inflammation mediators in pulmonary fibrosis mouse model induced by serial intratracheal injections of LPS. We assessed the levels of DNase-I and various immune factors in an animal model at early, intermediate, and late stages, which we hypothesized correspond to the development of post-infectious pulmonary fibrosis (Fig. 2B, C). Regarding DNase-I levels, the results indicated a significant decrease in DNase-I concentration in both murine plasma and BALF 48 h after direct intratracheal administration of LPS (Fig. 2D). Additionally, we noted an increase in the neutrophil population in the blood (Fig. S5), along with a decrease in monocyte infiltration into the BALF (Fig. 2E). This observation implies a shift in immune cell dynamics throughout the inflammatory response. By 72 and 96 h post-LPS injection, DNase-I levels in plasma showed a significant rebound compared to the 48 h time point (Fig. S6), mirroring our previous observations [19] of elevated DNase-I in severe COVID-19 patients. DNase-I levels in the BALF remained reduced throughout the 96 h period, despite the systemic rebound observed in the plasma (Fig. 2F, G). However, it is worth noting that treatment with free DNase-I and DNase-I@PDA NPs effectively restored DNase-I levels in the BALF (Fig 2F, G). DNase-I@PDA NPs achieved a more sustained elevation of DNase-I levels compared to free DNase-I, likely due to the enhanced release profile of DNase-I. Moreover, a marked reduction in blood neutrophil levels and monocyte infiltration into the BALF was observed in the D and D@P group. Immunohistochemical (IHC) analysis of monocytes also showed that the LPS group exhibited a greater presence of monocytes beyond the vascular boundary. In comparison, monocyte infiltration appeared reduced in both the D and D@P-treated groups. Such histological evidence is consistent with the observed decrease in monocyte levels within the BALF and supports the possibility that the treatment may help temper monocyte-associated inflammatory activity (Fig. S7). These findings suggest that early administration of DNase-I, particularly in its nanoparticle formulation, may help restore DNase-I levels in the context of pulmonary fibrosis and influence immune cell dynamics, including neutrophil and monocyte populations, which play important roles in the inflammatory cascade associated with fibrotic progression.
Pulmonary retention and coadministration of DNase-I@PDA NPs and Siv@PLGA NPs
Following the demonstrated efficacy of DNase-I formulations in attenuating acute lung inflammation, we sought to explore the synergistic therapeutic effects of co-administration of DNase-I@PDA NPs and Siv@PLGA NPs in vivo. Our primary objective was to assess pulmonary retention, systemic distribution, and potency of these nanoparticles to exert both localized and systemic anti-inflammatory effects, particularly in the setting of persistent inflammation and fibrosis.
To visualize nanoparticle biodistribution and pulmonary retention, fluorescence(Cy7)-conjugated DNase-I@PDA NPs and Siv@PLGA NPs were administered according to the outlined experimental scheme (Fig. 3A). Fluorescence imaging of lung tissues revealed sustained pulmonary localization of aerosol-administered DNase-I@PDA NPs, with a gradual decrease in fluorescence intensity over 24 h post-administration. This extended retention supports the hypothesis that inhalation delivery ensures effective deposition and persistence of DNase-I@PDA NPs within pulmonary tissue (Fig. 3A), enhancing their therapeutic window in mitigating early inflammatory processes. This result is also consistent with the previously conducted in vitro DNase-I degradation experiment (Fig. S3).
Coadministration of DNase-I and Sivelestat nanoparticle and drug release. A Ex vivo imaging of dissected organs after the i.v. administration of Cy7- Siv@PLGA NP and the i.t. administration of Cy7- DNase-I PDA@NP. B Schematic of LPS injection and treatment schedule. Mice were intratracheally (i.t.) administered three times with LPS (3 mg/kg). DNase-I PDA@NP was administrated intratracheally and Siv@PLGA NP was administrated intravenously, alternating 12 h apart. Mice were sacrificed at 48 h after the final administration of Siv@PLGA NP. C Heatmap illustrating the top 50 cytokines identified from a cytokine array analysis across the treatment conditions: LPS, DNase-I combined with Sivelestat (D + S), and each nanoparticle treatment (NP). The color scale denotes relative expression levels, with red indicating upregulation. Pathway enrichment analysis revealed significant involvement of inflammatory and immune-related pathways, including cytokine-cytokine receptor interaction, chemokine signaling, and the MAPK signaling pathway. D Neutrophil counts, E NET ratio, F DNase-I activity, G Concentration of NE, H MPO activity, and I cfDNA in murine BALF. Statistical analysis was performed using a two-tailed unpaired t-test. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 (v.s. LPS), # P < 0.05, ## P < 0.01, ### P < 0.001 (v.s. D + S)
Siv@PLGA NPs, delivered intravenously, were primarily expected to target peripheral neutrophils and inhibit NET formation upon migration into pulmonary tissues (Fig. 1E). While hepatic accumulation is an expected outcome due to the liver’s role in nanoparticle clearance, efficient entry to the lungs was also successfully achieved (Fig. 3A). Fluorescence tracking showed that NP-bound neutrophils migrated to the lungs within 6 h of administration, suggesting effective neutrophil targeting. The continued presence of Siv@PLGA NPs in peripheral tissues indicates that they may contribute to regulating systemic neutrophil activity, which could help limit excessive NET formation and reduce inflammation in the lungs.
Cytokine profiling and pathway analysis in LPS-induced lung fibrosis models developed according to the scheme (Fig. 3B) showed that treatment with DNase-I@PDA NPs and Siv@PLGA NPs (NP group) significantly modulated inflammatory and fibrotic responses compared to the LPS and DNase-I and Sivelestat (D+S) groups (Fig. S8). PCA identified distinct cytokine expression patterns, with NP-treated animals showing enrichment in cluster 4, indicating a unique immunomodulatory effect (Fig. S9). Pathway analysis of differentially expressed cytokines indicated a marked suppression of proinflammatory and profibrotic pathways, including extracellular matrix organization, cell migration, as well as the PI3 K-Akt, NF-κB, and MAPK signaling pathways. Notably, NP treatment suppressed key chemotaxis-related cytokines such as MCP-2, GRO, PF-4, and LD78beta, critical for neutrophil recruitment and NET formation. This NET inhibition, along with the regulation of cytokine-cytokine receptor interactions and chemokine signaling, reflects the potential anti-inflammatory and anti-fibrotic effects of DNase-I@PDA NPs and Siv@PLGA NPs. This outcome underscores their potential role in controlling fibrosis and facilitating lung tissue recovery in fibrotic conditions (Fig. 3C).
Pertaining to the impact of the nanoparticles on neutrophil activation and the inflammatory mediators released by neutrophils, the combined administration of DNase-I@PDA NPs and Siv@PLGA NPs was associated with a marked reduction in neutrophil infiltration in the BALF (Fig. 3D). This reduction was accompanied by a significant decrease in NET formation in the lungs (Fig. 3E), demonstrating the efficacy of the treatment in suppressing excessive neutrophil activity. Significantly, DNase-I enzymatic activity remained stable across the treatment period, confirming that nanoparticle formulation did not impair its functionality (Fig. 3F). Co-administration with Siv@PLGA NPs led to a further reduction in NE and MPO levels, which may have contributed to NET inhibition and enhanced the anti-inflammatory effect. Since NE and MPO are associated with extracellular matrix degradation and fibrosis progression, this reduction may have played a role in modulating these processes (Fig. 3G, H). The combined treatment also led to a decrease in circulating cfDNA levels, which are considered markers of immune dysregulation and have been linked to chronic inflammation and fibrosis (Fig. 3I and Figs. S10, 11). The reduction in NE and MPO levels, along with the decrease in cfDNA in both plasma (Fig. S12) and BALF, indicates that co-administration may help regulate acute inflammatory responses and limit pathways associated with fibrotic progression.
Relieved pathological phenotypes of pulmonary fibrosis in vivo
To evaluate the therapeutic efficacy of DNase-I@PDA NPs and Siv@PLGA NPs in the context of pulmonary fibrosis, we conducted detailed histopathological and functional assessments. Histological analysis using H&E staining revealed that NP-treated mice exhibited significant restoration of alveolar structure and a marked reduction in pneumonic damage compared to untreated LPS-exposed mice (Fig. 4A). Orange G staining revealed pronounced extracellular matrix deposition in LPS-treated lungs, with NP demonstrating superior efficacy in reducing matrix accumulation compared to D+S group, as evidenced by histological patterns most closely resembling PBS controls. (Fig. 4B). Cit-H3 and NE, well-established markers of NETs, were analyzed in pulmonary vascular tissue to assess the efficacy of nanoparticles in inhibiting NET accumulation and their potential role in preserving vascular integrity via IHC staining. In LPS group, prominent Cit-H3 and NE signals were observed within the vasculature, indicating persistent intravascular NET accumulation, inefficient NET clearance, and potential endothelial dysfunction driven by neutrophil-mediated cytotoxicity. This accumulation may indicate sustained neutrophil activation and prolonged inflammatory signaling, contributing to endothelial damage. In contrast, D+S and NP groups exhibited markedly reduced Cit-H3 and NE deposition in the vasculature, suggesting that the treatment effectively mitigated neutrophil hyperactivation and excessive NET release. This reduction in intravascular NET burden implies improved NET clearance mechanisms and decreased neutrophil-induced endothelial injury. These findings highlight the therapeutic potential of DNase-I@PDA NPs and Siv@PLGA NPs to attenuate neutrophil-driven vascular inflammation and improve (Fig. 4C). Trichrome staining further confirmed a reduction in collagen deposition, with both the area and intensity of collagen expression significantly diminished in NP-treated group, indicating that the treatment effectively limited collagen accumulation, a hallmark of fibrosis (Fig. 4D). Another IHC analysis demonstrated reductions in the expression of collagen I and α-SMA in the lungs of NP-treated mice. The decreased collagen I level suggests reduced vascular inflammation and fibrotic remodeling, helping to preserve lung architecture by preventing vascular occlusion. Additionally, suppression of α-SMA expression indicates that NP treatment effectively inhibited myofibroblast activation, a critical process in extracellular matrix remodeling and tissue stiffening (Fig. 4E). The reduction in collagen I and α-SMA expression was also quantitatively confirmed through real-time PCR analysis (Fig. S13). To further corroborate these findings, we measured hydroxyproline levels as a proxy for collagen synthesis. Hydroxyproline levels were significantly lower in the NP-treated group, suggesting reduced fibrotic activity and a decreased risk of progressive fibrosis (Fig. 4F). These results suggest that the treatment mitigates the pathological remodeling associated with fibrosis by maintaining structural integrity within the lungs.
Improved respiratory function by administrating of DNase-I@PDA NPs and Siv@PLGA NPs. A H&E analysis of lung tissue from LPS-induced pulmonary fibrosis mouse model. (Scale bar: 200 μm). B Orange G staining images. (Scale bar: 200 μm). C Immunohistochemistry (IHC) analysis (Cit-H3, NE, and Sytox-Green™) of lung sections of LPS-induced pulmonary fibrosis mouse model. (Scale bar: 40 μm). D Trichrome stained images of murine lung tissue. (Scale bar: 200 μm). E IHC analysis of fibrotic markers (collagen I and α-SMA). (Scale bar: 100 μm). F Measurement of hydroxyproline content. G Inspiratory capacity, lung resistance, compliance, and elastance ascertained by FlexiVent forced oscillation technique at endpoint. H PV curve. I Body weight of LPS-induced pulmonary fibrosis mouse model. J Survival rate of LPS-induced pulmonary fibrosis mouse model. Statistical analysis was performed using a two-tailed unpaired t-test. Data are presented as mean ± SEM. *P < 0.05, **P < 0.01, ****P < 0.0001 (v.s. LPS), ##P < 0.01, ####P < 0.0001 (v.s. D + S)
Pulmonary function assessments were conducted to investigate the physiological impact of NP treatment on respiratory mechanics in the LPS-induced lung injury model. LPS-treated mice exhibited a reduction in inspiratory capacity (IC), along with increased elastance (E) and decreased compliance (C), indicating impaired lung distensibility and increased tissue stiffness—features commonly associated with fibrotic remodeling (Fig. 4G). A reduction in IC reflects a limitation in the volume of air drawn into the lungs during inspiration. Elevated elastance and reduced compliance further support the presence of restricted mechanical expansion, as these measures describe the lung’s resistance to inflation and its ability to stretch under pressure. These functional impairments were further reflected in the pressure–volume (PV) curves, which were shifted downward in the LPS group, indicating reduced lung inflation capacity under applied pressure (Fig. 4H). Subsequent administrations of NPs were associated with trends toward improvement, as indicated by a modest recovery in IC and gradual normalization of E and C parameters (Fig. 4G). Correspondingly, The PV curves of NP-treated mice showed an upward shift compared to those of the untreated group (Fig. 4H). Together, these results provide evidence that NP administration contributed to the recovery of pulmonary mechanics by mitigating the functional consequences of inflammation-induced fibrotic injury.
In terms of overall physiological outcomes, NP-treated mice showed significant improvements in body weight maintenance and survival rates compared to untreated LPS-exposed controls. Mice in the NP-treated group experienced less weight loss and demonstrated a substantial increase in survival rates, underscoring the effectiveness of the treatment in mitigating the detrimental effects of LPS-induced lung injury and fibrosis (Fig. 4I, J). These results collectively demonstrate the potential of DNase-I@PDA NPs and Siv@PLGA NPs to attenuate both acute and chronic pathological features of pulmonary fibrosis, restoring lung structure and function while improving survival outcomes in treated animals.
Therapeutic efficacy of nanoparticles on neutrophils of COVID 19 patients
After confirming the in vivo restorative effects of the co-administration of DNase-I@PDA NPs and Siv@PLGA NPs, we extended our investigation to assess the therapeutic potential of these nanoparticles on neutrophils isolated from COVID-19 patients. Our results indicated that both free drug formulations and drug-encapsulated NPs contributed to a reduction in circulating cfDNA levels, which have been associated with inflammatory responses and immune dysregulation in COVID-19 patients (Fig. 5A). When DNase-I@PDA NPs were introduced to plasma samples from COVID-19 patients, we observed a notable enhancement in DNase-I enzymatic activity, suggesting that the nanoparticle formulation improved the degradation of extracellular DNA and enhanced the overall therapeutic potential in reducing cfDNA levels (Fig. 5B). Further analysis of neutrophil samples revealed that treatment with DNase-I@PDA NPs and Siv@PLGA NPs led to a substantial reduction in NET formation, as well as significant decreases in NE and MPO activity (Fig. 5C–E). These findings indicate that formulations of the nanoparticles are highly effective at suppressing neutrophil hyperactivation and limiting the downstream enzymatic processes that contribute to pulmonary tissue damage and inflammation. In addition, NP treatment markedly improved neutrophil viability (Fig. 5F), demonstrating the ability of the nanoparticles to stabilize immune cell function under inflammatory conditions. This improvement in neutrophil stability is particularly important in promoting immune homeostasis in the context of severe viral infections such as COVID-19. Collectively, these results suggest that DNase-I@PDA NPs and Siv@PLGA NPs exhibit strong therapeutic potential in mitigating the harmful effects of NETosis and reducing the risk of long-term fibrotic complications in COVID-19 patients.
Evaluation of NETosis following coadministration of free drugs and NPs in the blood of SARS-CoV-2 patients. A Circulating cfDNA. B DNase-I enzymatic activity. C NET formation index in PBMCs. D NE activity. E MPO activity. F Viability of the neutrophils. Statistical analysis was performed using a two-tailed unpaired t-test. Data are presented as mean ± SEM. *P < 0.05, ****P < 0.0001 (v.s. PBS), #P < 0.05, ####P < 0.0001 (v.s. D + S)