Introduction

Moderate/Severe Acute Pancreatitis (M/SAP) is a severe digestive system disorder marked by pancreatic tissue edema, bleeding, and necrosis, resulting from autodigestion, often accompanied by serious complications including systemic inflammatory response syndrome and multi-organ dysfunction. Hypertriglyceridemia (HTG) has emerged as a principal risk factor for M/SAP, due to a variety of causes, and accounts for over 10% of all SAP instances1,2,Statistical methods

All quantitative data are delineated as mean ± standard deviation. Paired t-tests facilitated the within-group comparisons relative to the baseline values, while independent sample t-tests facilitated the analyses of between-group disparities concerning treatment-related variations. The chi-square test was utilized to examine the overall therapeutic efficacy, presuming a normal distribution. A significance level of P < 0.05 was considered statistically significant. After data organization and verification, data analysis was performed using SPSS 23.0 statistical software.

Results

At the study's conclusion, two individuals from the control group were relocated to a superior-level hospital for advanced care, constituting a slight attrition in the participant pool. Consequently, the analysis incorporated data from 34 cases in the observation group and 32 in the control group, as delineated below.

Lipid concentrations pre and post treatment across both groups

Prior to the intervention, no significant disparities were detected between the groups regarding the levels of TG, TC, HDL, and LDL (P > 0.05). Following treatment, both contingents exhibited a notable diminution in TG and TC levels (Table 1). A comparative analysis revealed a more substantial decline in the TG and TC levels within the observation group at the 24-h post-treatment mark, attaining statistical significance (P < 0.05). Additionally, the observation group witnessed a significant escalation in HDL levels post-treatment, alongside a considerable decrement in LDL levels both pre and post intervention. Conversely, the control group demonstrated a singular decrease in LDL levels pre-treatment. A pronounced enhancement in HDL was observed 24 h post-treatment in the observation group in comparison to the control group, reaching statistical significance (P < 0.05). Nonetheless, no significant variations in lipid components were noted between the groups prior to discharge (P > 0.05). The data propose that the DFAPP intervention facilitated a swift and substantial reduction in triglycerides within the observation group. The respective t-values and P-values are enumerated as follows: Observation group: Post-treatment TG: t = 8.38, P < 0.0001; Pre-discharge: t = 8.02, P < 0.0001; Post-treatment TC: t = 15.3, P < 0.0001; Pre-discharge: t = 14.14, P < 0.001. Control group: Post-treatment TG: t = 6.47, P < 0.0001; Pre-discharge: t = 5.61, P < 0.0001; Post-treatment TC: t = 9.20, P < 0.001; Pre-discharge: t = 10.80, P < 0.001.

Table 1 Comparison of blood lipid levels between two groups of patients before and after treatment (mmol/L \({\overline{\text{X}}} \pm S\)).
Full size table

Cytokine levels before and after treatment across both groups

Prior to the intervention, no discernible differences in cytokine levels (IL-6, IL-17, IL-10, IL-35, TNF-α) between the two groups (P > 0.05). Post-treatment, a significant reduction in the pro-inflammatory cytokines IL-6 and TNF-α was noted in both groups, albeit without significant inter-group variations (Table 2). Notably, IL-17 levels diminished significantly within the observation group, a change not mirrored in the control group. Furthermore, the observation group experienced significant intra-group alterations in anti-inflammatory cytokines IL-10 and IL-35, compared to the control group, with IL-35 recording a more pronounced decrease (P = 0.003). This indicates that DFAPP treatment in the observation group effectively inhibited pro-inflammatory cytokines while enhancing anti-inflammatory cytokine activity, thereby modulating the inflammatory response within the body. The precise numerical comparisons are presented below: IL-6: Within-group comparison, observation group t = 13.24, P < 0.0001; control group t = 14.49, P < 0.0001. Between-group comparison after treatment showed no significant differences (P = 0.56). IL-35: Within-group comparison, observation group t = 6.44, P < 0.0001; control group t = 1.99, P = 0.051. TNF-α: Within-group comparison, observation group t = 19.33, P < 0.000; control group t = 19.65, P < 0.0001. Between-group comparison after treatment showed no significant differences (P = 0.19). IL-10: Within-group comparison, observation group t = 2.12, P = 0.03; control group t = 0.34, P = 0.95. There were no statistically significant differences between the groups after treatment (P > 0.05). IL-17: Within-group comparison, observation group t = 6.32, P < 0.001; control group showed no significant differences in both within-group and between-group comparisons (P > 0.05).

Table 2 Comparison of cytokine levels between two groups of patients before and after treatment (\({\overline{\text{X}}} \pm S\)).
Full size table

Serum biomarker levels before and after treatment in both groups

Prior to the intervention, the serum biomarker concentrations (CRP, PCT, BUN, ALB, WBC) exhibited no significant distinctions between the two groups (P > 0.05). Post-treatment, both groups manifested comparable efficacy in diminishing inflammation (Table 3), albeit the observation group displayed a markedly greater reduction in CRP levels (△P < 0.05). Furthermore, the observation group experienced a less pronounced decline in PCT and WBC levels compared to the control group, yet these changes were not statistically significant. Notably, the ALB concentrations in the observation group demonstrated a swifter recuperation post-treatment (△P < 0.05). The therapy yielded uniform beneficial impacts on kidney function across both groups. These findings suggest that DFAPP therapy possesses a substantial benefit in mitigating sepsis-related inflammation and enhancing hepatic and renal functions within the observation group. Detailed numerical analyses are presented below: CRP: Within-group comparison, observation group t = 21.89, P < 0.05; control group t = 19.52, P < 0.05. PCT: Within-group comparison, observation group t = 6.53, P < 0.05; control group t = 6.24, P < 0.05. BUN: Within-group comparison, observation group t = 5.0, P < 0.05; control group t = 5.07, P < 0.05. ALB: Within-group comparison, observation group t = 4.78, P < 0.05; control group t = 1.70, P = 0.08. WBC: There were no significant differences between the two groups after treatment (P > 0.05).

Table 3 Comparison of biochemical levels between two groups of patients before and after treatment (\({\overline{\text{X}}} \pm S\)).
Full size table

Comparison of Marshall score, APACHE II score, and MCTSI score before and after treatment in both groups

Initially, no significant variations were discernible in the three evaluated scores (Marshall, APACHE II, MCTSI) between the groups (P > 0.05). Post-intervention, the observation group exhibited diminished Marshall scores relative to the control group (Table 4), indicative of superior preservation of organ functionality. Both factions demonstrated efficacious enhancements in APACHE II scores, with no substantial variations observed within a 72-h frame in the pancreatic CT evaluations. Detailed numerical analyses are delineated below: Marshall score: Observation group t = 5.19, P < 0.05; control group t = 2.54, P = 0.01. APACHE II score: Observation group t = 8.50, P < 0.05; control group t = 5.66, P < 0.05. MCTSI: Observation group t = 1.99, P > 0.05; control group t = 1.47, P > 0.05.

Table 4 Comparison of Marshall score, APACHE II score, and MCTSI score between two groups of patients before and after treatment (\({\overline{\text{X}}} \pm S\)).
Full size table

Comparison of hospitalization duration, mortality rate, 6-month recurrence rate, and lipid levels between the two groups

In comparison to the control group, the observation group showcased commendable short-term and long-term outcomes, characterized by reduced average durations of hospital stay, diminished mortality rates, and a lower incidence of pancreatitis recurrence at the 24-week milestone, all of which denoted significant statistical disparities (P < 0.05). Although the observation group recorded lower average TG levels at the 24-week assessment, this discrepancy did not attain statistical significance (P < 0.05), and the results are shown in Table 5.

Table 5 Comparison of hospitalization time, mortality rate, 12-week pancreatitis recurrence rate, and blood lipid follow-up between two groups of patients.
Full size table

Discussion

Acute Pancreatitis (AP) is classified into mild AP, moderately severe AP, severe AP, and critical acute pancreatitis (CAP). The causes include cholelithiasis, alcoholism, and hypertriglyceridemia. Literature reports7,8 indicate that the mortality rate of hypertriglyceridemia-induced moderately/severe acute pancreatitis (HL-M/SAP) in the past decade has reached 30–42%. The pathogenesis is not yet clear but is closely related to the lipotoxicity of triglycerides, pancreatic microcirculation disorders, and cytokine storm sepsis (CSS).

Reducing triglycerides is an effective method for treating HL-M/SAP. Our study results suggest that three hours after treatment with the blood purification DFAPP mode, patients' triglyceride levels rapidly decreased to near-normal levels (3.75 ± 1.95). This was accompanied by an improvement in the body's inflammatory storm, which might be related to the rapid reduction of triglycerides by DFAPP, alleviating the toxic effects of fatty acids and improving microcirculation. However, the improvement in patient TG levels was relatively poor (9.57 ± 3.84) after treatment with the CVVH + PA purification mode. This was mainly due to the slow clearance of large molecules such as triglycerides by the CVVH + PA purification mode, leading to the chronic persistence of fatty acid toxicity. In physiological conditions, triglycerides account for over 80% of fat cell mass9, and obesity leads to fat accumulation around the pancreas and internal organs. Research by Saisho et al. has confirmed that pancreatic fat increases with BMI10. When there is an excess of triglycerides (TG) in the body's circulation, a high concentration of TG also accumulates in the pancreatic capillaries. The breakdown of these triglycerides into free fatty acids (FFA) induces glandular cell inflammation, edema, degeneration, necrosis, and other damages11. At the same time, the pancreatic microenvironment becomes acidic, activating pancreatic enzymes and leading to autodigestion of the pancreas. Additionally, high concentrations of fatty acids can directly damage the endothelial cells of pancreatic capillaries, causing contraction dysfunction and permeability disorders, blood circulation stagnation, and resulting in pancreatic acinar cell ischemia and hypoxia, inflammation and necrosis, further exacerbating the condition. Therefore, reducing triglycerides as early as possible can not only alleviate lipotoxicity and improve microcirculation but also protect acinar function and halt disease progression.

Reducing triglycerides also alleviates cytokine storms and prevents MODS. Our study found that after DFAPP treatment, the pro-inflammatory cytokines IL-6, IL-17, and TNF-α in the observation group significantly decreased compared to pre-treatment levels. Compared to the control group during the same period, the reduction of pro-inflammatory cytokines was even more pronounced. The control group also showed a decrease in pro-inflammatory cytokines after treatment with CVVH + PA purification, but the effect was not as good as with DFAPP treatment. Persistent systemic inflammation led to slower disease mitigation, thereby prolonging the average hospital stay for the control group. In animal experiments with HTG rats12, it was found that with the increase of fatty acid levels, cytokine levels including IL-6, TNF-α, and IL-17 also increased. Fatty acids rich in human necrotic bacteria were found, and acute unsaturated fatty acids produced by lipolysis caused pancreatic necrosis, systemic inflammation, and worsening of SAP-related damage. Inhibiting lipolysis reduced the production of FFA and improved the adverse outcomes of AP. Multiple studies10,13 found a close correlation between fat concentration in adjacent acinar tissue and organ damage in AP. Simultaneously, fatty acids in the pancreas had a direct toxic effect on pancreatic tissue during acute pancreatitis. Our study found that the incidence of concurrent MODS events within 48 h after DFAPP treatment was significantly lower than in the control group. This may be due to DFAPP rapidly reducing triglycerides, not only alleviating fatty acid toxicity but also blocking the resulting inflammatory response. At the same time, DFAPP quickly adsorbs and removes cytokines, reducing inflammatory damage and thus protecting organ function. Ultimately, the observation group had better APACHE II scores, suggesting that DFAPP promotes rapid recovery and significantly reduces mortality compared to the control group (2.9% vs 12.5%). A study on markers of severe pancreatitis14 found that fatty acids produced by lipolysis around the pancreas can cause more severe cytokine release and multi-organ failure as well as death. It also promotes the progression of mild acute pancreatitis to severe pancreatitis. Clinically, it has been observed that free fatty acids in the serum of patients with severe acute pancreatitis are significantly increased15.

Cytokine storm syndrome (CSS) plays a crucial role in the onset and progression of HL-M/SAP, and its initiation is inseparable from fatty acid toxicity16. Free fatty acids trigger a variety of cytokines, which mediate an inflammatory storm, leading to persistent organ failure, a primary cause of early mortality in severe acute pancreatitis (SAP). Studies have found that cytokines, particularly TNF-αand IL-6, along with lipid factors such as resistin and visfatin, are significantly elevated in the serum of SAP patients17,18,19. Our study discovered that pro-inflammatory factors such as IL-6, IL-17, TNF-α, CRP, WBC, PCT, etc., significantly increase after the onset of HL-M/SAP. Anti-inflammatory factors like IL-10 also rise. After blood purification treatment, these pro-inflammatory factors, along with triglycerides and cholesterol, decrease. Post-treatment changes in anti-inflammatory factors occur: IL-10 increases compared to pre-treatment levels, IL-35 decreases, but the anti-inflammatory factor IL-35 after DFAPP intervention is higher than the mean value after CVVH + PA intervention. This suggests that DFAPP exhibits a more pronounced effect in inhibiting inflammatory storms. Inflammatory response is a double-edged sword; activation is accompanied by suppression. Clinical research indicates that pro-inflammatory cytokines such as IL-17, IL-6, IL-33, TNF-α, etc., significantly increase in severe acute pancreatitis20. Anti-inflammatory cytokines like IL-10, IL-35 receptor antagonists, soluble IL-2 receptor levels are also higher in severe acute pancreatitis than in mild acute pancreatitis21, which is consistent with our study results. Animal experiments have found that in obese mice given IL-12, IL-18 or rats infused with free fatty acids in the ducts, the result induced SAP and increased mortality13,22. In these models, cytokines (TNF-α, IL-6 and MCP-1) levels in obese mice increased along with serum fatty acids. However, after treatment with the lipase inhibitor Orlistat, these cytokines and fatty acids levels decreased. This indicates that the increase in cytokines is a response to free fatty acids produced by lipolysis. It also suggests that fatty acids can trigger cytokine damage.

In our study, we found that as triglycerides were rapidly cleared in the observation group, the body's inflammatory storm was subsequently suppressed. The Marshall score was lower than the control group; albumin and creatinine levels recovered quickly. The effect of DFAPP treatment on protecting organ function was more apparent. Therefore, early clinical removal of high triglycerides and inflammatory mediators has become the primary goal for treating lipid-induced severe acute pancreatitis complicated by multiple organ dysfunction syndrome22. Our study also found that the recurrence rate of pancreatitis in the observation group was 10.3% lower than the control group after a 24-week follow-up. The mean triglyceride level was significantly lower than the control group (3.72 ± 0.84 vs 6.68 ± 2.52). This may be related to the high expression of anti-inflammatory factors IL-10, IL-35 after DFAPP purification, which is beneficial for liver lipid metabolism. At the same time, it may also be related to the rapid decline of triglycerides and cholesterol after DFAPP treatment, causing the restoration of lipid balance due to the increase in high-density lipoproteins and the decrease in low-density lipoproteins.

In the realm of blood purification research related to HL-AP, both domestic and international reports focus on aspects such as plasma exchange, double filtration plasmapheresis, and hemofiltration. The DFAPP model innovatively combines DFPP and CPFA techniques, earning a patent for artificial liver technology (Patent No. 202110671354.9). This study suggests that early use of blood purification through DFAPP treatment can rapidly reduce triglycerides, inhibit cytokine storm syndrome damage, decrease the incidence of multiple organ failure, enhance patient survival rates, and lower the recurrence rate of pancreatitis. In conclusion, the DFAPP blood purification model is worth promoting for clinical use in HL-M/SAP and warrants further in-depth research.