Polymyxin B-immobilized fiber column direct hemoperfusion (PMX-DHP) is an extracorporeal treatment initially developed to remove circulating endotoxins from gram-negative sepsis [4]. In sepsis, PMX-DHP has been shown to reduce levels of inflammatory cytokines such as interleukin-6, tumor necrosis factor-alpha, high mobility group box 1, leading to improved hemodynamics and organ function in a few studies [5,6]. These anti-inflammatory properties have led to exploratory applications in noninfectious inflammatory conditions, including AE-IPF and other interstitial lung diseases [7,8].

In this issue of The Korean Journal of Internal Medicine, Kim et al. reported the results of a prospective single-center pilot study assessing the feasibility and safety of PMX-DHP in 10 patients with AE-IPF [9]. All patients underwent two sessions of PMX-DHP in combination with corticosteroid pulse therapy. No procedure-related adverse events were observed. The c-reactive protein levels decreased significantly after PMX-DHP, and a trend toward improved oxygenation (P/F ratio) was observed (p = 0.054). Renal function, as assessed using the estimated glomerular filtration rate, was stable during the study period, supporting the renal safety of the intervention.

The current study shares several similarities with a previous retrospective analysis by Lee et al. [8], which investigated PMX-DHP in acute exacerbation of interstitial lung disease, including patients with IPF. Both studies observed a reduction in inflammatory markers and trends toward improved gas exchange. However, there are certain key differences. This investigation used a prospective design explicitly focused on AE-IPF, incorporated standardized eligibility criteria that excluded patients with severe hypoxemia or ventilatory support, and included detailed monitoring of renal parameters. These methodological enhancements offer a robust assessment of the feasibility and safety of this intervention in this population and represent a meaningful advancement in evaluating this intervention.

Although treatment was initiated promptly after hospital admission, the time interval between AE symptom onset and PMX-DHP administration has not been reported [9]. As AE-IPF often progresses rapidly, this information may influence the treatment response and should be considered in future studies.

Although the sample size was small and no survival benefit was demonstrated, this study was not powered to assess the clinical outcomes. As a pilot study, its primary value is demonstrating that PMX-DHP can be implemented safely and consistently in patients with AE, not in impending respiratory failure [9]. These biological responses support the rationale for further exploration in larger randomized controlled trials.

In summary, this study provided valuable preliminary data on the application of PMX-DHP to AE-IPF. Their findings suggested that the procedure is feasible and well-tolerated, with potential biological activity, as evidenced by improvements in inflammatory and oxygenation markers. These exploratory results contribute to the growing interest in extracorporeal strategies for AE-IPF and provide a useful foundation for designing future trials with more comprehensive temporal and mechanistic assessments.