Search Results (93)

Background/Objectives: Systemic sclerosis (SSc) is a heterogeneous systemic autoimmune rheumatic disease characterized by immune dysregulation, vasculopathy, and fibrosis involving the skin and internal organs. Interstitial lung disease (ILD), pulmonary arterial hypertension (PAH), and cardiac involvement remain major causes of morbidity and mortality, yet prediction of disease progression and therapeutic responsiveness remains difficult. Methods: This narrative review summarizes studies of circulating blood biomarkers in SSc, with emphasis on literature published since 2020 and on Japanese multicenter longitudinal cohort studies. Disease-specific autoantibodies were intentionally excluded from the main scope, and the review focuses on soluble biomarkers measurable in peripheral blood that reflect inflammation, endothelial injury, and fibrotic remodeling. Results: Multiple cytokines, chemokines, adhesion molecules, endothelial markers, extracellular vesicle-associated molecules, and extracellular matrix (ECM)-related molecules have been associated with disease activity, organ involvement, prognosis, and therapeutic response in SSc. Clinically established biomarkers such as KL-6 and surfactant protein-D (SP-D) for SSc-associated interstitial lung disease (ILD), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) for pulmonary arterial hypertension (PAH), are already used as adjunctive tools in routine clinical assessment, whereas many other candidate biomarkers, including interleukin (IL)-6, CCL2, CXCL8, CXCL4, intercellular adhesion molecule-1 (ICAM-1), CCL18, periostin, endostatin, endothelin-1, extracellular vesicle signatures, and ECM turnover markers remain at varying stages of clinical validation. In particular, Japanese multicenter longitudinal studies have demonstrated the prognostic significance of circulating chemokines and adhesion molecules in early SSc and, more recently, identified biomarker-based clusters associated with distinct pulmonary trajectories. Recent multidimensional proteomic and transcriptomic approaches further support biologically based patient stratification in SSc. Conclusions: Blood biomarkers may contribute to risk stratification, prediction of organ progression, and future precision medicine in SSc. Integrated biomarker signatures may better capture the biological heterogeneity of SSc than single biomarkers alone. However, most candidate biomarkers still require external validation, assay standardization, and demonstration of incremental value over conventional clinical variables before routine clinical implementation. Full article

Background: Acute bronchiolitis is one of the most common lower respiratory tract infections in early childhood and is frequently associated with recurrent wheezing and later development of asthma. Identifying biomarkers related to airway epithelial injury and disease severity may improve risk stratification. Materials and Methods: A total of 155 children aged 1–36 months who presented with their first episode of wheezing were enrolled. Clinical data and bronchiolitis symptom scores were recorded at admission. Serum levels of CC16, surfactant protein-D (SP-D), YKL-40, and isoprostane were measured. Patients were followed for one year to assess recurrence of wheezing. Results: According to symptom scores, 81 patients had mild and 74 had moderate bronchiolitis; no severe cases were observed. The distribution of bronchiolitis severity differed significantly between recurrent and non-recurrent wheezing groups. Serum YKL-40 levels were significantly correlated with disease severity (p < 0.05), and the effect size analysis indicated a moderate effect. SP-D levels showed a non-significant trend with severity (p = 0.17). No significant associations were observed for CC16 or isoprostane. Conclusions: Serum YKL-40 may be a potential biomarker reflecting disease severity in children with acute bronchiolitis. Further longitudinal studies are needed to evaluate the prognostic value of epithelial injury markers for recurrent wheezing and asthma development. Full article

This study evaluated the diagnostic usefulness of surfactant protein D (SP-D), chemokine C-C motif ligand 2/monocyte chemoattractant protein-1 (CCL2/MCP-1), and interleukin 18 (IL-18) in patients with SARS-CoV-2 infection. The authors focused on lung failure assessment, lung parenchyma involvement, and the early assessment of the risk of developing pulmonary fibrosis at the onset of COVID-19. The study group included 87 patients with COVID-19 and 45 healthy subjects. Concentrations of all three markers were measured using the enzyme immunoassay method. The serum SP-D, CCL2/MCP-1, and IL-18 concentrations were significantly higher in the COVID-19 patients before admission to the hospital than those in the controls (p < 0.001 for all comparisons). Differences were only found in the IL-18 levels between the groups categorized according to disease severity (p < 0.001); levels were significantly higher in patients with critical disease severity compared to those with moderate disease severity (p < 0.001). IL-18 also showed a positive correlation with the disease severity (p = 0.025). SP-D and IL-18 levels varied depending on the amount of oxygen administration (p = 0.017 and p < 0.001, respectively). Among the blood gas parameters, SP-D levels were negatively associated with the partial pressure of arterial oxygen (PaO₂) and oxygen saturation (O₂Sat) (p = 0.026 and p = 0.048, respectively), IL-18 with O₂Sat (p = 0.036), and CCL2/MCP-1 with PaO₂ (p = 0.042). SP-D and IL-18 were significantly negatively correlated with oxygen therapy (p = 0.003 and p = 0.014, respectively). Conversely, CCL2/MCP-1 was significantly positively correlated with the pulmonary involvement severity (p = 0.017) and level of hyaluronic acid (HA), a marker of fibrosis (p = 0.042). We also observed a significant correlation between the IL-18 level and the pulmonary involvement severity (p < 0.001), HA (p < 0.001), and other markers of fibrosis. In summary, our study’s results indicate that SP-D, CCL2/MCP-1, and IL-18 may be used to assess lung function in the early stage of COVID-19 infection; additionally, SP-D may serve as an indicator of alveolar injury, while CCL2/MCP-1 and IL-18 may be markers of lung parenchyma involvement and potential predictors of the development of pulmonary fibrosis. Full article

Background: Surfactant Protein D (SP-D) is a critical immunomodulatory collectin maintaining alveolar homeostasis. Obstructive sleep apnea (OSA)-related intermittent hypoxia (IH) disrupts pulmonary surfactant integrity; however, severity-dependent SP-D dynamics remain incompletely characterized. This study explores SP-D as a potential indicator of IH-induced alveolar stress and evaluates whether Galectin-3 (Gal-3) inhibition modulates surfactant homeostasis. Methods: Forty adult male Sprague-Dawley rats (8 per group) were randomized to Control (normoxia), Moderate IH (MIH; 15–30 events/hour), Severe IH (SIH; 30–60 events/hour), MIH + Gal-3 inhibitor (Modified Citrus Pectin, 800 mg/kg/day), or SIH + Gal-3 inhibitor. IH exposure lasted 8 h/day for 10 days. Outcomes included circulating SP-D, Surfactant Protein B (SP-B), inflammatory markers, physiological parameters, and histopathological lung injury scores assessed via American Thoracic Society guidelines. Results: SP-D levels showed numerical reductions with increasing IH severity (Control: 1969.07 pg/mL [IQR: 262.15]; SIH: 1404.30 pg/mL [IQR: 351.88]), representing a 28.6% decrease. However, between-group variability resulted in non-significant omnibus testing (Kruskal–Wallis p = 0.187). Gal-3 inhibition elevated SP-D levels, particularly in severe IH (2133.95 pg/mL [IQR: 1240.70]), though high inter-individual variability was observed (CV = 58.1%). SP-B showed significant suppression under moderate IH (p = 0.019) with restoration by treatment. Exploratory correlation analysis revealed moderate positive associations between SP-D and heart rate (r = 0.587) and respiratory rate (r = 0.419) in severe IH, though these did not reach statistical significance (p = 0.126 and p = 0.301, respectively). Histologically, severe IH induced diffuse alveolar damage (total lung score: 19.67 ± 0.82). Gal-3 inhibition produced context-dependent effects: protective in severe IH but paradoxically exacerbating inflammation under moderate IH (29.20 ± 4.64 vs. 20.00 ± 4.34; p < 0.05). Gal-3 inhibition significantly attenuated cardiac injury (injury score: 0.00 ± 0.00 vs. 7.17 ± 0.75 in severe IH; p < 0.001, η² = 0.859). Conclusions: SP-D demonstrates severity-associated alterations consistent with alveolar epithelial stress during IH, though high variability limits definitive biomarker validation in this sample. Gal-3 inhibition modulates surfactant homeostasis and attenuates cardiopulmonary injury in a context-dependent manner. These findings support further investigation into SP-D as a component of multimodal severity stratification in OSA and highlight Gal-3 inhibition as a context-dependent anti-inflammatory strategy, pending validation in larger cohorts with tissue-level confirmation. Full article

Asthma is increasingly recognized as a heterogeneous syndrome where traditional management fails, particularly given spirometry’s limitations in assessing small airway dysfunction. This review synthesizes the transition from clinical phenotyping to deep molecular endotyping, establishing a framework for precision medicine. We highlight the insufficiency of absolute eosinophil counts, proposing eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) as superior activation metrics. Furthermore, we explore Type 2 drivers (IL-4/IL-13, periostin) and epithelial alarmins like TSLP. Beyond classical immunology, the text describes metabolic dysregulation, specifically asymmetric dimethylarginine (ADMA) in obese-asthma phenotypes where nitric oxide synthase uncoupling promotes oxidative stress. We also analyze YKL-40 and surfactant protein D (SP-D) as markers of remodeling and barrier permeability, alongside microRNAs—specifically miR-21—in corticosteroid resistance. We conclude that managing refractory asthma requires shifting from reactive symptom control to an integrated analysis of multi-omic biomarkers. Establishing this comprehensive molecular profile via specialized centers is fundamental for addressing current diagnostic limitations, selecting biological therapies, and modifying the disease trajectory through an endotype-driven strategy addressing inflammatory, metabolic, and structural pathologies. Full article

Idiopathic Pulmonary Fibrosis (IPF) is a severe, chronic, progressive lung disease classified within interstitial lung disorders. It predominantly affects individuals aged 50 to 70 years, with a prognosis of 3–5 years post-diagnosis. The pathophysiology of IPF is complex, involving an interplay of genetic predisposition, environmental exposures, and age-related factors. A significant genetic component is evident, with key contributions from rare variants in telomere maintenance genes (e.g., TERT and TERC) and surfactant protein genes (e.g., SFTPA and SFTPC), as well as a strong association with a common promoter variant in the MUC5B gene. The diagnosis is established through high-resolution computed tomography (HRCT) and, when necessary, histopathological analysis. The search for reliable biomarkers is a key area of research, with molecules such as KL-6, SP-A, SP-D, and MMP-7 showing potential for aiding in diagnosis, prognosis, and monitoring disease activity. While antifibrotic therapies (Pirfenidone and Nintedanib) have revolutionized management by slowing the decline in lung function, the therapeutic landscape continues to evolve. Ongoing research efforts are focused on integrating clinical, radiological, genetic, and biomarker data to facilitate early diagnosis and develop personalized treatment strategies to improve patient outcomes. Full article

Studies in human medicine have demonstrated that rotavirus infection can also affect extraintestinal sites due to its systemic effects. However, in veterinary medicine, the injury caused by rotavirus diarrhea is limited to the intestines, and its effects on various systemic structures remain poorly understood. In this observational case–control study, we aimed to determine the effects of HSP-27, Caspase-3, IL-2, γ-H2AX, HMGB-1, SP-D, and GDH (or GLDH) on the pathogenesis of rotavirus infection by using biomarkers for diagnostic purposes in lung and liver injury in neonate diarrheic calves naturally infected with rotavirus, both alive and post-mortem. Fifty-two Simmental calves (1–28 days old) of both sexes, 40 infected with rotavirus and 12 healthy, were studied. Twenty-eight out of 40 survived, while the remainder underwent necropsy for histopathological and immunopathological (HSP-27, Caspase-3, IL-2, γ-H2AX) examination of the lungs and livers. Lung and liver-specific serum E-selectin, glutamate dehydrogenase, surfactant protein-D, and high mobility group box-1 were analyzed by a bovine-specific ELISA kit (Shanghai Coon Koon Biotech Co., Ltd., China). Histopathological and immunohistochemical analyses confirmed lung and liver injury in naturally infected calves. HMGB-1, SP-D, and GDH concentrations were significantly higher in naturally infected calves than in the control group (p < 0.001, p < 0.001, and p < 0.05, respectively), showing an excellent diagnostic predictive capacity for lung and liver injury. Also, IL-2, HSP-27, CASP-3, and γ-H2AX were significantly expressed in the lungs (p < 0.001, p < 0.001, p < 0.001, and p < 0.05, respectively) and liver (p < 0.001, p < 0.001, p < 0.01, and p < 0.01, respectively). All these observations led us to hypothesize that oxidative stress, apoptosis, and DNA damage may underlie the pathogenesis of this condition. Nevertheless, further studies on large populations of rotavirus-infected calves are needed to confirm the data reported in the current study. Full article

Background and Objectives: Surfactant protein-D (SP-D) enters the circulation when the alveolo-capillary barrier is injured. We synthesised evidence on the diagnostic and prognostic performance of circulating SP-D in children with acute infectious lung disease. Methods: We searched MEDLINE, Embase and Scopus (inception–1 June 2025) for human studies reporting serum/plasma SP-D in patients <18 years with community-acquired pneumonia (CAP), viral pneumonitis or paediatric ARDS (PARDS). Two reviewers independently screened, extracted data and assessed risk of bias (ROBINS-I). Primary outcomes were discrimination of severe versus non-severe disease and prediction of hard outcomes (mechanical ventilation, PARDS and mortality). Heterogeneity in assays and outcome definitions precluded meta-analysis; a narrative synthesis was undertaken. Results: Five studies (n = 723) from emergency and PICU settings met inclusion criteria. Admission SP-D was consistently higher in severe versus mild CAP; reported AUCs ranged 0.699–0.802. Thresholds of 110–180 ng/mL yielded sensitivities of 67–85% and specificities of 45–70%. In influenza-associated respiratory failure, SP-D correlated with ventilator days (r ≈ 0.45) and ICU length of stay (r ≈ 0.44). In multicentre PARDS cohorts, each 10 ng/mL increase in SP-D was associated with higher odds of severe PARDS and death (adjusted OR 1.02 per 10 ng/mL). Overall risk of bias across studies was low-to-moderate, with one study rated serious due to sampling and adjustment limitations. Conclusions: Across pathogens and care settings, elevated circulating SP-D correlates with radiographic consolidation, evolving PARDS and worse short-term outcomes. Although assay standardisation and external validation are needed, current evidence supports incorporating SP-D into multiparametric, age-aware risk-stratification algorithms for childhood pneumonia and viral lung injury. Full article

It is well known that environmental factors influence the risk of type 2 diabetes mellitus (T2DM). Several studies have linked the xenobiotics present in tobacco or air pollutants to T2DM development, although the underlying mechanisms remain unclear. Surfactant protein D (SP-D), an immune component released into the bloodstream after lung injury, has been associated with metabolic diseases. The aim of this study was to investigate whether SP-D mediates the effects of smoking or air pollution exposure on T2DM risk in the Spanish adult population. Socio-demographic, lifestyle (including smoking status) and clinical data from 2155 participants from the Di@bet.es cohort were analyzed. Annual concentrations of PM₁₀, PM_2.5, SO₂, CO and NO₂ according to participants’ residential address codes were used to study air pollution exposure. T2DM was diagnosed at baseline and after 7.5 years of follow-up. SP-D serum levels were measured by ELISA and categorized as above or below the 25th percentile. Our results revealed a higher percentage of smokers in the high SP-D category; however, no associations were observed between air pollutants (PM₁₀, PM_2.5, SO₂, CO) and SP-D categories. Both smoking and elevated SP-D levels were found to increase the risk of T2DM independently. Mediation analysis indicated that SP-D mediates 14% of the effect of smoking on T2DM incidence in the Spanish adult population. Full article

Sophorolipids (SLs) constitute a group of unique biosurfactants in light of their unique properties, among which their physicochemical characteristics and antimicrobial activity stand out. SLs can exist mainly in acidic and lactonic forms, both of which display inhibitory activity. This study explores the interaction of non-acetylated acidic SL with bovine serum albumin (BSA). SL significantly enhances BSA’s thermal stability, increasing its midpoint unfolding temperature from 61.9 °C to approximately 76.0 °C and ΔH from 727 to 1054 kJ mol⁻¹ at high concentrations, indicating cooperative binding. Fourier-Transform Infrared Spectroscopy (FTIR) analysis confirms SL’s protective effect against thermal unfolding, enabling BSA to maintain its helical structure at 70 °C, distinguishing it from other surfactants that cause denaturation. Furthermore, SL fundamentally alters the sequence of thermal unfolding events; β-aggregation precedes helical domain unfolding, suggesting protective binding to BSA’s helical regions. Computational docking reveals high-affinity binding (Kd = 14.5 μM). Uniquely, SL binds between BSA domains IB and IIIA, establishing hydrophobic interactions, salt bridges, and hydrogen bonds, thus stabilizing the protein’s 3D structure. This distinct binding site is attributed to SL’s amphipathic character. This work deepens the understanding of the molecular characteristics of SL–protein interactions and contributes to improving the general knowledge of this outstanding biosurfactant. Full article

Intracerebral hemorrhage (ICH) remains the least treatable form of stroke, with inflammation implicated as a major pathophysiological feature. Hence, this study sought to associate serum proteins and hormones associated with inflammation and ICH outcomes. Patients presenting to Duke University Hospital with computed tomography-verified spontaneous, supratentorial, non-traumatic ICH within 24 h of symptom onset were prospectively recruited. In this pilot study, equal numbers of men and women and Black and White individuals were included and matched by a 6-month modified Rankin Score (mRS). The primary analyses were the correlation of L-ratios (LR; Log2(Day 2/Day 1 concentrations)) of serum gonadal hormones and neuroinflammatory proteins with mRS > 3 at 6 months. A total of 40 participants were included in this pilot study. LRs were significantly higher for C-reactive protein (CRP; p = 0.013) and lower for interleukin-6 (IL-6; p = 0.026) and surfactant protein-D (p = 0.036) in participants with unfavorable outcomes at 6 months after ICH. Further, higher CRP (p = 0.02) and lower IL-6 (p = 0.035) and surfactant protein-D (p = 0.041) LRs were associated with mRS > 3 at 6 months after ICH in multiple logistic regression analyses, adjusted for race and sex. The relationship amongst gonadal hormones, neuroinflammatory proteins, and ICH outcome is complex. In this pilot study, unfavorable outcomes after ICH may have been associated with selected inflammatory biomarkers. A larger scale study is warranted to define interactions between hormones, proteins, and their effects on ICH outcomes. Full article

Background/Objectives: Severe COVID-19 pneumonia damages alveolar type II cells and disrupts surfactant homeostasis, contributing to acute respiratory distress syndrome (ARDS). Surfactant proteins (SP-A, SP-B, SP-C, SP-D) are critical for reducing alveolar surface tension and for innate immune defense. We aimed to evaluate whether surfactant protein gene expression varies with the severity of COVID-19. Methods: Peripheral blood was collected from 122 adults with confirmed COVID-19, categorized as asymptomatic (no symptoms), mild (requiring hospitalization), or severe (requiring ICU admission). We quantified mRNA expression of surfactant protein genes (SFTPA1, SFTPA2, SFTPB, SFTPC, SFTPD) in blood cells using RT-qPCR. Relative expression was normalized to GAPDH and compared among the groups using the 2^−ΔΔCt method. Outliers (Ct values > 3 SD from the mean) were excluded before analysis. Results: Distinct surfactant gene expression patterns were markedly associated with disease severity. Transcripts of SFTPB and SFTPC decreased with increasing severity of the disease. Notably, SFTPC expression was ~49-fold higher in mild cases compared to asymptomatic COVID-19-positive patients (p < 0.0001), but then decreased by ~54-fold in severe cases relative to mild (p < 0.0001), returning to near-baseline levels. In contrast, SFTPA2 and SFTPD were dramatically upregulated in severe cases. SFTPA2 was ~50-fold higher in severe versus mild cases (p < 0.0001), and SFTPD was ~4346-fold higher in severe versus asymptomatic cases (p < 0.0001; ~9.6-fold higher than in mild). SFTPA1 showed only a modest ~1.4-fold decrease in severe cases (vs. mild). All noted differences remained statistically significant after outlier exclusion. Conclusions: COVID-19 severity is correlated with profound changes in surfactant gene expression in blood. Critically ill patients exhibit loss of key surfactant components (SP-B and SP-C transcripts) alongside an excessive SP-D response. These preliminary findings suggest an imbalance that may contribute to lung injury in severe disease. However, further validation is needed to establish surfactant proteins, such as SP-D, as biomarkers of COVID-19 severity. Full article

It is becoming evident that the therapeutic effect of reawakening the immune response is to limit tumor cell growth and expansion. The use of immune checkpoint inhibitors, like blocking antibodies against programmed cell death receptor (PD) 1 and/or cytotoxic T lymphocyte antigen (CTLA) 4 alone or in combination with other drugs, has led to unexpected positive results in some tumors but not all. Several other molecules inhibiting lymphocyte antitumor effector subsets have been discovered in the last 30 years. Herein, we focus on the leukocyte-associated immunoglobulin (Ig)-like receptor 1 (LAIR1/CD305). LAIR1 represents a typical immunoregulatory molecule expressed on almost all leukocytes, unlike other regulatory receptors expressed on discrete leukocyte subsets. It bears two immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in the intracytoplasmic protein domain involved in the downregulation of signals mediated by activating receptors. LAIR1 binds to several ligands, such as collagen I and III, complement component 1Q, surfactant protein D, adiponectin, and repetitive interspersed families of polypeptides expressed by erythrocytes infected with Plasmodium malariae. This would suggest LAIR1 involvement in several cell-to-cell interactions and possibly in metabolic regulation. The presence of both cellular and soluble forms of LAIR would indicate a fine regulation of the immunoregulatory activity, as happens for the soluble/exosome-associated forms of PD1 and CTLA4 molecules. As a consequence, LAIR1 appears to play a role in some autoimmune diseases and the immune response against tumor cells. The finding of LAIR1 expression on hematological malignancies, but also on some solid tumors, could open a rationale for the targeting of this molecule to treat neoplasia, either alone or in combination with other therapeutic options. Full article

An experimental model of acute pulmonary damage was developed based on the intravenous injection of the phospholipase A₂ (PLA₂)-rich venom of Pseudechis papuanus (Papuan black snake) in mice. Venom caused pulmonary edema, with the accumulation of a protein-rich exudate, as observed histologically and by analysis of bronchoalveolar lavage fluid (BALF). In parallel, venom induced an increase in all of the pulmonary mechanical parameters evaluated, without causing major effects in terms of tracheal and bronchial reactivity. These effects were abrogated by incubating the venom with the PLA₂ inhibitor varespladib, indicating that this hydrolytic enzyme is responsible for these alterations. The venom was cytotoxic to endothelial cells in culture, hydrolyzed phospholipids of a pulmonary surfactant, and reduced the activity of angiotensin-converting enzyme in the lungs. The pretreatment of mice with the nitric oxide synthase inhibitor L-NAME reduced the protein concentration in the BALF, whereas no effect was observed when mice were pretreated with inhibitors of cyclooxygenase (COX), tumor necrosis factor-α (TNF-α), bradykinin, or neutrophils. Based on these findings, it is proposed that the rapid pathological effect of this venom in the lungs is mediated by (a) the direct cytotoxicity of venom PLA₂ on cells of the capillary–alveolar barrier, (b) the degradation of surfactant factor by PLA₂, (c) the deleterious action of nitric oxide in pulmonary tissue, and (d) the cytotoxic action of free hemoglobin that accumulates in the lungs as a consequence of venom-induced intravascular hemolysis. Our findings offer clues on the mechanisms of pathophysiological alterations induced by PLA₂s in a variety of pulmonary diseases, including acute respiratory distress syndrome (ARDS). Full article

Background/Objectives: The usefulness of presepsin, which is released from macrophages, in acute exacerbation of interstitial lung diseases (AE-ILDs) is unknown. We aimed to investigate the utility of monitoring presepsin with other AE-ILD markers before and after steroid pulse therapy in AE-ILDs. Methods: This pilot single-center retrospective observational study involved 16 patients with AE-ILDs, including the AE of idiopathic pulmonary fibrosis and idiopathic nonspecific interstitial pneumonia and rapidly progressive connective tissue disease-associated ILD. Patients who survived 90 days were assigned to the survival group (n = 9). The remaining patients were classified in the non-survivor group (n = 7). To evaluate the therapeutic efficacy of steroid pulse therapy, specific serum markers were selected—presepsin, as a novel AE-ILD marker, and surfactant protein D, C-reactive protein, and lactate dehydrogenase (LDH), as classical AE-ILD markers. Results: Thirteen out of sixteen patients with AE-ILDs showed high presepsin levels (presepsin ≥ 470 pg/mL) before steroid pulse therapy. The post-/pre-presepsin ratio and the post-/pre-LDH ratio, calculated by dividing the presepsin and LDH levels after therapy by the levels before therapy, respectively, showed a positive correlation (r = 0.579, p = 0.021). As a result of this correlation, the post-/pre-presepsin–LDH index was created, obtained from the “post-/pre-presepsin ratio” multiplied by the “post-/pre-LDH ratio”. In a receiver operating characteristic curve analysis for non-survival, the post-/pre-presepsin–LDH index showed good discrimination as a prognostic marker for a poor outcome (AUC: 0.873, 95% confidence interval: 0.655–0.999). Conclusions: Tracking presepsin and LDH simultaneously may be useful for determining treatment response to steroid pulse therapy in the clinical management of AE-ILDs. Full article