Table 1.
Demographic and clinical characteristics, hospitalization course, and acute-phase therapies in LC (n = 24), PC (n = 40) and pmC (n = 12) cohorts at baseline (T0). Group comparisons were performed using Chi-square, Kruskal–Wallis tests, Mann Whitney-U and Fisher`s exact test.
Table 2.
Symptom burden in LC (n = 24) and PC (n = 40) participants assessed at the beginning of rehabilitation (T0). Group comparisons were performed using the Chi-square and Wilson test.
Table 3.
Pulmonary function parameters and functional exercise capacity in LC (n = 24) and PC (n = 40) participants at baseline (T0). Group comparisons were performed using the Mann-Whitney U test.
Fig 1.
Lung function parameters and standard laboratory parameters at T0 comparing LC and PC participants.
At the timepoint T0 lung function examination and routine lab was performed in LC and PC participants and depicted in box plots including p-value. The box plots show the median including Q1 and Q3 (A) partial pressure of oxygen (pO2) measured in capillary blood from the ear. Normal value at 1500m: > 60mmHg (B) Vital capacity of the lung (VC) measured by body plethysmography. Normal value >80% of population-specific target value (measured by age, sex, height and weight). (C) 6-minute walk test (6MWT) carried out on the level at 1500m. Normal value >80% of the population-specific target value (D) Diffusing capacity of the lung for carbon monoxide (DLCO) was measured by standard diffusion testing. The corresponding reference values were calculated using established prediction equations, which account for demographic and anthropometric variables including age, sex, height, and weight. Normal values were defined as >80% of the population-specific predicted value derived from these equations [25] (E) Leukocytes in the unit G/l (109/L). Normal value 4–10 x109/ L. A complete blood count was performed. (F) Interleukin-6 (IL-6) in the unit ng/L. Normal value <2,0 ng/L. Laboratory chemistry did not allow analysis of values below 2.0ng/L. A result <2.0ng/L was entered as 2.0ng/L. (G) D-dimers in the unit µg/L. Normal value <500 µg/L. (H) Lactate dehydrogenase (LDH) in the unit U/L. Normal value < 232U/L. Statistical test: Mann-Whitney U test.
Table 4.
Laboratory assessment of inflammatory markers, coagulation parameters, and cardiac biomarkers in LC (n = 24) and PC (n = 40) participants at baseline (T0). Group comparisons were performed using the Mann-Whitney U test.
Fig 2.
Heatmap of OLINK proteins (inflammation panel and immune response panel) in LC, PC and pmC participants.
(A) Depicted is an unsupervised clustering of OLINK proteins in 3 groups. Forming a group of only PC participants (right), a group of mixed LC and PC participants (middle) and a group of pmC and LC participants (left). (B) Volcano plot with upregulated OLINK proteins of the groups LC and PC. (C) Principal component analysis of the three groups LC, PC and pmC. (D) Venn diagram of the upregulated OLINK proteins in the LC and PC groups. The diagram shows the number of upregulated OLINK proteins in the respective groups. In the LC group 31 proteins are upregulated, in the PC group 102. 30 of them are upregulated in both groups.
Fig 3.
OLINK proteins with a regulatory function in inflammation, comparing LC, PC and pmC participants at timepoint T0.
Depicted are boxplots representing three different participant groups. Each boxplot illustrates the median as well as the first (Q1) and third quartiles (Q3). Statistical significance between groups is indicated by asterisks (* p < 0.05; ** p < 0.01; *** p < 0.001). The y-axis displays NPX (Normalized Protein Expression) values on a log2 scale, representing relative protein abundance. (A) Chemokine ligand 1 + 5 (CXCL1 and CXCL5), both proteins in the pathway of attraction of neutrophils (B) Colony stimulating factor 1 (CSF-1) and Monocyte Chemoattractant Protein 1 (MCP-1) are both important proteins in recruiting of macrophages (C) Interleukin 5, 10 and Interleukin 10 receptor subunit beta (IL-5, IL-10, IL-10 RB) are chemokins in type 2 Inflammation (D) Interferon regulatory factor 9 (IRF-9) plays a role in the antiviral response (E) Interleukin 6 + 8 (IL-6 IL-8) play a role in acute Inflammation (F) Interleukin 17 A + C (IL17A, IL17C) are cytokins in type 3 inflammation (G) Interleukin 7 and Interleukin 15 receptor subunit alpha (IL7, IL15RA) play a role in T- and B-cell activation.
Fig 4.
Parameters to distinguish PC from LC.
(A) To distinguish PC from LC participants a machine learning algorithm was applied. The 10 most important parameters out of all 184 OLINK parameters and their respective significance are shown in the bar chart. (B) The three most important parameters from the machine learning algorithm - LAMP3 (Lysosome-associated membrane glycoprotein 3), KRT19 (Keratin 19), and CKAP4 (Cytoskeleton-associated protein 4) – are depicted as boxplots for the three groups PC, LC, and pmC. Boxplots display the median, first (Q1) and third quartiles (Q3). The y-axis shows NPX (Normalized Protein Expression) values on a log2 scale, indicating relative protein abundance. Statistical significance is indicated by asterisks (* p < 0.05; ** p < 0.01; *** p < 0.001).
Fig 5.
Relationship between diffusion capacity and OLINK proteins.
An analysis of clinical parameters, routine laboratory data, and OLINK proteins at timepoint T0 revealed a consistent relationship between reduced diffusion capacity and the upregulation of several OLINK proteins. (A) Heatmap of selected OLINK proteins grouped into three distinct clusters. The top annotation indicates the respective category of diffusing capacity of the lung for carbon monoxide (DLCO), which was measured as a percentage of the predicted value [25]. Patients were stratified into four DLCO groups: normal (>80%), mildly reduced (60–80%), moderately reduced (40–60%), and severely reduced (<40%) (B) Boxplots of OLINK proteins showing levels proportional to the severity of diffusion impairment: cluster of differentiation 83 (CD83); cytoskeleton-associated protein 4 (CKAP4); interleukin-10 receptor subunit beta (IL-10RB); interleukin-15 receptor subunit alpha (IL-15RA); integrin beta 6 (ITGB6); and transcription factor AP-1 (JUN). (C) Six linear regression plots with the according Pearson correlation coefficient illustrating the negative association between DLCO values and the expression levels of selected OLINK proteins from panel (B): CD83, CKAP4, IL-10RB, IL-15RA, ITGB6, and JUN. (D) Boxplots of additional OLINK proteins associated with reduced diffusion capacity: matrix metalloproteinase-1 (MMP-1); keratin 19 (KRT19); and colony stimulating factor 1 (CSF-1).