Fig 1: Different molecular hallmarks between cerebrospinal fluid (CSF) cells and peripheral blood leukocytes (PBLs) in sepsis-developed bacterial meningitis (BM). (A) Composite dot plots showing the total cell count (TCC) values and corresponding BM disease durations of 37 CSF samples (upper) and autologous PBLs (lower). Each point represents a CSF sample or PBL sample, and its TCC value is reflected on the y-axis, while the corresponding BM onset duration is reflected on the x-axis. The BM stages of each point are marked with different colors. (B) Bar chart demonstrating the cases of PBL samples in SB1 (brown color) and SB2 (blue–gray color) conditions, while their corresponding CSF samples are in S1–S5 and S6–S9 stages. (C) Volcano plots showing the differentially expressed genes (DEGs) of the pairwise bulk transcriptomic comparison between CSF cells in BM-S1 stage and PBLs in sepsis-SB1 stage (left), CSF cells in BM-S3 stage and PBLs in sepsis-SB1 stage (middle), and CSF cells in BM-S7 stage and PBLs in sepsis-SB2 stage (right). The x-axis shows log twofold change (log2FC) values, and the y-axis shows negative log10 adjusted p-values (padj). Each gene is represented by a single spot. Significantly downregulated (log2FC <-1 and padj <0.05) and upregulated (log2FC >1 and padj <0.05) DEGs are represented by blue and red spots, respectively. The thresholds of log2FC and padj are plotted with dashed lines. The names of downregulated and upregulated genes with top padj values are listed next to the corresponding spots. The background colors of the gene names represent the featured CSF cell types that highly express the corresponding genes. (D) Bar charts showing the terms of Gene Ontology [GO; “biological process” (BP) aspect] enrichments targeting the “G1-” and “G1+” (upper), “G2-” and “G2+” (middle), and “G3-” and “G3+” (lower) DEGs. Shades of red indicate the log P-value of each GO term from low to high (the more significant the P-value is, the redder the color) (scaled). Bar lengths indicate the number of genes enriched for each GO term. (E) Dot histograms showing the relative mRNA expression of TREM2 (left) and SLCO2B1 (right) in autologous CSF cells and PBLs by RT-qPCR. Each red spot or blue diamond point represents the gene expression in a PBL or CSF cell sample, respectively. (F) Combined dot histogram (left) and pseudocolor images (right) show the proportions of MФs in mononuclear (MN) cells of CSF and PBL samples. MФs are represented by the cell subset with VSIG4-positive (VSIG4+) expression within MNs. In the dot histogram, each red spot and yellow-green square point represents the proportion of the VSIG4+ cell subset in MNs of a PBL and CSF sample, respectively. Representative VSIG4 expressions in MNs of CSF and PBL samples are shown in pseudocolor images. The ratio of cell number in the Q3 (VSIG4+) and Q4 (VSIG4-) quadrants demonstrates the proportion of MФs in MNs. (G) Dot histogram showing the osteopontin (OPN) (encoded by SPP1) levels in CSF supernatants and blood plasmas. Each red spot or each blue square point represents the OPN level in the supernatant of a CSF sample or plasma of a blood sample, respectively. *t-test; Δ, chi-square test; p < 0.05.