Clinical characteristics of patients with ISR and DM
Patients who had undergone PCI with or without ISR and DM were enrolled in the study. Peripheral blood samples were collected from the patients and sent to the Clinical Laboratory for analysis. The clinical and laboratory characteristics of the patients are summarized in Table 2. We collected data for risk factor, medication, biochemical, and hematological variables, and performed comparisons among the groups. Significant differences in lipid metabolism and hematological variables like white blood cells and neutrophils were observed (Table 2), indicating that ISR and DM can trigger immune state changes.
Different clonal diversity of the BCR repertoire in patients associated with ISR and DM
The study cohort comprised 21 patients with or without ISR and DM. All of the DNA libraries were sequenced and complete BCR repertoire data were successfully obtained using an Illumina HiSeq Xten machine. On average, 5,177,449 (range: 3,839,975–8,001,683) raw Illumina sequencing reads were obtained for each sample. After performing the quality control requirements and data filtering described in the Methods section, an average of 1,799,447 (range: 2,660,587–1,303,608) unique sequence numbers were filtered out for the alignment blast. Detailed descriptions of the sequence numbers are provided in Supplementary Table 2.
BCR repertoire diversity is a key feature of the humoral immune system, and creates the potential for recognition of the wide variety of antigens. To evaluate the BCR repertoire diversity, we first analyzed the Simpson index, Shannon–Wiener index, and Chao 1 index values for amino acid sequences, and found that the diversity of amino acid sequences was higher than in − DM patients. This meant that DM affected the BCR repertoire diversity in ISR patients (Fig. 1). However, in non-DM patients, a decrease in diversity was observed in ISR patients. These results indicated that ISR and DM can both change the diversity of amino acid sequences in patients.
To learn more about the diversity, we created five sections based on the frequency of the BCR nucleotide sequences. The results showed that the number of productive unique BCR nucleotide sequences was highest in the 1–0.1% section, but had the lowest frequency in − ISR DM patients compared with the other groups (Fig. 2A and 2B). Similar results were found in − ISR DM patients for significantly higher percentages of high-frequency nucleotide sequences, regardless of being in the top 200, top 500, or top 1,000 BCR sequences (Fig. 2D and Supplementary Fig. 1). Regarding productive unique BCR nucleotide sequences, −ISR DM patients had a lower percentage compared with ISR DM or ISR − DM patients (Fig. 2C). These findings suggest that in DM patients, ISR can decrease the low frequency of BCR nucleotide sequence diversity, but increase the number of productive unique BCR nucleotide sequences. These data provide further evidence that ISR and DM can both affect the diversity of amino acid sequences in patients.
Differential V and J gene usage within groups compared with between groups
IgH genes are assembled from a large pool of variable (V), diversity (D), and joining (J) gene segments, and different V(D)J recombinations result in diversity of the BCR repertoire. In the present study, we did not find any significant differences in V gene or J gene segment usages within groups compared with between groups (Supplementary Figs. 2 and 3), with only some subdivisions of V gene segments showing differential usages (Fig. 3). In DM patients, we found that four V subdivision genes exhibited differences with and without ISR, namely IGHV1-18, IGHV1-3, IGHV2-70, and IGHV3-21 (Fig. 3A). Meanwhile, IGHV3-30 was lower in ISR − DM patients than in ISR DM patients (Fig. 3C), and a similar result was found in comparison with − ISR − DM patients (Fig. 3B). Therefore, IGHV3-30 appears to be affected by both ISR and DM, but whether it is regulated by both by ISR and DM in CAD patients requires further data.
The BCR repertoire is assembled by various numbers of V(D)J recombinations that affect the diversity. In total, 23 V/J paired gene usages differed between ISR DM and ISR − DM patients, comprising six down-regulated genes and 17 up-regulated genes (Fig. 3E). In non-DM patients, 12 V/J paired gene usages differed significantly in comparisons of patients with and without ISR (Fig. 3F). Compared with the ISR DM group, the − ISR DM and ISR − DM groups both had significantly lower gene usages in V subdivision genes and V/J paired genes. These findings reveal that ISR and DM can produce changes in V/J paired gene usages, and may have synergistic effects in CAD patients.
Next, we investigated the BCR sequences for shared sequences and determined whether sharing occurred between samples within groups. As shown in Fig. 4A, there was no significant difference in the unique clonotype overlap rates in individual groups, but an increasing trend in overlaps was observed. The − ISR − DM group had the highest clonotype overlap rate, with an average overlap rate of 0.53% detected between any two − ISR − DM patient samples, while ISR DM patients had the lowest overlap rate. Based on the section divisions described above, we analyzed the overlap rates based on the frequencies of the amino acid sequences. The results suggested that ISR and DM can change the shared amino acid sequences. We did not observe any differences in the section groups, except for the amino acid frequency between 0.1% and 0.01%. In the 0.1–0.01% section, ISR − DM patients had the highest rate among the four groups and differed significantly from the ISR DM and − ISR − DM groups (Fig. 4B). Thus, it seems that ISR can increase the shared sequence rates, while DM can reverse this effect.
We further analyzed the clonotype overlap rates among the four groups. ISR DM and ISR − DM patients shared 0.50% clonotype overlaps (range: 0.001–2.31%). A similar result was found in the other parallels (Fig. 4C). An interesting class polarization that can be observed in Fig. 4C and 4D drew our attention. We collected the higher overlap rate classes, and found differences for ISR DM versus ISR − DM and ISR DM versus − ISR DM. We also performed an analysis on the section groups described above, but found no significant difference in high or low frequencies of amino acid sequences (Fig. 4E). Nevertheless, ISR and DM can alter the diversity by changing the shared sequences, and further investigations regarding BCR specificity and activation state are warranted.