Background/Purpose: CTD is a disease with immune abnormalities which could alter normal cytokine profile. CTD-PH has a different pathogenesis from that of iPAH, and immunosuppressive therapy is effective. These facts suggest that the two PH conditions have different pathologies related to pulmonary artery inflammation. Various cytokine abnormalities have also been reported to be involved in the pathogenesis of CTD-PH. However, the relationship between these cytokine abnormalities and pulmonary artery pressure has not been fully elucidated.

To clarify the relationship between cytokines and mean pulmonary artery pressure by analysis of the cytokine profile in PH patients including CTD-PH. In addition, we will clarify the differences in cytokine profiles between CTD-PH and iPAH.

Methods: Patients who underwent RHC for PH diagnosis at our hospital from 2015 to 2020 years were included in the study. Right heart catheterization and left heart catheterization were tried, and pre- and post-pulmonary sera were collected to measure cytokines. The target cytokines were TIMP-1, MCP-1, IL-17 and IL-21, IL-12p70 and IL-6, which were measured by ELISA (ABCAM UK, Ella simple plex USA). The relationship between the measured cytokine profiles and hemodynamic parameters was compared.

Results: 21 CTD patients (SSc 12 cases, MCTD 7cases, SLE 2 cases) and 13 non-CTD patients were subjected to be analyzed cytokines in pulmonary vessels . As previously reported, there was a positive correlation between serum IL-6 level and mPAP (mean pulmonary arterial pressure) in all our patients, but not observed in CTD patients(Figure1.). Furthermore, serum TIMP-1 level showed a significant correlation with mPAP in all patients. Additionally, this correlation was observed more remarkable in CTD patients compared to non CTD patients (Figure 2.). In addition among CTD patients, serum MCP-1, IL-6, and TIMP-1 level in SSc-PH cases tend to be higher than those in those of non SSc CTD-PH. Serum IL-12p70 and IL-17 level were lower in SSc- PH compared that non SSc CTD-PH. In some CTD cases who were investigated before and after PH treatment, serum IL-17, IL-21, and TIMP-1 level were decreased along with improvement of pulmonary vascular hemodynamics.

Conclusion: The cytokine profile of pulmonary capillaries reflected hemodynamics, the significance of which was different in CTD-PH and iPAH. Measurement of IL-17, IL-21, and TIMP-1 in pulmonary vessels may be useful for diagnosis, monitoring, and evaluation of therapeutic effects in CTD-PH.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/measurement-of-timp-1-in-pulmonary-vessels-may-be-a-novel-marker-of-reflecting-mpap-in-ctd-ph/