Integrated Cytokine and Immune Cell Profiling Reveals a Distinct Immune Signature Associated with High-Altitude Pulmonary Edema.

High-altitude pulmonary edema (HAPE) is a rapidly progressive, life-threatening disorder arising in otherwise healthy individuals upon ascent to high altitude, yet the mechanisms underlying maladaptive vascular leak remain poorly defined. Although elevated pulmonary arterial pressure and capillary stress failure are recognized as central hemodynamic drivers, accumulating evidence indicates that innate immune dysregulation is an equally critical, largely unexplored determinant of HAPE. To systematically delineate the immune and molecular programs that distinguish pathological responses to hypobaric hypoxia from acclimatization, peripheral blood along with clinical details was collected from low-altitude controls (LA-Cntrl, number of participants, (n = 19), healthy high-altitude sojourners (HA-Cntrl, n = 47), and HAPE patients (n = 90). Plasma proteomic markers were quantified using a targeted panel, while monocyte and dendritic cell subsets in peripheral blood mononuclear cells were immunophenotyped by multicolor flow cytometry. HA-Cntrl subjects displayed an anti-inflammatory profile, marked by the suppression of CXC chemokine receptor 3 axis chemokines. HAPE patients, in contrast, exhibited a pro-inflammatory, vascular injury signature, with elevated levels of inflammatory interleukins and myeloid and chemotactic factors. This inflammatory signature was accompanied by the expansion of classical monocytes, implicating a myeloid vascular program associated with HAPE.