Primary Intestinal Lymphangiectasia (Waldmann Disease): Mechanobiological Flow-Shear Decompensation as an Active Driver of Lacteal Failure

Primary intestinal lymphangiectasia (PIL, Waldmann disease) has traditionally been conceptualized as a static, congenital vascular dysplasia characterized by permanently dilated mucosal and submucosal lacteals that passively extravasate chyle into the gastrointestinal lumen. This continuous leakage produces severe protein-losing enteropathy (PLE), profound hypoalbuminemia, systemic hypogammaglobulinemia, and absolute enteric lymphopenia. Because established etiology views the condition as an immutable developmental lesion, standard management remains largely palliative, relying on strict dietary restriction of long-chain triglycerides supplemented with medium-chain triglycerides (MCTs) to reduce lymph volume. Here, we articulate the Mechanobiological Flow-Shear Decompensation Theory, reframing Waldmann disease not as a static malformation, but as an active, acquired mechanotransductive failure of intestinal lymphatic endothelial cells (LECs). In this model, subclinical genetic, epigenetic, or molecular junctional vulnerabilities leave mucosal lacteals unable to adapt to postprandial fluid-shear stress and cyclic circumferential wall strain. Rather than triggering protective cytoskeletal reinforcement, lipid-rich chylomicron transit induces anomalous hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) cascade via mechanosensory transducers such as PIEZO1. This maladaptive kinase signaling drives uncoordinated endothelial hyperplasia, destabilizes specialized endothelial button junctions, accelerates progressive vessel ectasia, and exponentially increases circumferential tensile wall stress (Laplace hoop stress). Terminal barrier breakdown and PLE result from flow-induced mechanical micro-ruptures of the attenuated lacteal wall, compounded by downstream inflow-outflow resistance mismatches. This mechanobiological framework resolves key clinical paradoxes, including the immediate reversibility of leakage upon MCT-induced hydrostatic unloading, the curative efficacy of targeted lymphatic embolization and lymphaticovenous anastomosis, the therapeutic restoration of mucosal integrity by mTOR inhibitors (sirolimus, everolimus), and the arrest of enteric leakage by antifibrinolytic matrix stabilization (tranexamic acid). Finally, we provide a translational validation platform encompassing biomimetic enterocyte-stromal-LEC co-culture microfluidic chips, lymphatic-specific inducible transgenic murine models, and dynamic contrast-enhanced magnetic resonance lymphangiography (DCE-MRL) coupled with spatial transcriptomics.