The Spike Protein’s Fibro-Inflammatory Loop: How the Spike Protein’s Interaction with the Endothelium May Induce Systemic Fibrosis

The Spike injures the Endothelium, which activates the immune system, which releases cytokines, which activates fibroblasts, which leads to ECM deposition, which injures the Endothelium...

This is one of my most important posts. Thank you for being with me all the years of this journey.

There are diseases that we hear about in the shadows when speaking of the Spike Protein – and its mRNA “distribution system.” Systemic Sclerosis and Thrombotic Microangiopathy being two of the more insidious ones lurking.

Systemic sclerosis (SSc) has been reported in rare cases following COVID-19 vaccination, raising concerns about potential autoimmune triggers. Herein, we describe the third documented case of diffuse SSc post-vaccination in a 22-year-old woman with no prior autoimmune history.

New-Onset of Diffuse Systemic Sclerosis Following COVID-19 Vaccination: 3rd Case Described
https://esmed.org/covid-19-vaccination-linked-to-new-onset-systemic-sclerosis/

In the setting of COVID-19 vaccines, there is still no clear understanding of the thrombosis pathophysiology, and, again, exaggerated pro-inflammatory and immune-mediated processes seem to be leading causes. Definitely, with the rise in reported cases of serious complications and increased awareness of these phenomena, we learn new theories and explanations that help us understand and manage those patients. We report the case report of two patients we managed over the last three years who presented with thrombotic microangiopathy following the COVID-19 vaccination.

Thrombotic Microangiopathy Post-COVID-19 Vaccination
https://pmc.ncbi.nlm.nih.gov/articles/PMC11180482/

The appearance of these diseases is disturbing enough, yet it is a mechanism within these two diseases that causes me a high degree of concern. They each have a parallel mechanism which can lead to fibrosis. The mechanism that ties Systemic Sclerosis and Thrombotic Microangiopathy together is something that the Spike Protein itself excels at; TGF-β–driven fibroblast activation. So, downstream fibrosis caused by Systemic Sclerosis and Thrombotic Microangiopathy can also be caused by the Spike Protein alone. The presence of either of the above mentioned diseases is not requisite for systemic fibrosis to occur if one has been exposed to the Spike Protein.

Let’s discuss how the Spike Protein can initiate a self-sustaining fibro-inflammatory loop, parallel to those induced by Systemic Sclerosis and Thrombotic Microangiopathy.

STEP 1: ENDOTHELIAL INJURY/ACTIVATION

Emerging evidence demonstrates that spike protein-mediated effects, independent of productive viral infection, disrupt endothelial homeostasis through angiotensin-converting enzyme 2 (ACE2) dysregulation, integrin engagement, altered calcium signaling, junctional protein remodeling, oxidative stress, and pro-inflammatory and pro-apoptotic pathways. This review is intentionally focused on spike (S) protein-driven mechanisms of endothelial dysfunction; pathogenic vascular effects attributed to other SARS-CoV-2 structural proteins, including the nucleocapsid (N) protein, are beyond the scope of this discussion. In this review, we synthesize current experimental and translational data detailing the molecular mechanisms by which the SARS-CoV-2 spike protein drives endothelial dysfunction across multiple organ systems and discuss potential therapeutic strategies aimed at preserving endothelial integrity in acute COVID-19 and its long-term vascular sequela.

Cellular and Molecular Mechanisms of SARS-CoV-2 Spike Protein-Induced Endothelial Dysfunction
https://pmc.ncbi.nlm.nih.gov/articles/PMC12896700/

STEP 2: IMMUNE/CYTOKINE ACTIVATION

A recent study showed that 1–5 μg/mL of S protein serves as both a pro-inflammatory and pro-thrombotic signal, stimulating human endothelial cells and monocytes through activation of NFκB and subsequent cytokine release, resulting in priming and activation of NLRP3 inflammasome and production of mature pro-inflammatory IL-1𝛽 in both cell types [83]. In parallel, IL-1𝛽 stimulates prothrombotic cascades via production of vWF and factor VIII/tissue factor without an attendant increase in antithrombotic pathways mediated by ADAMTS-13, which most potently counteracts procoagulant activity of vWF multimers. TLR4 receptors mediate these effects in monocytes, but not in endothelial cells. Several studies have investigated pathway activation that underlies changes in endothelial cell function following SARS-CoV-2 infection. Subunit 1 of the S protein (S1), which contains the receptor binding domain of ACE2, may mediate pulmonary endothelial dysfunction through mechanisms independent of ACE2 enzymatic activity and viral replication [9].

Cellular and Molecular Mechanisms of SARS-CoV-2 Spike Protein-Induced Endothelial Dysfunction
https://pmc.ncbi.nlm.nih.gov/articles/PMC12896700/

STEP 3: TGF-β Signaling and Fibroblast Activation

Here, we report that cell-intrinsic interactions between the Spike (S) glycoprotein of SARS-CoV-2 and epithelial/endothelial cells are sufficient to induce barrier dysfunction in vitro and vascular leak in vivo, independently of viral replication and the ACE2 receptor. We identify an S-triggered transcriptional response associated with extracellular matrix reorganization and TGF-β signaling. Using genetic knockouts and specific inhibitors, we demonstrate that glycosaminoglycans, integrins, and the TGF-β signaling axis are required for S-mediated barrier dysfunction. Notably, we show that SARS-CoV-2 infection caused leak in vivo, which was reduced by inhibiting integrins. Our findings offer mechanistic insight into SARS-CoV-2-triggered vascular leak, providing a starting point for development of therapies targeting COVID-19.

SARS-CoV-2 Spike triggers barrier dysfunction and vascular leak via integrins and TGF-β signaling
https://www.nature.com/articles/s41467-022-34910-5

Results: Fibroblasts from scarred areas expressed higher levels of cytoskeletal proteins (alpha-smooth muscle actin) and inflammatory mediators (interleukin 6, prostaglandin E2) upon TGF-β stimulation compared to their unscarred counterparts. Treatment with SB-431542, a TGF-β receptor inhibitor, quelled these responses (P≤.05), indicating that these effects are mediated through the TGF-β pathway. Fibroblasts isolated from scarred tissues exhibit myofibroblast morphologies, but so do fibroblasts from unscarred areas.

Conclusion: TGF-β activates myofibroblasts and exacerbates inflammation in VLS cells from scarred areas. However, fibroblasts from both scarred and unscarred areas show similarities in morphology and ECM production, suggesting molecular changes may occur in VLS skin before visible changes are detected, which could lead to new diagnostic strategies to treat disease before irreversible architectural changes occur.

TGF-β drives myofibroblast activation and inflammatory mediator production in vulvar lichen sclerosus
https://pubmed.ncbi.nlm.nih.gov/40686784/

STEP 4: ECM Deposition and Further Endothelial Damage

Fibrotic diseases are characterized by net accumulation of extracellular matrix proteins in affected organs leading to their dysfunction and ultimate failure. Myofibroblasts have been identified as the cells responsible for the progression of the fibrotic process, and they originate from several sources, including quiescent tissue fibroblasts, circulating CD34+ fibrocytes and the phenotypic conversion of various cell types into activated myofibroblasts. Several studies have demonstrated that endothelial cells can transdifferentiate into mesenchymal cells through a process termed endothelial- mesenchymal transition (EndMT) and that this can give rise to activated myofibroblasts involved in the development of fibrotic diseases. Transforming growth factor β (TGF-β) has a central role in fibrogenesis by modulating the fibroblast phenotype and function, inducing myofibroblast transdifferentiation and promoting matrix accumulation.

TGF-β-Induced Endothelial-Mesenchymal Transition in Fibrotic Diseases
https://www.mdpi.com/1422-0067/18/10/2157

STEP 5: GO BACK TO STEP 1 ADDING ECM DEPOSITION AS AN INJURING PARTY

And here’s the point. The appearance of such horrifying specters like Systemic Sclerosis and Thrombotic Microangiopathy post Spike exposure may not be necessary to inform a form of systemic fibrosis is underway. It may be happening to a more or lesser degree in all of us exposed to the Spike Protein either by virus (much less) or mRNA (much, much more). We need studies of the general population according to both infection and vaccination statuses. We need to look for markers of fibrosis. We need to examine the microvasculature to see if fibrosis is occurring in an occult way. There is so much we need to know. I hope those with laboratories are reading this and will help launch these investigations. I will continue to seek understanding and healing. This has been a tremendous amount of work. Thank you, as always, for your dialogue, readership, and support. Please have a blessed week.

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