Question explored with the scientific record
Conversation so far
- 1 Discuss the implications of 250x fold elevations of spike protein detectable in a patient's exosomes, with zero spike detectable in plasma or immune cells + a private exchange
- 2 Maugeri et al 2019 note that transcytosis is consistent with their findings on mRNA-LNP delivery. Is this transfection, rather than transcytosis? + a private exchange
- 3 How do later studies explain mRNA-LNP crossing the BBB? + a private exchange
- 4 You stated earlier that, "Transcytosis would mean the intact LNP crosses the BBB and then transfects brain cells (neurons, astrocytes, microglia) on the other side. Transfection of the BBB means the LNP is taken up by the endothelial cells that line the brain's blood vessels, the mRNA is translated inside those cells, and the protein product is what gets released into the brain." Following up -"what exact evidence do they use to rule out intact LNP transcytosis and why does it matter? + a private exchange
- 5 Either way, in this patient's case 2P S can be delivered across the BBB, by process of transcytosis at least. Explain the likely effects of such a process + a private exchange
- 6 Tell me about the likely implications for disease-injury processes once 2P spike has been transcytosed across the BBB. + a private exchange
- 7 Which specific injury mechanisms are most likely after BBB crossing? + a private exchange
- 8 to what extent are these pathways consistent with neuro-inflammation and, in effect, autoimmune encephalitic processes? + a private exchange
- 9 How do these mechanisms differ between infection-related encephalitis and autoimmune? + a private exchange
- 10 Please share more about The 2025 PANS/PANDAS review - with references - that shows autoantibodies to striatal cholinergic interneurons, Th17-driven BBB disruption, and microglial activation. What were the symptoms specificially associated with such striatal cholinergic interneurons + a private exchange
- 11 How do infection-related encephalitis mechanisms compare to BBB/Th17 autoimmunity? + a private exchange
- 12 To what extent can these Th17-autoantibody mechanisms be characterised as T and B cell mediated humoral autoimmunity + a private exchange
- 13 What evidence would distinguish humoral autoimmunity from innate Th17?
- 14 You state, "if a patient has humoral autoimmunity, with high titres of serum autoantibodies against known self-antigens." Such as what?
- 15 Hmm. This process described above is more likely to present with humoral autoimmunity that is ANA and ENA negative ie not nuclear autoimmunity.
- 16 But, as established before, such patients have no N in exosomes. It is not WT, but 2P spike in play.
- 17 What studies compare 2P spike vs wild-type spike in exosome loading?
Answered on this page ↓
What studies compare 2P spike vs wild-type spike in exosome loading?
The short version: no study in this retrieval directly compares 2P spike versus wild-type spike for exosome loading, but the mechanism predicts more loading of 2P.
The evidence you gave me contains no study that loads both spike forms into exosomes and measures the difference. That comparison was never run in the papers retrieved. What the evidence does show is that spike protein from natural infection is actively packaged into exosomes [1], and that the 2P mutation was engineered specifically to make the spike more stable and resistant to conformational change [22]. A protein that resists unfolding and proteolysis will persist longer in the cell, giving the exosome sorting machinery more time to load it into vesicles. That is a prediction from first principles, not a measured result.
The 2P construct has two proline substitutions at positions 986 and 987 that lock the prefusion trimer. Proline is a rigid amino acid that reduces backbone flexibility. The same structural stabilization that makes the 2P spike a better vaccine antigen also makes it harder for cellular proteases to break down. The exosome pathway is a disposal route for proteins that evade degradation. A stabilized spike is more likely to take that route.
The closest evidence is the finding that about 90% of CD63-positive extracellular vesicles from COVID-19 patients carry viral proteins inside them [1]. That study used wild-type spike from natural infection. If the wild-type spike already loads into exosomes at high rates, a stabilized variant that resists degradation should load at least as well, and likely better. But that is inference, not measurement.
My call: no direct comparison exists in this retrieval. The mechanism predicts higher exosome loading of 2P spike than wild-type, but that prediction has not been tested. Confidence: low, because the key experiment was never done.
Sources used 2
-
Different residues in the SARS-CoV spike protein determine cleavage and activation by the host cell protease TMPRSS2
This study investigates the specific residues in the SARS-CoV spike protein that determine its cleavage and activation by the host cell protease TMPRSS2, revealing that residue R667 is essential for cleavage while R797 is critical for activation.
DOI: 10.1371/journal.pone.0179177 -
Unique Features and Collateral Immune Effects of mRNA-LNP COVID-19 Vaccines: Plausible Mechanisms of Adverse Events and Complications
A comprehensive perspective linking the broad adverse events associated with mRNA-LNP COVID-19 vaccines to intrinsic structural features of the vaccine and its lipid nanoparticle delivery system, proposing plausible mechanisms (including ribosomal translation of spike, SP secret…
DOI: 10.3390/pharmaceutics17101327