Are antigen-presenting cells 'auto'-targeted for destruction when introduced to COVID-19 modRNA products?

An unanswered question...

I have recently had one of these classic ‘Jessica’ moments thanks to Genervter Burger in a Telegram group I am in. Thanks to Arkmedic for the Telegram group and for bringing thinkers together. Burger and I have been back-and-forthing about the fate of professional antigen-presenting cells (APCs) (monocytes/macrophages, dendritic and B cells) when transfected with the COVID-19 modified mRNA-LNP injectable products. It hasn’t been obvious to me what the exact fate would be, but I have overwhelmingly believed up to this point that the fate would ultimately be cell death either by direct CTL killing or by apoptosis. But is this the case?

There’s a distinction I would like to make here that I haven’t been clearly making: there is a big difference between CTL-mediated targeted cell death and programmed cell death induced by too much junk dumped into the cell. The question for me now is: What’s the ratio? And what’s the ratio of APCs that survive as opposed to not surviving?

Since we do see induction of immune responses (ie: the APCs are doing their jobs of activating immune effector cells), APCs must be surviving, but again, what percentage of these APCs do die - either by their own hand, or by cytotoxic T lymphocytes (CTLs)? And how long do they survive as presenters of antigens that are as toxic as spike protein appears to be? And what about the off-target proteins?

Since we don’t really know what the percentage integrity of the mRNAs injected (ie: the percentage of the complete template that is introduced to the cell), how much is dumped into the cytoplasm as per the rate-limiting endosomal release step, and how these affect different types of APCs, it’s hard for anyone to accurately say at this point what percentage of APCs will be activating immune effector cells and what percentage will be targeted for destruction of die from apoptosis.

Here’s a visual to help you imagine what a professional APC goes through.

Figure 1: mRNA in vitro transcription, innate and adaptive immunity activation. https://en.m.wikipedia.org/wiki/MRNA_vaccine

There are a few options as per fates; I see three being the most important to address for now. These might also not be mutually-exclusive.

• Activation of APC: In this scenario, the APC gets activated upon recognizing foreign antigen (ie: produced spike protein), leading to antigen processing and presentation via MHC molecules to initiate adaptive immune response. In this scenario, we get the APC ‘doing what it does’, and activating B and T cells to effect their immunological roles. It is important to remember that since the APCs are producing spike protein, this is at the metabolic expense of the cell.

Question: If the APC serves its role as an immune response inducer ‘like normal’, for how long does this go on considering the toxicity of the spike protein, not to mention the foreign genetic material?

• Apoptosis: Since the modified mRNA encodes a toxic (and potentially destabilizing) protein, apoptosis (aka: programmed cell death) is also a likely outcome for the cell. It is really important for us to acknowledge that there’s more being dumped into the cell as per genetic material than modified mRNA; there’s also DNA. If I was an APC, I wouldn’t respond well to that.

• Function alteration: Because the modified mRNA is modified in specific ways, we don’t really know the effects on the various APCs. In the face of off-target protein production due to frame-shifting, and other unknowns with regard to intracellular immunological effects, it is conceivable that the transfected APCs may exhibit altered functions to include altered antigen presentation that could result in altered immune responses. Investigations into alterations in gene expression, protein function, or other effects must be done.

I am probably a little behind in the literature on this subject matter, so if anyone is keeping up and knows of studies that elucidate some the differential effects on various human APCs following transfection, let me know!

There is this paper, published in 2021 entitled: “Tuning the Immunostimulation Properties of Cationic Lipid Nanocarriers for Nucleic Acid Delivery” that demonstrates differential activities in specific APCs based on differences in the cationic charge properties and zeta potentials of LNPs. They argue that the immunological offsets induced by the cationic LNPs can be balanced by adding more negatively-charged genetic material.

We observed that the increase of the production of pro-inflammatory secretory molecules (IL-6, TNF-α, MCP-1 and NO) was proportional to the net surface charge of the lipid nanocarriers. In parallel, metabolic parameters, including basal respiration, maximal respiration capacity, ATP production, spare respiratory capacity and proton leak, were also modulated accordingly to the charge of the lipid nanocarriers.¹

So there is some data demonstrating differential immunological and metabolic responses by APCs depending on the charge of the LNPs that transfect them. This paper evidences a high survival rate of APCs: at 20 and 100 µg/mL (low and high standard doses of LNPs), they observed higher than 80% of cell viability after 24 h of incubation with bone-marrow-derived macrophages and dendritic cells. So it seems that neither neutral (zeta potential: –16.50 ± 0.53 mV) nor cationically-charged LNPs (zeta potential range from 45.80 ± 3.8 mV down to –9.97 ± 0.94 mV) resulted in apoptosis of these cells. At least, not in the experimental time frame.

N.B.: The genetic material they used in their experiments is not the same as was used in the COVID-19 shots, and this is merely a demo of LNP (charge)-mediated survival of APCs.

Let’s backtrack and then dive into an analogy.

The modified mRNA-LNP COVID-19 shots are injected into the deltoid muscle: an intramuscular (IM) injection. We know that the LNPs systemically bio-distribute, so although they can literally end up anywhere in the body, in all likelihood, the majority of the injection material heads to the nearest (local) draining lymph node first. At least that’s how I am envisioning it for the purposes of this article. In this case, that would mean that the injection material would head to the armpit, or axillary lymph nodes. Here’s a diagram of the axillary lymph node cluster.

Figure 2: Lymphatics of the breast and the axillary glands. https://en.wikipedia.org/wiki/Axillary_lymph_nodes

And here’s a close-up of the inside of a lymph node showing dense packing of T and B cells and APCs (macrophages in this example). The APCs process and present antigen information to T and B cells. The T and B cells are seeking to be activated by encountering their specific antigens. Once they do, they become activated to proliferate and differentiate and all sorts of immunological stuff.

Figure 3: Diagram of a lymph node showing lymphocytes and APCs. https://en.wikipedia.org/wiki/Lymph_sacs

So imagine the lymph node is like a speed-dating bar. Let’s assume the men are at fixed positions at tables in the bar, and the women rotate around to ‘sample’ the men. The men would be like macrophages (note: dendritic cells and B cells are highly mobile as professional APCs), and the women would be like T and B cells checking for specifics presented by the males. Ding ding. Five minutes are up! Move to the next table! By the way, there’s no reason why I picked the men to be the macrophages, just in case anyone is wondering.

For the purposes of this analogy, I don’t want to focus on whether or not a macrophage goes home with a T cell - ie: the stuff that happens once a woman bonds with a man or a T cell interacts with an APC - I want to focus on the men themselves and how they process information for presentation to the women. This might be an exercise in futility for me since I have no idea how men think, but I’ll give it a crack and try to be as general as I can. :D

Depending on the age of the man, he’s going to have encountered oodles of information throughout his life and processed it in a number of different ways. Think of this information like discrete packages of data. Most likely, he will have tried to discover the nature of each information package and maybe even tried to elucidate their truth values. He will have done this by de-convoluting the larger information package by breaking it down into its smaller component parts. Naturally, everything is nothing but the sum of smaller parts.

At any given time, let’s say a 38-year old man will have processed quite a bit of information by breaking it down into smaller bits of information. He will carry himself as a by-product of having processed all this infinite information that he has encountered in his 38 years. If he is seeking a mate, he will probably be manifesting these bits of information in specific ways to his potential mate in order to attract her. Bits that relate to his physical appearance like clothes, hair and style, and also bits that relate to his personality like his words, posture, mannerisms, etc. There will be all sorts of stuff that he will represent that comprise all the little bits of data that he has accumulated and processed over the years. If all goes well, when the right T cell comes along, he might bond with her, if that T cell likes his hair. Or, it might not be the best fit at first, but with a little somatic hypermutation, eh? You never know! And so it goes.

Let’s say, one day our 38-year-old guy discovers a bit of information that shakes him to his core: something toxic. I’ll leave it to you to put a specific on that. I don’t want to plant seeds because it limits the imagination of the individual reader. It also makes the example more ‘available’ to the reader if I don’t plant a specific image in your head. Let’s also say, that in the process of learning the details of this toxic piece of information, he realizes that it’s even more toxic than he originally thought. Let’s even say he finds it hard to live with.

Here’s where it gets a bit dark but I have to go here because I chose this stupid analogy. We’re only really talking about about programmed cell death and T-cell-medicated death here. Moving on.

If our man is like the APC, perhaps he can’t handle the toxicity of the information package and its component bits and he decides to ‘undergo apoptosis’. There. That’s politically correct enough! It’s also possible that our dear man will wear the processed toxicity on his figurative sleeve in the bar, and when a particular woman encounters him, she might see him as a threat, and apoptose his ass herself! Is this getting too weird? LOL

In any case, the point of this analogy is to try to think about what proportion of men will be ‘normally’ processing and presenting information to women in the bar, and what proportion might be apoptosed, either by self or by a woman. What do you think?

Let’s get back to APCs. I think that most APCs will be hard-pressed to tolerate the junk that they’re introduced to in the context of the COVID-19 modified mRNA-LNP injectable products and the cargo they dump. I really do. So I tend to believe that most of them will end up targeted for destruction, one way or the other.

With respect to what is dumped into the cell, it’s important to think about the exposure to toxicity from the point of view of both type and amount of toxin. For example, if an APC gets transfected by many LNPs and subsequently gets a lot of foreign modified mRNA and DNA dumped into it, it would be more likely to self-destruct than an APC with say, a bunch of empty LNPs, or one that doesn’t get as much DNA, in my opinion. If you want to go back to our speed-dating bar analogy, it would amount to the degree of foundation-shakery of the toxic information delivered to our dear man, and the amount of it that he was presented with at once. For example, if our dear man is exposed to a lot of different toxic things all at once, he would probably not fare as well as a man who was not exposed to a lot of toxic information and perhaps not be better of. It’s an interesting thing to think in reality, and it depends on what ‘better off’ means, I guess.

So the question remains: What percentage of the APCs die either by their own hand or by CTLs?

I will leave this article as is for now. I hope it induced thought or made you laugh, or something constructive. Let me know what you think in the comments!

1. Dey Arindam K. et al. Tuning the Immunostimulation Properties of Cationic Lipid Nanocarriers for Nucleic Acid Delivery, Frontiers in Immunology. Volume 12 (2021). DOI=10.3389/fimmu.2021.722411