Interferons – they’re there to help

some human interferon looks something like this, according to someone

When I first heard of interferon (singular), I thought it was a drug, some sort of miracle drug being touted as a cure-all. I had no idea. Recently I’ve heard that it, or they, are part of our innate immune system, which is different from our adaptive immune system, though what the differences are I have no idea. Again. So, it’s learning time.

Wikipedia vastly increases my knowledge with its first sentence on interferons (duh, I wonder why people don’t use it more):

Interferons … are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.

Host cells are the cells of larger organisms (such as ourselves) that ‘host’, willingly or not, viruses and other bugs, or organelles, whatever. Signalling proteins are explained, somewhat, in the second quoted sentence.

Anyway, interferons belong to the larger class of proteins known as cytokines, which I’ve heard of in relation to the ‘cytokine storm’, a reaction or over-reaction to viruses such as SARS-Cov2, but they do more than just signal, they interfere, as the name suggests. In fact they have multiple functions, such as ‘upregulating antigen presentation’. An antigen, as I almost recall, is a molecular structure, part of a pathogen that can be bound by an antigen-specific antibody. Antigen presentation is – well it’s too complex to explain here, though I feel I need to arm myself with as much immunological knowledge as possible against the misinformation out there.

So IFNs, as they’re known, come in 3 types, alpha, beta and gamma, based on the receptors through which they signal. They form part of the innate immune system, generally speaking, but there are in fact complex interactions between the innate and adaptive immune systems which immunologists are still trying to work out. I should point out here that my first understanding of interferon was no doubt based on a breakthrough in the eighties when interferons were created in the lab to treat certain types of cancer, and later in the treatment of hepatitis, multiple sclerosis and other conditions, though many of these interferon medications have been superseded by newer treatments with fewer side-effects.

My question arose through watching a Medcram video – update 128 – ‘innate immunity, interferon and Covid-19 in children’. I’ve used these updates in the past to reduce my general ignorance of immunology, virology and the like, but I’ve not watched any for a while. So, having just perused the Wikipedia article on IFNs and finding it way too complex for my small brain, I’ll base the rest of this piece on Dr Seheult’s Medcram presentation.

So, the innate and adaptive immune systems are presented pictorially. The innate system starts with a myeloid progenitor cell. These cells are described in ScienceDirect as ‘the precursors of red blood cells, platelets, granulocytes…’ and a bunch of other cells. In the Medcram pictorial, arrows from the myeloid progenitor cell lead to five other cell types – mast cells, basophils, neutrophils, monocytes and eosinophils. Arrows from the monocytes then lead to macrophages and dendritic cells. What do these have to with IFNs? I’m trying to find out.

Mast cells are types of granulocyte, and they contain granules ‘rich in histamine [which induces inflammation] and heparin [which prevents blood clotting]’. They play an important protective role in the immune and neuroimmune systems.

Basophils are also granulocytes, and a type of white blood cell (leukocyte). They’re the rarest and largest type of granulocyte, and are an inflammatory agent.

A neutrophil is ‘a type of immune cell that is one of the first cell types to travel to the site of an infection. Neutrophils help fight infection by ingesting microorganisms and releasing enzymes that kill the microorganisms. A neutrophil is a type of white blood cell, a type of granulocyte, and a type of phagocyte’ (National Cancer Institute – USA).

Eusinophils ‘are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates’ (Wikipedia).

A monocyte is ‘a type of immune cell that is made in the bone marrow and travels through the blood to tissues in the body where it becomes a macrophage or a dendritic cell. Macrophages surround and kill microorganisms, ingest foreign material, remove dead cells, and boost immune responses. During inflammation, dendritic cells boost immune responses by showing antigens on their surface to other cells of the immune system. A monocyte is a type of white blood cell and a type of phagocyte’ (National Cancer Institute).

Now to return to the Medcram video, which tells me that the innate immune system includes macrophages and killer T cells (which are also part of the adaptive immune system). These combine to phagocytise, or ingest, viral or pathogenic material. This innate immune system is generally very strong in childhood and gets weaker with age. Interferon is a product of this innate system. Dr Seheult cites a recent article from Nature Biotechnology with the revealing title ‘Pre-activated antiviral innate immunity in the upper airways controls early SARS-Cov2 infection in children’. I’m fascinated with the idea of ‘pre-activated’ immunity here. As far as I know vaccines pre-activate immunity to viruses or pathogens by presenting the immune system with a part of that pathogen, or a protein unique to it. But with children, how is their immune system pre-activated? In any case, the article explains that ‘children displayed higher basal expression of relevant pattern recognition receptors [involving interferons] in upper airway epithelial cells, macrophages and dendritic cells, resulting in stronger innate antiviral responses upon SARS-Cov2 infection than in adults’. This finding highlights the importance of interferons and of perhaps trying to maintain their prevalence in older subjects. The article described children presenting in emergency with severe Covid19 as having an impaired IFN response, though the molecular mechanisms for this, and for the protective effects on those children with mild or no symptoms, were unknown.

So the article explains that higher levels of genes coding for RIG-1, MDA5 and LGP2 in the epithelial cells of the upper airways were found in children, but not in adults. RIG-1 is a pattern recognition receptor (PRR) of the innate immune system, responsible for type 1 interferon responses. MDA5 and LGP2 are members of the same family of PRRs. The key being more innate immune cells in that region in children, exhibiting strong antiviral action against SARS-Cov2. This is apparently what is meant by ‘pre-activated’, because these primed cells were already in the upper airways (i.e the nose) of children. However, there appears to be a narrow window of opportunity before viral reproduction, which is especially intense with SARS-Cov2, shuts down this innate immune response. The paradox, it seems here, is that SARS-Cov2’s proteins can effectively shut down interferon production, but at the same time the virus is highly sensitive to interferon. Anyway, it seems that if we can step up IFN production, assisting the body’s innate immune system, this may enable us to resist the virus (along with vaccination, effective mask wearing and physical distancing of course). One way to do this is by raising the core temperature of the body (inducing hyperthermia). At a core temp of 39 degrees celsius, the amount of IFN released from lymphocytes after mitogen stimulation (i.e inducing mitosis) increases ten-fold from just a degree or so below, at least in vitro. This may sound crazy, but the benefits of induced fever have been proven in various treatments for various infections, including viral infections, in the past, along with other ways of boosting the immune system (vitamin D, zinc and selenium) mentioned previously by Dr Seheult and other experts.

Science science science science science science. Don’t use social media to find out about SARS-Covid19 and its treatment. Never never never never. There are dozens of reputable scientific sites that will inform you, in the USA and in every other country – at least the WEIRD ones. Knowledge is power. Get informed.

References

https://en.wikipedia.org/wiki/Interferon

https://www.webmd.com/drug-medication/interferons-guide#1

Innate Immunity, Interferon, and COVID 19 in Children: Update 128 (video)

https://www.sciencedirect.com/topics/immunology-and-microbiology/myeloid-progenitor-cell

https://en.wikipedia.org/wiki/Mast_cell

https://www.healthline.com/health/basophils

https://www.cancer.gov/publications/dictionaries/cancer-terms/def/neutrophil

https://en.wikipedia.org/wiki/Eosinophil

https://www.cancer.gov/publications/dictionaries/cancer-terms/def/monocyte

https://en.wikipedia.org/wiki/RIG-I

https://en.wikipedia.org/wiki/MDA5