Example of product: https://www.amazon.com/HiruCream-forte-cream-bruises-sprains/dp/B095MGYWK4/ref=asc_df_B095MGYWK4/

It seems scientifically plausible that this will help our skin barrier through a little-used mechanism -- the heparinoid in the cream can promote an important component of tight junctions. With stronger junctions, it's harder for irritants to come into contact with immune cells and promote inflammation.

My thought process:
1) Arcutis, makers of Zoryve, sponsored a study on the molecular biology of seb derm: https://www.arcutis.com/new-research-reveals-genomic-profile-of-seborrheic-dermatitis-and-answers-key-questions-on-immune-response-and-skin-barrier-dysfunction/

They found that we have upregulation of inflammation in our skin (big surprise), that specific kinds of T-cells are involved, and that we have weaker skin barriers due to downregulation of some of the tight junction proteins like claudin-1. Atopic dermatitis patients also have weakened claudin-1, especially in lesional skin, but have more claudin-4 to partly compensate. Most of our meds suppress inflammation and/or Malassezia without addressing the skin barrier, and some of them actually damage the skin barrier (like steroids -- all the more reason to avoid those). I was looking for products that reinforce the skin barrier instead. I know about MCT oil, ceramides, hyaluronic acid, pH 5.5, etc, and I have heard of but not tried taurine, but does anything upregulate the genes that make the tight junctions?

2) I found a few studies:
(a) saying that heparinoid (aka mucopolysaccharide polysulfate) and phosphy-pyroxidal (p-Pyr) boost claudin-1 in vitro in skin cells ( https://www.nature.com/articles/s41598-024-53649-1 );

(b) that mucopolysaccharide polysulfate (MPS) counteracts the tight junction-disrupting effects of steroids in a skin model (https://karger.com/spp/article/36/4/186/836855/The-Effects-of-Mucopolysaccharide-Polysulfate-on );

(c) a meta-analysis supports the conclusion that MPS helps with eczema, but the meta-analysts don't love the studies they meta-analyzed (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8738087/);

(d) heparinoid improves the skin barrier in mice ( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6663615/ );

(e) heparinoid is available as a medicine in the UK (incidentally not where I live) ( https://www.nhs.uk/medicines/heparinoid/ )

Note that heparinoid and MPS are synonyms.

3) If heparinoid / MPS can improve our skin barrier, let's look up a product that has it and is available internationally. HiruCream is an example. The active ingredient seems promising. Anyone try it?