Issue #9 Primer (August - October Review)

Dear readers, as we get back into full-scale publishing for November, here’s a specially curated roundup of the important biological news that you may have missed during this period, from unfortunate food poisoning to prestigious award ceremonies.

A Patho-genic Lunch

Food catering company Yunhaiyao was convicted for food safety lapses under the Sale of Food Act and Environmental Public Health (Food Hygiene) Regulations.

This, for context, is the company behind the mass food poisoning incident at ByteDance, where 60 employees contracted stomach flu after consuming its catered food. According to the Singapore Food Agency’s inspection, more than 10 cockroaches were found on its premises, while the pathogen levels on its wok fried diced chicken exceeded acceptable levels by over 2000 times.

This incident reiterates the importance for food caterers, and on a more personal level, ourselves, to uphold rigorous food hygiene standards so as to avoid endangering others and ourselves.

Interrupted Circulation

On 17 July 2025, the White House announced that US President Donald Trump was diagnosed with chronic venous insufficiency (CVI) after his legs were observed to be swollen. This disease is caused by damaged valves in leg veins, which normally prevent backflow of blood back to the legs.

In CVI, these valves are weakened and less elastic, reducing the speed at which the blood travels up the vein back to the heart. This has the dual effect of increasing blood vein pressure (leading to venous hypertension throughout the body, which is associated with many health complications including but not limited to stroke and heart disease) and causing blood to pool in the legs, as was observed in Mr Trump. While this condition is not serious (in fact, about 1 in 20 adults have CVI, and it gets increasingly common with age), the increased blood pressure might burst tiny blood capillaries, causing the skin in that area to easily break open upon rough contact. This may lead to venous stasis ulcers, which may get infected and lead to serious medical issues.

A Nobel Update

On 6th October, the 2025 Nobel Prize in Physiology and Medicine was awarded to Dr Mary Brunkow, Dr Fred Ramsdell and Dr Shimon Sakaguchi for “for their discoveries concerning peripheral immune tolerance”. Through their research, the three scientists discovered a new class of cells, “regulatory T cells”, which prevent our immune system from attacking our own cells.

In 1969, a group of Japanese scientists made some mysterious observations. When they removed the thymus gland of newborn mice, they observed a runaway autoimmune reaction that led to widespread tissue damage and inflammation.

Around 26 years later, Dr Sakaguchi discovered that thymic lymphocytes (white blood cells) possessed a unique surface marker molecule called CD25. He observed that mice without white blood cells that express CD25 developed autoimmune conditions where its immune system attacked various organs, including its pancreas and thyroid. However, when cells that express CD25 were injected in mice, the progression of the autoimmune conditions halted.

This was useful in explaining the initial “mysterious” observations. They are now attributed to the thymus gland being the only part of the body where cells with the CD25 marker, now called regulatory T cells, are formed. Hence, its removal results in the lack of cells that express CD25, causing the autoimmune response.

While Dr Sakaguchi was working on identifying regulatory T cells, Dr Brunkow and Dr Ramsdell identified a gene, Foxp3, linked to an autoimmune disease in mice. Mice with the Foxp3 mutation, also known as scurfy mice, developed flaky skin, oversized organs, and eventually had shorter lives than healthy mice. This gene codes for a transcription factor, which regulates gene expression. In addition, its human counterpart, FOXP3, was linked to IPEX syndrome, a severe rare autoimmune disease with similar symptoms in humans.

Dr Sakaguchi synthesised both groups’ research into the finding that Foxp3 controlled regulatory T cell production. Without regulatory T cells, the mice (and the humans) developed autoimmune responses as their immune systems remained unchecked, leading to their severe symptoms. Sure enough, scurfy mice were found to lack regulatory T cells.

This groundbreaking work kickstarted the field of peripheral tolerance, where regulatory T cells suppress rogue immune cells that attack one’s own organs. With these developments, new treatments for autoimmune diseases, including Type 1 Diabetes, as well as more successful methods for transplantation are being trialled and developed.

As scientists translate this discovery into tangible life-saving treatments, we can appreciate how seemingly distant discoveries lend themselves to real applications with a noble purpose.

References:

1. https://www.straitstimes.com/singapore/courts-crime/bytedance-food-poisoning-catering-firm-convicted-after-cockroach-infestation-found-on-premises

2. https://www.biography.com/political-figures/donald-trump

3. https://my.clevelandclinic.org/health/diseases/16872-chronic-venous-insufficiency-cvi

4. https://heartcenteraz.com/conditions/peripheral-vascular/cvi

5. https://www.nobelprize.org/prizes/medicine/2025/press-release/

6. https://www.nature.com/articles/d42859-022-00048-z#:~:text=In%201995%2C%20Japanese%20scientist%20Shimon,on%20the%20body's%20immune%20system.

7. https://www.nature.com/articles/ng0101_68

8. https://www.science.org/content/article/medicine-nobel-researchers-who-studied-how-body-polices-immune-system

9. https://www.sciencedirect.com/science/article/abs/pii/S1567576924012451