In this episode, Neutrophil, Normal Cell and NK Cell visit the large intestine. They notice that the large intestine smells bad due to toxic gases being released by harmful bacteria. Normal Cell leaves Neutrophil and NK Cell to seek the place where the last Lactic Acid Bacterium lives. Normal Cell visits the gut epithelium, where Intestinal Epithelial Cell and Goblet Cell work desperately to keep the gut epithelium strong despite persistent attacks by harmful bacteria. Despite their efforts; though, the gut epithelium breaks, forcing the cells to run away as harmful bacteria enter through the broken epithelium.

As discussed in my introductory blog post on the gut microbiota, the gut microbiota serves a variety of functions that are essential to optimal human health. One of the main functions of the gut microbiota is to maintain the integrity of the gut epithelium. In this blog post, I will talk about how the gut epithelium serves as an important physical barrier to prevent gut contents and bacteria from entering the human body before explaining how its integrity is maintained. I will then explain how the breakdown of the gut epithelium can lead to inflammatory bowel disease (IBD).

In this episode, Lactic Acid Bacterium, washed away from Normal Cell in the last episode, is picked up and tended by Dendritic Cell. Meanwhile, Normal Cell, Neutrophil and NK Cell move to the small intestine, where they encounter Influenza Virus that mutates and becomes resistant to the immune cells’ attacks. Just as the immune cells fall into despair, the dressed-up NK Cell suddenly appears with Lactic Acid Bacterium. By consuming the biscuits produced by Lactic Acid Bacterium, Dendritic Cell is motivated to spread embarrassing photos of immune cells’ past lives, motivating the immune cells to eliminate Influenza Virus.

Influenza is an infection that I covered in a previous blog post as part of an episode in the last season of Cells at Work!. In that blog post, I talked about what the influenza virus is and how T cells are activated by dendritic cells to eliminate influenza-infected cells. This blog post builds on the previous blog post, where I first provide more information about the influenza virus itself. This will lead to the big mistake the anime makes in regards to the different ways influenza viruses can evolve. Following this, I will then explain what cytokines are and how they assist in immune responses against pathogens.

In this episode, Neutrophil is called to the stomach when Helicobacter pylori (H. pylori) invades the stomach, taking the Lactic Acid Bacteria from Cell Boy. In the stomach, H. pylori breaks down the lining of the stomach, creating rubble, and splashes gastric acid that melts the other bacteria. While the gastric acid presents a barrier for neutrophils to defeat H. pylori, it also energises one of the Lactic Acid Bacterium, allowing him to grow and beat up H. pylori. H. pylori tries to retreat, but his emergence from the gastric acid allows Neutrophil, accompanied by the Lactic Acid Bacterium, to kill him. Neutrophil realises that the bacteria he brought are good bacteria that help the human body and leaves the Lactic Acid Bacteria alone as he continues his patrol. 

H. pylori is an interesting and important pathogen that causes many gastrointestinal diseases, yet the episode did not look too much into the biology of this bacterium or the numerous problems in the stomach this bacterium produces. This blog post will describe what Helicobacter pylori (H. pylori) are and how it causes disease in the human body. I will then explain how drugs and lactic acid bacteria eradicate H. pylori from the human body, drastically reducing the risk of developing gastrointestinal diseases.  

In this episode, Mast Cell releases a lot of histamine when she detects a harmless substance near the skin. Histamine splashes on the cells, making them wet and prone to electrical shocks while white blood cells are attracted to nothing. Mast Cell tries to defend herself from the angry comments of the other cells, but after being called “hysterical”, Mast Cell goes on a rampage, vowing never to do anything again. Afterwards, dengue virus is injected from a mosquito and infects Langerhans Cell and his co-workers, where they blow the other cells away. Mast Cell stops herself from releasing histamine, fearing she will only trouble the other cells. However, on Basophil’s urging, she releases histamine which attracts the white blood cells to kill the dengue virus-infected cells, saving the other cells.

In this blog post, I will touch on both the disease dengue fever and the chemical histamine. I will talk about the dengue virus and dengue fever. I will then describe what histamine does in the body before discussing whether mast cells play a good or bad role in dengue fever.

In this episode, Neutrophil visits an infected hair root where the hair cells are enslaved by Acne Bacteria. Neutrophil saves young Hair Matrix Cell who tries to fight the Acne Bacteria, but the Acne Bacteria injure Neutrophil and throw him and Hair Matrix Cell into the pit. In the pit, Hair Matrix Cell tells the story of how the hair cells were enslaved by Acne Bacteria when a pimple was formed before showing Neutrophil the stacks of dead neutrophils. This motivates Neutrophil to eliminate the Acne Bacteria, so after coming back up, he battles against the Acne King. As Neutrophil struggles to defeat the Acne King, Hair Matrix Cell motivates the other hair cells to not give up, leading them to raise the sebum levels in an attempt to drown the Acne King. The Acne King tries to flee but moves too slowly, allowing Neutrophil to kill him. Neutrophil later re-emerges from a sebum pipe after all the Acne Bacteria are killed, to the relief of the other neutrophils and hair cells. 

Even though the episode gives a good overview of what acne is, particularly that bacteria are involved, that is only part of the story. There are many factors that contribute to the development of acne. In fact, the presence of white blood cells such as neutrophils is not only insufficient for curing acne but can also worsen acne. In this blog post, I will explain what acne is, how it develops in real life and how it can be treated.