TeachableMedicalNews article 07262020

Teachable moment in classrooms:

  1. chemical basis of life chapter – protein structure determines biological activity
  2. cellular basis of life chapter – concept of receptor proteins in cell membranes
  3. tissue chapter – locations of smooth muscle
  4. immune system chapter – cytokines as stimulators of immune functions
  5. cardiovascular system chapter – white blood cell types in circulating blood
  6. respiratory system chapter – dilation and constriction of bronchioles

The news item:  Recently a new form of asthma treatment was in the news:

‘Life-changing’ asthma injection will be offered to patients

Around 100,000 patients in the UK whose symptoms are too bad for traditional inhalers or steroids will be eligible for treatment with benralizumab.

The article mentions the disorder eosinophilic asthma, that it is caused by too many white blood cells in the lungs, and that this asthma limits what sufferers may do in their day to day lives.

So, Why Do I Care??  Asthma is a respiratory disorder that afflicts 2.5 million people in the USA. In the age group of 35-50 year olds the eosinophilic asthma is the most frequent. Inhaled pharmaceuticals, common for asthma treatment, come with undesirable side effects after long-term use.  Attacking asthma from a different angle provide a new way to treat patients, and it may help people where inhaled asthma treatments fail.

Plain English, Please!!! First, let’s talk about asthma. While asthma may be started by different conditions, like allergies, cold temperature, the root cause of asthma is always the unwanted restriction of airflow into the lungs.  An important part of our respiratory system is made up of tubes that channel air deep into our lungs, to the air sacks. A set of those tubes, the bronchioles, are 1/20 of an inch in diameter, and they have the ability to narrow and restrict airflow, because the bronchioles have smooth muscle in their walls. When those smooth muscles contract, the narrowed bronchiole restricts airflow to the air sacks.

Second, let’s talk about the meaning of “eosinophilic”. Eosinophil is a type of white blood cell that circulate in our blood stream.  In many asthma patients these eosinophils have increased numbers, and they accumulate around bronchioles. Eosinophils release molecules that make the smooth muscles of bronchioles to contract, thus, narrowing the bronchiole and restricting airflow, causing the eosinophilic asthma.

Third, let’s talk about the way this new treatment works. The increase in the number of the eosinophils, and their accumulation around bronchioles are happening because eosinophils are instructed to do that. The molecule that instructs eosinophils is called IL-5 (interleukin 5). The delivery of instruction is like when a wide receiver catches the football in the end zone.  The football is IL-5, and the eosinophil end zone needs to have a receptor (the wide receiver) that grabs onto IL-5. Once that catch happens, the instruction is delivered to the eosinophil.  The drug Fasenra, and some others, acts like a cornerback who blocks the reception of the football. Fasenra blocks the action of the IL-5 receptor, so the instruction is not delivered, so the eosinophils do not multiply and they do not accumulate near bronchioles.

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