HPV: Transitions (cont'd Henrietta)

               Often times, the connection between patient symptoms and cellular problems is difficult to either define or appreciate.  If you are in pain, the answer is Advil (or Tylenol, Motrin, YourFavoritePainRevliever, etc).  Very few people pause to ask how YFPR actually takes care of pain; they just want the discomfort gone.  Typically, the answer is quite straightforward (and I’ll explain it in another post!)  Unfortunately, some problems are multi-variable situations where you can’t easily say “This Issue” leads to “These Symptoms.”

                Interestingly, in the case of HPV infection, we are partially able to explain the relationship.  I say partially only because different experiments have shown conflicting results as to exactly what pressures will lead to faster or slower cancer growth, but they all agree how HPV sets the cell up to become cancerous.  (Scientists also use the term “transform” or “transformation” to define a cell that has changed from healthy to cancerous.)   

                So, let’s transition from clinical symptoms (covered in HPV & Personal Reasons Post) to proteins/viruses inside cells by first looking closer at stratified epithelium, which is the type of tissue that comprises a cervix.

                Figure 18.1 shows a cross-section of stratified epithelium.  It contains all different kinds of cells that are represented here as purple, white, and beige rectangles.  The very top white/beige cells are the outermost layer of the tissue and are exposed to the environment outside the body.  The lower cells are what you would find if you removed the outer layer and went deeper into the tissue.  

                Let’s ignore the green cells for right now and focus on the purple, beige and white cells to the far right.  I’m going to use this section to explain how stratified epithelium works.

  First, compare the bottom purple cells to the upper-most beige/white cells.  They look very different, yes?  This is because, while they are similar cells, they have two very different jobs.

The upper-most beige/white cells are forming a layer between the outside world and the inside body.  Their job is to protect the cells underneath.  In the course of their job, these cells will come off and be shed to the environment.  This means that the body will need to have more protective cells on hand to ensure proper protection from the outside environment.  Unfortunately, these upper-most beige/white cells cannot replicate themselves anymore.  So, how does the body ensure that it will have plenty of replacements?

The bottom purple cells (known as basal cells) serve this function.  They are actively dividing and constantly providing new cells for the epithelium.  

 Interestingly, when a basal cell replicates, it does not spit out a cell that is immediately ready to serve and protect.  The cell must be properly prepared and trained.  All the cells between the bottom purple ones and the upper-most beige/white ones are in the process of changing from an actively dividing basal cell to protective cell.  This process is called differentiation.

Think for a moment about old-school battle practices where the infantry used to line up in rows and rows of men.  The first row of men would be in battle.  They’d fire, some men would go down, and then the next row of men would move up to take their place.  Way back behind all this, the lines of men were constantly being prepared from soldiers in the camp.  Think of epithelium in the same way.  The camp serves as the basal cells and the front line of men are the upper-most beige/white cells facing the elements.  All the soldiers in between are preparing to fight.

Now let’s focus on the green cells.  What are they?

They are cells infected with HPV, my friend.  They look different because they aren’t like the cells around them.  They aren’t changing from basal cells into upper-most beige/white cells; they are completely doing their own thing.  More disturbingly, you have actively dividing cells on the surface of your cervix, meaning they aren’t protecting the cells underneath at all.  Morphologically, they look and behave so differently that if you look at the surface of a cervix containing these cells, you can visibly pick out the diseased cells.

A Pap smear removes some cervical cells and places them on a slide.  Looking under a microscope, a pathologist can see if the cells look like they normally should or not.  A colposcopy allows for a doctor to view the cervix under magnification and look for patches of cells that do not look like the others.  They spray acetic acid on the cells to enhance the differences and more easily define infected cells from healthy cells. These HPV infected cells that can be visibly seen are referred to as lesions.

HPV can only infect (“get inside,” see Spanish Influence, Part 2 post) basal cells.  The virus comes from the environment.  How does the virus get down to the basal cells if these upper-most beige/white cells are protecting them?  Just like a skinned knee, the cervix can get microabrasions.  This is depicted as the long break on the right side of Figure 18.1.  HPV can travel down the abrasion and reach the basal cells.  You may think those upper-most beige/white cells aren’t doing their job, but remember that we all get cuts and scrapes during life that sometimes get infected.  This is no different.

We are getting deeper into how an HPV infection leads to cancer.  What I’ve shown here is how a healthy epithelium works, how HPV can infect it, and how that can damage the tissue.  The cancer actually arises from these green cells that are actively dividing all over the epithelium. 

Transform: when a cell has a changed from healthy to malignant/cancerous

Differentiation: the process a cell undergoes to change from type of cell to another

Lesions: a localized abnormal or diseased spot in the body

REFERENCES

Doorbar, J. Journal of Clinical Virology (2005) 32, pgs S7 – S15

HPV & Personal Reasons (cont'd Henrietta)

                Chlamydia.  Gonorrhea.  Syphilis!  

                Every good blog post begins with some scary words.  These are mine for today.  They are all sexually transmitted diseases, but I’m sure most of you knew that already.  With those words come some very negative connotations, both about the diseases themselves and the people who are infected.  It’s unfortunate because the more open people are about their problems, the more they can help others in similar situations. 

                The human papillomavirus is also a sexually transmitted disease.  For me, it is the virus that I am most passionate about: it served as the basis for half my doctoral thesis and I was infected with a strain of the virus at age 23.

Here the facts about HPV:

More than 130 different types of human papillomaviruses (HPVs) have been identified.

30 of these 130 are mucosal HPVs that can infect the genital tract; they are broken into two groups known as high risk and low risk viruses.

Nearly 50% of the population has been or will be infected with a strain of HPV at some point in their lives; most will never know it.

Many infections cause no symptoms and are eventually cleared by our immune systems.

Low risk HPVs (ex. types 6 and 11) can cause benign cellular proliferations, also known as warts.

High risk HPVs (ex. types 16 and 18) are associated with carcinomas of the anogenital tract (ex. cervical cancer).

Cervical cancer is one of the leading causes of women’s death in developing countries.

Cervical cancer is the sixth most common cancer in women worldwide.

Condoms cannot cover every area that is infected by the virus so it is possible to infect others even when using protection.

Yearly Pap smears test the cervix for cellular transformation.  Get a Pap smear at your annual check-up.  Follow up on any abnormal results.  Please.  I beg you.  Even if you have the vaccine, get a pap smear every year.

The HPV vaccines serve as a way to boost your immune system against a few of the high and low risk viruses.  This way, your immune system is more likely to clear the infection before it has a chance to turn your cells cancerous.

                I was at work when I received a phone call from my gynecologist’s office.  “Call us back immediately” are never good words.  When I did call back, I was inundated with words like “abnormal cells,” “colposcopy,” “CIN III,” and “cancer.”    

            

                I panicked.  Closing myself in a conference room, I called my Dad, who is a family doctor.  He helped calmed me down some, but both of us were still slightly concerned upon hanging up.

                I scheduled a follow up appointment then turned to the most daunting place possible for answers: Google.

                I’d been getting Pap smears for five years.  I’m ashamed to admit it, but I had no idea why I needed a Pap smear.  It was just what was done each year at my annual check up.  The results always came back normal so it never occurred to find out what “abnormal” meant.  Google answered those questions for me quickly, I assure you.  

Cancer.  Cancer!  The word was everywhere.  Did I have cancer?  Will I get cancer?  What the hell does CIN III even mean?  Do I have a …sexually transmitted disease…?  The words were too hideous to even say out loud.  

A week later, my colposcopy confirmed that I had abnormal cells on my cervix, which needed to be removed.  One month later, they were cut away by a loop electrosurgical excision procedure (LEEP) in an operating room of Brigham and Women’s Hospital in Boston, Massachusetts.  I refused general anesthesia so I talked with my anesthesiologist during the procedure, which was headed by my excellent gynecologist and witnessed by no less than five medical students.  (The second part didn’t thrill me.)  Follow up tests confirmed she had removed all the abnormal cells and two years of Pap smears every three months followed.  At age 26, I was cleared to be back on a schedule of yearly Pap smears and I haven’t had an abnormal result since.  

Medically, I was cured.  Scientifically, I was intrigued.

When I asked to be tested for HPV immediately following the LEEP, I was told that it was unnecessary: an abnormal cervix was almost always due a high risk HPV infection so I could safely assume I had it.  This killed me.  I wanted so badly to believe that I was one of the few who had this happen without an HPV infection.  I didn’t want the stigma or pain of knowing I had an STD or that I was somehow “impure.”  Her swift and concise statement shut the door on that one little hope so I had to face it.  

I started graduate school about four months after my LEEP.  When it came time to choose an avenue of research, we were subjected to weekly meetings and discussions about different labs and their research topics.  The minute I heard one man discuss an HPV project in his lab, I was hooked.  I picked his lab immediately, asked for the HPV project, and never looked back.  I spent six years studying a single protein from human papillomavirus type 16.  I took tremendous pride in that work.

It can take up to ten years (or longer!) for an abnormal cervix to turn cancerous.  Typically, this is not a fast process (although, it can be).  Because of this, abnormal Pap smear results are broken down further to tell the patient to what degree their cervix has changed from normal (also termed “dysplasia”).  CIN stands for cervical intraepithelial neoplasia and is rated from I (mild) to III (severe).  The dysplasia can also be graded as low, high or malignant.

Lucky me: I had a high grade CIN III.  However, I was treated properly and timely.  Today, I’m a very healthy 30 year old woman.  This is why you get Pap smears.  HPV is so prevalent in our society.  It can turn your cervix into a ticking time bomb that you don’t even know is rigged until it is too late.  By the time you start to show outward symptoms (such as bleeding), you are very far along in the process and, quite possibly, have developed cancer.  This is how Henrietta Lacks first realized she had cervical cancer – her tumor bled with barely a touch according to her treating doctor.

For any more reason why women should openly discuss HPV, forget the shame of having an STD, get regular Pap smears and see their doctors annually, I highly recommend googling the story of Jade Goody.  

   

I hope this post has provided you with a background on HPV and, at the patient level, what happens with an infection.  My next post is going to dive down inside the infected cervical cells to show you, at the protein level, what HPV is doing and how that leads to clinical symptoms.  We’re going to connect the macro world with the micro world…

Pap smear – a test invented by Georgios Papanikolaou where cells are gathered from the cervix and placed on a slide for view under a microscope.

Colposcopy – a way to magnify a doctor’s view of the cervix and confirm a Pap smear result.  A small concentration of acetic acid is applied to the cervix to enhance the doctor’s view of abnormal cells.

LEEP – electricity is passed through a wire loop and used to both cut and cauterize the cervix as the area of abnormality is removed

Dysplasia – term meaning abnormal development

Neoplasia – term meaning abnormal growth or proliferation

References

de Villiers EM, Fauquet C, Broker TR, Bernard HU, Hausen Hz (2004) Classification of papillomaviruses. Virology 324: 17

Hausen Hz (1996) Papillomavirus infections - a major cause of human cancers. Biochim Biophys Acta 1288

Hausen Hz (2002) Papillomaviruses and cancer: from basic studies to clinical application. Nature Reviews Cancer 2: 342

Baseman J, Koutsky L (2005) The epidemiology of human papillomavirus infections. Journal of Clinical Virology 32(suppl1): S16 - S24

http://www.nlm.nih.gov/medlineplus/ency/article/001491.htm

Skloot, Rebecca.  “The Immortal Life of Henrietta Lacks” (2010) Crown Publishers, New York, New York.

Me, myself, and I

Henrietta's Cells

Hello!  I’m fresh back from a lovely wedding and honeymoon in the Caribbean.  We saw no pirates, but did venture by areas named “Port Royal.”  Is it wrong that I giggled a little?

                While away, I finished up a book that many have already heard of, but I knew nothing about until a few weeks ago – “The Immortal Life of Henrietta Lacks” by Rebecca Skloot.  I’m going to use this book as the setting for my next set of posts, which will pertain to cervical cancer, human papillomavirus, and laboratory tissue culture.

                Before we jump into that, I want to step back and discuss the book for those who have not read it.  Ms. Skloot picks up the reins to tell the story of a woman who died in 1951 of metastasized cervical cancer.  Her pain, treatment, and death were difficult to read about, not the least of which is because cancer is a horrible disease that steals your body, your dignity and eventually your life.  Having the details displayed before you, especially when juxtaposing cancer and medicine in the 1950s to present day, is eye-opening.  During her treatment at Johns Hopkins Hospital, a small portion of Henrietta’s cervical tumor was removed and sent to Dr. George Gey, who figured out how to make these cells divide and thrive in a laboratory setting.  Until Henrietta’s cells came along, no one had been able to successfully grow (also called “culture”) cells outside a body.  

This was a huge breakthrough.  Human bodies are composed of tissues (like liver, skin, heart, etc.) and each tissue is made up of specialized cells (see Central Dogma post).  Remember that every cell in the human body contains the exact same DNA molecule and that DNA molecule encodes for every protein the human body could ever need.  It should make sense that skin cells are expected to do different functions than heart cells so skin cells will need different proteins than heart cells.  Pretend you are cupcake baker.  You will need different ingredients than the bread baker, but the bakery kitchen will hold all the ingredients that both of you will need.  You, the cupcake baker, will take what you need from the kitchen to perform your function, while the bread baker will do the same.  Cells work very similarly.

Scientists were very interested in culturing individual tissue cells to ease and advance experimental techniques.  Imagine you want to know how the kidney will react to a certain drug.  Technically, it is possible to treat the entire animal with the drug, kill it, and then study the kidney directly, but that procedure is tedious and unnecessarily sacrifices research animals.  What if you could just have a bunch of kidney cells and see how they respond instead?  How much easier that would be?!

Until Henrietta’s cells came along, culturing tissue cells had been wildly unsuccessful.  Amazingly though, her cells grew well and allowed scientists to develop and standardize growing procedures for tissue cells, in addition to much larger advances, such as the polio vaccine.  

Ms. Skloot takes this story and places it firmly in the middle of medical ethics.  Henrietta Lacks never consented to donation of her cells to medical science, but consent was not required in the 1950s.  Neither Henrietta nor her family was ever compensated for her cells, which have proven to be exceedingly valuable and a large money maker for certain companies.  However, these companies and this business was never dreamed of at the time of her donation and none of the scientists that originally cultured her cells (such as Dr. George Gey and his assistant Mary Kubicek) received compensation, either.  These are just a few of the issues broached in this book.

Also explored within these ~300 pages are Henrietta’s descendants, their feelings on this story, their financial background, and, what I consider to be the most egregious issue, the lack and importance of scientific education among all Americans.  Hence, this is why I’m using the book as a backdrop for several posts.  

Let’s jump back to Henrietta’s cells for a moment.  Scientists are still growing these cells in cultures all over the world.  I have a few plates of them myself in an incubator at work.  We know these cells as “HeLa” for Henrietta Lacks (current cell cultures are no longer named for the human who donated them due to new laws that protect patient’s privacy).  Her cells came from her cervical cancer tumor.  These cells aren’t representing a woman’s healthy cervix; they are representing cells from a diseased cervix.  This is an important clarification.  In fact, her diseased cervix was infected with the human papillomavirus and, it is due to this infection, that her cells were able to thrive outside her body.  

Would I recommend this book?  It certainly brings up controversial topics and invites many to have knee-jerk reactions to medical science.   I think Ms. Skloot does an excellent job describing Henrietta, her life, cancer and death, as well as framing her story with explanations of 1950s Baltimore, Johns Hopkins and research on African Americans.  The second half of the book introduces you to Henrietta’s current descendants and this part isn’t nearly as thought-provoking or interesting as the first.  Her afterword is the most valuable portion of this half.  For a nice summary of current ethics, research practices and problems that face researchers, doctors, and patients, definitely read the afterword.

REFERENCES

Picture of book came from www.amazon.com

Pictures of HeLa cells came from www.atcc.com, which cells HeLa cells for $279/vial