The 'Silent Inflammation' Beyond Constipation: Rethinking CKD Through Gut Environment and Immunity

"I've been feeling a bit constipated lately..."
I often hear this concern when talking with patients who have CKD (Chronic Kidney Disease).

Last time, I discussed the latest research suggesting that the constipation medication lubiprostone might help protect the kidneys.

▶︎ Click here for the previous article

The keywords that briefly appeared in that discussion were "gut environment," "chronic inflammation," and "immunity."
As a follow-up, I would like to talk a bit more about
this topic.

When people hear CKD,
they tend to think of it as "a disease of the kidneys only."
But in reality, inside a patient's body, the gut and the immune system are gradually interacting, and inflammation that is like a "silent fire" may be smoldering.
Moreover, this inflammation
does not easily show up clearly in test results.

"Constipation"
"Feeling somewhat low on energy"
"Catching colds often lately"
"Wounds are slow to heal"

Behind these small signs,
there is often a story of the gut and immunity hidden away.

This time, I will try to keep technical terms to a minimum,
and together, let's take a look at
"the silent inflammation beyond constipation."

■ A "slight anomaly" occurring inside the gut

First, I would like to take a look "inside the gut" of a CKD patient.

Inside our intestines,
many gut bacteria live.
It is a world like a "small town"
where various bacteria live while maintaining a balance.
However, it has become clear that when one develops CKD,
the balance of this town gradually begins to collapse.

Roughly speaking,

• Bacteria that perform beneficial functions for the body decrease

• Bacteria that create the source of uremic toxins increase

• "Short-chain fatty acids (such as butyric acid)" that keep the gut wall healthy decrease

The situation gradually tilts in this direction.

There is not just one cause.
Dietary restrictions (especially a tendency toward a lack of dietary fiber),
constipation,
the effects of medication,
a decrease in physical activity...
the very lifestyle of a CKD patient can easily become a quite harsh environment for gut bacteria.

"The small town inside the gut is losing a bit of its vitality."
It might be easier to understand the gut environment of CKD if you think of it with that image.

■ The "wall" of the gut becomes loose

When the condition of the small town inside the gut collapses,
another troublesome thing happens.
That is, the "gut wall" becomes loose.

Our intestinal wall is
naturally a very excellent 'gatekeeper'.
While properly absorbing necessary nutrients into the body,
it firmly blocks bacteria and their fragments (toxins) that we do not want entering the body.

However,

• persistent constipation

• an increase in the source of uremic toxins

• lack of dietary fiber

• a decrease in short-chain fatty acids (such as butyrate)

When conditions like these overlap,
the 'gaps' in the intestinal wall can gradually widen. This is a state known as 'leaky gut'.leaky gut.'

When the gaps in the wall widen, bacterial fragments and toxins that should ideally remain only inside the intestine leak into the bloodstream little by little.
The amount is by no means large.
However, if this continues slowly every day, it remains in the body as an 'invisible spark'.

▼ Related article: We have organized more detailed information about uremic toxins.

This is also why we do not want to dismiss 'constipation' in CKD patients as just constipation.

■ 'Silent inflammation' smoldering in the body

Bacterial fragments and uremic toxins that have leaked little by little from the intestinal wall.

These travel throughout the body via the bloodstream,
causing small reactions here and there.

When the body's immune system detects that 'a foreign substance has entered!', it immediately switches on and reacts.

While this is naturally a very grateful mechanism,
if the amount leaking out continues 'a little bit at a time, all the time,' the immune switch ends up staying on.

What is happening at this time is 'chronic inflammation (microinflammation),' which is a problem in CKD.
It is not a flashy inflammation that causes a fever,
but a very 'silent' level, where, in terms of test values, the CRP is just slightly high.
But this silent inflammation, over a long period of time,

promotes the decline of kidney function

damages blood vessels, increasing the risk of heart and brain diseases

accelerates muscle loss (sarcopenia/frailty)

becomes the background for anemia and malaise

It is becoming clear that it gradually affects the entire body.

CKD is not just a 'disease of the kidneys';
in fact, there are many situations where it is better understood as a 'chronic inflammatory disease of the whole body that involves the gut, immune system, blood vessels, and muscles' to explain a patient's condition.

■ The gut, kidneys, and immune system are connected

Let's organize what we have discussed so far.

• When you have CKD, the balance of the small town inside your gut is disrupted

• The gut wall loosens, and bacterial fragments and uremic toxins gradually leak into the bloodstream

• The immune system keeps catching this, and 'silent inflammation' smolders inside the body

• That inflammation gradually affects the kidneys, blood vessels, muscles, anemia, and fatigue

When laid out like this,
it becomes clear that in the bodies of CKD patients,
the 'gut,' 'kidneys,' and 'immune system' are not separate,
but are connected by a single thread.

Why is 'lubiprostone,' which appeared in the previous article, said to potentially protect the kidneys?

It is believed that this 'gut-kidney-immune' connection is involved in the background.
Regulating constipation and caring for the gut environment is not just about 'improving bowel movements';
it is also the work of gradually reducing the embers smoldering inside the body.

■ Subtle signs of 'silent inflammation'

The tricky thing about chronic inflammation is that
it does not produce 'flashy symptoms.'
You do not get a fever,
nor does any part of you become red and swollen.

However, if you look closely,
you may find small signs appearing in your daily life.

These are all signs that tend to be dismissed as 'well, it's just my age' or 'it can't be helped because I have CKD.'
But behind that, the balance between the gut and the immune system
may be gradually breaking down.

Even in convalescent rehabilitation wards, I sometimes encounter 'patients who don't feel quite right even though their test results aren't that bad.'
At such times, if you look at the whole body, including bowel movements, diet, and how well wounds are healing, you can sometimes faintly see the shadow of 'silent inflammation.'

■ Small steps you can take starting today

When asked, 'So, what should I do?'
it does not require special medicine or tests.
What is important is the small, daily accumulation of caring for your gut and body.

• Regularly review the usage and dosage of laxatives to maintain regular bowel movements.

• Consume dietary fiber while consulting with a registered dietitian about potassium intake.

• Do not focus only on restrictions; it is equally important to ensure that protein and fluid intake are sufficient.

• Stay physically active by participating in rehabilitation to maintain muscle mass.

• Maintain a healthy oral environment through post-meal oral care.

As a pharmacist,
my role is to consider options such as laxatives, uremic toxin adsorbents, and lubiprostone in conjunction with the patient's daily life.

By quietly sharing the perspective of 'gut, inflammation, and immunity' with nurses, registered dietitians, and rehabilitation staff, the view shared by the team should broaden just a little.

■ Summary | Caring a little more about what lies 'beyond constipation'

Constipation in CKD patients is
not just simple constipation.
Deep down, there is a disruption of the gut environment, a loosening of the intestinal wall, and a smoldering 'silent inflammation'.

While this inflammation may not cause a stir in laboratory test results, it quietly affects the kidneys, blood vessels, muscles, and even vitality.

That is why I would like you to take another look at bowel habits, food intake, wound healing, and even slight lack of energy, with the perspective that they 'might be signs from the gut and immune system'.

Next time, we will reach the final installment of the gut-kidney axis series.
From the perspective of a convalescent rehabilitation ward, I plan to deliver a message that connects everything discussed so far, focusing on the theme of 'kidneys, constipation, and life after discharge'.

Thank you very much for reading until the end.

▼ Information regarding kidneys and medication is summarized here.

▼ Articles regarding kidneys for the general public are summarized here.