Hello, I’m Dr. Hocheol Shin, or “Dr. Shin.” I study feline kidney health and aging at Greycoat Research.

I earned my Ph.D. studying cancer and immunology, and I’m now building on that experience to explore how we can help cats stay healthier for longer.

In “Reading Papers with Dr. Shin,” we’ll explore research related to feline health together. We’ll look a little deeper into how things work, what the studies actually found, and what those findings might mean for our cats. I’ll explain any unfamiliar terms as we go.

Ready to open today’s paper with Lulu? 

< Three-Sentence Summary >

1. In a study comparing kidney tissue and clinical test results from 80 cats, interstitial fibrosis was closely associated with several markers related to kidney function.

2. This gives us a reason to study fibrosis, but it does not establish that reducing scarring restores kidney function.

3. The same starting point matters when evaluating nutritional ingredients at Greycoat Research: we need to look beyond “good for the kidneys” and ask which changes in the feline kidney an ingredient might actually influence.

< Introduction — There Is Scarring, but What Does That Tell Us? >

When you read about kidney disease, you may come across the phrase “scarring builds up in the kidneys.” You can probably picture something firm remaining where tissue has been damaged.

For a researcher, though, that raises another question. Does more scarring actually go together with poorer kidney function? Or is it simply one of the changes commonly seen in diseased kidneys?

Those are different possibilities. A change that stands out in a tissue image does not automatically explain how well the organ works.

Today’s paper examines that connection. The researchers compared changes in kidney tissue with test results collected while the same cats were alive.

 

< Background — When There Is Too Much Material Between Cells >

Body tissues are not just collections of cells. They also contain material that supports the spaces between those cells. Collagen is one example.

Collagen itself is not the problem. Healthy tissue needs it. The issue is what happens when too much of this material accumulates and the tissue’s structure changes. That is the fibrosis we’re discussing today.

In the kidney, these changes can occur in the interstitium, the tissue between the tubules. The name may be unfamiliar, but the idea is simple: we need to look at the tubules and their surroundings together.

One more distinction will help. If cats with more fibrosis tend to have higher creatinine, we can say the two are associated. That does not tell us which came first, or whether reducing one would reduce the other. Moving together is not the same as changing one by changing the other.

< The Study — Putting Tissue and Test Results Side by Side >

Chakrabarti and colleagues published this study in Veterinary Pathology in 2013.

The researchers compared postmortem kidney tissue from 80 cats with clinical information, including blood tests obtained within the final two months of life. They assessed interstitial fibrosis and inflammation, glomerular changes, and other lesions. The pathologist examining the tissue did not know the cats’ clinical test results.

Among the lesions examined, interstitial fibrosis was most closely associated with the severity of nitrogenous waste accumulation, elevated blood phosphorus, and anemia. Proteinuria was also associated with interstitial fibrosis and changes in glomerular size. 

< Reading the Results — Why the Filter Is Only Part of the Story >

What stands out to me is that changes in the interstitium were linked to several clinical measurements, not just one.

When we describe the kidney simply as a blood filter, it is easy to focus on the glomeruli. But as we discussed in the previous article, the kidney also reclaims useful substances and regulates what happens after filtration. We cannot leave out the tubules and the tissue around them.

This paper shows that scarring in that surrounding tissue was not just an interesting feature in a microscope image. In these cats, it was closely connected with their clinical test results.

That changes the question we ask. We move from “How high are the kidney-related values?” to “What is happening inside the kidney?” We are connecting measurements of function with the tissue that performs that function. 

< A Point to Keep in Mind — This Was Not a Trial of Reducing Scarring >

There is a step we should not skip. This study did not treat fibrosis and then test whether kidney function improved.

It does not establish that reducing fibrosis lowers creatinine, or that a creatinine result can tell us exactly how much scarring is present.

What it does is identify a lesion worth paying attention to. What happens when we intervene in that process is a question for another experiment. The value of an observational study and proof of a treatment effect are not the same thing.

< Personal Thoughts — Being More Specific About “Good for the Kidneys” >

When I hear “protecting the kidneys,” I first ask what, exactly, we are trying to protect. Are we trying to reduce cell damage? Or influence how the tissue changes after that damage? The same phrase can cover quite different goals.

That is one reason fibrosis interests me. Starting with a lesion observed in actual cats helps us narrow down which cells and which responses we should study.

It is also a standard I consider important when evaluating nutritional ingredients at Greycoat Research. Calling an ingredient “antioxidant” or “anti-inflammatory” is only a starting point. We need to ask how that activity might connect with a particular change in the feline kidney, and how much of that connection has actually been demonstrated.

Of course, today’s paper did not test the efficacy of any nutritional ingredient or product. I am not reading it as a substitute for product evidence. I am reading it to help define the questions we need to investigate.

Next time, we’ll move from tissue to cells. When cells from feline kidneys are grown in culture, which signals do the cells involved in scarring respond to? 

The findings discussed in this article reflect associations, mechanisms, and early translational evidence rather than confirmed efficacy in cats with kidney disease. Please consult a veterinarian before starting any supplementation protocol.

< References >

1.  Chakrabarti S, Syme HM, Brown CA, Elliott J. Histomorphometry of Feline Chronic Kidney Disease and Correlation With Markers of Renal Dysfunction. Veterinary Pathology. 2013. 

 < About the Author >

Hocheol Shin, Ph.D.

B.S./M.S./Ph.D. in Biological Sciences, KAIST (Korea Advanced Institute of Science and Technology)

Research background in cancer immunology, tumor microenvironment, and translational oncology. Currently engaged in companion animal health and longevity research.

[Educational Disclaimer]

This article is for educational purposes only and is not a substitute for professional veterinary advice, diagnosis, or treatment. It is not intended to diagnose, treat, cure, or prevent any disease.

Please consult your veterinarian before making changes to your cat’s diet, supplements, or care routine.