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  • Writer's pictureKalaichitra

A thorough solution for Rheumatoid Arthritis Discovery with Zebrafish

Updated: May 29





Current Clinical Challenges:

In progressive Rheumatoid Arthritis (RA) candidates are designed to target inflammatory mediators - cytokines, chemokines, and factors responsible for inflammatory response.


Considering a healthy state of the physiology, the drug candidate is distributed evenly due to circulation. However in a pathological state, due to decreased circulation in and around the bone joints, which is the site of pathology in RA, candidates are relatively less available for activity. Although inflammatory response modulation is physiological and not local, immune modulation at the local site have shown promising results in rescue of RA disease pathology. Recent evidence points to increase cross talk between site of RA inflammation and the body's physiological response.

Key Discovery Challenge 1: Drug design factors fail to enable drug permeability into bone joints under pathological states


On the second note, Gut dysbiosis is a factor more than a contributor to the inflammatory condition. First there is a lack of healthy microbiota when is responsible for drug retention in the gut, second, there is an increase in fluid activity within the gut which affects the half life of drug and third the presence of a higher volume of drug metabolism enzyme, which may further eliminate drug activity. Drug retention in the gut is therefore a deciding factor for success of candidates.

Key Discovery Challenge 2: Drug candidates should survive a dysbiosis environment.


On the final note, grading RA progress is an important step. In most cases, patients are RA-negative until stage 3 of the disease when the bone destruction has begun. At stage 3 where most patients are identified, there is more than an inflammatory response; now, there is also pathological fluid buildup along with additional inflammatory contributions from cartilage and tendons. Key Discovery Challenge 3: Drug Candidates operate in an inflammatory environment among cartilage and tendons.


Our Assay to evaluate compound performance:

The four stages of grading in clinical RA can be identified in zebrafish using a Functional assay,


Temporo-Mandibular Joint (TMJ) Assay

A functional assay employing clinical scoring in zebrafish


The quantitative assay can evaluate

  1. Dose-Response relationship to identify rescue candidates and

  2. Dose-response grading by "clinical grading" score for translational application

Medium-throughput Assay: Morphologically, zebrafish TMJ is an excellent region to score arthritic phenotype due to its collagen rich region, and skeletal rich nature. Moreover, fish TMJ is in continuous motion for vital functions. Deviation in TMJ phenotype provides an accurate response of the musculoskeletal region to drug response. Through video tracking and data analysis of the TMJ function a functional score is developed for each candidate dosed in RA model. RA model induction is through adjuvant-induced Rheumatoid Arthritis (AIRA and is employed for drug screening.


A score of "0" in TMJ indicates candidates with potential to rescue RA in a clinical setting.


Process Flow of TMJ Functional Scoring using Medium Throughput assay


Histology of Zebrafish showing progress to stage IV RA pathology with severe joint inflammation in WT vs RA comparison

Rheumatoid Arthritis Pre-Clinical Grading

Reach out to Viji@pentagrit.com for a full fact pack on endpoints and model validation data in RA zebrafish.


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