Abstract

Purpose Retinitis Pigmentosa (RP) is a progressive and hereditary disease that primarily affects the retina, leading to partial or complete vision loss. In addition to the direct impact on vision, the degeneration of the retina in RP also leads to inflammation in the eye, which can further damage the retina and make it difficult to treat the condition with cell therapy. This inflammation led to oxidative stress and cell death, creating an unfavourable environment for the introduction of new cells via cell therapy.

Methods The potential of Transforming Growth Factor-Beta1 (TGF-B1) as an anti-inflammatory agent to treat ocular inflammation was investigated done by administering TGF-B1 intravitreally to the eyes of rd1 mice. However, due to the transient effect of TGF-B1 injection, the in-vitro-induced Treg (iTregs) cells that secrete TGF-B1, were generated and transplanted into the conjunctiva of 4 weeks old rd1 mice to achieve a sustained release of TGF-B1. After administering iTregs, Retinal Neuron-Like Cells (RNLCs) were transplanted into the rd1 mouse retina as a form of cell therapy to improve vision perception.

Flow cytometry was used to estimate the number of Qtracker labelled RNLCs post 30 days of transplantation. The potential of iTregs as an adjunct transplantation with RNLCs to improve cell therapy survival and vision rescue was investigated by conducting Electroretinography and behavioural studies.

Results The study found that ocular inflammation can be reduced by treating with TGF-B1. After 30 days, mice transplanted with iTregs showed a significant increase in the number of transplanted RNLCs that survived compared to the mice who only received RNLCs. In the total fluid of the eye (aqueous plus vitreous), there was a significant increase in the levels of anti-inflammatory cytokines TGF-B1 and IL-10, and some decrease in the levels of pro-inflammatory cytokines Monocyte Chemoattractant Protein-1 (MCP1). The adjunct therapy of iTregs transplantation resulted in improvement in ERG wave functions and vision preservation compared to the group without adjunct iTregs.

Conclusions The administration of TGF-B1-secreting iTregs to the affected eye reduced the inflammatory environment, which enabled transplanted RNLCs to stay longer compared to without TGF-B1. The iTregs mediated sustained anti-inflammatory adjunct therapy can improve the outcome of cell therapy for RP.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This work was supported by a grant received from the Department of Science and Technology, Government of India (DST/ICPS/EDA/2018) and the core grant received from the Department of Biotechnology, Government of India to the National Institute of Immunology, New Delhi. P.S. was granted a research fellowship by the Department of Biotechnology.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

This investigation was approved by the Institutional Human Ethics Committee (IHEC#100/17) of the National Institute of Immunology (NII), New Delhi. The investigation on mice was approved by the Institutional Animal Ethics Committee (IAEC# 480/18) of NII, New Delhi.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

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Footnotes

Email Addresses of Co-authors: K Varsha Mohan1, kvarshamohangmail.com

Alaknanda Mishra1, alaknanda.bhugmail.com

Prakriti Sinha1, prakritisinhagmail.com

Abaranjitha Muniyasamy1, abaranjitha95gmail.com

Perumal Nagarajan1, nagarajannii.ac.in

Kiran Chaudhary2, drchaudharykyahoo.co.in

Data Availability

All data produced in the present work are contained in the manuscript

List of abbreviationsRPRetinitis PigmentosaTGF-B1Transforming Growth Factor-Beta1RNLCsRetinal Neuron Like CellsiTregsinduced-Treg cellsTNFαTumor necrosis factor-alphaAAVAdeno-Associated VirusGMPGuanosine 3’,5’-cyclic monophosphate cyclicIVCIndividual Ventilated CagesCBACytokine Bead AssayERGElectroretinographyMCP1Monocyte Chemoattractant Protein-1