Live conjunctiva-associated lymphoid tissue analysis in rabbit under inflammatory stimuli using in vivo confocal
Hong Liang1, Christophe Baudouin, Benedicte Dupas
1Department of Toxicology, Faculty of Biological and Pharmacological Sciences, Paris Descartes University, Paris, France.
Insights
This study visualizes conjunctiva-associated lymphoid tissue (CALT) in vivo, revealing inflammatory cell behavior during ocular inflammation. In vivo confocal microscopy offers a new way to study ocular surface immunity and inflammation.
Area of Science:
- Ocular immunology
- Ophthalmology
- Immunology
Background:
- Conjunctiva-associated lymphoid tissue (CALT) is crucial for ocular surface immunity.
- Previous studies lacked in vivo visualization of CALT's dynamic responses to inflammation.
- Understanding CALT's role in pathological conditions is limited.
Purpose of the Study:
- To investigate in vivo cell reactions within organized CALT during experimental conjunctival inflammation in rabbit eyes.
- To visualize inflammatory cell infiltration and circulation within CALT lymph vessels.
- To explore in vivo CALT patterns in human vernal keratoconjunctivitis (VKC).
Main Methods:
- In vivo confocal microscopy (IVCM) was used to observe CALT in rabbit eyes.
- Inflammatory stimuli included LPS, TNFalpha, and anti-TNF antibodies.
- Morphology was assessed with Cresyl violet staining; CD45(+) lymphocytes were detected via immunohistology.
Main Results:
- LPS-induced conjunctivitis showed inflammatory cell infiltration and circulation in CALT lymph vessels.
- TNFalpha induced moderate CALT inflammation, significantly reduced by anti-TNF antibodies.
- CD45(+) lymphocyte expression peaked at 4 hours post-LPS/TNFalpha and decreased with anti-TNFalpha treatment.
- CALT patterns were observed in a human VKC patient.
Conclusions:
- This study provides the first in vivo visualization of normal and pathological cell reactions in rabbit CALT.
- IVCM-CALT is a promising tool for understanding ocular surface defense mechanisms.
- CALT inflammatory cell analysis may serve as a novel criterion for assessing ocular surface inflammation.
Purpose:
Conjunctiva-associated lymphoid tissue (CALT) plays an important role in ocular surface immunity. No study until now has been able to show its in vivo aspects, and few have demonstrated its reactions after pathologic patterns. The authors investigated in rabbit eyes the cell reactions occurring in the organized CALT during conjunctival inflammation models.
Methods:
Using in vivo confocal microscopy (IVCM), the authors analyzed, for the first time in vivo inflammatory cell infiltration and circulation inside the lymph vessels in rabbit CALT after inflammatory stimuli (LPS, TNFalpha, LPS+/-anti-TNF). Cresyl violet staining was performed to observe the morphology of CALT, and immunohistology was performed in whole mount conjunctiva and cryosections for detecting CD45(+) lymphocytes. Human CALT in vivo aspects were also explored in a patient with vernal keratoconjunctivitis (VKC).
Results:
The conjunctivitis model induced by LPS was characterized by inflammatory cell infiltration in the dome and intrafollicular layers of CALT and cell circulation inside the lymph vessels. TNF alone induced moderate inflammatory infiltration in CALT. However anti-TNF antibodies could significantly decrease LPS/TNFalpha-induced inflammation. CD45(+) lymphocytes were strongly expressed in the CALT after injection of LPS or TNFalpha at 4 hours and decreased with injection of anti-TNFalpha. The authors also showed the presence of the CALT pattern in VKC.
Conclusions:
The authors showed for the first time the in vivo aspects of normal and pathologic cell reactions in rabbit CALT after inflammatory stimuli. IVCM-CALT could be a pertinent tool in the future for the comprehension of ocular surface defense mechanisms, and inflammatory cell analysis in CALT could constitute a new criterion for evaluating ocular surface inflammation.
