Matta Bharati, Bora Puran S, Neuhouser Adam J, Bora Nalini S
Department of Ophthalmology, Jones Eye Institute, Pat and Willard Walker Eye Research Center, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham, Mail Slot 523, Little Rock, AR, 72205, USA.
The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, USA.
Graefes Arch Clin Exp Ophthalmol. 2019 May;257(5):953-960. doi: 10.1007/s00417-019-04255-9. Epub 2019 Feb 5.
Experimental autoimmune anterior uveitis (EAAU) is a clinically relevant animal model for human idiopathic anterior uveitis (IAU). The role of the immunomodulator transforming growth factor β2 (TGF-β2) in EAAU pathology is unknown. In this study, we investigated the regulatory role of TGF-β2 in EAAU.
EAAU was induced in male Lewis rats by footpad injection of melanin-associated antigen (MAA). TGF-β2 was administered intravenously (iv) in MAA-sensitized rats during the induction of EAAU, or after the clinical onset of uveitis. MAA-sensitized rats injected similarly with an equal volume of PBS served as control. Animals were examined daily between days 7 and 30 post-injection for the clinical signs of uveitis using slit lamp biomicroscopy. Animals were sacrificed at various time points and eyes were harvested for histological analysis to assess the course and severity of inflammation. For histopathological analysis, paraffin sections of harvested eyes were stained with hematoxylin and eosin. Popliteal lymph nodes (LNs) were used for CD4CD25FoxP3 T regulatory (Tregs) population analysis and for CD4 T cell proliferation assay.
Administration of recombinant TGF-β2 during the early stages of EAAU prevented the induction of uveitis. Compared to PBS, the presence of TGF-β2 in the cell culture significantly (p < 0.05) inhibited the proliferation of CD4 T cells in response to MAA. In MAA-sensitized Lewis rats, iv treatment with recombinant TGF-β2 resulted in significantly (p < 0.05) increased percentage of Tregs compared to animals treated similarly with PBS. Thus, TGF-β2 inhibited the induction of EAAU by inhibiting CD4 T cell proliferation and increasing the number of Tregs. Injection of TGF-β2 in rats with active EAAU resulted in diminished disease activity. Unfortunately, this treatment did not lead to the early resolution of EAAU.
TGF-β2 plays a critical role in regulation of intraocular inflammation in EAAU. Findings reported in this study improve our understanding of immunopathology of IAU and suggest that recombinant TGF-β2 may be a promising therapeutic agent for human IAU.
实验性自身免疫性前葡萄膜炎（EAAU）是人类特发性前葡萄膜炎（IAU）的一种具有临床相关性的动物模型。免疫调节剂转化生长因子β2（TGF-β2）在EAAU病理过程中的作用尚不清楚。在本研究中，我们调查了TGF-β2在EAAU中的调节作用。
通过足垫注射黑色素相关抗原（MAA）在雄性Lewis大鼠中诱导EAAU。在EAAU诱导期间或葡萄膜炎临床发作后，对MAA致敏的大鼠静脉内（iv）给予TGF-β2。同样注射等量PBS的MAA致敏大鼠作为对照。在注射后第7天至第30天期间，每天使用裂隙灯生物显微镜检查动物的葡萄膜炎临床体征。在不同时间点处死动物，摘取眼睛进行组织学分析，以评估炎症的过程和严重程度。对于组织病理学分析，摘取眼睛的石蜡切片用苏木精和伊红染色。腘窝淋巴结（LNs）用于CD4CD25FoxP3调节性T细胞（Tregs）群体分析和CD4 T细胞增殖测定。
在EAAU早期给予重组TGF-β2可预防葡萄膜炎的诱导。与PBS相比，细胞培养中TGF-β2的存在显著（p < 0.05）抑制了CD4 T细胞对MAA的增殖反应。在MAA致敏的Lewis大鼠中，与同样用PBS处理的动物相比，重组TGF-β2静脉内治疗导致Tregs百分比显著（p < 0.05）增加。因此，TGF-β2通过抑制CD4 T细胞增殖和增加Tregs数量来抑制EAAU的诱导。在患有活动性EAAU的大鼠中注射TGF-β2导致疾病活动度降低。不幸的是，这种治疗并未导致EAAU的早期缓解。
TGF-β2在EAAU眼内炎症调节中起关键作用。本研究报告的结果增进了我们对IAU免疫病理学的理解，并表明重组TGF-β2可能是治疗人类IAU的一种有前景的治疗剂。
