STAT3-Specific Single Domain Nanobody Inhibits Expansion of Pathogenic Th17 Responses and Suppresses Uveitis in Mice

Abstract

STAT3 activates transcription of genes that regulate cell growth, differentiation, and survival of mammalian cells. Genetic deletion of Stat3 in T cells has been shown to abrogate Th17 differentiation, suggesting that STAT3 is a potential therapeutic target for Th17-mediated diseases. However, a major impediment to therapeutic targeting of intracellular proteins such as STAT3 is the lack of efficient methods for delivering STAT3 inhibitors into cells. In this study, we developed a novel antibody (SBT-100) comprised of the variable (V) region of a STAT3-specific heavy chain molecule and demonstrate that this 15 kDa STAT3-specific nanobody enters human and mouse cells, and induced suppression of STAT3 activation and lymphocyte proliferation in a concentration-dependent manner. To investigate whether SBT-100 would be effective in suppressing inflammation in vivo, we induced experimental autoimmune uveitis (EAU) in C57BL/6J mice by active immunization with peptide from the ocular autoantigen, interphotoreceptor retinoid binding protein (IRBP651-670). Analysis of the retina by fundoscopy, histological examination, or optical coherence tomography showed that treatment of the mice with SBT-100 suppressed uveitis by inhibiting expansion of pathogenic Th17 cells that mediate EAU. Electroretinographic (ERG) recordings of dark and light adapted a- and b-waves showed that SBT-100 treatment rescued mice from developing significant visual impairment observed in untreated EAU mice. Adoptive transfer of activated IRBP-specific T cells from untreated EAU mice induced EAU, while EAU was significantly attenuated in mice that received IRBP-specific T cells from SBT-100 treated mice. Taken together, these results demonstrate efficacy of SBT-100 in mice and suggests its therapeutic potential for human autoimmune diseases.

Icariin alleviates uveitis by targeting peroxiredoxin 3 to modulate retinal microglia M1/M2 phenotypic polarization

“…Human IRBP 651–670 (500 mg) was dissolved in PBS (1 ml) and M. tuberculosis strain H37Ra (40 mg) was dissolved in Freund's adjuvant (1 ml). Next, IRBP and Freund's adjuvant were emulsified with an equal volume (1:1, v/v) for 1 h. Mice received subcutaneous injection of IRBP (500 μg) and intraperitoneal injection of PTX (1 μg) for EAU model [ 21 ]. After EAU induction for 7 days, all immunized mice were examined with slit lamp to guarantee model success.…”

IFN-γ-Primed hUCMSCs Significantly Reduced Inflammation via the Foxp3/ROR-γt/STAT3 Signaling Pathway in an Animal Model of Multiple Sclerosis

“…IL-10 is an anti-inflammatory cytokine that plays a crucial role in preventing inflammatory and autoimmune pathologies and is involved in the regulation of the Janus kinase/signal transducers and activators of transduction (JAK/STAT) signaling pathway. Genetic deletion of STAT3 in T cells has been shown to abrogate Th17 differentiation, suggesting that STAT3 is a potential therapeutic target for Th17-mediated diseases ( 10 ). Tregs can exert their functions by releasing inhibitory cytokines (IL-10 and IL-35) ( 11 ).…”

Photoreceptor Cells Constitutively Express IL-35 and Promote Ocular Immune Privilege

“…EAU is characterized by the recruitment of proinflammatory lymphocytes of the Th1 and/or Th17 subsets into the retina, and the intraocular inflammation or uveitis is generally manifested between post-immunization (p.i.) day 14 and day 22 [ 11 , 24 , 25 ]. We monitored progression and severity of uveitis during this time period by fundoscopy, a non-invasive procedure that allows visualization of the fundus of the eye (retina, macula, optic disc, fovea and blood vessels) using an ophthalmoscope or fundoscopy.…”