Generation of aptamers for the selective detection and neutralization of soluble lymphotoxin alpha

Lymphotoxin alpha (LTα) is a potent inflammatory cytokine implicated in the pathophysiology of numerous human autoimmune and inflammatory diseases. Existing as a soluble homotrimer (LTα₃) or membrane-bound heterotrimer (LTα₁β₂), the differential and distinct functions of lymphotoxin signaling have meant that selective targeting of the cytokine with traditional pharmacological agents has proven difficult. While monoclonal antibodies that can neutralize human LTα₃ <i>in vivo</i> do exist (e.g., pateclizumab), their efficacy and subsequent use within the clinic have been limited. This may be in part perhaps due to cross-reactivity between the homotrimeric and heterotrimeric forms, leading to LTα₃-independent effects. Herein, we implement a counter-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) protocol to enrich aptamers targeting LTα₃ but not LTα₁β_2. Through a combination of <i>in silico</i> and <i>in vitro</i> tests, we also refine the aptamer sequences and test their ability to limit LT⍺₃-TNFR1 engagement and subsequent cellular cytotoxicity in L929 fibroblasts. We highlight the generation of 4 aptamer candidates that can selectively detect LTα₃ but not LTα₁β₂. Using rational design, we optimize the sequences and show that LTa1 and LTa5 can significantly reduce LTa₃-TNFR1 engagement-associated cytotoxicity <i>in vitro</i>, highlighting their future therapeutic potential. These data highlight aptamers for the future investigation of lymphotoxin signaling, limiting off-target impacts on other LT⍺₃-dependent mechanisms.