The Effect of Ophthalmic and Systemic Formulations of Latilactobacillus sakei on Clinical and Immunological Outcomes of Patients With Dry Eye Disease: A Factorial, Randomized, Placebo-controlled, and Triple-masking Clinical Trial.

Dry eye disease (DED) is one of the most prevalent eye diseases. This study aimed to evaluate the efficacy and safety of Latilactobacillus sakei (L. sakei) either as an ophthalmic bacterial lysate (drops, no live organism) or as an oral probiotic (capsules) on immunological and clinical outcomes of patients with DED. This study was a randomized, placebo-controlled, triple-masking clinical trial with four parallel arms. Patients were randomly assigned in a 2x2 factorial design combining active vs placebo capsules and active vs placebo eye drops in a 1:1x1:1 ratio. The ophthalmic drops are approved for use in the European Union as a medical device (CE registration code 0425-MED-004235). A total of 40 patients were evaluated. DED signs and symptoms decreased significantly by using active drops compared to placebo, as measured by the Ocular Surface Disease Index (OSDI), Tear Break-up Time (TBUT), and Schirmer I tests (all p<0.0001). Conversely, neither active capsules nor their interaction effect with active drops achieved significance vs placebo. There was also a significant decrease in the tear levels of IL-6 (p=0.0007), TNFα (p<0.0001), and IFNγ (p<0.0001) in patients receiving active drops. Intake of both active products (drops and capsules) was well tolerated. Postbiotic ophthalmic formulation containing L. sakei lysate significantly improved the signs and symptoms of DED and suppressed ocular surface inflammatory response. Conversely, oral intake of L.sakei as a probiotic capsule had no effect in these patients (ClinicalTrials.gov: NCT04938908).