I haven't tried NLD, but I know that last year there was a lot of chatting about it on a different site (Inspire) that I am part of for my scleroderma. It obviously wouldn't have information regarding it's effectiveness for spondylitis, but it might give you some info on dose, titration, and side effects. Note: You do have to join Inspire to post there and you will end up getting spam emails from their 'partners'
Female, early 50's, HLA B27+, family history of SpA
Diagnoses: USpA (9/17), limited Scleroderma/Raynaud's phenomenon/Sjogren's syndrome (1/16), stroke (8/15), Factor V Leiden (8/15)
AS symptoms: right heel enthesitis/tendonitis; elbow tendonitis; mild low back/buttocks and hip pain/stiffness; normal MRI
Treatment: Cosentyx; Xarelto; vitamins D3, B12, folate Primary non-responder to Enbrel