Increased Transcriptional Activity of Milk-Related Genes following the Active Phase of Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis

Abstract

We analyzed global transcriptional changes in the lymph nodes of mice with experimental autoimmune encephalomyelitis in a longitudinal fashion. Most of the transcriptional activity was observed between 3 and 5 days postimmunization. After that period, gene expression changes decayed sharply back to baseline levels. A comparison of transcriptional profiles between immunized and control mice at the time of peak disease activity revealed 266 transcripts, mostly involved in cell-cell interaction and protein synthesis. When the same comparison was performed at the time of recovery from an attack, increased expression of genes coding for milk components were identified. Specifically, casein α (Csn1s1), β (Csn2), γ (Csn1s2a), and κ (Csn3), in addition to lactoalbumin α and extracellular proteinase were elevated >3-fold in immunized animals compared with CFA-injected controls. We confirmed these findings by quantitative RT-PCR and immunostaining of Csn3. Interestingly, the expression of Csn3 was also found elevated in the blood of multiple sclerosis (MS) patients after a relapse. Altogether, our data suggest that increased production of milk-related transcripts in the lymph nodes and blood succeeds an inflammatory event in experimental autoimmune encephalomyelitis and MS. The potential role of lactogenic hormones in MS is discussed.