Fatty acid binding proteins, FABPs, have been identified as central regulators of both metabolic and inflammatory pathways. Mice deficient for expression of E‐FABP display protection from development of experimental autoimmune encephalomyelitis, exhibiting reduced expression of proinflammatory cytokines, including IFNγ and IL‐17, as compared to wild‐type mice. FABP‐deficient macrophages and dendritic cells (DC) are defective in expression of inflammatory cytokines and are inefficient in the promotion of proinflammatory T cells responses during antigen presentation. However, E‐FABP expression by T cells, themselves, was found to influence T cell cytokine expression. Purified naive CD4+ T cells from female wild‐type and E‐FABP‐deficient mice were driven towards a Th17 phenotype by culture with TGFβ and IL‐6. Flow cytometric analysis revealed that wild‐type T cell cultures contained over twice the levels of IL‐17 positive cells than did T cells isolated from E‐FABP‐deficient mice. Interestingly, when these experiments were performed using naive T cells from male mice, no differences in IL‐17 expression were observed. Overall, our studies demonstrate that E‐FABP expression by macrophages and DC promotes Th1 and Th17 differentiation. However, T cell expression of E‐FABP also plays a role in Th17 differentiation, directly, in a gender specific manner.

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The Tachinidae are natural enemies of many lepidopteran and coleopteran pests of crops, forests, and fruits. However, host-tachinid parasitoid interactions have been largely unexplored. In this study, we investigated the effects of tachinids on host biological traits, using Exorista japonica, a generalist parasitoid, and the silkworm Bombyx mori, its lepidopteran host, as models. We observed that E. japonica parasitoidism did not affect silkworm larval body weight gain and cocooning rate, whereas they caused shortened duration of molting from the final instar to the pupal stage, abnormal molting from larval to pupal stages, and a subsequent decrease in host emergence rate. Moreover, a decrease in juvenile hormone (JH) titer and an increase in 20-hydroxyecdysone (20E) titer in the hemolymph of parasitized silkworms occurred. The transcription of JH and 20E responsive genes was downregulated in mature parasitized hosts, but upregulated in parasitized prepupae while Fushi tarazu factor 1 (Ftz-f1), a nuclear receptor essential in larval ecdysis, showed dramatically reduced expression in parasitized hosts at both the mature and prepupal stages. Moreover, the transcriptional levels of BmFtz-f1 and its downstream target genes encoding cuticle proteins were downregulated in epidermis of parasitized hosts. Meanwhile, the content of trehalose was decreased in the hemolymph, while chitin content in the epidermis was increased in parasitized silkworm prepupae. These data reveal that the host may fine-tune JH and 20E synthesis to shorten developmental duration to combat established E. japonica infestation, while E. japonica silences BmFtz-f1 transcription to inhibit host pupation. This discovery highlights the novel target mechanism of tachinid parasitoids and provides new clues to host/tachinid parasitoid relationships.