RESUMO
The recovery of patients after severe burns is a long and complex process. Recently, genomic analysis of white blood cells from burn and trauma patients revealed excessive and prolonged innate immune activation in patients with complicated outcomes. However, translating this knowledge into practical biomarkers has not been possible yet. Although several biomarkers for monitoring burn patients have been proposed, their ability to accurately distinguish between inflammation stemming from initial tissue destruction, infections, and organ failure complications is limited. Here, we focused on monocytes, critical innate immune cells in the response to burn injured tissues. We measured the monocyte anisocytosis (quantified as monocyte distribution width, MDW, a recently emerged marker of sepsis) throughout the recovery of patients from the time of burn injury until the end of the hospital stay. We observed that MDW increases in patients during the first week after major burns. Among the patients with major burns who survive, MDW starts decreasing in the second week and normalizes by the end of the hospital stay. The duration of hospital stay appears to be proportional to how fast MDW decreases during the second week after the injury. We also found that MDW decreases significantly in most patients after excision and debridement surgeries but not after allo- and auto-graft surgeries. Moreover, high MDW values correlated with a higher rate of positive microbiology blood culture samples and respiratory infections. These findings underscore the importance of monitoring MDW as a potential biomarker for the risk of complications during burn patient recovery.
RESUMO
The Atlantic cod immune system deviates from antigen presentation processes seen in other vertebrates in that it lacks the necessary genes for exogenous antigen presentation (i.e., MHC-II and li) and a key MHC-II interacting molecule necessary for T-helper cell function (i.e., CD4), while possessing an expanded repertoire of MHC-I genes that facilitate endogenous antigen presentation. These observations, combined with the identification of putative endosomal sorting signals in MHC-I cytoplasmic tails, have led to speculation that cod rely on cross-presentation of exogenous antigens to elicit cytotoxic T-lymphocyte responses against extracellular threats. In light of this suggestion, we investigated MHC-I transcriptional profiles and endosomal sorting signals in a closely related gadoid species, the haddock. Analysis of transcripts from one individual identified 13 unique MHC-I molecules, including two non-classical molecules as determined by the level of conservation at their peptide anchoring sites. This suggests that like the cod, the haddock has an expanded MHC-I repertoire. Analysis of haddock MHC-I cytoplasmic tail sequences revealed that the dileucine- and tyrosine-based endosomal signaling motifs, that are suggested to facilitate cross-presentation in cod, were absent. Closer examination of the cod signaling motifs, including their relative position in the cytoplasmic tail region, indicates that these motifs might be non-functional, further supporting the need for functional studies to assess cross-presentation. Finally, in silico analysis and in vitro N-type de-glycosylation experiments demonstrate that haddock and cod beta-2-microglobulin (ß2M) are glycosylated at the same NQT sequon. Interestingly, whole genome tBLASTn searches also revealed that putative ß2 M glycosylation sites appear frequently within the Gadiformes lineage, as the predictive NQT and other N-X-S/T sequons were located in ß2M orthologues from 19 of the 25 additional gadoid genomes analyzed. Though the exact significance of ß2M glycosylation has yet to be elucidated, phylogenetic comparisons predict that the same NQT glycosylation sequence occurs in 13 additional species comprising four different orders of Actinopterygii (Gymnotiformes, Esociformes, Beryciformes and Perciformes). This suggests either that this feature has arisen independently in multiple lineages or that it comes from a common ancestor and has been lost or modified in many species. Together, the analysis of gadoid MHC-I genes and ß2M molecules highlights the challenges in generalizing immune system paradigms across the most diverse vertebrate lineage (i.e., fish) and between fish and more well-studied mammals.
