title: Synthesis and fragmentation of hyaluronan in renal ischaemia.
abstract: BACKGROUND
  The turnover of hyaluronan (HA), especially the production of low-molecular-weight fragments of HA, was examined in a model of unilateral renal ischaemia-reperfusion (IR) in rats.
  
  
  METHODS
  HA was extracted from the outer and inner stripe of the outer medulla (OSOM and ISOM) at different times following IR. Its fragmentation was measured using membrane filtration and size-exclusion chromatography. Quantitative reverse transcription-polymerase chain reaction, zymography and immunohistochemistry were used to assess the expression and localization of various forms of HA synthase (HAS) and hyaluronidase (HYAL). Macrophage infiltration was evaluated using immunohistochemistry.
  
  
  RESULTS
  HA accumulated at Day 1 mostly as high-molecular-weight (HMW) species with an elution profile similar to a reference 2500 kDa HA and at Day 14 mostly as medium- to low-size fragments. Within 1 day, HAS1 messenger RNA was up-regulated > 50- and 35-fold in OSOM and ISOM, respectively. Thereafter, HAS1 tended to normalize, while HAS2 increased steadily. Both synthetic enzymes were localized around tubules and in the interstitium. Conversely, HYAL1, HYAL2 and global hyaluronidase activity were repressed during the first 24 h. The patterns were identical in the OSOM and ISOM despite markedly different amounts of HA at baseline. There was no obvious correlation between HA deposits and macrophage infiltration.
  
  
  CONCLUSIONS
  In the post-ischaemic kidney, HA starts to accumulate at Day 1 mostly as HMW species. Later on, a large proportion becomes degraded into smaller fragments. This pattern is explained by coordinated changes in the expression of HA synthases and hyaluronidases, especially an early induction of HAS1. The current data open the door to timed pharmacological interventions blocking the production of HA fragments.
authors.affiliation: University of Namur, Namur, Belgium.
authors.forename: Anne-Emilie
authors.initials: AE
authors.lastname: Declèves
authors.forename: Nathalie
authors.initials: N
authors.lastname: Caron
authors.forename: Virginie
authors.initials: V
authors.lastname: Voisin
authors.forename: Alexandre
authors.initials: A
authors.lastname: Legrand
authors.forename: Nadine
authors.initials: N
authors.lastname: Bouby
authors.forename: Anne
authors.initials: A
authors.lastname: Kultti
authors.forename: Markku I
authors.initials: MI
authors.lastname: Tammi
authors.forename: Bruno
authors.initials: B
authors.lastname: Flamion
mesh_terms: D000818:Animals; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D006821:Hyaluronoglucosaminidase / Q000235:genetics / Q000378:metabolism; D007511:Ischemia / Q000235:genetics / Q000378:metabolism*; D007668:Kidney / Q000098:blood supply* / Q000293:injuries / Q000378:metabolism* / Q000473:pathology; D007679:Kidney Medulla / Q000378:metabolism; D008264:Macrophages / Q000473:pathology; D008297:Male; D008970:Molecular Weight; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D006820:Hyaluronic Acid; D014453:Glucuronosyltransferase; C491097:Has2 protein, rat; D000076002:Hyaluronan Synthases; D006821:Hyaluronoglucosaminidase