Proinflammatory cytokine profile during transition period of dairy cows

Proinflammatory cytokines (PIC) are crucial regulators of the immune function and mediate the acute phase response (APR). Information available on the pattern of changes of PIC production in transition period of dairy cows are fragmentary as well as their consequences on metabolism and health conditions. To verify the potential relevance of the PIC level with health status of periparturient dairy cows, the changes of the plasma IL-1β and IL-6 have been investigated in 21 Holstein-Friesian cows from 4 weeks before to 4 weeks after parturition. Besides PIC concentrations and health status, cows were monitored for dry matter intake (DMI), milk yield, body condition score and a wide metabolic profile. The overall PIC production was higher during dry period compared the first month of lactation, but showed a high variability among the cows. Thus cows were retrospectively divided in 3 groups according to the concentrations of IL-1β before parturition and designated as up (UPIL), intermediate (INIL) and low (LOIL) IL-1β group. The concentrations of IL-1β were 43.4 pg/ml, 78.7 pg/ml and 205.8 pg/ml for LOIL, INIL and UPIL, respectively (P <0.01). The level of IL-6 is well related to the grouping based on IL-1β (P<0.01) and showed a similar pattern of changes in transition period. UPIL group had worse health status, lower DMI, more body reserves lost, less milk production and lower plasma albumin compared to INIL and LOIL. The UPIL cows also showed a more severe APR after calving, as suggested by the marked increase of haptoglobin and the decrease of Zn (index of metallothionein) and albumin during the first week of lactation (P< 0.05). Our results demonstrate a high variability of the levels of PIC in late pregnant cows and the good relation among the high levels of PIC with health troubles (clinical and subclinical) after calving. Thus, PIC levels could be used as prognostic markers for a risky transition period.