Innate immune responses to metabolic stress can be detected in rumen fluids

Abstract

Many production diseases of dairy cows are related to digestive troubles. The rumen subacute acidosis is the most relevant one, albeit not easily recognized. Recent studies suggest that forestomachs can perform regulatory actions at both regional and systemic levels, since forestomach walls express immune receptors and cytokines, and the rumen liquor is infiltrated by leukocytes. Therefore, the rumen fluid could be conveniently collected for investigating metabolic production diseases. Thus, we investigated the origin of the leukocytes of the rumen fluid and demonstrated that they partly derive from saliva. Next, we carried out a field survey of innate immunity in rumen fluids of 128 cows from 12 dairy farms, along with clinical inspections, assessment of milk yield, rumen pH, volatile fatty acids (VFA) and major inflammo-metabolic parameters. Significant statistical correlations were found between immune markers in rumen fluids and biochemical parameters. A significant negative correlation was found in rumen between CD45 gene expression (leukocyte infiltration) and pH level. B cells were the most frequent mononuclear leukocyte population in the rumen liquor and their infiltration was negatively affected by low ruminal pH and high concentrations of VFA. Moreover, total Ig and IgM in rumen fluids were negatively correlated with ruminal pH and positively correlated with uremia.Our data suggest that forestomach immune responses could be directed to "dangers" arising within the forestomach environment. The immune markers could integrate consolidated diagnostic parameters (e.g. rumen pH) and contribute to robust, early diagnosis of tricky digestive troubles of cattle.

The role of altered immune function during the dry period in promoting the development of subclinical ketosis in early lactation

“…As indicated above, ketotic animals in our study had preeclampsia-like conditions; interestingly, the condition of preeclampsia is known to weaken the body defenses (Cornelius, 2018). If such effects oc-curred in the early dry period (or even before), they could have allowed bacterial cell components to enter the organism (Trevisi et al, 2018), challenging immune cells and inducing a condition of endotoxin tolerance in them. This is a protective mechanism against overexuberant inflammation that could have developed when the WBC faced an endotoxin challenge.…”

Effects of a Change from an Indoor-Based Total Mixed Ration to a Rotational Pasture System Combined with a Moderate Concentrate Feed Supply on Immunological Cell and Blood Parameters of Dairy Cows

“…The authors concluded that the digestive system and its host need several weeks to adapt to the new feeding system. Gut health can be influenced by diet, microflora, immune system and intestinal integrity [12,13,46,47]. It plays a major role in dairy farming and is essential for production [46,47,48].…”

“…This could lead to inflammation of the papillae and thus to the activation of an immune response. Trevisi et al [12,13] hypothesized in their study that forestomachs can sense sterile and infectious stressors and react to them, and that there and elsewhere in the body immune response can occur in case of local inflammation or inflammatory conditions, too.…”

Bovine Immunology: Implications for Dairy Cattle

“…While the information regarding rumen-associated lymphoid tissues is limited, rumen fluid leukocyte populations (including monocytes, T and B cells) are likely to play a significant role in regulation of cattle immune and biochemical parameters ( 50 ). So, CD45 gene expression in rumen fluids (indicative of leukocyte infiltration) negatively correlated with ruminal pH, while the frequencies of B cells (as well as numbers of total IgG and IgM) were negatively affected by ruminal pH and high concentrations of volatile fatty acids.…”

“…Further, some findings suggest that release of fetal membranes can be an immune/hormone-mediated process because increased incidence of retained placenta (RP) is observed in cows sharing MHCI antigen specificity with their calves ( 127 ). It is well established that daily food intake decreases (~30%) as calving approaches ( 128 ), which coincides with increases in levels of pro-inflammatory cytokines ( 50 ). Dairy cows do not consume enough nutrients to meet the increased demand to support lactation which leads to a negative energy balance (NEB).…”