No fever and leucocytosis in response to a lipopolysaccharide challenge in an insectivorous bat

Abstract

Bat immune systems may allow them to respond to zoonotic agents more efficiently than other mammals. As the first line of defence, the taxonomically conserved acute phase immune reaction of leucocytosis and fever is crucial for coping with infections, but it is unknown if this response is a key constituent to bat immunological success. We investigated the acute phase reaction to a standard lipopolysaccharide (LPS) challenge in Pallas's mastiff bats ( Molossus molossus ). Challenged bats lost mass, but in contrast to other mammals showed no leucocytosis or fever. There also was no influence on body temperature reduction during torpor. When compared to recent genome-wide assays for constituent immune genes, this lack of a conserved fever response to LPS contributes to a clearer understanding of the innate immune system in bat species and of the coevolution of bats with a wide diversity of pathogens.

Metabolic Cost of the Activation of Immune Response in the Fish-Eating Myotis (Myotis vivesi): The Effects of Inflammation and the Acute Phase Response

“…This may be attributable to high variance in T skin values observed at this time point due to the unusually low T skin (26.5°C) recorded in one individual that was almost identical to the temperature of its chamber (25.6°C) indicating that it was torpid. In particular, the increase in T skin temperature is different from the lack of change in T b previously reported for Pallas´s mastiff bats challenged with a higher dose of LPS (4.53 mg kg -1 ) [38]. T b in Pallas´s mastiff bats after LPS administration was similar to the T skin recorded in fish-eating Myotis injected with PBS.…”

“…T b in Pallas´s mastiff bats after LPS administration was similar to the T skin recorded in fish-eating Myotis injected with PBS. Interestingly, body mass loss in fish-eating Myotis after 11 hours of LPS administration (~8%) was similar to the loss in Pallas´s mastiff bats and short-tailed fruit bats after 24 hours of being treated treated with LPS (~7–8%) [37, 38]. In contrast to Pallas´s mastiff bats in which thermosensitive tags were implanted subcutaneously to measure T b , our measurements relied on external radiotransmitters that determine T skin .…”

“…bacteria, protozoa, viruses) [31–34]. In spite of the importance of the activation of the immune response in the regulation of and defense against disease agents, only some aspects of the inflammatory response have been examined in bats [35–38] and information on the metabolic cost associated with APR activation is scant. For example, there is evidence that RMR increases and body mass decreases after Pallas’ long-tongued nectar bat ( Glossophaga soricina ) were administered an LPS challenge (Herrera M. and Cruz-Neto, personal communication).…”

“…For example, there is evidence that RMR increases and body mass decreases after Pallas’ long-tongued nectar bat ( Glossophaga soricina ) were administered an LPS challenge (Herrera M. and Cruz-Neto, personal communication). This finding is intriguing since LPS administration in Pallas´s mastiff bat ( Molossus molossus ) elicits loss of body mass but no fever response [38]. We measured RMR before and after PHA and LPS were administered to compare the metabolic costs of the immune response activated by each antigen.…”

A Potent Anti-Inflammatory Response in Bat Macrophages May Be Linked to Extended Longevity and Viral Tolerance

“…Likewise, previous whole genome analyses revealed that all bats lack the PYHIN gene family involved in inflammasome formation in other mammals (Ahn et al, 2016). Interestingly, wild caught Molossus molossus bats injected with LPS showed no leucocytosis or fever (Stockmaier et al, 2015), which could be hypotheticaly explained by increased levels of antipyretic Il-10. However this observation might be speciesor experimental set-up-specific, as LPS induced fever was observed in Myotis vivesi (Otálora-Ardila et al, 2016) and leukocytosis occurred in challenged Carollia perspicillata (Schneeberger et al, 2013); therefore the LPS induced systemic responses in bats require further investigation.…”