The multi-organ origin of interleukin-5 in the mouse

Sex-dependent responses to exertional heat stroke in mice

With increasing participation of females in endurance athletics and active military service, it is important to determine if there are inherent sex-dependent susceptibilities to exertional heat injury or heat stroke. In this study we compared responses of male and female adult mice to exertional heat stroke (EHS). All mice were instrumented for telemetry core temperature measurements and were exercise-trained for 3 wk before EHS. During EHS, environmental temperature was 37.5°C (35% RH) while the mice ran on a forced running wheel, using incremental increases in speed. The symptom-limited endpoint was loss of consciousness, occurring at ~42.2°C core temperature. Females ran greater distances (623 vs. 346 m, P < 0.0001), reached faster running speeds (7.2 vs. 5.1 m/min, P < 0.0001), exercised for longer times (177 vs. 124 min, P < 0.0001), and were exposed to greater internal heat loads (240 vs.160°C·min; P < 0.0001). Minimum Tc during hypothermic recovery was ~32.0°C in both sexes. Females lost 9.2% body weight vs. 7.5% in males ( P < 0.001). Females demonstrated higher circulating corticosterone (286 vs 183 ng/ml, P = 0.001, at 3 h), but most plasma cytokines were not different. A component of performance in females could be attributed to greater body surface area/mass and greater external power performance. However, there were significant and independent effects of sex alone and a crossed effect of "sex × power" on performance. These results demonstrate that female mice have greater resistance to EHS during exercise in hyperthermia and that these effects cannot be attributed solely to body size. NEW & NOTEWORTHY Female mice are surprisingly more resistant to exertional heat stroke than male mice. They run faster and longer and can withstand greater internal heat loads. These changes cannot be fully accounted for by increased body surface/mass ratio in females or on differences in aerobic performance. Although the stress-immune response in males and females was similar, females exhibited markedly higher plasma corticosteroid levels, which were sustained over 14 days of recovery.

Growth and Differentiation Factors

This review is restricted to neutrophilic granulocytes (granulocytes), monocytes (macrophages), and eosinophils, with only passing reference to cells that are also usually included in the "myeloid" category-megakaryocytes, mast cells, and erythroid cells. Although some dendritic cells are of myeloid origin, they are discussed elsewhere. The validity of the information to be described depends on two assumptions: (a) that in vitro data are applicable to events in vivo and (b) that mouse data reflect events in man. Both assumptions are likely to be broadly correct.

Early severe inflammatory responses to uropathogenic E. coli predispose to chronic and recurrent urinary tract infection

Chronic infections are an increasing problem due to the aging population and the increase in antibiotic resistant organisms. Therefore, understanding the host-pathogen interactions that result in chronic infection is of great importance. Here, we investigate the molecular basis of chronic bacterial cystitis. We establish that introduction of uropathogenic E. coli (UPEC) into the bladders of C3H mice results in two distinct disease outcomes: resolution of acute infection or development of chronic cystitis lasting months. The incidence of chronic cystitis is both host strain and infectious dose-dependent. Further, development of chronic cystitis is preceded by biomarkers of local and systemic acute inflammation at 24 hours post-infection, including severe pyuria and bladder inflammation with mucosal injury, and a distinct serum cytokine signature consisting of elevated IL-5, IL-6, G-CSF, and the IL-8 analog KC. Mice deficient in TLR4 signaling or lymphocytes lack these innate responses and are resistant, to varying degrees, to developing chronic cystitis. Treatment of C3H mice with the glucocorticoid anti-inflammatory drug dexamethasone prior to UPEC infection also suppresses the development of chronic cystitis. Finally, individuals with a history of chronic cystitis, lasting at least 14 days, are significantly more susceptible to redeveloping severe, chronic cystitis upon bacterial challenge. Thus, we have discovered that the development of chronic cystitis in C3H mice by UPEC is facilitated by severe acute inflammatory responses early in infection, which subsequently are predisposing to recurrent cystitis, an insidious problem in women. Overall, these results have significant implications for our understanding of how early host-pathogen interactions at the mucosal surface determines the fate of disease.

Hematopoietic cytokines

The production of hematopoietic cells is under the tight control of a group of hematopoietic cytokines. Each cytokine has multiple actions mediated by receptors whose cytoplasmic domains contain specialized regions initiating the various responses-survival, proliferation, differentiation commitment, maturation, and functional activation. Individual cytokines can be lineage specific or can regulate cells in multiple lineages, and for some cell types, such as stem cells or megakaryocyte progenitors, the simultaneous action of multiple cytokines is required for proliferative responses. The same cytokines control basal and emergency hematopoietic cell proliferation. Three cytokines, erythropoietin, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor, have now been in routine clinical use to stimulate cell production and in total have been used in the management of many millions of patients. In this little review, discussion will be restricted to those cytokines well established as influencing the production of hematopoietic cells and will exclude newer candidate regulators and those active on lymphoid cells. As requested, this account will describe the cytokines in a historical manner, using a sequential format of discovery, understanding, validation, and puzzlement, a sequence that reflects the evolving views on these cytokines over the past 50 years.

The preleukemic state of mice reconstituted with Mixl1-transduced marrow cells

Murine granulocytic cells, in becoming leukemic, need to acquire enhanced self-generation and a capacity for autocrine growth stimulation. Mice transplanted with bone marrow cells transduced with the Mixl1 homeobox gene develop a very high frequency of myeloid leukemia derived from the transduced cells. Preleukemic mice contained a high frequency of transduced clonogenic granulocytic cells. They exhibited an abnormally high capacity for self-replication and could generate immortalized granulocytic cell lines that remained absolutely dependent on either GM-CSF or IL-3 and were not leukemic. Organs from mice repopulated by marrow cells transduced either with Mixl1 or the control murine stem cell virus vector exhibited a capacity to produce IL-3 in vitro, activity being highest with the lungs, marrow, bladder, and thymus. Supporting evidence for the in vivo production of IL-3 was the frequent development of mast cells in the marrow. Overexpression of Mixl1 appears capable of inducing an abnormal self-renewal capacity in granulocytic precursors. Aberrant production of IL-3 was not present in the continuous Mixl cell lines and was therefore not in itself likely to be a leukemogenic change but it could support the enhanced survival and proliferation of the Mixl1 granulocytic populations until a final leukemogenic mutation occurs in them.

Crowding-dependent production of colony-stimulating factors by cultured syngeneic or allogeneic hematopoietic cells

Mitogenic stimulation in vitro of mouse T lymphocytes induces the production of the hematopoietic cytokines granulocyte-macrophage colony-stimulating factor and IL-3. The present experiments showed that simple crowding of murine spleen or lymph node cells was a sufficient inducing stimulus. Crowding did not have this consequence for thymus or marrow cells or spleen cells from nu/nu or Rag-1-/- mice lacking T lymphocytes. Crowding for as short a period as 24 h was sufficient to allow subsequent cytokine production in sparse cultures. Purified T lymphocytes also exhibited low levels of crowding induction of cytokine production and cytokine production was enhanced by IL-2 and IFN-gamma. However, IFN-gamma-/- spleen cells exhibited similar crowding-induced colony-stimulating factor production to that of control spleen cells. Excess cell crowding inhibited cytokine production. This inhibition was not caused by receptor internalization of cytokines but may contribute to the failure to observe IL-3 production in lymphoid organs in vivo. Coculture of allogeneic spleen or peritoneal cells was a strong inducing signal for colony-stimulating factor production but this parameter was unable to detect autoreactivity of T lymphocytes in mice that lack suppressor of cytokine signaling 1 and exhibit T lymphocyte activation.

Production of colony-stimulating factors and IL-5 by organs from three types of mice with inflammatory disease due to loss of the suppressor of cytokine signaling-1

Organs from neonatal mice dying from IFN-gamma-dependent inflammatory disease initiated by loss of the gene encoding the suppressor of cytokine signaling-1 (SOCS-1) had a normal capacity to produce G-CSF in vitro but a reduced capacity to produce GM-CSF, most evident with the lung, and some reduction in the production of M-CSF by muscle tissue. In contrast, organs from mice lacking the genes for both SOCS-1 and IFN-gamma had a normal capacity to produce CSFs. Organs from young adult mice dying with polymyositis and myocarditis that lacked SOCS-1 but were heterozygous for IFN-gamma had a normal capacity to produce GM-CSF and M-CSF, but muscle tissue produced significantly increased amounts of G-CSF and IL-5 with IL-5 production also being elevated for the salivary gland, thymus, and heart. Loss of the IFN-gamma gene alone had no impact on organ production of these cytokines in vitro. In none of the inflammatory disease models was IL-3 production detected. The SOCS-1 protein appears to have no direct influence on the cellular production of these cytokines and the abnormalities observed either depend on the coaction of IFN-gamma, or more likely, are linked with the invasion and destruction of tissue by T lymphocytes, macrophages, eosinophils, and neutrophils. The ability of local organs to produce these proinflammatory cytokines could contribute to the development and progression of these inflammatory lesions.