Pattern of Disease after Murine Hepatitis Virus Strain 3 Infection Correlates with Macrophage Activation and Not Viral Replication

Murine hepatitis virus strain (MHV-3) produces a strain-dependent pattern of disease which has been used as a model for fulminant viral hepatitis. This study was undertaken to examine whether there was a correlation between macrophage activation and susceptibility or resistance to MHV-3 infection. Peritoneal macrophages were isolated from resistant A/J and susceptible BALB/cJ mice and, following stimulation with MHV-3 or lipopolysaccharide (LPS), analyzed for transcription of mRNA and production of interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), mouse fibrinogen-like protein (musfiblp), tissue factor (TF), leukotriene B4, and prostaglandin E2 (PGE2). Macrophages from BALB/cJ mice produced greater amounts of IL-1, TNF-alpha, TGF-beta, leukotriene B4, and musfiblp following MHV-3 infection than macrophages from resistant A/J mice, whereas in response to LPS, equivalent amounts of IL-1, TNF-alpha, TGF-beta, and TF were produced by macrophages from both strains of mice. Levels of mRNA of IL-1, TNF-alpha, and musfiblp were greater and more persistent in BALB/cJ than in A/J macrophages, whereas the levels and kinetics of IL-1, TNF-alpha, and TF mRNA following LPS stimulation were identical in macrophages from both strains of mice. Levels of production of PGE2 by MHV-3-stimulated macrophages from resistant and susceptible mice were equivalent; however, the time course for induction of PGE2, differed, but the total quantity of PGE2 produced was insufficient to inhibit induction of musfiblp, a procoagulant known to correlate with development of fulminant hepatic necrosis in susceptible mice. These results demonstrate marked differences in production of inflammatory mediators to MHV-3 infection in macrophages from resistant A/J and susceptible BALB/cJ mice, which may explain the marked hepatic necrosis and fibrin deposition and account for the lethality of MHV-3 in susceptible mice

Immunity to murine sarcoma virus induced tumours. IV. Direct cellular cytolysis of 51Cr labelled target cells in vitro and analysis of blocking factors which modulate cytotoxicity.

The antigen specific cell mediated cytotoxicity of MSV immune spleen lymphocytes to 51Cr labelled murine lymphoma cells was wholly abolished by pretreatment of the spleen cells with anti-theta antibody and complement. Early during the immune response to MSV the cytotoxic acitivity was inhibited by incubation of immune lymphocytes with "late progressor" or "early regressor" serum. Immune lymphocytes at later times were more refractory to such inhibition by serum blocking factors. Although unfractionated cytotoxic lymphocytes, irrespective of the time after MSV infection at which they were tested, were inhibited by soluble tumour associated antigen (TAA), a subpopulation of cytotoxic T cells was identified which was inhibited neither by antigen nor serum

Tumour-cell susceptibility to cytotoxic or cytostatic effector cells in vitro and the regulation of tumour-cell growth in vivo.

Tumour-cell growth in lung nodules after i.v. transfer to sublethally irradiated mice has been followed after adoptive transfer of different populations of lymphoid cells. Spleen cells deliberately immunized in vitro and in vivo against stimulator cells bearing embryo-associated antigens and which are cytostatic in vitro for targets bearing such antigens, can diminish the number of lung nodules found after i.v. transfer. In contrast, cytotoxic (in vitro) spleen cells, while capable of diminishing local (s.c.) growth of tumour cells, cannot control systemic tumour growth. Within a given solid tumour mass, the subpopulations resistant to cytostatic effector cells in vitro are the ones most likely to produce lung colonies after adoptive transfer in vivo, though they show no more local (s.c.) growth than to cytostatic-sensitive cells in vivo

Inhibition of cell proliferation rather than of cell lysis as a measure of immune reactivity in embryo-antigen-challenged mice.

An assay system is described in which effector cells added along with suitable target cells inhibit, in a quantitative fashion, the subsequent uptake of 3H-thymidine by those target cells. Effector cells active in this assay, using embryonic fibroblast cells as targets, develop spontaneously in cultures of mouse lymphoid cells, but are apparently different from those described earlier by investigators of activity in cytotoxic assays. Further evidence is presented to show the development of spleen-derived effector cells with cytostatic activity (for embryonic fibroblast target cells) in mice during the course of normal pregnancy, or growth of spontaneously appearing mammary adenocarcinomas. Indeed, such effector cells can also be found within the growing solid mass itself. Different populations of tumour cells isolated from a solid tumour apparently differ in their susceptibility to growth inhibition by tumour-bearer-derived cytostatic effector cells, a phenomenon which may be related to metastatic spread of tumour cells

Immunity to Murine Sarcoma Virus Induced Tumors. III. Analysis of the Cell Populations Involved in Protection from Lethal Tumour Progression of Sublethally Irradiated, MSV Inoculated, Mice

A comparison was made between the cells responsible for demonstrable activity against MSV antigens, using both in vivo and in vitro assays. Similar cells (in terms of size and sensitivity to anti-theta serum) were detected in both assays. However, while lymphoid cells from animals at all stages post-MSV infection were active in protecting irradiated mice from the lethal effect of induction of MSV sarcomata, cells from animals at early stages post-MSV infection (when the tumour was in a progressive phase of growth) were not active in the in vitro assay. By manipulation of the in vivo assay conditions a situation was observed in which cells from “progressor animals” were able to suppress both the in vitro and in vivo activity of regressor lymphoid cells. The potential physiological role of this cell type is disussed

Reduced expression of monocyte CD200R is associated with enhanced proinflammatory cytokine production in sarcoidosis

In sarcoidosis, the proinflammatory cytokines interferon gamma, tumour necrosis factor and interleukin-6 are released by monocyte-derived macrophages and lymphocytes in the lungs and other affected tissues. Regulatory receptors expressed on monocytes and macrophages act to suppress cytokine production, and reduced expression of regulatory receptors may thus promote tissue inflammation. The aim of this study was to characterise the role of regulatory receptors on blood monocytes in patients with sarcoidosis. Cytokine release in response to stimulation of whole blood was measured in healthy controls and Caucasian non-smoking patients with sarcoidosis who were not taking disease modifying therapy. Expression of the regulatory molecules IL-10R, SIRP-α/β, CD47, CD200R, and CD200L was measured by flow cytometry, and functional activity was assessed using blocking antibodies. Stimulated whole blood and monocytes from patients with sarcoidosis produced more TNF and IL-6 compared with healthy controls. 52.9% of sarcoidosis patients had monocytes characterised by low expression of CD200R, compared with 11.7% of controls (p < 0.0001). Patients with low monocyte CD200R expression produced higher levels of proinflammatory cytokines. In functional studies, blocking the CD200 axis increased production of TNF and IL-6. Reduced expression of CD200R on monocytes may be a mechanism contributing to monocyte and macrophage hyper-activation in sarcoidosis

Quantifying the Functional Impact of Chronic Patellofemoral Pain and Its Relationship to Perceived Duty-related Medical Readiness Among Active Duty Service Members

Introduction Chronic patellofemoral pain (PFP) is a heterogeneous pain condition that may significantly burden active duty service members, whose rigorous physical training demands include activities such as running and heavy load carriage. While chronic PFP is often defined by its pathoanatomical characteristics, evidence from other pain conditions (e.g., chronic low back pain) suggests classifying pain by its functional impact on work, social, and self-care activities may better inform personalized treatment approaches. As this approach has not been previously undertaken in chronic PFP or younger populations with chronic pain, this study aimed to characterize the global impact of PFP on day-to-day function and evaluate its relationship with perceived duty-related medical readiness among young, active service members. Materials and Methods Institutional Review Board approval was obtained at Naval Medical Center San Diego. Electronic health records were retrospectively reviewed among 295 service members referred to physical therapy for “knee pain” from April 2021 to April 2022. For service members with chronic PFP (i.e., anterior knee pain present for at least 3 months and on at least half the days in the past 6 months), demographic, pain-related, and standardized outcome measure data were extracted from physical therapy intake documentation. Knee function was quantified using the validated Anterior Knee Pain Scale, scored from 0 to 100 (100 = highest function). Patient-reported Outcomes Measurement Information System Computer Adaptive Tests for physical function and pain interference were collected and subcategorized from 0 (within normal limits) to 3 (severe limitation) based on t-score cut-points, then summed to create a Pain Impact Score (0 = no impact to 6 = severe impact). Finally, perceived duty-related medical readiness was averaged across 2 questions assessing confidence in performing deployment and military duties with well-managed pain, each scored from 0 to 100 (100 = highest readiness). Relationships between Pain Impact Scores and perceived duty-related medical readiness were evaluated using linear regression after controlling for age, sex, symptom chronicity, and knee function. Results Overall, 56 active duty service members, of whom 66% were males, met the criteria for chronic PFP and had outcome measures documented in their electronic health records. Most service members were classified as having mildly impaired physical function (46%) and moderately impaired pain interference (41%), while only 12 (21%) fell within normal limits for both physical function and pain interference domains. Median (25th-75th percentile) Pain Impact Scores were 2 (1-3). The overall regression model was statistically significant (R2 = 0.540, F(5,50) = 11.76, P \u3c .001). Beyond covariates, Pain Impact Scores explained an additional 21.0% of the variance in perceived duty-related medical readiness (P \u3c .001). Conclusions Service members with chronic PFP frequently report impaired physical function and pain interference, opposing assumptions that PFP is a mild, self-limiting condition. As each 1-point increase in Pain Impact is associated with a 10-point decrease in perceived duty-related medical readiness, functional pain impact should be evaluated alongside other condition-specific factors (e.g., knee function) to identify rehabilitation targets among service members with chronic PFP. Future work should explore whether similar associations are found between functional pain impact and other objective readiness measures (e.g., physical fitness tests)