IFN-γ Promotes Apoptosis of the Uterus and Placenta in Pregnant Rat and Human Cytotrophoblast Cells

Evidence of Placental Villous Inflammation and Apoptosis in Third-Trimester Symptomatic SARS-CoV-2 Maternal Infection

PURPOSE

In view of conflicting reports on the ability of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) to infect placental tissue, this study aimed to further evaluate the impact of inflammation and placental damage from symptomatic third-trimester maternal COVID-19 infection.

MATERIALS AND METHODS

This case-control study included 32 placenta samples each from symptomatic COVID-19 pregnancy and normal non-COVID-19 pregnancy. The villous placental area's inflammatory expression [angiotensin converting enzyme-2 (ACE-2), transmembrane protease serine-2 (TMPRSS2), interferon-γ (IFN-γ), interleukin-6 (IL-6), and SARS-CoV-2 spike protein] and apoptotic rate were examined using immunohistochemistry and Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) assay. Comparison and correlation analysis were used based on COVID-19 infection, placental SARS-CoV-2 spike protein evidence, and maternal severity status.

RESULTS

Higher expressions of TMPRSS2, IFN-γ, and trophoblast apoptotic rate were observed in the COVID-19 group (p<0.001), whereas ACE-2 and IL-6 expressions were not significantly different from the control group (p>0.05). Additionally, SARS-CoV-2 spike protein was detected in 8 (25%) placental samples of COVID-19 pregnancy. COVID-19 subgroup analysis revealed increased IFN-γ, trophoblast, and stromal apoptosis (p<0.01). Moreover, the results of the current study revealed no correlation between maternal COVID-19 severity and placental inflammation as well as the apoptotic process.

CONCLUSION

The presence of SARS-CoV-2 spike protein as well as altered inflammatory and apoptotic processes may indicate the presence of placental disturbance in third-trimester maternal COVID-19 infection. The lack of correlation between placental disruption and maternal severity status suggests the need for more research to understand the infection process and any potential long-term impacts on all offsprings born to COVID-19-infected pregnant women.

The role of immune cells and mediators in preeclampsia

Preeclampsia is a hypertensive disorder of major concern in pregnancy than can lead to intrauterine growth restriction, placental abruption and stillbirth. The pathophysiology of preeclampsia is multifactorial, including not only kidney dysfunction but also endothelial dysfunction, as the maternal endothelium becomes exposed to placental factors that are released into the circulation and increase systemic levels of vasoconstrictors, oxidative stress, anti-angiogenic factors and inflammatory mediators. Importantly, inflammation can lead to insufficient placental perfusion and low birthweight in offspring. Various innate and adaptive immune cells and mediators have been implicated in the development of preeclampsia, in which oxidative stress is associated with activation of the maternal inflammatory response. Immune cells such as regulatory T cells, macrophages, natural killer cells, and neutrophils are known to have major causative roles in the pathology of preeclampsia, but the contributions of additional immune cells such as B cells, inflammatory cytokines and anti-angiotensin II type 1 receptor autoantibodies are also now recognized. Immunological interventions, therefore, have therapeutic potential in this disease. Here, we provide an overview of the immune responses that are involved in the pathogenesis of preeclampsia, including the role of innate and adaptive immune cells and mediators.

Neurotrophins: are they involved in immune tolerance in pregnancy?

In this review, an attempt was made to substantiate the possibility for neurotrophins to be involved in the development of immune tolerance based on data accumulated on neurotrophin content and receptor expression in the trophoblast and immune cells, in particular, in natural killer cells. Numerous research results are reviewed to show that the expression and localization of neurotrophins along with their high-affinity tyrosine kinase receptors and low-affinity p75NTR receptor in the mother-placenta-fetus system indicate the important role of neurotrophins as binding molecules in regulating the crosstalk between the nervous, endocrine, and immune systems in pregnancy. An imbalance between these systems can occur with tumor growth and pathological processes observed in pregnancy complications and fetal development anomalies.

Phospholipase A and acyltransferase 4/retinoic acid receptor responder 3 at the intersection of tumor suppression and pathogen restriction

Phospholipase A and acyltransferase (PLAAT) 4 is a class II tumor suppressor with phospholipid metabolizing abilities. It was characterized in late 2000s, and has since been referred to as ‘tazarotene-induced gene 3’ (TIG3) or ‘retinoic acid receptor responder 3’ (RARRES3) as a key downstream effector of retinoic acid signaling. Two decades of research have revealed the complexity of its function and regulatory roles in suppressing tumorigenesis. However, more recent findings have also identified PLAAT4 as a key anti-microbial effector enzyme acting downstream of interferon regulatory factor 1 (IRF1) and interferons (IFNs), favoring protection from virus and parasite infections. Unveiling the molecular mechanisms underlying its action may thus open new therapeutic avenues for the treatment of both cancer and infectious diseases. Herein, we aim to summarize a brief history of PLAAT4 discovery, its transcriptional regulation, and the potential mechanisms in tumor prevention and anti-pathogen defense, and discuss potential future directions of PLAAT4 research toward the development of therapeutic approaches targeting this enzyme with pleiotropic functions.

Apoptotic responses stimulated by the trichloroethylene metabolite S-(1,2-dichlorovinyl)-L-cysteine depend on cell differentiation state in BeWo human trophoblast cells

During pregnancy, the placental villous cytotrophoblasts differentiate via cell fusion and multinucleation to create syncytiotrophoblasts, a cell type at the maternal-fetal interface. Apoptosis of syncytiotrophoblasts is associated with adverse pregnancy outcomes. The human trophoblast BeWo cell line has been used as an in vitro model for this differentiation process, also known as syncytialization. In the current study, we exposed unsyncytialized BeWo cells, BeWo cells undergoing syncytialization, and syncytialized BeWo cells to S-(1,2-dichlorovinyl)-L-cysteine (DCVC), a metabolite of the industrial chemical trichloroethylene (TCE). DCVC exposure at 50 μM for 48 h decreased cell viability, increased cytotoxicity, increased caspase 3/7 activity, and increased nuclear condensation or fragmentation in BeWo cells regardless of their differentiation status. Investigating mechanisms of apoptosis, DCVC increased H2O2 abundance and decreased PRDX2 mRNA in all three BeWo cell models. DCVC decreased tumor necrosis factor-receptor 1 (TNF-R1) concentration in media and decreased NFKB1 and PRDX1 mRNA expression in syncytialized BeWo cells only. DCVC decreased BCL2 mRNA expression in syncytializing BeWo cells and in syncytialized BeWo cells only. Decreased LGALS3 mRNA was seen in unsyncytialized BeWo cells only. Together, these data suggest roles for oxidative stress and pro-inflammatory mechanisms underlying apoptosis in BeWo cells with differences depending on differentiation state.

Adoptive transfer of placental ischemia-stimulated natural killer cells causes a preeclampsia-like phenotype in pregnant rats

PROBLEM

The Reduced Uterine Perfusion Pressure (RUPP) rat model of placental ischemia recapitulates many characteristics of preeclampsia including maternal hypertension, intrauterine growth restriction (IUGR), and increased cytolytic natural killer cells (cNKs). While we have previously shown a 5-fold higher cytotoxicity of RUPP NKs versus normal pregnant NKs, their role in RUPP pathophysiology remains unclear. In this study, we tested the hypotheses that (1) adoptive transfer of RUPP-stimulated NKs will induce maternal hypertension and IUGR in normal pregnant control (Sham) rats and (2) adoptive transfer of Sham NKs will attenuate maternal hypertension and IUGR in RUPP rats.

METHOD OF STUDY

On gestation day (GD)14, vehicle or 5 × 106 RUPP NKs were infused i.v. into a subset of Sham rats (Sham+RUPP NK), and vehicle or 5 × 106 Sham NKs were infused i.v. into a subset of RUPP rats (RUPP+Sham NK; n = 12/group). On GD18, Uterine Artery Resistance Index (UARI) was measured. On GD19, mean arterial pressure (MAP) was measured, animals were sacrificed, and blood and tissues were collected for analysis.

RESULTS

Adoptive transfer of RUPP NKs into Sham rats resulted in elevated NK activation, UARI, placental oxidative stress, and preproendothelin expression as well as reduced circulating nitrate/nitrite. This led to maternal hypertension and IUGR. RUPP recipients of Sham NKs demonstrated normalized NK activation, sFlt-1, circulating and placental VEGF, and UARI, which led to improved maternal blood pressure and normal fetal growth.

CONCLUSION

These data suggest a direct role for cNKs in causing preeclampsia pathophysiology and a role for normal NKs to improve maternal outcomes and IUGR during late gestation.

Fetal Weight Outcomes in C57BL/6J and C57BL/6NCrl Mice after Oral Colonization with Porphyromonas gingivalis

Porphyromonas gingivalis is considered a keystone pathogen that contributes to the initiation and progression of periodontitis in humans. P. gingivalis has also been detected in human placentas associated with adverse pregnancy outcomes. The spread of P. gingivalis from the oral cavity to the reproductive tract thus represents a potential mechanism whereby periodontitis can lead to adverse pregnancy outcomes. In a murine model of pregnancy and oral infection with P. gingivalis, C57BL/6J mice developed low fetal weight, whereas C57BL/6NCrl mice did not. Although C57BL/6NCrl mice harbor segmented filamentous bacteria that drive a Th17 response, fetal weight was independent of frequency of Th17 or Th1 in either substrain. Low fetal weight was instead correlated with increasing amounts of P. gingivalis DNA in the placentas of the C57BL/6J dams. In contrast, fetal weight in C57BL/6NCrl mice was independent of P. gingivalis in the placenta. Differences in genetics or microbiome that influence the ability of P. gingivalis to colonize the placenta may drive differential fetal weight outcomes between C57BL/6J and C57BL/6NCrl mice and, potentially, between diverse human populations.

Transcriptional and Functional Programming of Decidual Innate Lymphoid Cells

A successful pregnancy requires many physiological adaptations from the mother, including the establishment of tolerance toward the semiallogeneic fetus. Innate lymphoid cells (ILCs) have arisen as important players in immune regulation and tissue homeostasis at mucosal and barrier surfaces. Dimensionality reduction and transcriptomic analysis revealed the presence of two novel CD56^Bright decidual ILCs that express low T-bet and divergent Eomes levels. Transcriptional correlation with recently identified first trimester decidual dNKs suggests that these novel decidual ILCs might be present throughout pregnancy. Functional testing with permutation analysis revealed production of multiple factors by individual cells, with a preference for IFNγ and VEGF. Overall, our data suggests continuity of a unique decidual innate lymphocytes across pregnancy with a polyfunctional functional profile conducive for pregnancy.

The association between polymorphisms of genes related to inflammation and recurrent pregnancy loss

AIM

Recurrent pregnancy loss (RPL) occurs in 1-2% of pregnant women and about 50% of RPL cases are unexplained. Previous studies have shown that genetic variation in immune response genes can contribute to the risk in pregnancy maintenance during pregnancy. The aim of the present study was to evaluate the relationship between RPL and genes those have previously been associated with an inflammatory process on 107 RPL cases and 187 healthy controls.

METHODS

In this work, the single-nucleotide polymorphisms was examined by utilizing the direct sequencing and the Sequenom MassARRAY system.

RESULTS

The FAU rs769440 G allele had higher frequencies in patients with RPL (p = .019). No association was observed between other polymorphisms and RPL.

CONCLUSION

The results showed an association between FAU rs769440 polymorphism and RPL in Chinese Han population.

A SNP in pri-miR-10a is associated with recurrent spontaneous abortion in a Han-Chinese population

MicroRNA-10a (miR-10a) has a wide range of functions in nearly all mammalian tissues and is involved in the occurrence of many diseases. However, it remains unknown whether miR-10a is associated with human recurrent spontaneous abortion (RSA). In this study, we found that rs3809783 A > T in miR-10a coding region was significantly associated with the increase of the risk of human unexplained RSA (URSA) acquisition in a Han-Chinese population. The T allele of rs3809783 hindered the production of mature miR-10a. A to T substitution in miR-10a rs3809783 repressed cell proliferation and migratory capacity. Further investigation discovered that Bcl-2-interacting mediator (Bim) was the functional target of miR-10a and inversely regulated Bim expression. Dual-luciferase assay indicated that A allele in miR-10a rs3809783 could more effectively suppress Bim expression than T allele. In addition, A to T substitution in miR-10a rs3809783 attenuated the sensibility of cells to progesterone and its antagonist mifepristone. Collectively, our data suggest that rs3809783 A > T in pri-miR-10a may be conductive to the genetic predisposition to RSA by disrupting the production of mature miR-10a and reinforcing the expression of Bim.

Altered cytokine network in gestational diabetes mellitus affects maternal insulin and placental-fetal development

Pregnancy is characterized by an altered inflammatory profile, compared to the non-pregnant state with an adequate balance between pro-and anti-inflammatory cytokines needed for normal development. Cytokines are small secreted proteins expressed mainly in immunocompetent cells in the reproductive system. From early developmental stages onward, the secretory activity of placenta cells clearly contributes to increase local as well as systemic levels of cytokines. The placental production of cytokines may affect mother and fetus independently. In turn because of this unique position at the maternal fetal interface, the placenta is also exposed to the regulatory influence of cytokines from maternal and fetal circulations, and hence, may be affected by changes in any of these. Gestational diabetes mellitus (GDM) is associated with an overall alteration of the cytokine network. This review discusses the changes that occur in cytokines post GDM and their negative effects on maternal insulin and placental-fetal development.

Interferon gamma is involved in apoptosis of trophoblast cells at the maternal-fetal interface following Toxoplasma gondii infection

OBJECTIVE

To assess whether interferon gamma (IFN-γ) secreted by decidual natural killer (dNK) cells at the maternal-fetal interface is involved in the apoptosis of trophoblast cells (trophoblasts) following Toxoplasma gondii infection.

METHODS

Human dNK cells were infected with T. gondii and then co-cultured with trophoblasts. The infected co-cultured cells were treated with or without IFN-γ neutralizing antibodies. Uninfected co-cultured cells were used as controls. The level of IFN-γ in the supernatant of co-culture was measured by ELISA and the apoptosis of trophoblasts was analyzed by flow cytometry. The expression of caspase 3 and caspase 8 of trophoblasts cells was determined by Western blotting and real-time RT-PCR.

RESULTS

The levels of IFN-γ were increased at <24h following T. gondii infection and were maintained thereafter. Caspase 3, caspase 8, and the apoptosis of trophoblasts co-cultured with dNK cells were increased compared with the control. Meanwhile, IFN-γ, caspase 3, caspase 8, and trophoblast apoptosis were up-regulated upon increased ratios of dNK cells to trophoblasts. Compared to the infected group, the levels of IFN-γ, caspase 3, caspase 8, and trophoblast apoptosis were significantly decreased upon treatment with the IFN-γ neutralizing antibody. IFN-γ levels were correlated positively with the apoptosis of trophoblasts (r=0.7163, p < 0.01).

CONCLUSIONS

The levels of IFN-γ secreted by dNK cells at the maternal-fetal interface were closely correlated with the apoptosis of trophoblasts upon T. gondii infection. The apoptosis of trophoblasts induced by the increase in IFN-γ depended on the caspase pathway, which may contribute to the abnormal pregnancy outcomes that occur with T. gondii infection.

IFN-γ induces aberrant CD49b⁺ NK cell recruitment through regulating CX3CL1: a novel mechanism by which IFN-γ provokes pregnancy failure

Interferon-γ (IFN-γ), a pleiotropic lymphokine, has important regulatory effects on many cell types. Although IFN-γ is essential for the initiation of uterine vascular modifications and maintenance of decidual integrity, IFN-γ administration can also cause pregnancy failure in many species. However, little is known about the effector mechanisms involved. In this study, using an IFN-γ-induced abortion mouse model, we reported that no Dolichos biflorus agglutinin lectin-positive uterine natural killer (uNK) cells were observed in the uteri from IFN-γ-induced abortion mice. By contrast, the percentage of CD3⁻CD49b⁺ NK cells in the uterus and blood from a foetal resorption group was significantly higher than that of the control group. Similarly, significantly upregulated expression of CD49b (a pan-NK cell marker), CX3CL1 and CX3CR1 (CX3CL1 receptor) was detected in the uteri of IFN-γ-induced abortion mice. Using isolated uterine stromal cells, we showed that upregulated expression of CX3CL1 by IFN-γ was dependent on a Janus family kinase 2-signal transducers and activators of transcription 1 (JAK2-STAT1) pathway. We further demonstrated the chemotactic activity of CX3CL1 in uterine stromal cell conditioned medium on primary splenic NK cells. Finally, we observed increased recruitment of CD49b⁺ NK cells into the endometrium after exogenous CX3CL1 administration. Collectively, our findings indicate that IFN-γ can significantly increase uterine CX3CL1 expression via activation of the JAK2-STAT1 pathway, thus inducing CD49b⁺ NK cell uterine homing, and eventually provoke foetal loss. Thus, we provide a new line of evidence correlating the deleterious effects of IFN-γ on pregnancy with the aberrant regulation of CX3CL1 and CD49b⁺ NK cells.

High-dose interferon-γ promotes abortion in mice by suppressing Treg and Th17 polarization

As a classic type I cytokine, interferon-gamma (IFN-γ) is known to manifest a miscarriage-inducing effect, although the specific mechanism is still unclear. To determine whether immune cells such as regulatory T (Treg) and Th17 cells are involved in these abortions, syngeneically pregnant (BALB/c×BALB/c) mice were subjected to intravaginal IFN-γ administration (5 × 10(3) IU/mouse on D3 of gestation). These mice experienced significant fetal loss on D7/D8 of pregnancy, and a remarkable drop in the Treg cell ratio was observed in the peripheral blood and the spleen by flow cytometry. In situ detection of the uterine tissue peri-implantation revealed that IFN-γ treatment also caused statistically significant reductions in forkhead box P3, RAR-related orphan receptor gamma, and IL-17 levels, which indicated local decreases in Treg and Th17 cells at uterine implantation sites. The IFN-γ receptor alpha (IFN-γRα) level was also lowered in the uterus. These results demonstrate that in murine pregnancy, a supraphysiological dose of IFN-γ could induce peri-implantation failure. Moreover, in this study, the decreases in both Treg and Th17-type cells, which may be relevant to the role of IFN-γRα, may be one of the main reasons that IFN-γ causes abortion.

Mast cell-induced lung injury in mice infected with H5N1 influenza virus

Although an important role for mast cells in several viral infections has been demonstrated, its role in the invasion of highly pathogenic H5N1 influenza virus is unknown. In the present study, we demonstrate that mast cells were activated significantly by H5N1 virus (A/chicken/Henan/1/2004) infection both in vivo and in vitro. Mast cells could possibly intensify the lung injury that results from H5N1 infection by releasing proinflammatory mediators, including histamine, tryptase, and gamma interferon (IFN-γ). Lung lesions and apoptosis induced by H5N1 infection were reduced dramatically by treatment with ketotifen, which is a mast cell degranulation inhibitor. A combination of ketotifen and the neuraminidase inhibitor oseltamivir protected 100% of the mice from death postinfection. In conclusion, our data suggest that mast cells play a crucial role in the early stages of H5N1 influenza virus infection and provide a new approach to combat highly pathogenic influenza virus infection.

Effects of Thai medicinal herb extracts with anti-psoriatic activity on the expression on NF-κB signaling biomarkers in HaCaT keratinocytes

Psoriasis is a chronic inflammatory skin disorder characterized by rapid proliferation of keratinocytes and incomplete keratinization. Discovery of safer and more effective anti-psoriatic drugs remains an area of active research at the present time. Using a HaCaT keratinocyte cell line as an in vitro model, we had previously found that ethanolic extracts from three Thai medicinal herbs, namely Alpinia galanga, Curcuma longa and Annona squamosa, possessed anti-psoriatic activity. In the current study, we aimed at investigating if these Thai medicinal herb extracts played a molecular role in suppressing psoriasis via regulation of NF-κB signaling biomarkers. Using semi-quantitative RT-PCR and report gene assays, we analyzed the effects of these potential herbal extracts on 10 different genes of the NF-κB signaling network in HaCaT cells. In accordance with our hypothesis, we found that the extract derived from Alpinia galanga significantly increased the expression of TNFAIP3 and significantly reduced the expression of CSF-1 and NF-κB2. Curcuma longa extract significantly decreased the expression of CSF-1, IL-8, NF-κB2, NF-κB1 and RelA, while Annona squamosa extract significantly lowered the expression of CD40 and NF-κB1. Therefore, this in vitro study suggested that these herbal extracts capable of functioning against psoriasis, might exert their activity by controlling the expression of NF-κB signaling biomarkers.

Acute pyelonephritis during pregnancy changes the balance of angiogenic and anti-angiogenic factors in maternal plasma

OBJECTIVE

Angiogenic factors have been implicated in the pathophysiology of sepsis. In experimental models of sepsis (endotoxemia and/or cecal ligation puncture), there is increased expression of vascular endothelial growth factors (VEGF) and the administration of exogenous soluble VEGF receptor (sVEGFR)-1, an antagonist to VEGF, reduces morbidity and mortality. Moreover, a dramatic elevation in sVEGFR-1 has been demonstrated in human sepsis. Although a balance between angiogenic and anti-angiogenic factors is essential for feto-placental development, the changes of angiogenic factors during pregnancy in the context of infection have never been explored. Angiogenic factors also play crucial roles in the pathophysiology of preeclampsia (PE). This study was conducted to determine if maternal plasma concentrations of placental growth factor (PlGF), sVEGFR-2, and soluble endoglin (sEng) change in pregnancies complicated by acute pyelonephritis (AP) compared with normal pregnancy and PE.

STUDY DESIGN

A case-control study was conducted in patients with AP, normal pregnant (NP) women, and patients with PE (n=36 for each group) matched for gestational age. AP was diagnosed in the presence of fever (temperature >or=38 degrees C), clinical signs of infection, and a positive urine culture for microorganisms. Plasma concentrations of PlGF, sVEGFR-2, and sEng were determined by ELISA. The results of plasma sVEGFR-1 concentrations have previously been reported, but were included in this study to provide a complete picture of the angiogenic/anti-angiogenic profiles. Serum concentrations of interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, interferon (IFN)-gamma, granulocyte macrophage colony stimulating factor, and tumor necrosis factor (TNF) were also determined using high sensitivity multiplexed immunoassays in patients with AP and NP.

RESULTS

AP was associated with a lower median plasma concentration of PlGF and sVEGFR-2 than NP (both p<0.001). There were no significant differences in the median plasma concentrations of sEng and sVEGFR-1 between AP and NP (p=0.7 and 0.5, respectively). In contrast, there was a 5-fold decrease of the median plasma concentration of PlGF, and an 8-10-fold increase of the median plasma concentrations of sVEGFR-1 and sEng in PE compared with those in AP (all p<0.001). No significant difference in the median plasma concentration of sVEGFR-2 was observed between patients with PE and AP (p=0.5). Pregnant women with AP had median plasma concentrations of IL-6, IL-7, IL-8, IL-10, IFN-gamma, and TNF-alpha significantly higher than those in NP women (all p<0.001, except IL-7 p=0.004).

CONCLUSION

AP is associated with changes in the profile of angiogenic and anti-angiogenic factors. Although some of these changes resemble those in PE (decreased PlGF and sVEGFR-2), the magnitude of the changes of PlGF is much higher in PE. We conclude that despite high plasma inflammatory cytokine concentrations, acute systemic inflammation in pregnancy has a different angiogenic/anti-angiogenic profile than that of PE.

Gamma interferon signaling in macrophage lineage cells regulates central nervous system inflammation and chemokine production

Intracranial (i.c.) infection of mice with lymphocytic choriomeningitis virus (LCMV) results in anorexic weight loss, mediated by T cells and gamma interferon (IFN-gamma). Here, we assessed the role of CD4(+) T cells and IFN-gamma on immune cell recruitment and proinflammatory cytokine/chemokine production in the central nervous system (CNS) after i.c. LCMV infection. We found that T-cell-depleted mice had decreased recruitment of hematopoietic cells to the CNS and diminished levels of IFN-gamma, CCL2 (MCP-1), CCL3 (MIP-1alpha), and CCL5 (RANTES) in the cerebrospinal fluid (CSF). Mice deficient in IFN-gamma had decreased CSF levels of CCL3, CCL5, and CXCL10 (IP-10), and decreased activation of both resident CNS and infiltrating antigen-presenting cells (APCs). The effects of IFN-gamma signaling on macrophage lineage cells was assessed using transgenic mice, called "macrophages insensitive to interferon gamma" (MIIG) mice, that express a dominant-negative IFN-gamma receptor under the control of the CD68 promoter. MIIG mice had decreased levels of CCL2, CCL3, CCL5, and CXCL10 compared to controls despite having normal numbers of LCMV-specific CD4(+) T cells in the CNS. MIIG mice also had decreased recruitment of infiltrating macrophages and decreased activation of both resident CNS and infiltrating APCs. Finally, MIIG mice were significantly protected from LCMV-induced anorexia and weight loss. Thus, these data suggest that CD4(+) T-cell production of IFN-gamma promotes signaling in macrophage lineage cells, which control (i) the production of proinflammatory cytokines and chemokines, (ii) the recruitment of macrophages to the CNS, (iii) the activation of resident CNS and infiltrating APC populations, and (iv) anorexic weight loss.