In situ production of interleukin-6 within human lung allografts displaying rejection or cytomegalovirus pneumonia

SARS-CoV-2 superinfection in CD14+ monocytes with latent human cytomegalovirus (HCMV) promotes inflammatory cascade

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of coronavirus disease 2019 (COVID-19), has posed significant challenges to global health. While much attention has been directed towards understanding the primary mechanisms of SARS-CoV-2 infection, emerging evidence suggests co-infections or superinfections with other viruses may contribute to increased morbidity and mortality, particularly in severe cases of COVID-19. Among viruses that have been reported in patients with SARS-CoV-2, seropositivity for Human cytomegalovirus (HCMV) is associated with increased COVID-19 risk and hospitalization. HCMV is a ubiquitous beta-herpesvirus with a seroprevalence of 60-90 % worldwide and one of the leading causes of mortality in immunocompromised individuals. The primary sites of latency for HCMV include CD14+ monocytes and CD34+ hematopoietic cells. In this study, we sought to investigate SARS-CoV-2 infection of CD14+ monocytes latently infected with HCMV. We demonstrate that CD14+ cells are susceptible and permissive to SARS-CoV-2 infection and detect subgenomic transcripts indicative of replication. To further investigate the molecular changes triggered by SARS-CoV-2 infection in HCMV-latent CD14+ monocytes, we conducted RNA sequencing coupled with bioinformatic differential gene analysis. The results revealed significant differences in cytokine-cytokine receptor interactions and inflammatory pathways in cells superinfected with replication-competent SARS-CoV-2 compared to the heat-inactivated and mock controls. Notably, there was a significant upregulation in transcripts associated with pro-inflammatory response factors and a decrease in anti-inflammatory factors. Taken together, these findings provide a basis for the heightened inflammatory response, offering potential avenues for targeted therapeutic interventions among HCMV-infected severe cases of COVID-19. SUMMARY: COVID-19 patients infected with secondary viruses have been associated with a higher prevalence of severe symptoms. Individuals seropositive for human cytomegalovirus (HCMV) infection are at an increased risk for severe COVID-19 disease and hospitalization. HCMV reactivation has been reported in severe COVID-19 cases with respiratory failure and could be the result of co-infection with SARS-CoV-2 and HCMV. In a cell culture model of superinfection, HCMV has previously been shown to increase infection of SARS-CoV-2 of epithelial cells by upregulating the human angiotensin-converting enzyme-2 (ACE2) receptor. In this study, we utilize CD14+ monocytes, a major cell type that harbors latent HCMV, to investigate co-infection of SARS-CoV-2 and HCMV. This study is a first step toward understanding the mechanism that may facilitate increased COVID-19 disease severity in patients infected with SARS-CoV-2 and HCMV.

Current Understanding of Cytomegalovirus Reactivation in Critical Illness

Cytomegalovirus (CMV) reactivation has been described in adults with critical illness caused by diverse etiologies, especially severe sepsis, and observational studies have linked CMV reactivation with worse clinical outcomes in this setting. In this study, we review observational clinical data linking development of CMV reactivation with worse outcomes in patients in the intensive care unit, discuss potential biologically plausible mechanisms for a causal association, and summarize results of initial interventional trials that examined the effects of CMV prevention. These data, taken together, highlight the need for a randomized, placebo-controlled efficacy trial (1) to definitively determine whether prevention of CMV reactivation improves clinical outcomes of patients with critical illness and (2) to define the underlying mechanism(s).

Plasma and bronchoalveolar lavage samples in acute lung allograft rejection: the potential role of cytokines as diagnostic markers

The role of differential cytology patterns in peripheral blood and bronchoalveolar lavage samples is increasingly investigated as a potential adjunct to diagnose acute and chronic allograft dysfunction after lung transplantation. While these profiles might facilitate the diagnosis of acute cellular rejection, low sensitivity and specificity of these patterns limit direct translation in a clinical setting. In this context, the identification of other biomarkers is needed. This review article gives an overview of cytokine profiles of plasma and bronchoalveolar lavage samples during acute cellular rejection. The value of these cytokines in supporting the diagnosis of acute cellular rejection is discussed. Current findings on the topic are highlighted and experimental settings for future research projects are identified.

Aberrant expression of interleukin-6 and its receptor in Fallopian tubes bearing an ectopic pregnancy with and without tubal cytomegalovirus infection

Cytomegalovirus (CMV) has recently been suggested as a potential risk factor for the development of ectopic pregnancy (EP) following upper genital tract infection in women. However, little is known about its associated underlying pathogenic mechanisms. This was a prospective case-control study that measured the prevalence of CMV infection in Fallopian tubes (FT) bearing an EP and its effects on the tubal expression of interleukin (IL)-6 and its signaling molecules, which are known to play significant roles in the immune response against CMV infection as well as embryo implantation. Fresh FTs from 96 EPs during salpingectomy and another 61 women at the midluteal phase during total abdominal hysterectomy (TAH) were collected to measure the rate of CMV by an IVD CE PCR kit. The participants were then classified to measure the expression of IL-6, its receptor (IL6R) and intracellular mediators (gp-130, STAT3) by immunohistochemistry and quantitative RT-PCR. The results showed significantly higher (P = 0.01) rates of CMV in FTs obtained from EP (22.9 %) compared with controls (8.2 %). IL-6 (P = 0.003), IL6Rα (P = 0.02), gp 130 (P = 0.008) and STAT3 (P = 0.03) were significantly higher in TAH-positive (n = 5) compared with TAH-negative FTs by immunohistochemistry. Furthermore, the expression in the non-infected EP samples was significantly higher for IL-6 (P = 0.004), IL6R (P = 0.007), gp130 (P = 0.006) and STAT3 (P = 0.007) compared with negative TAH. Similar results were observed by quantitative PCR. CMV-positive EP samples showed the highest significant increase of the studied molecules by all techniques. In conclusion, Fallopian tubal infection with CMV is higher in EP and could predispose to embryo implantation by up-regulating the expression of IL-6 and its related molecules as part of tubal innate immune response. Further in vitro and in vivo studies are compulsory to illustrate the roles of IL-6 and CMV in the pathogenesis of EP.

Infectious Triggers of Chronic Lung Allograft Dysfunction

Survival after lung transplantation is limited in large part due to the high incidence of chronic rejection, known as chronic lung allograft dysfunction (CLAD). Pulmonary infections are a frequent complication in lung transplant recipients, due both to immunosuppressive medications and constant exposure of the lung allograft to the external environment via the airways. Infection is a recognized risk factor for the development of CLAD, and both acute infection and chronic lung allograft colonization with microorganisms increase the risk for CLAD. Acute infection by community acquired respiratory viruses, and the bacteria Pseudomonas aeruginosa and Staphylococcus aureus are increasingly recognized as important risk factors for CLAD. Colonization by the fungus Aspergillus may also augment the risk of CLAD. Fostering this transition from healthy lung to CLAD in each of these infectious episodes is the persistence of an inflammatory lung allograft environment.

Human cytomegalovirus-encoded pUL7 is a novel CEACAM1-like molecule responsible for promotion of angiogenesis

Persistent human cytomegalovirus (HCMV) infection has been linked to several diseases, including atherosclerosis, transplant vascular sclerosis (TVS), restenosis, and glioblastoma. We have previously shown that factors secreted from HCMV-infected cells induce angiogenesis and that this process is due, at least in part, to increased secretion of interleukin-6 (IL-6). In order to identify the HCMV gene(s) responsible for angiogenesis promotion, we constructed a large panel of replication-competent HCMV recombinants. One HCMV recombinant deleted for UL1 to UL10 was unable to induce secretion of factors necessary for angiogenesis. Fine mapping using additional HCMV recombinants identified UL7 as a viral gene required for production of angiogenic factors from HCMV-infected cells. Transient expression of pUL7 induced phosphorylation of STAT3 and ERK1/2 MAP kinases and production of proangiogenic factors, including IL-6. Addition of recombinant pUL7 to cells was sufficient for angiogenesis and was again associated with increased IL-6 expression. Analysis of the UL7 structure revealed a conserved domain similar to the immunoglobulin superfamily domain and related to the N-terminal V-like domain of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1). Our report therefore identifies UL7 as a novel HCMV-encoded molecule that is both structurally and functionally related to cellular CEACAM1, a proangiogenic factor highly expressed during vasculogenesis.

IMPORTANCE

A hallmark of cytomegalovirus (CMV) infection is its ability to modulate the host cellular machinery, resulting in the secretion of factors associated with long-term diseases such as vascular disorders and cancer. We previously demonstrated that HCMV infection alters the types and quantities of bioactive proteins released from cells (designated the HCMV secretome) that are involved in the promotion of angiogenesis and wound healing. A key proangiogenic and antiapoptotic factor identified from a proteomic-based approach was IL-6. In the present report, we show for the first time that HCMV UL7 encodes a soluble molecule that is a structural and functional homologue of the CEACAM1 proangiogenic cellular factor. This report thereby identifies a critical component of the HCMV secretome that may be responsible, at least in part, for the vascular dysregulation associated with persistent HCMV infection.

Increased HCMV seroprevalence in patients with hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common primary liver cancer, usually arising after years of chronic liver inflammation that could result from viral infections such as hepatitis B virus (HBV) and hepatitic C virus (HCV) infections. Human cytomegalovirus (HCMV) infects primary human hepatocytes and remains an important cause of morbidity in immunocompromised persons where it may manifest as symptomatic end-organ disease including hepatitis. The goal of the present study was to determine a potential correlation between HCMV infection and the appearance of HCC.

Methods

First, we analyzed the seroprevalence of HCMV in a cohort of 11,318 patients hospitalized between 2003 and 2009 in different departments of a French University Hospital. Second, we studied HCMV seroprevalence in a cohort of 190 subjects who were stratified on the basis of age, gender, HCC, cirrhosis (Cir), and the exposition to hepatotropic viruses (HCV, HBV). We further determined whether HCMV DNA was present specifically in tumour area in liver biopsies from HCC-positive patients by using nested PCR.

Results

We found that the HCMV seroprevalence was high in the Hepatology department. The HCMV seroprevalence was significantly higher in patients infected with HCV and/or HBV than in patients who were not infected by those later viruses (76.2% versus 56.5%, p < 0.001). The HCMV seroprevalence was significantly higher in patients with HCC (74%) and lower in patients without HCC (54% for HCC-/Cir+ patients, 57% for HCC-/Cir- subjects). We observed a positive correlation between serum IL-6 levels and HCMV seroprevalence in cirrhotic patients, but not in HCC patients. Serum IL-6 levels correlated positively with C-reactive protein (CRP) levels. Preliminary histological studies from liver biopsies from HCC-positive patients highlighted that HCMV DNA can be detected in tumour area of some of the patients studied.

Conclusions

Our results indicate that HCMV seroprevalence in patients with HCC is significantly higher than in patients without HCC, is positively correlated with serum IL-6 levels in cirrhotic patients, and is positively associated with the presence of other hepatotropic viruses such as HCV and HBV.

Paracrine inhibition of GM-CSF signaling by human cytomegalovirus in monocytes differentiating to dendritic cells

A primary HCMV infection or virus reactivation may cause severe disease in hosts with a deficient immune system. The virus can disturb both innate and adaptive immunity by targeting dendritic cell (DC) functions. Monocytes, the precursors of DCs in vivo (MoDCs), are the primary targets of HCMV; they can also harbor latent virus. The DCs generated from infected monocytes (CMV-MoDCs) have an altered phenotype and functional defects. We have shown that CMV-MoDCs do not secrete IL-12 in response to lipopolysaccharide stimulation, cannot ingest dead cells, induce T(H)1 differentiation, or the proliferation of naive allogeneic CD4(+) T cells. We found that the GM-CSF signaling in an entire population of CMV-MoDCs was impaired, although only half of the cells were productively infected, and that IL-6 secretion and suppressors of cytokine signaling 3 induction contributed to this bystander effect. We also showed that MoDCs derived ex vivo from monocytes of viremic patients had the same altered phenotype as CMV-MoDCs, including decreased STAT5 phosphorylation, indicating defective GM-CSF signaling. We have thus described a new mechanism of HCMV-induced immunosupression, indicated how infection may disturb both GM-CSF-dependent physiologic processes and proposed GM-CSF-based therapeutic approaches.

CMV in critically ill patients: pathogen or bystander?

Despite broad variability in study populations, methodologies for CMV detection, and analytic methods used, multiple studies have documented frequent CMV infection in non-immunocompromised adults with critical illness due to a variety of causes. Higher rates of CMV infection in studies of seropositive patients suggest that reactivation of latent infection rather than primary infection is the main mechanism in this setting. Risk factors for CMV reactivation (other than seropositivity) have not been clearly defined and there does not appear to be a consistent association with severity of illness. Furthermore, CMV reactivation in this setting has been associated with important adverse clinical outcomes, including increased duration of mechanical ventilation, longer length of stay and all-cause mortality. There are several biologically plausible mechanisms that could link CMV reactivation with adverse outcomes, including: direct lung injury (CMV pneumonia), amplification of inflammation systemically and within the lung, or predisposition to other nosocomial infections, but clinical data in the ICU setting are limited. Further observational studies are unlikely to significantly advance our understanding of the role of CMV in critically ill patients. Given the significant impact of critical illness, limited current therapeutic options, the availability of generally well-tolerated antiviral options for CMV, and the clinical data supporting a possible pathogenic role for CMV, there is a strong rationale for a randomised controlled trial of CMV prevention as a novel means of improving the outcomes of critically ill patients.

IL-6 in human cytomegalovirus secretome promotes angiogenesis and survival of endothelial cells through the stimulation of survivin

Human cytomegalovirus (HCMV) is linked to the acceleration of vascular diseases such as atherosclerosis and transplant vasculopathy. One of the hallmarks of these diseases is angiogenesis (AG) and neovessel formation. Endothelial cells (ECs) are an integral part of AG and are sites of HCMV persistence. AG requires multiple synchronous processes that include EC proliferation, migration, and vessel stabilization. Virus-free supernatant (secretome) from HCMV-infected ECs induces AG. To identify factor(s) involved in this process, we performed a human cytokine array. Several cytokines were significantly induced in the HCMV secretomes including interleukin-6 (IL-6), granulocyte macrophage colony-stimulating factor, and IL-8/CXCL8. Using in vitro AG assays, neutralization of IL-6 significantly reduced neovessel formation. Addition of the HCMV secretome to preformed vessels extended neovessel survival, but this effect was blocked by neutralization of IL-6. In these cells, IL-6 prevented apoptosis by blocking caspase-3 and -7 activation through the induction of survivin. Neutralization of IL-6 receptor on ECs abolished the ability of HCMV secretome to increase survivin expression and activated effector caspases. Moreover, survivin shRNA expression induced rapid regression of tubule capillary networks in ECs stimulated with HCMV secretome and activated effector caspases. These observations may explain how CMV accelerates vascular disease despite limited infection in tissues.

Posttranscriptional suppression of interleukin-6 production by human cytomegalovirus

Human cytomegalovirus (HCMV) has evolved multiple strategies for suppression of the antiviral response of the infected cell. DNA array technology has revealed that HCMV clearly regulates host gene expression during the course of a productive infection by enhancing, sustaining, or suppressing steady-state levels of cellular transcripts. Interleukin-6 (IL-6) is a pleiotropic cytokine that plays a central role in the immune response to infection. Here we report a detailed study of the effects of HCMV infection on IL-6 expression by human fibroblasts. UV-inactivated virus was found to induce high levels of IL-6 mRNA and protein expression, and IL-6 mRNA remained abundant in cells 16 h after inoculation even though the level of ongoing IL-6 transcription was not significantly enhanced. In lytic HCMV infections, the onset of viral gene expression resulted in two apparently antagonistic effects on IL-6 expression: (i) transcriptional activation, mediated at least in part by the IE2p86 protein, and (ii) posttranscriptional suppression mediated by destabilization of IL-6 mRNA. Transcriptional activation was outweighed by the suppressive effect, such that cells undergoing productive infection produced less IL-6 than cells challenged with inactivated virus. Suppression of IL-6 expression was independent of the viral IL-10 homologue, cmvIL-10. Destabilization of IL-6 mRNA was observed to coincide with the enhanced expression and aberrant intracellular localization of HuR, an mRNA-binding protein known to interact with IL-6 and other mRNAs containing 3' AU-rich elements. Our data suggest a novel mechanism for gene regulation by HCMV at the posttranscriptional level.

Interleukin-6 and interferon-gamma gene polymorphisms in the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

A number of genetic polymorphisms have been shown to regulate the production and secretion of tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, interferon (IFN)-gamma, interleukin (IL)-6, and IL-10. Several of these genetic polymorphisms have been shown to be associated with either acute or chronic rejection of kidney, liver, and heart allografts and with development of allograft fibrosis after lung transplantation. The aim of this study was to assess the effect of these genetic polymorphisms on the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

Genetic polymorphisms were detected by means of polymerase chain reaction in 93 lung allograft recipients for functional polymorphisms in the TNF-alpha (-308), TGF-beta1 (+869 and +915), IL-6 (-174), IFN-gamma (+874), and IL-10 (-1082, -819, and -592) genes. Then, a correlation between BOS development and the presence of these cytokine genotypes was determined using Kaplan-Meier actuarial analysis.

RESULTS

A significant correlation was detected between the presence of high-expression polymorphisms of the IL-6 and IFN-gamma genes and BOS development after lung transplantation (P =0.045 and 0.039, respectively). Also, patients with high-expression polymorphisms in both genes developed BOS significantly earlier than patients with low-expression polymorphisms in one or both genes, suggesting a synergistic effect of the alleles during BOS pathogenesis (P =0.016). No correlation was detected between polymorphisms of the TNF-alpha, TGF-beta1, and IL-10 genes and development of BOS after lung transplantation.

CONCLUSIONS

The presence of high-expression polymorphisms at position -174 of the IL-6 gene and position +874 of the IFN-gamma gene significantly increases the risk for BOS development after lung transplantation.

Association of cytokine single nucleotide polymorphisms with B7 costimulatory molecules in kidney allograft recipients

African-American race is associated with an increased risk of allograft loss, suggesting that African-American patients may form an immunologically higher risk group. Previously, we demonstrated that immune cell costimulatory molecule expression is significantly higher in African-Americans than in Caucasians. Polymorphic variations in the genes for cytokines have been associated with a number of immunological conditions, and with transplant rejection. This study was performed to determine the distribution, in African-American and Caucasian renal transplant recipients, of single nucleotide polymorphisms (SNPs) in the following cytokine genes: tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL)-6, IL-10, and transforming growth factor-beta (TGF-beta). Cytokine production from blood cells was determined, and cell-surface B7 (CD80, CD86) expression was measured. There was a significant link between IL-10 genotype and acute rejection episodes, but only in African-American patients (p < 0.01). Also, African-American patients had a significantly higher probability of having the IL-6 G-allele (p < 0.0001), which is associated with a high production of IL-6 protein. Incubation of blood cells with IL-6 resulted in increased expression of surface CD80 and CD86, while IL-10 decreased CD80 expression. This study demonstrated a clear correlation of the IL-6 G-allele with increased cellular CD80 expression and the IL-10 G-allele with decreased CD80 expression. These data raise the possibility that specific genotypes are associated with local cytokine regulation of cell-surface costimulatory molecule expression. African-American patients may have a genetically determined, quantitatively different immune response than Caucasian patients, contributing to adverse transplant outcomes.

Eosinophilic granulocytes and interleukin-6 level in bronchoalveolar lavage fluid are associated with the development of obliterative bronchiolitis after lung transplantation

In a prospective cohort study, we assessed whether changes in total cell counts and differentiation and interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein-1 (MCP-1) concentrations in bronchoalveolar lavage fluid (BALF) are associated with a higher risk to develop obliterative bronchiolitis (OB). We investigated 60 lung transplant patients (follow-up of 2 to 8 yr) with either histologic evidence of OB within 1 yr after lung transplantation (n = 19) or no pathology, good outcome (GO) for at least 24 mo and well-preserved lung function, i.e., FEV > or = 80% of baseline (n = 41). Median time between lung transplantation and the first BAL was 42 d for the GO group and 41 d for the OB group (p > 0.05). In the bronchial fraction, median total cell counts (0.06 x 10(3)/ml versus 0.04 x 10(3)/ml), lymphocyte (9 x 10(3)/ml versus 2 x 10(3)/ml), and eosinophilic granulocyte counts (1 x 10(3)/ml versus 0) were significantly higher in the OB group than in the GO group (p < 0.05). In the alveolar fraction, this was the case for the median value of neutrophilic granulocyte counts (19 x 10(3)/ml versus 4 x 10(3)/ml), respectively. Median values of IL-6 and IL-8 concentrations in both bronchial (IL-6: 23 versus 6 pg/ml, IL-8: 744 versus 102 pg/ml) and alveolar fractions (IL-6: 13 versus 3 pg/ml, IL-8: 110 versus 30 pg/ml) of the BALF were significantly higher in the OB group than in the GO group. By means of logistic regression, we showed that higher total cell, neutrophilic granulocyte, and lymphocyte counts, the presence of eosinophilic granulocytes, and higher concentrations of IL-6 and IL-8 were significantly associated with an increased risk to develop OB. We conclude that monitoring cell counts, neutrophilic and eosinophilic granulocytes, IL-6, and IL-8 in BALF within 2 mo after lung transplantation in addition to the transbronchial lung biopsy (TBB) pathology will contribute to a better identification and management of the group of patients at risk for developing OB within a year.

Increased expression of inflammatory cytokines and adhesion molecules by alveolar macrophages of human lung allograft recipients with acute rejection: decline with resolution of rejection

BACKGROUND

Alveolar macrophages (AM) are the major population in bronchoalveolar lavage (BAL) cells; we assessed their role in human lung allograft recipients by correlating the expression of adhesion molecules and inflammatory cytokines with clinical outcome of allograft.

METHODS

We obtained BAL samples from patients and enriched them for AM in plastic petri dish for 2 hours at 37 degrees C in 5% CO(2). Expression of intercellular adhesion molecule-1 (ICAM-1, CD54), platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31), and CD11c was assessed by flow cytometry using monoclonal antibodies. We assessed cytokine profile using Multi-Probe RNase protection assay.

RESULTS

Alveolar macrophages that express CD11c, CD31 and CD54 were increased in patients with either rejection or infection compared with those without rejection and infection. The difference in the percentage of AM expressing CD11c and CD31 between the rejection group and patients without rejection and infection group was statistically significant (CD11c, p < 0.01; CD31, p < 0.03). Interleukin (IL)-1 alpha, IL-1 beta, IL-1 receptor antagonist (IL-1Ra), and IL-6 expression was higher in the rejection group than in patients without rejection. Five out of 9 patients in the rejection group expressed high levels of IL-15 and tumor necrosis factor-alpha compared with patients without rejection and infection. The increased number of AM expressing adhesion molecules and elevated expression of cytokines observed during acute rejection declined to basal levels after successful treatment and resolution of rejection. This study demonstrates that lung allograft rejection is associated with increased expression of adhesion molecules and inflammatory cytokines by AM, which could facilitate mononuclear cell adhesion and extravasation contributing to the allograft injury in lung transplant recipients.

Bronchoalveolar lavage in lung transplantation. State of the art

Fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) has become a crucial tool in the management of lung transplant recipients. Detection of pulmonary infectious pathogens by culture, cytology, and histology of BAL, protected brush specimens, and transbronchial biopsies (TBB) is highly effective. Morphologic and phenotypological analyses of BAL cells may be suggestive for certain complications after lung transplantation. For interpretation of BAL findings, the natural course of BAL cell morphology and phenotypology after lung transplantation must be considered. During the first 3 months after pulmonary transplantation, elevated total cell count in BAL and neutrophilic alveolitis are common, representing the cellular response to graft injury and interaction of immunocompetent cells of donor and recipient origin. With increasing time after transplantation the CD4/CD8 ratio decreases due to lowered percentages of CD4 cells in BAL. During bacterial pneumonias, the cellular profile of BAL is characterized by a marked granulocytic alveolitis. Lymphocytic alveolitis with a decreased CD4/CD8 ratio is suggestive of acute rejection, but is also found in viral pneumonias and obliterative bronchiolitis. In the case of a combined lymphocytosis and neutrophilia without any evidence of infection, obliterative bronchiolitis should be considered. Functional analyses of BAL cells can give additional information about the immunologic status of the graft, even before histologic changes become evident but have not been established in routine transplant monitoring. However, functional studies suggest an important role of activated, alloreactive and donor-specific T lymphocytes in the pathogenesis of acute and chronic lung rejection. Investigations of soluble components in BAL have given further insight into the immunologic processes after lung transplantation. In this overview, the characteristics of BAL after lung transplantation will be summarized, and its relevance for the detection of pulmonary complications will be discussed.

Bronchiolitis obliterans: pathogenesis, prevention, and management

Increasing early success-post lung transplant has been tempered by the long-term development of histologic bronchiolitis obliterans (OB) or of the progressive airway obstruction which is called bronchiolitis obliterans syndrome (BOS). Multiple lines of evidence suggest that OB/BOS is due to an injury directed against the epithelial cells in the airways of the donor lung by the immune system of the recipient. Acute rejection is the strongest risk factor for the subsequent development of this process. Efforts to prevent or minimize acute rejection may reduce the prevalence of OB/BOS. Results of treatment with augmented immunosuppression have been disappointing but the treatment of complicating infections in the allograft can be beneficial. Multicenter studies are needed to assess the efficacy of new immunosuppressive agents in preventing or treating OB/BOS.

Cytomegalovirus infection in the liver transplant recipient. Epidemiology, pathogenesis, and clinical management

The effects of cytomegalovirus (CMV) on the liver transplant patient can be divided into two general categories: the direct infectious disease effects (e.g. CMV mononucleosis, hepatitis, pneumonitis, GI infection) and the indirect effects that are mediated by cytokines elaborated as a consequence of the infection. These indirect effects include an immunosuppressive effect that contributes to the development of superinfection with fungi, bacteria, and Pneumocystis carinii; a role in the pathogenesis of allograft injury; and a role in the development of post-transplant lymphoproliferative disease. The two key steps in the pathogenesis of CMV infection-reactivation of the virus from latency and systemic spread-are modulated by the immunosuppressive therapy administered. New antiviral programs, primarily those involving ganciclovir, have resulted in considerable progress in the prevention and treatment of CMV disease among liver transplant recipients.

Expression of ICAM-1 and TNF alpha in human alveolar macrophages from lung-transplant recipients

Local activation of macrophages may play an important role in the immune process of pulmonary infections and in the inflammatory response of lung allograft rejection. To document macrophage activation within human lung allografts displaying various complications, we have investigated ICAM-1 expression in freshly isolated alveolar macrophages (AM) from lung-transplant recipients by immunocytofluorimetric analysis, and rIFN gamma induced in vitro by ELISA. A total of 21 bronchoalveolar lavage fluids (BAL) from 13 transplanted patients displaying no complication, acute rejection, bacterial/fungal infection, or CMV infection entered the study. ICAM-1 was expressed at a higher level in rejecting patients. Surprisingly, TNF alpha release from AM upon in vitro activation was significantly decreased during rejection. Furthermore, we have studied the effects of the glucocorticoid dexamethasone, the key drug for the treatment of allograft rejection, on the expression of ICAM-1 and TNF alpha induced in vitro in AM, at the levels of protein production and of transcription. Whereas dexamethasone did not influence ICAM-1 expression in AM, it downregulated TNF alpha production at least in part at the transcriptional level. Our results suggest strongly that the anti-inflammatory effects of corticosteroids are not related to ICAM-1 modulation on human AM but to the downregulation of the proinflammatory cytokine TNF alpha that is produced early in the inflammatory process. Moreover, our model of human AM activation induced in vitro by rIFN gamma appears a useful tool for in vitro investigation of the cellular and molecular targets of anti-inflammatory drugs for a more appropriate use.

Cytomegalovirus modulates interleukin-6 gene expression

Complications after lung transplantation include the development of rejection and an increased incidence of infection, particularly with cytomegalovirus (CMV). Several recent studies have suggested that interleukin (IL)-6 may be used to detect both infection and rejection after lung transplantation. In addition, IL-6 may play a role in the development of bronchiolitis obliterans after transplantation. Because CMV is also associated with the development of bronchiolitis obliterans after transplantation, we determined whether CMV induces IL-6 gene expression. We demonstrated that CMV infection increased both IL-6 protein and mRNA in peripheral blood mononuclear cells. We also demonstrated that the CMV immediate early 1 gene product increased expression of the IL-6 promoter. This effect of the CMV immediate early 1 gene product was dependent upon the presence of specific transcription factor binding sites in the IL-6 promoter. These studies demonstrate that CMV may be an important cofactor in the development of rejection and infection after transplantation through its effects on IL-6.

Development of monoclonal gammopathy precedes the development of Epstein-Barr virus-induced posttransplant lymphoproliferative disorder

Epstein-Barr virus (EBV)-induced posttransplant lymphoproliferative disorder (PTLD) develops in 3% to 10% of solid organ transplant recipients with a resultant mortality of up to 70%. Unfortunately, there is no current marker which identifies patients who will develop this disease. We therefore conducted a risk factor analysis of variables that might predict the development of PTLD. Specifically, since EBV may cause both PTLD and the development of monoclonal proteins (M protein), we sought to determine if the development of an M protein preceded and therefore might serve as a predictive marker of subsequent PTLD. Before and after liver transplantation, 201 patients were evaluated for the presence of urine and serum M proteins. Patients were followed to monitor the development of PTLD for a mean of 1,733 days. PTLD developed in seven patients (3.5%), three (43%) of whom died from disseminated PTLD. PTLD was classified as polymorphous in six patients and monomorphous in one patient. Fifty-seven patients (28%) developed an M protein after transplantation: five of seven patients (71%) with PTLD and 52/194 (27%) of patients without PTLD. Multivariate risk factor analysis for the development of an M protein after transplantation identified cytomegalovirus (CMV) donor seropositivity (P = 0.0002) and postoperative symptomatic CMV infection (P = 0.019) as risk factors. Whereas EBV serostatus of either the donor or recipient was not found to be a risk factor for the occurrence of either an M protein or PTLD, the development of a serum immunoglobulin M (IgM) M protein (P = 0.04) and of any urine M protein (P = 0.01) was identified by univariate analysis as being associated with the development of PTLD. Further studies are needed to determine the predictive value of M proteins as a marker for PTLD. Until such time, the development of serum or urine M protein should heighten the suspicion of developing PTLD.

Interleukin 6 (IL-6) levels in the monitoring of surgical trauma. A comparison of serum IL-6 concentrations in patients treated by cholecystectomy via laparotomy or laparoscopy

Interleukin 6 (IL-6) is involved in the processes of inflammation and tissue repair. We have been looking for the correlation between IL-6 concentration in patient's serum and the other factors related to the gravity of surgical trauma. Out of 25 patients with acute cholecystitis, 11 were randomly selected for laparoscopic cholecystectomy and the other 14 for open (laparotomic) cholecystectomy. The diagnostic and prognostic factors, age, and duration of disease did not differ significantly in either group. IL-6 serum levels were monitored by using commercially available ELISA tests throughout 72 h following the surgery. In patients who underwent laparoscopy, average IL-6 serum levels were significantly (up to fourfold) lower than in their laparotomy-treated counterparts, and the monitoring of IL-6 serum levels seems to be useful in the evaluation of the extent of trauma caused by surgery.

Human cytomegalovirus infection induces transcription and secretion of transforming growth factor beta 1

Human cytomegalovirus (CMV) infection can elicit a transitory, but profound, immunodepression in immunocompetent individuals. Cytopathogenic destruction of CMV-infected leukocytes alone does not seem sufficient to explain this phenomenon, which suggests that immune system mediators (cytokines) may play a role in amplifying local modifications wrought by CMV infection. We reported previously that transforming growth factor beta 1 (TGF-beta 1) stimulates CMV replication (J. Alcami, C. V. Paya, J. L. Virelizier, and S. Michelson, J. Gen. Virol. 74:269-274, 1993). Since TGF-beta 1 can have profound negative effects on cell growth and immune responses, we investigated the induction of TGF-beta 1 following CMV infection of permissive fibroblasts. TGF-beta 1 promoter was activated by immediate-early (IE) proteins in the absence of infection and transactivated at 5 and 9 h after infection. TGF-beta 1 mRNA increased during the early phase of infection, suggesting that this phenomenon is due to enhanced transcription of the TGF-beta 1 gene. A comparative study of the influence of CMV infection and IE protein expression on TGF-beta 1 promoter function in permissive cells pointed to a possible cooperative role between IE proteins and protein(s) expressed during the early phase of viral infection. Induction of TGF-beta 1 by CMV infection could modify infected cells individually, surrounding tissues, and systemic immune reactions to the advantage of virus replication by both upregulating CMV replication and downregulating host immune responses.