The long-term survival of subjects with nonalcoholic fatty liver disease (NAFLD) in comparison with both individuals with elevated transaminases attributable to other causes and the general poulation is poorly characterized. This study was undertaken to determine the frequency of NAFLD in a cohort of subjects who underwent liver biopsy from 1980 to 1984 because of elevated liver enzymes, and to assess mortality among subjects with NAFLD in comparison with the general Swedish population. The 256 subjects (61% men) had a mean age of 45 ؎ 12 years at the inclusion. Liver biopsies were blindly scored for NAFLD and nonalcoholic steatohepatitis (NASH). Causes of death were ascertained from the national Swedish Cause of Death Registry.

Human cytomegalovirus (HCMV) infects cells by a series of processes including attachment, penetration via fusion of the envelope with the plasma membrane, and transport of the viral DNA to the nucleus. The details of the early events of HCMV infection are poorly understood. We have recently reported that CD13, human aminopeptidase N, a metalloprotease, is present on blood cells susceptible in vitro to HCMV infection (C.

Cytomegalovirus (CMV) infection has been suggested to be associated with certain autoimmune phenomena as well as with the development of chronic graft-versus-host disease (cGVHD) following allogeneic bone marrow transplantation. Earlier we found that the CMV-associated host protein CD13 is immunogenic during CMV infection in allogeneic bone marrow transplant patients, resulting in production of CD13-specific antibodies (7). Here we found a close correlation between CD13-specific immunity and later development of cGVHD in 26 of 33 patients who could be evaluated for this disease. Of seven patients with CMV disease, six developed extensive cGVHD, all of whom had CD13 specific antibodies (P=0.0002). All 14 patients who were CD13-immune later developed either limited or extensive cGVHD (P=0.0008). Antibodies in sera from the CD13-immune patients suffering from cGVHD recognized normal structures in cryosectioned skin biopsies from control individuals, producing a staining pattern similar to that of CD13-specific monoclonal antibodies. The antibody binding could be specifically blocked by preincubation of the skin sections with a mixture of monoclonal antibodies against CD13, and was also abolished after preabsorption of sera to mouse cells expressing human CD13. No other common autoantibodies were identified in more than single patients. Furthermore, in vivo binding of IgM antibodies in a CD13-like fashion was preferentially demonstrated in skin and oral mucosa biopsies from the CD13-immune patients suffering from cGVHD. Thus, we suggest that CMV-induced CD13-specific autoimmunity contribute to tissue damage in chronic graft-versus-host reactions.

Cytomegalovirus (CMV) infection has been suggested to be associated with various autoimmune manifestations, such as hemolytic anemia, granulocytopenia, and the formation of autoantibodies. Earlier we found that CMV is associated with a human protein, CD13 (aminopeptidase N), emanating from CMV-infected cells and serving an important function during CMV infection of susceptible cells. We hypothesized that CD13 might become immunogenic if presented to the immune system as a part of the CMV virion. The presence of CD13-specific antibodies was tested using a microcytotoxicity assay against CD13-positive human monocytes, or by flow cytometric assays against mouse cells transfected with human CD13; specificity was assessed by specific blocking with monoclonal antibodies. CD13 reactivity was also demonstrated in immunoprecipitation experiments. CD13-specific antibodies were identified in 15 of 33 bone marrow transplant patients, but exclusively in patients who had experienced either CMV disease (9/10) or CMV viremia (6/9), and appeared at the time of CMV detection. None of the remaining 14 patients without signs of CMV infection were positive for CD13 antibodies (P<0.0001). No antibody of this specificity was found in any of the control individuals (0/24), including patients with various autoimmune diseases, CMV-seropositive or -seronegative healthy individuals, and patients with acute EBV or HSV-1 infections. Thus, the CMV-associated autoantigen CD13 is immunogenic during CMV infection in bone marrow transplant patients. A specific response against autoantigens associated with infectious virus particles is suggested as a new and general mechanism to explain virus-induced autoimmune manifestations in man.

The identity of cells responsible for transmission of human cytomegalovirus (HCMV) in blood products or bone marrow transplants is unknown. We have tested the capacity of HCMV to in vitro infect human peripheral blood mononuclear cells (PBMC) from healthy donors and found that certain PBMC are permissive to HCMV infection. In vitro-infected viable cells were double stained for surface expression of different HMCV proteins and for cell-type-specific antigens to allow the identification of sensitive cells. All analysis were performed on viable cells, using HCMV-specific monoclonal antibodies and automated flow cytofluorimetry. PBMC were infected either with the laboratory-adapted HCMV strain AD169 or with a virus isolate obtained from a viremic patient. Up to 25% of all PBMC could express the major immediate-early antigen as well as the pp65 antigen, known as the lower matrix protein. Infected cells were mainly CD14+ monocytes, but also a small population of large CD8+ cells were susceptible to HCMV infection. CD19+ B lymphocytes were resistant to HCMV infection. Different populations of infected cells were enriched by using Dynabeads coated with cell-type-specific antibodies, and the presence of infectious virus was demonstrated by incubating the selected and sonicated cell material on human fibroblasts. Only material from infected monocytes and from CD3+ CD8+ cells gave rise to HCMV-specific plaques. The presence of HCMV mRNA as a sign of active viral transcription of the major immediate-early and late ppl50 genes in infected cells was demonstrated by using nested reversed polymerase chain reaction. A common denominator was found for all cells that could be infected with HCMV. The CD13 antigen, a 130to 150-kDa integral membrane protein identical to the enzyme aminopeptidase N, was expressed on all HCMV-permissive cells.

Mast cells (MCs) are powerful immune cells that mature in the peripheral tissues from bone marrow (BM)-derived mast cell progenitors (MCp). Accumulation of MCs in lung compartments where they are normally absent is thought to enhance symptoms in asthma. The enrichment of lung MCs is also observed in mice subjected to models of allergic airway inflammation. However, whether other types of lung inflammation trigger increased number of MCp, which give rise to MCs, is unknown. Here, mouse-adapted H1N1 influenza A was used as a model of respiratory virus infection. Intranasal administration of the virus induced expression of VCAM-1 on the lung vascular endothelium and an extensive increase in integrin β7hi lung MCp. Experiments were performed to distinguish whether the influenza-induced increase in the number of lung MCp was triggered mainly by recruitment or in situ cell proliferation. A similar proportion of lung MCp from influenza-infected and PBS control mice were found to be in a proliferative state. Furthermore, BM chimeric mice were used in which the possibility of influenza-induced in situ cell proliferation of host MCp was prevented. Influenza infection in the chimeric mice induced a similar number of lung MCp as in normal mice. These experiments demonstrated that recruitment of MCp to the lung is the major mechanism behind the influenza-induced increase in lung MCp. Fifteen days post-infection, the influenza infection had elicited an immature MC population expressing intermediate levels of integrin β7, which was absent in controls. At the same time point, an increased number of toluidine blue+ MCs was detected in the upper central airways. When the inflammation was resolved, the MCs that accumulated in the lung upon influenza infection were gradually lost. In summary, our study reveals that influenza infection induces a transient accumulation of lung MCs through the recruitment and maturation of MCp. We speculate that temporary augmented numbers of lung MCs are a cause behind virus-induced exacerbations of MC-related lung diseases such as asthma.

Great progress has been made in understanding the development of non-alcoholic fatty liver disease (NAFLD) but less is known about the mechanisms underlying the progress from steatosis to steatohepatitis (NASH). Our aim was to evaluate if the amount and type of storage of fat in hepatocytes is of importance for hepatocyte injury. We also wanted to show if not only the innate immunity but also the adaptive immunity is involved in NASH. Thirty-one patients with NASH or borderline NASH and 18 non-NASH patients were investigated. Liver biopsies were scored for NASH according to Kleiner et al. Paraffin-embedded liver biopsies were stained with antibodies against CD3, TLR4, CD68, Cleaved Caspase-3, ICAM1, Foxp3 and ApopTag by immunohistochemistry. Serum soluble ICAM-1 (sICAM-1) were analysed by ELISA. The volume density of fat was 59% in the NASH patients and microvesicular fat, increased in high NAS score patients. ICAM-1 positive hepatocytes were seen in NASH patients and were localized in areas with microvesicular fat. Non-NASH biopsies were negative for ICAM-1 positive hepatocytes. The sICAM-1 were significantly higher in NASH-patients (339.8 ± 34.07) than in non-NASH patients (229.5 ± 12.14), p = 0.0015. Patients with NAS score over four had higher area of CD68 positive cells p = 0.0011 and Foxp3 positive cells (p = 0.024) than non-NASH patients. In liver tissue with NASH, hepatocytes with microvesicular steatosis seem to be expressing more inflammatory markers, and in this liver tissue an increased number of CD68 cells and regulatory T-cells (Tregs, e.g. Foxp3+ cells) were seen, indicating an involvement of, both the innate and the adaptive immunity.

The mechanisms of inhibition of cytomegalovirus (CMV) infection by human CD13 (aminopeptidase N)-specific antibodies were studied. These antibodies protect CD13-negative and -positive cells from CMV infection only if incubated with the virus inoculum, suggesting they bind to CMV virions. The association of a CD13-like molecule with virions was further supported by the transfer of CD13 immunoreactivity to the surface of CD13-negative cells upon binding of CMV; the binding of CD13-specific antibodies directly to the surface of CMV virions; and the presence of anti-CD13 immunoreactive bands, including one with mobility similar to that of native cellular CD13 on immunoblots of proteins of purified CMV particles. Importantly, CD13-specific antibodies neutralize CMV in urine of neonates with congenital CMV, indicating that the CD13-like molecule is associated with natural CMV and not acquired in vitro. These studies demonstrate that a CD13-like molecule is associated with CMV particles and may be important in CMV pathogenesis.