Inhibition of human hemopoiesis by non-A, non-B hepatitis virus

Hematopoietic stem cell mobilization into the peripheral circulation in patients with chronic liver diseases

OBJECTIVE

The present study was aimed to investigate and compare the kinetics of bone marrow-derived hematopoietic stem cells (BMHSC) migration in the peripheral blood and liver in response to liver injury in patients with chronic liver disease (CLD).

METHODS

In all, 45 CLD patients staged with Child-Pugh A, B and C and 15 healthy participants were evaluated for the concentration of circulating BMHSC by a flow cytometric analysis of CD133(+) /CD34(+) cells. In addition, homing BMHSC and hepatic progenitors were assessed by the immunohistochemical detection of CD133(+) and OV6(+) cells in liver biopsy specimens from Child-Pugh A and B patients.

RESULTS

No significant difference in the percentage of circulating CD133(+) /CD34(+) cells was observed among all groups of patients. In liver tissues, OV6(+) cells increased significantly in Child-Pugh B cases (P < 0.05), while CD133(+) cells were distributed sparsely in the periportal region in Child-Pugh A and B patients. OV6(+) cells were significantly correlated with CD34(+) cells but not with CD133(+) cells in Child-Pugh A and B patients (P < 0.01 and P < 0.05, respectively).

CONCLUSIONS

Various degrees of severity in CLD neither evoked the mobilization of BMHSC into the circulation nor triggered their homing into liver tissue, thus excluding extrahepatic stem cell-mediated repair. The recovery process seems to be dependent on proliferating endogenous liver progenitors (OV6(+) cells).

Recombinant human interleukin-11 improves thrombocytopenia in patients with cirrhosis

To elucidate the hematopoietic activity of recombinant human interleukin-11 (rhIL-11, [Neumega, Cambridge, MA]) in patients with cirrhosis and thrombocytopenia, we administered rhIL-11 at 50 microg/kg/d subcutaneously to 10 patients for 10 days with a 30-day follow-up period. All treated patients (n = 9) experienced a gradual, yet significant increase in their platelet count above the baseline value (P < or =.01) reaching the peak value (median, 93,000/microL; range, 60,000-206,000/microL) at a median of 13 days (range, 6-23 days). Eight patients (89%) had a significant increase of > or =50% over the baseline value (P <.05). Moreover, further increases to > or =60,000/microL, > or =80,000/microL, and > or =100,000/microL were observed in 100%, 78%, and 33% of the patients, respectively. A subsequent decline in platelet count was observed at a median of 19 days (range, 7-26 days) after the occurrence of peak concentration. A significant increase in neutrophil count was also demonstrated starting on the third day of treatment (P < or =.01). Concurrent with an increase in the serum level of fibrinogen, transaminase levels declined significantly during treatment period, while bilirubin levels continued to drop for up to 20 days after the initiation of treatment (P <.05). The most frequent effects were due to plasma volume expansion, including conjunctival redness and edema. In conclusion, rhIL-11 can improve platelet counts in patients with early cirrhosis and these patients could benefit from rhIL-11 treatment. However, given the high frequency of regimen-related toxicity, the use of rhIL-11 in patients with cirrhosis should be administered with caution.

Bone marrow B cell apoptosis during in vivo influenza virus infection requires TNF-alpha and lymphotoxin-alpha

Suppression of bone marrow myeloid and erythroid progenitor cells occurs after infection with a variety of different viruses. In this study, we characterize the alterations in bone marrow (BM) lymphocytes after influenza virus infection in mice. We found a severe loss of BM B cells, particularly CD43(low/-)B220(+) pre-B and immature B cells, in influenza virus-infected mice. Depletion of BM B lineage cells resulted primarily from cell cycle arrest and most likely apoptosis within the BM environment, rather than from increased trafficking of BM emigrants to peripheral lymphoid tissues. Use of gene-knockout mice indicates that depletion of BM B cells is dependent on TNF-alpha, lymphotoxin-alpha, and both TNF receptors, TNFR1-p55 and TNFR2-p75. Thus, TNF-alpha and lymphotoxin-alpha are required for loss of BM B lineage cells during respiratory infection with influenza virus.

Erythrocytes: Anemias in Chronic Liver Diseases

Anemia is a frequently observed manifestation during the clinical course of chronic liver disease. In this study, we retrospectively reviewed the hospital files of 500 chronic liver disease patients and assessed the frequency, etiology and morphology of anemia in 50 patients who fulfilled the criteria to be included in the study. The mean age of the patients was 48+/-16 years and male/female ratio was 1.4/1. The mean hemoglobin value was 9.54+/-2.03 g/dl. The mean MCV was 82.9+/-10.52 fl. Iron deficiency anemia, defined as absent bone marrow iron stores, was the most common anemia present in 50% of patients. Classical laboratory criteria used in the diagnosis of iron deficiency anemia (MCV < 80 fl, ferritin < 10 ng/ml) could not be applicable to all of the patients with iron deficiency anemia and hepatic disorders. Hemolytic anemia due to hypersplenism was the second most common anemia (24%) followed by anemias, namely anemia due to gastrointestinal hemorrhage (22%), anemia of chronic disease (8%), beta-thalassemia major (8%), folate deficiency (6%), vitamin B12 deficiency (4%), macrocytic anemia (2%), aplastic anemia (2%) and immune hemolytic anemia (2%). Twenty-eight percent of the patients had more than a single cause of anemia. Morphologically, microcytic anemia was the most common seen in 46% of the patients followed by normocytic (42%) and macrocytic anemia (12%). As patients do not always present with classical laboratory findings and may have more than a cause of anemia, a complex diagnostic approach should be considered in anemic patients with hepatic disorders.

Hepatitis B virus differentially suppresses myelopoiesis and displays tropism for immature hematopoietic cells

The hematopoietic cell lines HL-60 and THP-1 were challenged with hepatitis B virus (HBV) in vitro to study interactions between the virus and host cell. Exposure to HBV suppressed the ability of HL-60 cells to differentiate into granulocytes after treatment with retinoic acid (RA) or dimethyl sulfoxide (DMSO), and RA-induced activation of the monocytic cell line THP-1 was also suppressed. Terminal differentiation of both cell lines by phorbol 12-myristate 13-acetate (PMA) was not affected by HBV. The suppressive effect on RA- or DMSO-induced differentiation was unique to HBV, since cell exposure to human cytomegalovirus, another virus that inhibits hematopoiesis, failed to block cellular differentiation. At 5 days postinfection, extracellular viral DNA was detected in immature but not in differentiated cultures and higher levels of core antigen (HBcAg) and surface antigen (HBsAg) were seen in undifferentiated cells than in RA- or PMA-treated cells. In addition, release of HBsAg into the medium was 2 to 12 times greater in untreated cultures than for RA- or PMA-treated cells. Thus, HBV suppresses hematopoiesis by blocking the maturational development of progenitors and selectively infects immature myeloid cells compared with mature end-stage cells.

Reduced production of immunoreactive interleukin-1 by peripheral blood monocytes of patients with acute and chronic viral hepatitis

The in vitro production of interleukin-1 beta by peripheral blood monocytes derived from patients with various liver diseases was studied. An impaired production of immunoreactive interleukin-1 (IL-1) (mean +/- SEM) by monocytes stimulated with an optimal dose (100 ng/ml) of lipopolysaccharide was observed in patients with chronic hepatitis B (N = 13; 32 +/- 6 pg/ml) or chronic hepatitis C (N = 13; 61 +/- 12 pg/ml) as compared to those of healthy control individuals (N = 35; 166 +/- 24 pg/ml; P = 0.0003 and P = 0.015, respectively), whereas an unaltered IL-1 production was seen in patients with alcoholic cirrhosis (N = 23; 125 +/- 28 pg/ml) and primary biliary cirrhosis (N = 6; 111 +/- 33 pg/ml). Similar to the situation seen in chronic viral hepatitis, lipopolysaccharide-stimulated monocytes from patients with acute hepatitis also showed a decreased IL-1 production in the first week after onset of jaundice (N = 17; 55 +/- 20 pg/ml; P = 0.001) and a return to normal in the second and third week. An impaired production of IL-1 in chronic as well as acute viral hepatitis is a further example of the known disturbed immunoregulation in this disease.

Severe aplastic anemia associated with seronegative community-acquired hepatitis C virus infection

Aplastic anemia (AA) is a rare complication of viral hepatitis affecting mainly children or young adults. Most reported cases have been associated with community-acquired non-A, non-B hepatitis, but hepatitis A and B have also been implicated in a few patients. We report on a 43-year-old woman with severe AA, in association with acute hepatitis C virus (HCV) infection, diagnosed by detection of HCV RNA by the polymerase chain reaction technique. Her AA was successfully treated with anti-thymocyte globulin and cyclosporin A. The hepatitis C progressed to chronic disease but, despite a follow-up time of 2 years, the patient still has no detectable anti-HCV antibodies, as evaluated with a second-generation anti-HCV assay.

Infection of a leukemic cell line (K562) by hepatitis B virus induces cell growth inhibition

Hepatitis B virus inhibits the in vitro growth of the human leukemic cell line K562; however, the mechanism of this growth inhibition is not understood. One to 12 days after exposure, viral DNA and RNA were detected in K562 cells by Southern blot and reverse-transcriptase polymerase chain reaction analyses. Virus-containing serum that was heat-inactivated failed to inhibit cell growth and no viral DNA or RNA was detected in these cells. In addition, murine monoclonal antibodies directed to hepatitis B virus surface epitopes neutralized the virus-induced growth inhibition whereas antibodies to hepatitis B virus core epitopes failed to suppress the inhibition. These results indicate that in vitro infection of K562 cells by hepatitis B virus causes inhibition of hematopoietic cell line growth.

Myelopoiesis in vitro is suppressed by hepatitis A virus

Perturbations of hematopoietic regulation ranging from transient granulocytopenia to rare cases of bone marrow failure are associated with infections due to hepatitis A virus (HAV). In an attempt to elucidate the pathogenetic mechanisms we had previously established that HAV has a direct suppressive effect on human bone marrow progenitors (CFU-GM, -GEMM, BFU-E). These studies were extended to long-term bone marrow cultures (LTBMC): Inoculation of bone marrow mononuclear cells with HAV did not interfere with the establishment of an adherent stromal layer, nor did the inoculation of already established layers cause any morphologically recognizable changes to the stroma. In contrast, a significant and progressive decline of the CFU-GM content in the culture supernatants was demonstrated. HAV antigen was detected by APAAP stain in a subpopulation of stromal cells, and sequential estimations of virus titers in the supernatants provided evidence for viral replication in primary bone marrow cultures. Interferon-gamma and tumor necrosis factor-alpha levels of infected cultures did not differ from those of uninfected controls. These findings argue for a direct suppression of (pre-) CFU-GM by HAV in a model system (LTBMC) lacking an immune defense which would limit viral replication.

Therapeutic response of chronic active hepatitis B (CAHB) to a new immunomodulator: AM3. Immunohematological effects

AM3, a biological response modifier (BRM) of polysaccharide/protein nature, was given by the oral route to 13 patients with chronic active hepatitis B (CAHB). After 12 months of daily treatment, 8 patients cleared serum HBV-DNA and HBeAg together with ALT normalization. Immunohaematologic studies showed how time of inhibition of viral replication was related to significant decreases of CD4, CD8 and B cell blood lymphocytes. After serum viral elimination, however, a significant haematologic rebound of peripheral blood mononuclear cells (PMNC): CD3, CD4 and CD8 lymphocytes was seen. These data, suggest that the antiviral activities of AM3 may be due to its immunodulatory capacities. These promising results, together with the absence of any side effects, justify the entry to trials with a larger number of patients. Furthermore, treatment with AM3 may help to elucidate the pathophysiology of CAHB.

Viruses and bone marrow failure

Many agents are associated with bone marrow failure, including toxins, inherited metabolic defects, ionizing radiation, and viral infection. In most cases, the etiologic agent is unknown. Many of these unclassified cases have symptomatic, immunologic, or epidemiologic similarities to viral infections. Viruses from different taxonomic families have been implicated in bone marrow failure syndromes, and they appear to cause hematosuppression by a variety of mechanisms. Some of the viruses involved in relatively well characterized suppressive interactions will be reviewed, including parovovirus B19, dengue, hepatitis viruses, Epstein-Barr virus, cytomegalovirus and the human immunodeficiency virus.

In vitro suppression of normal human bone marrow progenitor cells by human immunodeficiency virus

Incubation of normal human nonadherent and T-cell-depleted bone marrow cells with HIVIIIB at multiplicities of infection (MOI) ranging from 0.0001:1 to 1:1 reverse transcriptase (RT) units resulted in the dose-dependent suppression of the in vitro growth of erythroid burst-forming unit (BFU-E), granulocyte-macrophage (CFU-GM), and T-lymphocyte (CFU-TL) colonies of progenitor cells. Maximum inhibition of colony formation was observed at a 1:1 ratio of virus to bone marrow cells. At this MOI, BFU-E and CFU-GM colonies were inhibited by 60 to 80%, while CFU-TL colonies were totally suppressed. Inhibition of colony formation was also observed at an MOI of 0.1:1 but not with further log dilutions of the virus. Incubation of the virus with antibody to gp160 resulted in the complete reversal of stem cell suppression and the normalization of colony growth in vitro. For BFU-E and CFU-GM colonies, this reversal was observed with dilutions of antibody up to 1:100 and was no longer observed at titers greater than 1:500. The CFU-TL colony number normalized at titers between 1:10 and 1:50. Human immunodeficiency virus (HIV) also suppressed by 50% the growth of colonies derived from CD34+ stem cell fractions. Infection of CD34+ cells and T-cell-depleted, nonadherent cell fractions was demonstrated by detection with HIV-specific DNA probe following amplification by polymerase chain reaction. The results suggest that HIV can directly infect human bone marrow progenitor cells and affect their ability to proliferate and give rise to colonies in vitro. The results indicate a direct role for the virus in bone marrow suppression and a possible mechanism for the cytopenias observed in patients with AIDS.