Effect of alpha-2-macroglobulin on cytokine-mediated human C-reactive protein production

Transcriptional reprogramming in nonhuman primate (rhesus macaque) tuberculosis granulomas

BACKGROUND

In response to Mtb infection, the host remodels the infection foci into a dense mass of cells known as the granuloma. The key objective of the granuloma is to contain the spread of Mtb into uninfected regions of the lung. However, it appears that Mtb has evolved mechanisms to resist killing in the granuloma. Profiling granuloma transcriptome will identify key immune signaling pathways active during TB infection. Such studies are not possible in human granulomas, due to various confounding factors. Nonhuman Primates (NHPs) infected with Mtb accurately reflect human TB in clinical and pathological contexts.

METHODOLOGY/PRINCIPAL FINDINGS

We studied transcriptomics of granuloma lesions in the lungs of NHPs exhibiting active TB, during early and late stages of infection. Early TB lesions were characterized by a highly pro-inflammatory environment, expressing high levels of immune signaling pathways involving IFNgamma, TNFalpha, JAK, STAT and C-C/C-X-C chemokines. Late TB lesions, while morphologically similar to the early ones, exhibited an overwhelming silencing of the inflammatory response. Reprogramming of the granuloma transcriptome was highly significant. The expression of approximately two-thirds of all genes induced in early lesions was later repressed.

CONCLUSIONS/SIGNIFICANCE

The transcriptional characteristics of TB granulomas undergo drastic changes during the course of infection. The overwhelming reprogramming of the initial pro-inflammatory surge in late lesions may be a host strategy to limit immunopathology. We propose that these host profiles can predict changes in bacterial replication and physiology, perhaps serving as markers for latency and reactivation.

Analysis of differentially expressed genes in hepatocellular carcinoma using cDNA arrays

Hepatocellular carcinoma (HCC) is characterized by multiple somatic mutations, including DNA rearrangements, that affect many cell-growth regulatory pathways. Many genes differentially expressed in HCC have been reported previously, but the patterns of expression varied significantly between patients who bore different risk factors for HCC. To identify genes whose differential expression could serve as a "signature" for diagnosis and prognosis of HCC, we performed analyses of differentially expressed genes in three cases of HCC with different risk factors using the Atlas Human Cancer cDNA Expression Arrays. Among all 597 genes present on the array, only three were found to be coordinately differentially expressed in all three HCC cases, in agreement with published data. These three genes, Cu/Zn superoxide dismutase, osteonectin/secreted protein acidic and rich in cysteine, and matrix metalloproteinase 14, could serve as candidates for the HCC "signature." Ten genes were found to be coordinately differentially expressed in only two of three tested HCC cases. On the other hand, many genes that had been reported previously as differentially expressed in HCC failed to show the described pattern of expression in this group. The results of this study confirm the great variability in gene-expression patterns in HCC and establish the utility of the array technology for identifying both the HCC signature genes and individual gene-expression patterns for purposes of patient-oriented therapy.

Acute phase proteins and transformed cells

Acute phase proteins (APP) are plasma proteins whose concentration and glycosylation alters in response to tissue injury, inflammation, or tumor growth. Significant interspecies and sex differences in APP response exist. APP are produced mainly by hepatocytes, and their synthesis and glycosylation are controlled by a network consisting of cytokines, their soluble receptors, and glucocorticoids. The major cytokines involved in these processes belong to a group of interleukin-6-type cytokines that act through the hematopoietin receptor complex on hepatocytes and JAK-STAT signal transduction pathway. Transformed cells (hepatoma) display significant differences in synthesis of APP, cytokine responsiveness, expression of cytokine-receptor subunits and signal-transduction machinery. The most striking variability relates to the glycosylation alterations induced by cytokines. However, transformed cells (hepatoma) form a basic model for studying and understanding mechanisms controlling the synthesis and glycosylation of APP. Furthermore, APP may be secreted by transformed (tumor) cells of various origins and may display a growth factor-like function in certain cancer types.

Pre-operative plasma levels of C-reactive protein, albumin and various plasma protease inhibitors for the pre-operative assessment of operability and recurrence in cancer surgery

Pre-operative levels of the acute phase protein C-reactive protein (CRP), albumin (assessing nutritional status), the tumour marker CEA and three plasma protease inhibitors, i.e. C1-esterase inhibitor, alpha-2-macroglobulin and antithrombin III, were prospectively studied in 183 patients with various solid cancers. First, the predictive value of abnormal levels for operability at the primary operation was studied. Secondly, the predictive value of abnormal levels for cancer recurrence and metastases was evaluated during 2 years of follow-up. The results show that malignancy induces increased CRP and C1-esterase inhibitor levels and decreased albumin levels in serum. These changes, as well as raised alkaline phosphatase and lowered haemoglobin levels, also correlate to the 'overall' tumour burden. The most important conclusion is, that increased pre-operative CRP levels (CRP > or = 10 mg/l; sensitivity, 79%; specificity, 71%) and/or low albumin levels (albumin <37 g/l; sensitivity, 94%; specificity, 54%) are seen in inoperable cancer patients compared with patients having operable cancers. The second main important conclusion is, that high pre-operative C1-esterase inhibitor levels (C1-esterase inhibitor >152%; sensitivity, 45%; specificity, 90%), and in some patients a high alkaline phosphatase level, are seen in patients exhibiting early cancer recurrence (within 2 years post-operatively).

Dysregulation between TH1 and TH2 T cell subpopulations in the elderly

We investigated the influence of zinc and its binding proteins on the immune system in 21 elderly and 20 young subjects. We detected a deficiency of zinc in the serum of the elderly. Albumin levels were within physiological range, but alpha 2-macroglobulin was significantly increased in the serum of elderly subjects. Using a whole blood assay, we found decreased production of interferon-gamma (IFN-gamma) and soluble interleukin-2 receptors (SIL-2R) in the elderly, whereas interleukin-10 (IL-10) production was greater than in the young controls. To exclude cellular defects, we measured lymphocyte subpopulations. In elderly subjects, we detected lower quantities of CD8+, CD8+/CD45RA+ and CD4+/CD45RO+ cells, but not CD4+ cells, than in young subjects. Other lymphocyte subpopulations were comparable for both groups. These findings suggest a dysregulation between TH1 cells and TH2 cells in the elderly, which may be a result of long-term zinc deficiency. Zinc reconstitution showed no beneficial effects as measured by T cell activity.

Cytokine production and serum proteins in depression

One, as yet unemployed, approach to investigating immunology in depression is the assessment of the cytokine production by leucocytes, which would allow the determination of immune response under standardized conditions. Thus we measured the production of mitogen-induced cytokines (IL-1 beta, IL-2, IL-6, IL-10, interferon-gamma) and sIL-2R in a whole blood assay, and serum protein levels such as C-reactive protein (CRP), haptoglobin (Hp) and alpha 2-macroglobulin (alpha 2 M) in a longitudinal 6-week study in an attempt to assess leucocyte function during and after acute clinical stage of depression in 39 patients. Shortly after admission to hospital we found higher levels of all measured cytokines in the patients. Serum protein levels were significantly higher in the patients than in controls, and decreased over the study period. Whereas slightly elevated monokine levels in patients tended to reach control values, lymphokines showed a significant decrease over the 6 weeks as compared to baseline. These results suggest that the increase in immune activity seen at the beginning of the study may be followed by a suppressed cell-mediated immune function.

The acute phase response: general aspects

The acute phase response in a given individual represents the integrated sum of multiple, separately regulated changes. Although many of these changes commonly occur together in affected individuals, clinical experience indicates that not all of them occur in all individuals, indicating that they must be individually regulated. For example, febrile patients may have normal blood levels of CRP and vice versa, leukocytosis does not always accompany other acute phase phenomena, and many instances of discordance between levels of the various acute phase proteins are seen. Cytokines function as part of a complex regulatory network, a signalling language in which information is conveyed to cells by combinations, and perhaps sequence, of intercellular messenger molecules. The effects of combinations of cytokines are complex. To use a somewhat crude simile, individual cytokines can be thought of as words which bear informational content and which may, on occasion, communicate a complete message. More commonly, however, the actual messages received by cells probably resemble sentences, in which combinations and sequences of words convey information. Currently available data suggest that hepatocytes receive a complex mixture of humoral or paracrine signals during the acute phase response. These are integrated by multiple interacting signal transducing mechanisms to cause finely regulated changes in plasma protein synthesis. Regulation largely occurs by transcriptional control, but post-transcriptional mechanisms, including translational regulation, may also participate. Both the extracellular and intracellular mechanisms that mediate the response of the hepatocyte to inflammatory stimuli appear to be highly complex and involve multiple overlapping, concurrent and parallel pathways. Enough is known at present to conclude that IL-6 is a major participant in these plasma protein changes. Regulation of non-hepatocyte acute phase phenomena has not been delineated as thoroughly, but clearly involves a number of inflammation-associated cytokines.