A synthetic peptide homologous to the envelope proteins of retroviruses inhibits monocyte-mediated killing by inactivating interleukin 1

The synthetic peptide CKS-17 has homology to a highly conserved region of the immunosuppressive retroviral envelope protein P15E, to envelope proteins of HTLV I, II, III, and to that encoded by an endogeneous C-type human retroviral DNA. CKS-17 inhibits the immune response of lymphocytes and the respiratory burst of human monocytes. Because P15E-related antigens are present in human malignant cell lines and cancerous effusions, we sought to determine the effect of CKS-17 on monocyte-mediated tumor cell lysis. Lysis of A375 tumor cells by lymphokine or lipopolysaccharide-activated human monocytes was inhibited by 10 microM CKS-17 (control, 79%; CKS-17-treated, 19%). Another synthesized peptide, CS-2, which has partial homology to CKS-17, failed to block monocyte-mediated killing. Thus, the inhibition by CKS-17 appeared to be specific. Because interleukin 1 (IL-1) is a cytocidal factor produced by activated monocytes, we also investigated the effect of CKS-17 on IL-1 production by monocytes and on direct IL-1-mediated cytotoxicity. CKS-17 did not block production or secretion of IL-1 by lipopolysaccharide- or interferon-gamma-activated monocytes. However, the direct cytocidal activity of both recombinant IL-1 alpha and IL-1 beta against A375 tumor cells was blocked by CKS-17. The cytotoxic activity of IL-1 was inhibited by CKS-17 if (a) IL-1 was preincubated with CKS-17 for 1 hr at 37 degrees C or (b) the A375 cells were incubated with CKS-17 for 1 hr prior to the addition of IL-1. CKS-17 also blocked IL-1-induced proliferation of murine thymocytes, the D10 T cell line, and an IL-1-responsive astrocytoma cell line. These data suggest that CKS-17 may be a potent inhibitor of IL-1.     

Human IFN-gamma production is inhibited by a synthetic peptide homologous to retroviral envelope protein

A synthetic 17 amino acid peptide (CKS-17) homologous to a highly conserved region of human and animal retroviral transmembrane proteins was investigated for its influence on the in vitro production of IFN-gamma from human peripheral mononuclear cells. The results showed that CKS-17 coupled to a carrier protein, BSA, inhibited production of IFN-gamma in a dose-dependent manner. Controls, consisting of BSA, which had undergone the coupling procedure or neurotensin coupled to BSA in an identical manner as CKS-17, showed no such inhibition. Reduction in IFN-gamma production could not be attributed to decreased viability of cells, delay of IFN-gamma production or to involvement of suppressor cells. Moreover, inhibition of IFN-gamma production was not related to the inhibition of DNA synthesis. The inhibition appeared to be a direct effect of CKS-17 on IFN-gamma-producing cells. Kinetic studies revealed that this suppression occurred when CKS-17 was introduced to the culture concurrent with or within 48 h after introduction of IFN inducers. Preincubation experiments showed that the presence of CKS-17 in the culture medium was not necessary to exert its inhibitory effect. These results suggest that a portion of retroviral envelope proteins possess important immunomodulatory actions.     

Production of a retroviral P15E-related chemotaxis inhibitor by IL-1-treated endothelial cells. A possible negative feedback in the regulation of the vascular response to monokines

The effects of IL-1 on vascular endothelium result in a complex set of alterations which are potentially disruptive of vessel wall and underlying tissue integrity. The present study was aimed at investigating possible regulation of such potentially destructive responses elicited by IL-1 on endothelial cells. Culture supernatants of IL-1-treated human umbilical vein endothelial cells (HEC) were depleted of retroviral p15E-related Ag with immobilized anti-p15E mAb. The monocyte chemotactic and polarizing activity of supernatants of IL-1-treated HEC (presumably related to colony-stimulating factors being released by HEC) was markedly augmented by absorption on immobilized anti-p15E antibodies. Irrelevant IgG had no effect and anti-p15E antibodies did not affect the chemotactic activity of supernatants from unstimulated HEC. The material eluted from Sepharose-bound anti-p15E antibodies was devoid of chemotactic and polarizing activity and suppressed the polarization and migration of monocytes in response to chemoattractants. The alpha and beta molecular species of IL-1 were equally effective in inducing the production of p15E-related inhibitor. The production of a p15E-related inhibitor of chemotaxis induced by IL-1 in HEC may represent a negative signal in the regulation of the potentially destructive responses to pro-inflammatory cytokines.     

Preadipocyte Recruitment in Stromal Vascular Cultures After Depletion of Committed Preadipocytes by Immunocytotoxicity

Glucocorticoids or the glucocorticoid analog dexamethasone (DEX) enhances the differentiation of preadipocytes in the presence of insulin and influences preadipocyte proliferation. The purpose of the present study was to determine if DEX can induce the recruitment of preadipocytes. Using monoclonal antibodies for complement-mediated cytotoxicity, preadipocytes were removed from porcine stromal vascular (S-V) cell cultures. Our experiments demonstrated for the first time that after removal of preadipocytes by cytotoxicity, preadipocytes or fat cells could be induced by DEX or DEX plus insulin but not by insulin alone. However, many more fat cells were induced (258 ± 15/unit area) when DEX was added with fetal bovine serum (FBS) followed with insulin treatment, compared to DEX with insulin (21.3 ± 5.1/ unit area) after removal of preadipocytes. Immunocyto-chemistry with AD-3, a preadipocyte marker, showed that DEX with FBS for 3 days after seeding (i.e., the proliferation phase) produced many more preadipocytes (AD-3 positive, 223 ± 45/unit area) than FBS alone (10.5 ± 1.4/unit area). Bromodeoxyuridine (BrdU) incorporation assays demonstrated that the efficiency of DEX with FBS (i.e., during proliferation) was mitosis dependent. Accordingly, we conclude that: porcine S-V cultures contain preadipocytes at different stages of differentiation and that DEX induced early preadipocyte differentiation depends on mitosis.     

Incidence and levels of fumonisin contamination in Colombian corn and corn products

A survey was conducted to determine the levels of fumonisins B1 and B2 in corn and corn-based products available in Colombia for human and animal consumption. A total of 120 samples were analyzed by acetonitrile-water extraction, cleanup with a strong-anion-exchange column, and liquid chromatography with o-phthaldialdehyde-2-mercaptoethanol derivatization and fluorescence detection. The samples of corn and corn-based products for animal intake were taken at different feed manufacturing plants, whereas the samples used for human foods where purchased from local retail stores. The number of positive samples for fumonisin B1 was 20.0% higher in corn and corn-based products for animal intake (75.0%) than in corn and corn-based products for human consumption (55.0%). The levels of fumonisin B1 were also higher in corn and corn-based products for animal intake (mean = 694 μg/kg; range = 32–2964 μg/kg), than in corn and corn-based products for human intake (mean = 218 μg/kg; range = 24–2170 μg/ kg). The incidence and levels of fumonisin B2 were lower than those for fumonisin B1. Corn and corn-based products for animal consumption had an incidence of fumonisin B2 of 58.3%, with a mean value of 283 μg/kg, and a range of 44–987 μg/kg. The incidence of fumonisin B2 in corn-based products for human intake was 35.0%, with a mean value of 118 μg/kg and a range of 21–833 μg/kg. The highest incidence and levels of fumonisins were found in samples of hominy feed, with concentrations ranging from 86 to 2964 μg/kg fumonisin B1 and 57 to 987 μg/kg fumonisin B2.     

Airway cellularity, lipid laden macrophages and microbiology of gastric juice and airways in children with reflux oesophagitis

Background and methods

Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.

Results

We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 10⁵ viral copies/ml in nasal lavage and 1.88 × 10⁵ viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.

Conclusion

HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely.     

The properties of rabbit alpha1-macroglobulin upon activation are distinct from those of rabbit and human alpha2-macroglobulins

We have characterized native and activated forms of rabbit alpha1M and compared them to rabbit and human alpha2M. Similar to human alpha2M, rabbit alpha1M is a tetramer associated via disulfide bonds and non-covalent interactions that exhibits autolysis into two fragments when heated. Like human alpha2M, rabbit alpha1M is cleaved by trypsin at one site; however, rabbit alpha1M shares characteristics with rabbit alpha2M that are different from the properties of human alpha2M. Amine or trypsin treatment of rabbit alpha-macroglobulins does not result in a significant conformational change or cleavage of four thiolester bonds. Full thiolester cleavage is only observed for rabbit alpha1M after exposure to both trypsin and a small amine. Additionally, amine-treated rabbit alpha-macroglobulins retain trypsin inhibitory potential and do not fully shield bound proteinases. Methylamine and trypsin treatment of rabbit alpha1M results in two dissimilar conformations that display differing exposure of the receptor-recognition site. While ammonia- and methylamine-modified rabbit alpha1M bind to macrophages with similar affinity to that of human alpha2M, trypsin-treated rabbit alpha1M exhibits dramatically lower affinity. This suggests that rabbit alpha1M may not play the same proteinase-inhibiting physiological role as human alpha2M.     

Requirement for a uroplakin 3a-like protein in the development of zebrafish pronephric tubule epithelial cell function, morphogenesis, and polarity

Uroplakin (UP)3a is critical for urinary tract development and function; however, its role in these processes is unknown. We examined the function of the UP3a-like protein Upk3l, which was expressed at the apical surfaces of the epithelial cells that line the pronephric tubules (PTs) of the zebrafish pronephros. Embryos treated with upk3l-targeted morpholinos showed decreased pronephros function, which was attributed to defects in PT epithelial cell morphogenesis and polarization including: loss of an apical brush border and associated phospho-ERM proteins, apical redistribution of the basolateral Na(+)/K(+)-ATPase, and altered or diminished expression of the apical polarity complex proteins Prkcz (atypical protein kinase C zeta) and Pard3 (Par3). Upk3l missing its C-terminal cytoplasmic domain or containing mutations in conserved tyrosine or proline residues did not rescue, or only partially rescued the effects of Upk3l depletion. Our studies indicate that Upk3l promotes epithelial polarization and morphogenesis, likely by forming or stimulating interactions with cytoplasmic signaling or polarity proteins, and that defects in this process may underlie the pathology observed in UP3a knockout mice or patients with renal abnormalities that result from altered UP3a expression.