Cutaneous leishmaniasis responds to daylight-activated photodynamic therapy: proof of concept for a novel self-administered therapeutic modality

BACKGROUND

Cutaneous leishmaniasis (CL) is endemic in Israel, with hundreds of new cases reported in recent years. Photodynamic therapy (PDT) is highly effective for treatment of CL, but requires equipment available only at specialized centres. Daylight-activated PDT (DA-PDT) abolishes the need for artificial light sources and allows the patient to administer the treatment with no professional assistance.

OBJECTIVES

The objective of this single-centre, open study was to establish proof of concept for the efficacy of DA-PDT in the treatment of CL using clinical, microbiological and molecular clearance as outcome measures.

METHODS

Thirty-one patients with CL (11 Leishmania major and 20 Leishmania tropica) underwent DA-PDT. Fourteen patients were treated in the hospital garden under professional supervision and 17 patients underwent DA-PDT as a self-administered treatment modality at home. Following application of a thick layer of 16% methyl aminolaevulinate and 30-min occlusion, the lesions were exposed to daylight for 2·5 h. Treatment sessions were repeated at weekly intervals until clinical and microbiological cure. Control lesions were either treated with cryotherapy or left untreated.

RESULTS

The overall cure rate for DA-PDT was 89% (intention-to-treat cure rate 77%); this was 86% for the hospital-based treatment group and 92% for the self-administered group.

CONCLUSIONS

DA-PDT proved to be effective in the treatment of CL caused by L. major and L. tropica. More patients were treated according to a self-administered protocol, suggesting that DA-PDT can be adopted even in technologically deprived countries where the majority of Leishmania infections are encountered.

Beta-glucosylceramide: a novel method for enhancement of natural killer T lymphoycte plasticity in murine models of immune-mediated disorders

BACKGROUND

beta-Glucosylceramide, a naturally occurring glycolipid, exerts modulatory effects on natural killer T (NKT) lymphocytes.

AIM

To determine whether beta-glucosylceramide can alter NKT function in opposite directions, colitis was induced by intracolonic installation of trinitrobenzenesulphonic acid, and hepatocellular carcinoma (HCC) was induced by transplantation of Hep3B cells.

METHODS

The immunological effect of beta-glucosylceramide was assessed by analysis of intrahepatic and intrasplenic lymphocyte populations, serum cytokines and STAT protein expression.

RESULTS

Administration of beta-glucosylceramide led to alleviation of colitis and to suppression of HCC, manifested by improved survival and decreased tumour volume. The beneficial effects were associated with an opposite immunological effect in the two models: the peripheral:intrahepatic CD4:CD8 lymphocyte ratio increased in the colitis model and decreased in the HCC group. The peripheral:intrahepatic NKT lymphocyte ratio decreased in beta-glucosylceramide-treated mice solely in the HCC model. The effect of beta-glucosylceramide was associated with decreased STAT1 and 4 expression, and with overexpression of STAT6, along with decreased interferon gamma levels in the colitis model, whereas an opposite effect was noted in the HCC model.

CONCLUSIONS

beta-glucosylceramide alleviates immunologically incongruous disorders and may be associated with "fine tuning" of immune responses, by changes in plasticity of NKT lymphocytes.

Adoptive transfer of regulatory NKT lymphocytes ameliorates non-alcoholic steatohepatitis and glucose intolerance in ob/ob mice and is associated with intrahepatic CD8 trapping

The aim of this study was to determine the effect of adoptive transfer of regulatory natural killer T (NKT) lymphocytes on the metabolic disorder in leptin-deficient ob/ob mice, which feature depletion and defective function of NKT and CD4 lymphocytes. Leptin-deficient ob/ob mice were subjected to transplantation of 1 x 10(6) of either ob/ob or wild-type-derived NKT lymphocytes, or to transplantation of either ob/ob or wild-type-derived splenocytes. The effect on hepatic fat content was measured by magnetic resonance imaging (signal intensity index) and histology, using the steatohepatitis grading scale. The degree of glucose intolerance was measured by an oral glucose tolerance test (GTT). Adoptive transfer of wild-type or ob/ob-derived regulatory NKT cells led to a 12% decrease in hepatic fat content. A significant histological shift from macrosteatosis to microsteatosis was observed. Marked improvement in the GTT was noted in wild-type or ob/ob-derived NKT recipients. Metabolic effects were associated with a significant decrease in peripheral and intrahepatic CD4/CD8 lymphocyte ratios. Intrahepatic CD8 trapping was observed in all responders. Serum interleukin 10 levels decreased significantly. In conclusion, adoptive transfer of a relatively small number of regulatory NKT lymphocytes into ob/ob mice results in a significant reduction in hepatic fat content, a shift from macro to microsteatosis, and significant improvement in glucose intolerance. These effects were associated with decreased peripheral and intrahepatic CD4/CD8 ratios and decreased interleukin 10 levels. The results further support a role for regulatory NKT lymphocytes in the pathogenesis of non-alcoholic steatohepatitis in the leptin-deficient murine model.

Adoptive transfer of small numbers of DX5+ cells alleviates graft-versus-host disease in a murine model of semiallogeneic bone marrow transplantation: a potential role for NKT lymphocytes

Natural killer T (NKT) lymphocyte cells are a subset of regulatory lymphocytes with important immunemodulatory effects. Our aim was to evaluate the effect of transplantation of NKT lymphocytes on graft versus host disease (GVHD) in a murine model of semiallogeneic BMT. GVHD was generated by infusion of 2 x 107 splenocytes from C57BL/6 donor mice into irradiated (C57BL/6 x Balb/c)F1 recipient mice. Adoptive transfer of increasing numbers of DX5+ cells was performed. Recipient mice were followed for histological parameters of GVHD-associated liver, bowel, and cutaneous injury. Intrahepatic and intrasplenic lymphocytes were isolated and analyzed by FACS for CD4+ and CD8+ subpopulations. It was seen that adoptive transfer of 4.5 x 106 DX5+ cells significantly alleviated GVHD-related hepatic, bowel, and cutaneous injury, and improved survival (85% survival on day 28). In contrast, depletion of DX5+ cells led to severe GVHD-associated multiorgan injury and 100% mortality. A direct correlation with the number of transplanted DX5+ cells was noted (maximal effect with transplantation of 4.5 x 106 DX5+ cells). Tolerance induction was associated with an increased peripheral CD4/CD8 ratio, intrahepatic trapping of CD8 lymphocytes and a shift towards a Th2-type cytokine profile, manifested by decreased IL-12/IL10, IL-12/IL-4, IFNgamma/IL-10, and IFNgamma/IL-4 ratios. Transplantation of DX5+ cells holds promise as a novel therapeutic measure for GVHD.

Suppression of hepatocellular carcinoma growth in mice by the alkaloid coccidiostat halofuginone

Halofuginone, a widely used alkaloid coccidiostat, is a potent inhibitor of collagen alpha 1 (I) and matrix metalloproteinase 2 gene expression. Halofuginone also suppresses extracellular matrix deposition and fibroblast proliferation. It was recently shown to be effective in suppression of bladder carcinoma and glioma. This study sought to evaluate the effect of treatment with halofuginone on growth of hepatocellular carcinoma (HCC) in mice. Athymic Balb/c mice were injected subcutaneously with 10(7) human hepatoma cells (Hep3B), followed by treatment with halofuginone administered in the diet (750 microg/kg) starting on day 3, before tumour innoculation. The control group was received a normal diet. Mice were followed for survival, tumour volume and serum alpha-fetoprotein (alpha FP). The mechanism of the anti-tumour effect of halofuginone was determined in vitro by assessing tumour cell growth, and by measuring the serum concentrations of interferon-gamma (IFN gamma) and interleukin 2 (IL2). Halofuginone treatment induced almost complete tumour suppression in treated mice. Mortality rates were 10% and 50%, in halofuginone-treated and control mice, respectively (P<0.001). No visible tumour was observed in treated mice, as compared with a 364 mm3 tumour in control mice. Serum alpha FP were 0.1 and 212 ng/ml in treated and control mice, respectively (P<0.005). Halofuginone significantly inhibited HCC proliferation in vitro. Maximal inhibition of 64% of tumour cell growth was observed at a concentration of 10(-8) M. The anti-tumour effect was mediated via a significant increase in IFN gamma and IL2 (90 vs. 35, and 210 vs. 34 pg/ml in treated and control groups, respectively, P<0.005). Treatment with halofuginone effectively suppressed the progression of HCC in mice. This effect may be associated with a direct anti-tumour effect, and/or enhancement of a systemic immune response.

Induction of oral tolerance in bone marrow transplantation recipients suppresses graft-versus-host disease in a semiallogeneic mouse model

Graft-versus-host disease (GVHD) is the major obstacle for successful allogeneic stem cell transplantation (SCT). Morbidity and mortality are high, and novel therapeutic strategies are required. Current therapy, which is based mainly on immunosuppression, is associated with a high degree of complications. Immune hyporesponsiveness induced by oral antigen administration has recently been shown to prevent the development of chronic GVHD (cGVHD) in a murine model. The aim of the present study was to evaluate whether it is possible to induce tolerance and to alleviate GVHD in a semiallogeneic transplantation model in mice. GVHD was generated by infusing 2 x 10(7) splenocytes from C57BL/6 donor mice into (C57BL/6 x Balb/c)F1 recipient mice, which received 7 Gy (60)Co total body irradiation (TBI) prior to transplantation. Oral tolerance was induced by feeding recipient F1 mice with five oral doses of proteins, 50 micro g/mouse, extracted from C57BL/6 splenocytes on alternate days following transplantation. In vitro mixed lymphocyte reaction (MLR) from tolerized and nontolerized mice was performed. Recipient mice were followed for chimerism, and for clinical and histological parameters of GVHD. Induction of tolerance was documented by a significant reduction in MLR response of tolerated vs nontolerated splenocytes. A significant alleviation of the clinical and pathological manifestation of GVHD was observed in the liver, small bowel, and skin. Tolerance induction did not jeopardize engraftment. These results may constitute a step towards reducing the frequency of GVHD via manipulation of the immune system.

Immunomodulation of experimental colitis: the role of NK1.1 liver lymphocytes and surrogate antigens--bystander effect

The imbalance between Th1 pro-inflammatory and Th2 anti-inflammatory cytokine-producing cells plays a major role in the pathogenesis of inflammatory bowel disease (IBD). Induction of oral tolerance to colitis-extracted proteins was previously shown to down-regulate the anti-colon immune response, thereby alleviating experimental colitis. Immune bystander effect and liver-associated lymphocytes expressing the NK1.1 marker (NK1.1(+) LAL) have been suggested as being important in tolerance induction. The aims of the present study were to determine whether oral administration of inflammatory and non-inflammatory colon-extracted proteins of different species can induce peripheral immune tolerance and alleviate experimental colitis; and to examine the role of NK1.1(+) LAL in oral tolerance induction. Colitis was induced in C57/B6 mice by intracolonic instillation of trinitrobenzene sulphonic acid (TNBS). Mice received six oral doses of colonic proteins extracted from TNBS-colitis colonic wall, or normal colonic wall, from four different species. Standard clinical, macroscopic, and microscopic scores were used for colitis assessment. Serum interferon gamma (IFNgamma) and interleukin 10 (IL10) levels were measured by ELISA. To evaluate the role of NK1.1(+) LAL in maintaining the balance between immunogenic and tolerogenic subsets of cells, their cytotoxicity functions were tested in tolerized and non-tolerized-mice. The administration of mouse-derived colitis-extracted proteins, or of surrogate proteins extracted from normal mouse colon, or from rat or human inflammatory colons, was found to alleviate experimental colitis. Tolerized mice had less diarrhoea; showed a marked reduction of colonic ulceration, intestinal and peritoneal adhesions, wall thickness, and oedema; and demonstrated a significant improvement of all microscopic parameters for colitis. Induction of tolerance led to an increase in IL10 and a decrease in IFNgamma serum levels. NK1.1(+) LAL cytotoxicity function increased markedly in tolerized mice. In contrast, mice fed with proteins extracted from normal rat, rabbit, and human colon, or from rabbit inflammatory colon, developed severe colitis, with a marked increase in IFNgamma and a decrease in IL10 serum levels, and down-regulation of NK1.1(+) LAL function. This study has shown that oral tolerance can be induced in experimental colitis by means of the feeding of surrogate antigens; this alleviates experimental colitis. NK1.1(+) LAL cytotoxicity function is associated with peripheral tolerance induction and may help to maintain the Th1/Th2 immune balance.

Amelioration of immune-mediated experimental colitis: tolerance induction in the presence of preexisting immunity and surrogate antigen bystander effect

Oral tolerance is a recognized procedure for induction of antigen-specific peripheral immune hyporesponsiveness. Recently, it has been shown that oral tolerance can be used to prevent experimental colitis. The aim of this study was to test whether induction of oral tolerance toward proteins extracted from inflammatory and noninflammatory colons can alleviate preexisting experimental colitis. Colitis was induced in BALB/c mice by intracolonic instillation of 2,4,6-trinitrobenzenesulfonic acid (TNBS). Mice received five oral doses of colonic proteins extracted from TNBS-induced colitis or normal colons, before, or 7 days after colitis was induced. Standard clinical, macroscopic, and microscopic scores were used for colitis assessment. Serum interferon gamma (IFNgamma) and interleukin (IL)4 levels were measured by enzyme-linked immunosorbent assay. Feeding of colitis- or normal colon-extracted proteins before, or following colitis induction, ameliorated colonic inflammation as shown by decreased diarrhea, increased body weight, reduction of colonic ulcerations, intestinal and peritoneal adhesions, wall thickness, and edema. Histological parameters for colitis were markedly improved in tolerized animals, and there was a significant reduction in inflammatory response and mucosal ulcerations. Tolerized mice developed an increase in IL4 and a decrease in IFNgamma serum levels. The results show that induction of oral tolerance to colitis- or normal colon-extracted proteins down-regulated preexisting anticolon immune response, thereby ameliorating experimental colitis. Tolerance induction was mediated via a shift from a proinflammatory T helper (Th)1 to an anti-inflammatory Th2 immune response.

Pregnancy rate and embryo loss in the NK1.1+ T cell-depleted mouse

OBJECTIVE

To determine the role of natural killer cell (NK) 1.1+ T cells in pregnancy and in embryo loss.

STUDY DESIGN

Four groups of C57 mice, consisting of 20 animals each, were studied. Groups A and B included pregnant females treated with anti-NK1.1 monoclonal antibodies until they gave birth or non-NK1.1-depleted antibodies, respectively. In order to evaluate the role of NK1.1+ T cells in pregnancy, female mice in group C were treated with anti-NK1.1 monoclonal antibodies every seven days starting seven days prior to mating until they gave birth. Control mice in group D were not NK1.1-depleted. NK1.1+ T cell depletion was determined by flow cytometric analysis.

RESULTS

Depletion of NK1.1+ T cells did not significantly change the pregnancy rate, nor did it significantly alter the number of live births. Numbers of live births tended to decrease in NK1.1-depleted mice, with a mean number of live births of 4.66 as compared with 6.09 in NK1.1-depleted and nondepleted mice, respectively. Similarly, mice treated with anti-NK1.1 monoclonal antibodies every seven days starting seven days prior to mating became pregnant at a rate of 40% as compared with 60% in non-NK1.1-depleted controls. A comparable trend was observed in the number of live births, with a mean number of live births of 5.0 as compared with 6.1 in NK1.1-depleted and non-NK1.1-depleted mice, respectively.

CONCLUSION

In the NK1.1-depleted mouse model, NK1.1+ T cells do not have any direct effect on pregnancy rate or on early embryo loss.

Induction of oral tolerance towards hepatitis B envelope antigens in a murine model

BACKGROUND

Hepatitis B virus (HBV) is a non-cytopathic virus, and the hepatocellular injury that occurs as a consequence of HBV infection is mediated by the host antiviral immune response. Subjects with natural tolerance to HBV have minimal or no liver injury despite chronic viremia. We have shown that immune tolerance towards viruses can be induced by oral administration of viral proteins.

AIMS

To test whether oral induction of tolerance can be induced towards HBV antigens, and whether oral tolerance induction downregulates preexisting anti-HBV immune response.

METHODS

Oral tolerance was induced via feeding of five low oral doses of HBV proteins (HBsAg+preS1+preS2, BioHepB). This was followed by two inoculations with the BioHepB vaccine. Humoral immune tolerance was evaluated by measuring serum levels of anti-HBs antibody titers at monthly intervals. To determine if oral tolerance induction downregulates pre-existing anti-HBs immunity, mice were inoculated twice with the BioHepB vaccine, followed by feeding of BioHepB-HBV proteins.

RESULTS

Feeding of HBV proteins markedly inhibited production of anti-HBs antibodies in naive mice. Anti-HBs titers were 45 versus 135 mIU/ml, in tolerized versus non-tolerized controls (P<0.005). Moreover, oral tolerance induction effectively down-regulated pre-existing immunity and reduced the anti-HBs titers in previously immunized mice to 112 versus 223 mIU/ml, in tolerized compared with non-tolerized controls (P<0.01).

CONCLUSIONS

Induction of oral tolerance towards HBV proteins downregulates the antiviral humoral immune response in naive mice, and in the presence of preexisting anti-HBV immunity. This approach should be further investigated as a method for alleviation of antiviral-mediated liver injury in chronic HBV hepatitis.

Enhancement of immune tolerance via induction of NK1.1 positive liver-associated-lymphocytes under immunosuppressive conditions

BACKGROUND/AIMS

The liver was previously shown to play a critical role in oral tolerance induction. A subset of liver-associated-lymphocytes expressing NK1.1 marker (NK1.1+ LAL) have killing activities and it has been suggested that they play a role in immune modulation. FK506 is a powerful immunosuppressive agent affecting T-cell differentiation and function. The exact pathway involved in peripheral tolerance induction using this drug remains unknown. The aim of the present study was to determine the interaction between FK506 and NK1.1+ LAL in induction of peripheral immune tolerance in the experimental colitis model.

METHODS

Colitis was induced in C57 mice by intracolonic instillation of trinitrobenzenesulfonic acid (TNBS). Mice received five oral doses of colonic proteins extracted from TNBS-colitis colonic wall with and without FK506 treatment. The effect of FK506 treatment on NK1.1+ LAL was tested by cell-sorting and cytotoxicity assay. Colitis was assessed by standard clinical, macroscopic and histologic scores.

RESULTS

Both FK506 treatment and oral tolerance induced a significant increase in NK1.1+ LAL number and cytotoxicity function. FK506 treatment enhanced the effect of oral tolerance on amelioration of disease activity. Orally tolerized mice treated with FK506 had no mortality nor increase in body weight, and manifested significant improvement in disease macroscopic and microscopic scores.

CONCLUSIONS

This study shows for the first time that immune tolerance induced by both oral administration of an antigen and by FK506 treatment may be mediated via enhancement of NK1.1+ LAL. This subset of lymphocytes may play an immunoregulatory role in immune tolerance induction.

Liver-associated lymphocytes expressing NK1.1 are essential for oral immune tolerance induction in a murine model

Oral tolerance is the induction of immunological hyporesponsiveness towards orally administered antigens. Tolerance initiation involves induction of anti-inflammatory (Th2) lymphocytes, with downregulation of pro-inflammatory (Th1) lymphocytes. The liver was previously shown to play a critical role in oral tolerance induction. The aim of the present study was to test whether liver-associated-lymphocytes expressing the NK1.1 marker (NK1.1+ LAL) are substantial for induction of oral tolerance in an experimental colitis model. Colitis was induced in C57 mice by intracolonic instillation of trinitrobenzensulfonic acid (TNBS). Mice received five oral doses of colonic proteins extracted from TNBS-colitis colonic wall. Anti-NK1.1 monoclonal antibodies were injected before tolerance induction. Colitis was assessed by standard clinical, macroscopic, and microscopic scores. Serum IFN-gamma, TGF-beta1, and IL4 levels were measured by enzyme-linked immunosorbent assay. To evaluate the role of NK1.1+ LAL in keeping the balance between immunogenic and tolerogenic subsets of cells, we tested whether peripheral lymphocytes harvested from tolerized and NK1.1-depleted nontolerized mice can adoptively transfer the tolerance into naive irradiated rats. Depletion of NK1.1+ LAL prevented immune tolerance induction in the experimental colitis model. NK1.1+ LAL-depleted nontolerized mice, disclosed severe clinical, macroscopic, and microscopic parameters of colitis. These mice had significantly lower TGF-beta1, IL4, and higher IFN-gamma serum levels, and their lymphocytes failed to transfer the tolerance into naive animals. In contrast, the feeding of colitis-extracted proteins, without NK1.1+ LAL depletion, markedly alleviated the disease. Tolerized mice had higher IL4 and TGF-beta1 and lower IFN-gamma serum levels, and adoptive transfer of their suppressor splenocytes markedly alleviated colitis in naive recipients. NK1.1+ LAL plays a critical role in oral tolerance induction. Depletion of this subset of LAL prevents a shift from Th1 to a Th2 type of immune response, hindering the ability to induce immune tolerance.

Collagen metabolism in ultraviolet irradiated hairless mouse skin and its correlation to histochemical observations

Early biochemical studies of ultraviolet (UV) irradiated human skin reported a loss of insoluble collagen with a concomitant increase in the soluble fraction. Recent work has described an early increase in type III collagen during chronic irradiation of hairless mice as determined by cyanogen bromide digests of whole skin. In order to understand the correlation of these events and those seen with histochemistry, in the present study we irradiated hairless mice for up to 24 weeks with approximately 4 minimal erythema doses (MEDs) of UVB thrice weekly with Westinghouse FS-40 bulbs. Skin samples were taken at 4-week intervals from irradiated and age-matched control mice. Collagen was isolated from other skin proteins by acid extraction, pepsin digestion, and salt precipitation. Estimates of types I and III collagen were made by interrupted polyacrylamide gel electrophoresis and densitometric scanning. Compared with unirradiated controls, there was a small increase in the ratio of type III to total collagen after 8 weeks of UV. There were no significant increases at later time points until after 24 weeks of radiation. Total collagen in normal mouse skin, determined by hydroxyproline content, remained constant over the 24 weeks, while UV radiation produced significant increases at 4, 8, 12, and 16 weeks, returning to control levels at week 20. There was no change in the degree of hydroxylation at any time point in either group. Thus, chronic UV exposure resulted in increased collagen synthesis until late in the course of irradiation. Because there is a lack of consistent change in the ratio of type III to total collagen, the early increases in collagen content may represent both types I and III, synthesized in relatively unchanging proportions.

Partial characterization of a low molecular weight proteoglycan isolated from bovine parietal pericardium

Knowledge of the nature of pericardial connective tissue components is incomplete. To gain a better understanding of the composition of this tissue, bovine parietal pericardium was extracted with 4 M guanidine hydrochloride yielding a proteoglycan-containing protein mixture. This was fractionated by a three-step chromatographic procedure with the resultant purification of a 75-110 Kd proteoglycan. The purified proteoglycan was susceptible to chondroitinase ABC digestion but resistant to chondroitinase AC and nitrous acid degradation suggesting the presence of dermatan sulfate glycosaminoglycan(s). This is the first reported isolation of a proteoglycan from parietal pericardium.

The bovine corneal SGP-complex is related to the tissue form of type VI collagen

A polyclonal antiserum was prepared in rabbits against the structural glycoprotein (SGP) complex previously isolated from a bacterial collagenase digest of bovine corneal stroma (R. Alper, Curr. Eye Res. 2:479, 1983). Direct and indirect enzyme-linked immunosorbent assays indicated that the antiserum was specific for the SGP-complex and did not react with Types I, III and IV collagen, fibronectin, laminin or actin. Immunoblot experiments indicated that the antiserum reacted with all of the components of the SGP-complex as well as with the cell matrix laid down by bovine keratocytes in culture. An attempt was made to isolate individual antibodies from the antiserum by selective elution from immunoblots of the components of the SGP-complex separated by SDS-PAGE. It was found that regardless of the protein band from which the antibody was eluted, every antibody isolated reacted with every protein component of the SGP-complex suggesting that the SGP-complex may have been derived from a single precursor protein and that the observed heterogeneity of the SGP-complex may have been the result of proteolytic breakdown of the protein held together by disulfide bonds. When the anti-SGP antiserum was used to immunoprecipitate 14C-proline labeled proteins from the media of bovine keratocytes in culture, the major protein observed had a Mr of about 140,000 daltons, similar to that of GP-140 also known as CL-glycoprotein. These proteins have been shown to represent the tissue form of Type VI collagen. To test the hypothesis that the SGP-complex may be related to the GP-140 (CL-glycoprotein), ELISA and immunoblotting studies were performed comparing the properties of the anti-SGP serum with those of a polyclonal antibody specific for Type VI collagen. The SGP-complex reacted positively by ELISA with the anti-human Type VI collagen antiserum and, conversely, human Type VI collagen gave a positive ELISA reaction with an antiserum against the SGP-complex. The anti-human Type VI collagen antiserum reacted with most of the major components of the SGP-complex on immunoblots of SDS-PAGE gels. These data indicate that the SGP-complex is related to and probably is derived from the tissue form of Type VI collagen.

Isolation and characterization of the nephritogenic antigen producing anti-tubular basement membrane disease

Using monoclonal antibody affinity chromatography, we isolated a 48,000 mol wt, glucose-rich glycoprotein (3M-1) from collagenase-solubilized rabbit renal tubular basement membrane (SRTA). The purified 3M-1 protein is noncollagenous, and is capable of inducing anti-TBM (tubular basement membrane) antibodies and interstitial nephritis in susceptible hosts. Further, when SRTA, at a normally nephritogenic dose, was selectively depleted of 3M-1, it lost its ability to induce disease. As shown by immunofluorescent techniques, 3M-1 appears to be localized on rodent TBM to the exclusion of the glomerular basement membrane, but was lacking in the TBM of the LEW rat, a strain devoid of the relevant antigen of anti-TBM disease. Immunoelectron microscopy revealed that 3M-1 was associated with the most lateral aspect of the TBM, which borders, and lies in the interstitium. These results indicate that 3M-1 is the nephritogenic antigen producing experimental anti-TBM disease.

Relation between reduced alveolar PO2 and collagen biosynthesis in the perfused rat lung

Collagen biosynthesis was studied in a perfused rat lung system by measuring the extent of [14C]proline incorporation into TCA-insoluble [14C]hydroxyproline-containing protein over a 2 hr perfusion period. It was found that [14C]hydroxyproline formation was linear over the 2 hr period after an initial lag period of 20 to 30 min. [14C]Hydroxyproline constituted between 5% and 6% of the total [14C]proline incorporation, indicating that about 10% of the proline incorporated went into collagen. In the presence of phosphate buffers, collagen biosynthesis was markedly reduced, although total proline incorporation was unaffected. When lungs were ventilated at progressively lower Po2's, no significant effects were observed until the Po2's were below 12 mm Hg, at which point both [14C]hydroxyproline formation and the percentage of [14C]hydroxyproline declined. The PO2 at which hydroxylation was decreased by 50% was approximately 5 mm Hg. When lungs were ventilated with a 90% carbon monoxide, 5% oxygen, 5% carbon dioxide mixture (PO2, 36 mm Hg), protein synthesis was inhibited but the proline hydroxylation system was unaffected. (J Lab Clin Med 99:441, 1982.)

Isolation and preliminary characterization of a structural glycoprotein complex from bovine corneal stroma

After extraction of bovine corneal stroma with 1M CaC1(2) and subsequent digestion of the insoluble residue with purified bacterial collagenase, two crude structural glycoprotein (SPG) fractions were obtained; one which precipitated upon dialysis against water of the collagenase solubilized material and the other which was extracted by 8M urea from the collagenase insoluble material. Amino acid analyses of these crude SGP fractions indicated that they were primarily non-collagenous but that very small amounts of collagen-derived amino acids were present. Upon gel filtration of these SGP fractions on Sepharose 4B-CL, void volume fractions were isolated from each of the crude fractions which were enriched, relative to the original crude fractions, in the collagen-derived amino acids. Carbohydrate analysis indicated that the void volume fractions had the properties of glycoproteins rather than proteoglycans. Upon disulfide reduction and SDS-PAGE, each of these fractions was resolved into five major protein bands with molecular weights of 155,000, 137,000, 117,000 82,000 and 34,000. Only the three largest bands contained the collagen derived amino acids. These data are consistent with the presence within bovine corneal stroma of a large structural glycoprotein complex comprised of at least five protein components associated through disulfide bonds. Collagen apparently is associated with three of these, either through covalent crosslinkage, or as part of the primary structure.

Effects of a molecular change in collagen on lung structure and mechanical function

Semicarbazide, a lathyrogen, was given to growing rats to elucidate the consequences of altering the molecular structure of fibrous proteins within the lung. Static pressure-volume (P-V) measurements during deflation of saline-filled lungs showed normal recoil pressure and compliance values within the physiological range of lung volume. Quasi-static P-V measurements were also normal during slow reinflation, even beyond physiological limits to a recoil pressure of 20 cm H20. However, the lungs of experimental rats ruptured at much lower recoil pressures than controls. Histology was normal in lungs fixed at 20 cm H20. In contrast, lungs showed dilation of terminal air spaces, rupture of alveolar walls, and an increase in mean linear intercept in experimental compared with control specimens, when fixed at 30 cm H20. Biochemical analyses revealed reduced cross-linking of lung collagen without change in its total content. There were no detectable changes in the quantity or quality of lung elastin. It is concluded that semicarbazide may selectively impair the maturation of lung collagen and that immaturity of lung collagen is associated with a reduction in the tensile strength of lung tissue, without changes in elasticity within physiological volume limits.