Mifepristone (RU486) restores humoral and T cell-mediated immune response in endotoxin immunosuppressed mice.

Sepsis and septic shock can be caused by Gram-positive and -negative bacteria and other microorganisms. In the case of Gram-negative bacteria, endotoxin, a normal constituent of the bacterial wall, also known as lipopolysaccharide (LPS), has been considered as one of the principal agents causing the undesirable effects in this critical illness. The response to LPS involves a rapid secretion of proinflammatory cytokines such as tumour necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, interferon (IFN)-γ and the concomitant induction of anti-inflammatory mediators such as IL-10, transforming growth factor (TGF)-ß or glucocorticoids, which render the host temporarily refractory to subsequent lethal doses of LPS challenge in a process known as LPS or endotoxin tolerance. Although protective from the development of sepsis or systemic inflammation, endotoxin tolerance has also been pointed out as the main cause of the non-specific humoral and cellular immunosuppression described in these patients. In this report we demonstrate, using a mouse model, that mifepristone (RU486), a known glucocorticoid receptor antagonist, could play an important role in the restoration of both adaptive humoral and cellular immune response in LPS immunosuppressed mice, suggesting the involvement of endogenous glucocorticoids in this phenomenon. On the other hand, using cyclophosphamide and gemcitabine, we demonstrated that regulatory/suppressor CD4(+) CD25(+) forkhead boxP3(+) and GR-1(+) CD11b(+) cells do not play a major role in the establishment or the maintenance of endotoxin tolerance, a central mechanism for inducing an immunosuppression state.

Two different types of concomitant resistance induced by murine tumors: morphological aspects and intrinsic mechanisms.

Concomitant resistance (CR) is the phenomenon according to which a tumor-bearing host inhibits the growth of a secondary implant of the same tumor at a distant site. Confirming and extending previous results of our laboratory, histological studies have revealed that two temporally separate peaks of CR can be detected throughout tumor evolution. The first peak induced by immunogenic small tumors, in euthymic but not in nude mice, is associated with extensive necrosis of the secondary tumor implant and a profuse infiltration of polymorphonuclear granulocytes and mononuclear cells resulting in its final destruction; these features correspond to a typical immunological rejection. The second peak of CR induced by both immunogenic and non-immunogenic large tumors, in euthymic as well as in nude mice, is characterized by a dormant tumor stage with scarce or null mononuclear infiltration, associated with a significant reduction of tumor mitotic index and of the number of PCNA+ cells along with an increase in apoptosis and an arrest in S phase. In previous reports we suggested that a 1000 D serum fraction from mice bearing large tumors could be responsible for the induction of this dormant tumor stage. In this study tumor cells incubated in vitro with that serum factor mimicked the inhibition and cellular alterations observed in vivo in the secondary tumor inhibited by the second peak of CR. Moreover, the passive transfer of this factor by the intra-peritoneal (i.p.) route induced an in vivo inhibition of an i.p. tumor reproducing the image characteristic of the second peak of CR. This represents a direct proof that this serum factor can restrain tumor growth in vivo and that it is, most probably, the effector of the second peak of CR.

Inhibition of metastases by a serum factor associated to concomitant resistance induced by unrelated murine tumors.

Murine lung metatases growing undisturbed by the primary tumor were significantly inhibited by the concomitant resistance induced by a secondary subcutaneous implant of two unrelated tumors. Such inhibition was T-independent since it was also observed in nude mice; its full expression was dependent on the presence of the secondary tumor implant and it was exerted on both macroscopic and microscopic established metastases and not on the process of tumor cell dissemination from the primary tumor. Direct and indirect mechanisms seemed to be involved, the former affecting the metastatic cells per se by causing a decrease in proliferation and an increase in apoptosis while the latter affected neo-vascularization. These antitumor and antiangiogenic effects could be attributed to a serum factor induced by the unrelated tumors generating concomitant resistance. This factor proved to be heat, acid and alkaline resistant and dialysable; it was recovered in an HPLC column with maximum absorption at 215 and 266 nm; it was anionic at neutral pH, exhibiting free carboxil groups and one or more molecules of tyrosine, with a molecular weight between 870 and 1300 Dalton. Intravenous administration of this factor significantly inhibited lung metastases, decreasing mitosis and increasing apoptosis similar to that observed in the presence of the unrelated tumors.

A serum-mediated mechanism for concomitant resistance shared by immunogenic and non-immunogenic murine tumours.

Resistance of tumour-bearing mice to a second tumour challenge, that is concomitant resistance, was evaluated in euthymic and nude mice using nine tumours with widely different degrees of immunogenicity. Two temporally separate peaks of concomitant resistance were detected during tumour development. The first one was exhibited only by small immunogenic tumours; it was tumour specific and mediated by classical immunological T-cell-dependent mechanisms. The second peak was shared by both immunogenic and non-immunogenic large tumours; it was non-specific, thymus independent and correlated with the activity of a serum factor (neither antibody nor complement) that inhibited the in vitro proliferation of tumour cells. This factor was eluted from a Sephadex G-15 column at fractions corresponding to a molecular weight of approximately 1000 Da and it was recovered from a high-performance liquid chromatography column in one peak presenting maximum absorption at 215 and 266 nm. The data presented in this paper suggest for the first time, to our knowledge, that in spite of the differences between immunogenic and non-immunogenic tumours, a common serum-mediated mechanism seems to underlie the concomitant resistance induced by both types of tumours at late stages of tumour development.

[Role of connective tissue in the tumor-host relationship]. / Rol del tejido conectivo en la relación tumor-huésped.

In the embryo, both differentiation and temporospatial organization are regulated by the mesoderm. Some of these functions are expressed by the connective tissue during wound or organ repair and regeneration. The normal development of the latter depends on the epithelium-mesenchyme interrelationship and the formation of an adequate amount of stroma and a certain type of collagen or proteoglycans. Our hypothesis proposes that cancer is a regenerative process which has failed as a consequence of alterations in the connective tissue. The object of this paper was to investigate whether the connective tissue and the amorphous fundamental substance (SFA) are capable of regulating the proliferation and death of normal and tumor cells and to duplicate the mechanisms involved. The results obtained in vivo, ex-vivo and in vitro experiments indicate that following: 1) SFA exerts a direct and selective cytotoxic effect on tumor cells; 2) SFA reduces the proliferative capacity of normal and tumor cells; 3) both the cytotoxic and antiproliferative effects of SFA are independent of cellular and humoral immune responses but are dependent on the chemical integrity of its component since its denaturalization reduces its antitumoral activity; 4) the tumor cells modulate the regulatory effects of SFA through endocellular enzymes liberated by cell death induced by the cytotoxic action of SFA itself. These results suggest that in the absence of the inhibitory effect of SFA, the tumor cells which remain viable con now proliferate actively due to enzyme stimulation. In conclusion, the regulatory function of the connective tissue on the proliferation and viability of tumor cells would depend on the molecular constitution of SFA.

[Concomitant antitumor resistance]. / Resistencia concomitante antitumoral.

Concomitant resistance of tumor-bearing mice against a second tumor challenge was evaluated in euthymic and athymic mice using 17 tumors with different degrees of immunogenicity. Two temporarily separated peaks of concomitant resistance were detected during tumor development: the first peak was only observed associated with small immunogenic tumors (< 500 m3., it was tumor-specific and mediated by T cell-dependent immunological mechanisms. The second peak was exhibited by large tumors (> 2000 mm3) independently of their immunogenicity; it was non-tumor specific, thymus-independent and correlated with a serum-activity (neither antibodies nor complement) which inhibited the in vitro proliferation of tumor cells. Out of 17 tumors studied, 15 tumors exhibited a moderate or strong concomitant resistance. The remaining two, which exhibited a weak or undetectable concomitant resistance and correlatively, a low or absent serum-inhibitory activity were the only tumors which included lung metastases. This fact suggested a correlation between concomitant resistance, absence of metastases and the existence of an inhibitory factor(s) in the serum. This inhibitory factor was partially characterized: it was resistant to boiling (5-10' at 100 degrees C) and to variations of pH; its molecular weight was estimated between 850 and 1200 D; it was recovered in only one fraction from HPLC (high power liquid chromatography) columns presenting maximum absorption at 215 and 266 nm; amino acid analysis and magnetic nuclear resonance studies suggested the presence of a molecule of thyrosine and one or two molecules of carbohydrates in its structure.

The role of apoptosis in the inhibition of a secondary tumor by concomitant resistance in a mouse model of metastases.

Resistance of tumor-bearing mice to a second tumor challenge, that is, concomitant resistance, was studied using the LB tumor model. In a secondary LB tumor implant inhibited by concomitant resistance an increase in the percentage or apoptotic cells and alterations in cell cycle distribution were observed. Similar alterations were observed in LB tumor cells incubated with serum from tumor-bearing mice. The data presented in this paper suggest that apoptosis is one of the mechanisms involved in tumor dormancy due to concomitant resistance.

Correlation between seric antitumor activity and concomitant resistance in mice bearing nonimmunogenic tumors.

Serum from mice bearing five weakly immunogenic or nonimmunogenic tumors inducing concomitant resistance exhibited a growth-inhibitory activity on in vitro proliferation of the tumor cells. This activity was proportional to the intensity of concomitant resistance and correlated with the capacity to restrain metastatic development. It was not attributable to cytotoxic antibodies, was relatively nonspecific, and operated through a cytostatic and reversible mechanism. All attempts to transfer antitumor resistance in vivo by serum inoculation have failed, but this could be attained by parabiosis. Physical and chemical serum treatments suggest that heat-, acid-, and alkali-resistant peptide(s) with molecular weights ranging from 1000 to 3000 could account for this inhibitory effect.

Anti-inflammation induced by counter-irritation or by treatment with non-steroidal agents inhibits the growth of a tumour of non-detected immunogenicity.

Counter-irritation (CI) triggered by different non-specific irritant stimuli delayed the growth of a murine tumour of non-detected immunogenicity. The syngeneic LB tumour transplant by itself also induced CI and decreased the number of leukocytes migrating to a secondary s.c. irritant stimulus, e.g. sponge or carrageenan. On the other hand, partial inhibition of cell migration by treatment with either 0.5 mg kg-1 indomethacin or 0.3 mg kg-1 piroxicam retarded LB tumour growth, presumably by a mechanism unrelated to inhibition of immune responses by PGE2. It is suggested that CI may play a role in the early stages of concomitant resistance.

Inmunidad concomitante antitumoral: un posible mecanismo de control de las metástasis / Antitumor concomitant immunity: a possible metastasis control mechanism

Se entiende por inunidad concomitante (IC) la falta de desarrollo de un segundo implante tumoral distante del primario, atribuyéndole una explicación inmunológica. El objeto de estos trabajos fue estudiar la IC asociada a tumores espontáneos. En ratones BALB/c, se comprobó que el transplante de varios tumores singenecicos, de indetectable inmunogenicidad, inhibían el desarrollo de un segundo implante del mismo tumor, y a veces de otro tumor, evidenciándose cierta inespecificidad. Esta IC se observada también en ratones atímicos, jóvenes y adultos, y en los tratados con sílica, descartándose la participación de linfocitos T, células NK y macrófagos. La falta de desarrollo del implante secundario no se debía a rechazo tumoral, contrariamente a lo que pudimos observar con un tumor inmunogénico en un sistema alogeneico, sino a citostasis. Este estado de tumor dormido se debería a la falta de aflujo de células del huésped, ya que cualquier estimulo inflamatorio local abrogaba la IC llevando a un rápido crecimiento tumoral. Estaría en juego un fenómeno de anti-inflamación ya que se comprobó que un foco inflamatorio inhibía el desarrollo de un implante tumoral en el flanco contralateral, que el mismo efecto se conseguía con la administración de piroxicam, y que el propio tumor disminuía la reacción inflamatoria creada por la implantación de un cuerpo extraño. Considerando a las metástasis como implantes secundarios naturales, se compararon dos tumores de mama de origen común, pero diferente...

Inmunidad concomitante antitumoral: un posible mecanismo de control de las metástasis / Antitumor concomitant immunity: a possible metastasis control mechanism

Se entiende por inunidad concomitante (IC) la falta de desarrollo de un segundo implante tumoral distante del primario, atribuyéndole una explicación inmunológica. El objeto de estos trabajos fue estudiar la IC asociada a tumores espontáneos. En ratones BALB/c, se comprobó que el transplante de varios tumores singenecicos, de indetectable inmunogenicidad, inhibían el desarrollo de un segundo implante del mismo tumor, y a veces de otro tumor, evidenciándose cierta inespecificidad. Esta IC se observada también en ratones atímicos, jóvenes y adultos, y en los tratados con sílica, descartándose la participación de linfocitos T, células NK y macrófagos. La falta de desarrollo del implante secundario no se debía a rechazo tumoral, contrariamente a lo que pudimos observar con un tumor inmunogénico en un sistema alogeneico, sino a citostasis. Este estado de tumor dormido se debería a la falta de aflujo de células del huésped, ya que cualquier estimulo inflamatorio local abrogaba la IC llevando a un rápido crecimiento tumoral. Estaría en juego un fenómeno de anti-inflamación ya que se comprobó que un foco inflamatorio inhibía el desarrollo de un implante tumoral en el flanco contralateral, que el mismo efecto se conseguía con la administración de piroxicam, y que el propio tumor disminuía la reacción inflamatoria creada por la implantación de un cuerpo extraño. Considerando a las metástasis como implantes secundarios naturales, se compararon dos tumores de mama de origen común, pero diferente... (AU)

[Antitumor concomitant immunity: a possible metastasis control mechanism]. / "Inmunidad" concomitante antitumoral: un posible mecanismo de control de las metástasis.

Concomitant immunity (CI) is defined as the lack or retardation or proliferation of a secondary tumor implant at a distant site; it has been given an immunological interpretation. Our experiments were designed to investigate CI in association with spontaneous tumors with or without metastases. In BALB/c mice, various syngeneic tumors, of undetectable immunogenicity, induced CI, preventing the development of a secondary implant of the same and occasionally of another tumor, indicating some degree of nonspecificity. This CI could also be observed in young and adult nude mice with high and low NK level, and in those treated with silica, discarding and participation of T lymphocytes, NK cells and macrophages, respectively. The lack of development of the secondary implant was not due to tumor rejection--contrarily to observations in allogeneic systems with immunogenic tumor--but to cytostasis. This "dormant tumor" state is observed together with the absence of host cell infiltration. The creation of a local inflammatory reaction abrogated CI, resulting in rapid tumor growth. On the other hand, an inflammatory reaction created by a foreign body inhibited the development of a tumor implant in the contralateral flank and tumor growth could be inhibited by piroxicam; furthermore, the tumor itself diminished the inflammatory reaction created by a foreign body at a distant site. Considering metastases as natural secondary implants, two mammary adenocarcinomas with a common origin were compared, one with 0 and the other with 100% metastatic incidence. The non-metastatic tumor induced stronger and earlier CI against both tumors and prevented the development of experimental and spontaneous metastases; moreover; its surgical extirpation led to the appearance of lung metastases.(ABSTRACT TRUNCATED AT 250 WORDS)

[quot ]Inmunidad[quot ] concomitante antitumoral: un posible mecanismo de control de las metástasis. / [Antitumor concomitant immunity: a possible metastasis control mechanism]

Concomitant immunity (CI) is defined as the lack or retardation or proliferation of a secondary tumor implant at a distant site; it has been given an immunological interpretation. Our experiments were designed to investigate CI in association with spontaneous tumors with or without metastases. In BALB/c mice, various syngeneic tumors, of undetectable immunogenicity, induced CI, preventing the development of a secondary implant of the same and occasionally of another tumor, indicating some degree of nonspecificity. This CI could also be observed in young and adult nude mice with high and low NK level, and in those treated with silica, discarding and participation of T lymphocytes, NK cells and macrophages, respectively. The lack of development of the secondary implant was not due to tumor rejection--contrarily to observations in allogeneic systems with immunogenic tumor--but to cytostasis. This [quot ]dormant tumor[quot ] state is observed together with the absence of host cell infiltration. The creation of a local inflammatory reaction abrogated CI, resulting in rapid tumor growth. On the other hand, an inflammatory reaction created by a foreign body inhibited the development of a tumor implant in the contralateral flank and tumor growth could be inhibited by piroxicam; furthermore, the tumor itself diminished the inflammatory reaction created by a foreign body at a distant site. Considering metastases as natural secondary implants, two mammary adenocarcinomas with a common origin were compared, one with 0 and the other with 100

metastatic incidence. The non-metastatic tumor induced stronger and earlier CI against both tumors and prevented the development of experimental and spontaneous metastases; moreover; its surgical extirpation led to the appearance of lung metastases.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis can facilitate the appearance of metastases.

The non-metastatic murine mammary adenocarcinoma M3 and its metastatic variant MM3 were used to evaluate the role of intratumoral necrosis in cell detachment and metastasis. Accelular extracts from necrotic areas of both tumors increased in vitro cellular detachment from M3 but not from MM3 fragments. Furthermore, the in vivo inoculation of the necrotic extracts within non-metastatic M3 tumors gave rise to pulmonary metastases. Histological studies revealed in M3 a central necrosis limited by an uninterrupted peripheral ring of well preserved cells, while in MM3 necrotic and non-necrotic areas alternated. It is concluded that the distribution of necrosis within the primary tumor by facilitating cell detachment is, at least in part, responsible for the development of metastases.

Role of concomitant resistance in the development of murine lung metastases.

An attempt was made to explain the distinct lung metastatic patterns of 2 mammary adenocarcinomas with a common BALB/c origin: M3, which does not induce spontaneous metastases, and MM3 with an almost 100% incidence. No difference between the 2 tumors was detected with respect to host mononuclear cell content, degree of immunogenicity or lung-colony-forming ability. Conversely, there was a marked difference in the capacity to induce concomitant resistance: M3-bearing mice induced stronger and earlier resistance against i.v. challenge of both M3 and MM3 tumor cells than MM3-bearing mice; this resistance was expressed as lower number of lung metastases and lower tumor-cell proliferation in metastatic nodules. M3 was also able to control the development of spontaneous metastases: metastases developed in all M3-excised mice, compared with none in M3-bearing mice, while MM3-bearing mice also bearing a secondary M3 tumor developed fewer metastases than mice bearing MM3 only. This anti-metastatic effect does not appear to depend on classical immunological mechanisms since no difference could be detected between the 2 tumors in response to T cells, NK, macrophages or antibodies.

Histologic aspects of concomitant resistance induced by nonimmunogenic murine tumors.

Concomitant resistance to a second tumor implant was induced in both conventional and nude BALB/c mice by two nonimmunogenic syngeneic tumors of spontaneous origin, an epidermoid carcinoma and a lymphoid leukemia. In the secondary tumor, which was significantly inhibited by concomitant resistance, histologic examination revealed the presence of well-preserved tumor cells without any sign of necrosis and without any host cell infiltration, contrasting with classical immunologic rejection. Tumor cell proliferation as evaluated by the number of mitoses per high-power field was significantly inhibited in the secondary tumor as compared with the corresponding controls. No effect of concomitant resistance could be detected on primary tumor growth.

"Concomitant immunity" in murine tumours of non-detectable immunogenicity.

Various immunization assays were used to demonstrate the lack of immunogenicity of three BALB/c tumours of spontaneous origin and of a fourth one resulting from foreign body tumorigenesis. All four tumours inhibited the growth of a second implant of the same tumour into the contralateral flank. In our tumour models "concomitant immunity" (1) was not mediated by macrophage or T-cell dependent immune reactions: both thymectomized BALB/c and nude mice (treated or untreated with silica) gave the same results as intact mice; (2) showed some degree of non-specificity, inhibiting the growth of a different tumour in 3/4 cases; though, the existence of a specific component could not be discarded; (3) was proportional to the volume of the primary tumour at the time of the second challenge; (4) was dependent on actively growing primary tumour, not being obtained with progressively increasing daily inocula of irradiated tumour cells; (5) was detectable in an actively growing secondary tumour; recurrent growth after partial surgical excision was inhibited and (6) involved cytostasis of the secondary tumour: a syngeneic graft of the overlying skin led to tumour growth while histological studies revealed the presence of viable tumour cells. It is postulated that "concomitant immunity" or resistance can be generated without the active participation of the immune system and that tumour-related factors are, in certain cases, responsible for blocking the growth of secondary tumours.

[Lack of relationship between viral leukemogenesis and immunosuppression in the mouse]. / Falta de relación entre la leucemogénesis viral y la inmunodepresión en el ratón.

The relationship between immunodepression and leukemogenesis induced by a murine retro-virus. PLLV-T2, was studied in different strains of mice. Cellular immunity, using as parameters both allograft rejection and graft versus host reaction, was not affected during the early phase of leukemia development. As for humoral immunity, determined by the response to xenogeneic red blood cells and to lipopolysaccharides, no direct relationship between the immunodepression caused by the retrovirus and leukemogenesis could be encountered: in certain strains, such as DBA/2, with susceptibility to leukemogenesis similar to that of BALB/c, no decrease in the immune response was registered during the early phase of the disease. The results obtained demonstrate that immunodepression is not a necessary condition for the clinical appearance of this viral-induced leukemia indicating that humoral and/or cellular immunity would not play an important role as surveillance mechanism against this neoplasia.

Falta de relacion entre la leucemogenesis viral y la inmunodepresion en el raton. / Lack of relation between viral leukomogenesis and immunodepression in mice

Se estudio la relacion entre la inmunodepresion y la leucemogenesis causadas por un retrovirus murino, el PLLV-T2, en distintas cepas de ratones. Se demostro que la inmunidad celular, medida por la reaccion de rechazo de tejido alogenico y por la reaccion de injerto contra huespede, no fue afectada por el virus en una etapa temprana del desarrollo leucemico.Con respecto a la inmunidad humoral aun cuando PLLV-T2 producia una marcada inmunodepresion temprana en algunas cepas de ratones, se demostro que este fenomeno no era universal porque no solo no habia una relacion directamente proporcional entre susceptibilidad a la oncogenesis e inmunodepresion sino que habia algunas cepas, como la DBA/2, que teniendo una susceptibilidad a los efectos leucemogenos del virus similar a los de la cepa BALB/c, no mostraban una respuesta humoral disminuida en la primera fase de enfermedad. Los datos de este trabajo muestran que un fenomeno de inmunodepresion so seria un prerrequisito para la manifestacion clinica de la leucemia inducida por PLLV-T2, indicando que ni la respuesta humoral ni la celular actuarian como um mecanismmo de vigilancia inmunologica contra esta neoplasia

Falta de relacion entre la leucemogenesis viral y la inmunodepresion en el raton. / Lack of relation between viral leukomogenesis and immunodepression in mice

Se estudio la relacion entre la inmunodepresion y la leucemogenesis causadas por un retrovirus murino, el PLLV-T2, en distintas cepas de ratones. Se demostro que la inmunidad celular, medida por la reaccion de rechazo de tejido alogenico y por la reaccion de injerto contra huespede, no fue afectada por el virus en una etapa temprana del desarrollo leucemico.Con respecto a la inmunidad humoral aun cuando PLLV-T2 producia una marcada inmunodepresion temprana en algunas cepas de ratones, se demostro que este fenomeno no era universal porque no solo no habia una relacion directamente proporcional entre susceptibilidad a la oncogenesis e inmunodepresion sino que habia algunas cepas, como la DBA/2, que teniendo una susceptibilidad a los efectos leucemogenos del virus similar a los de la cepa BALB/c, no mostraban una respuesta humoral disminuida en la primera fase de enfermedad. Los datos de este trabajo muestran que un fenomeno de inmunodepresion so seria un prerrequisito para la manifestacion clinica de la leucemia inducida por PLLV-T2, indicando que ni la respuesta humoral ni la celular actuarian como um mecanismmo de vigilancia inmunologica contra esta neoplasia