The effect of B-cell depletion therapy on serological evidence of B-cell and plasmablast activation in patients with rheumatoid arthritis over multiple cycles of rituximab treatment.

B-cell depletion therapy (BCDT) based on rituximab (RTX) induces clinical remission in a majority of seropositive patients with Rheumatoid arthritis (RA). However, all patients eventually relapse. The aim of this study was to determine whether dynamic changes in combinations of serological measures of B-cell activation were associated over up to three cycles of BCDT. We included only RA patients who gave an adequate clinical response, as measured by DAS28. Twenty three patients were studied over 1 cycle, 21 over 2, and 15 over 3 cycles of BCDT. Serum analytes including isotypes of Rheumatoid factors (RhF) and anti-citrullinated protein/peptide antibodies (ACPA), B-cell activating factor (BAFF), serum free light chains (SFLC), soluble CD23 (sCD23), antibodies to tetanus toxoid (TT) and to pneumococcal capsular polysaccharide (PCP) were measured by ELISA at 4 key points in each cycle, namely: Baseline (pre-RTX in each cycle); when B-cell depleted (CD19+B-cells < 5/µl); at B-cell return (CD19+B-cells ≥ 5/µl); and at clinical relapse (ΔDAS28 > 1.2). SFLC were used as a measure of plasmablast activity. As sCD23 is cleaved from naïve B-cells coincident with attaining CD27 expression, levels were used as a novel measure of maturation of B-cells to CD27+. The most consistent changes between baseline and B-cell depletion within all 3 cycles were in SFLC, sCD23 and IgM-RhF which fell and in BAFF levels which rose. After 3 complete cycles of BCDT, both IgM autoantibodies and IgG-CCP had decreased, BAFF levels were higher (all p < 0.05); other analytes remained unchanged compared with baseline. Dynamic changes in λSFLC, sCD23, IgM-RhF and BAFF were also consistently associated with relapse in patients with longer clinical responses after B-cell return. Incremental rises in sCD23 levels in cycles 2 and 3 were correlated with time to relapse. Repopulation of the periphery after BCDT is initiated by naïve B-cells and precedes relapse. Our study showed that differentiation into plasmablasts, attended by sCD23 and SFLC production and IgM-RhF specificity may be required to precipitate relapse in patients experiencing longer responses after RTX. These studies also provide novel information related to the resumption of autoimmune responses and their association with B-cell kinetics following BCDT.

Augmentation of immune responses to HIV-1 and simian immunodeficiency virus DNA vaccines by IL-2/Ig plasmid administration in rhesus monkeys.

The potential utility of plasmid DNA as an HIV-1 vaccination modality currently is an area of active investigation. However, recent studies have raised doubts as to whether plasmid DNA alone will elicit immune responses of sufficient magnitude to protect against pathogenic AIDS virus challenges. We therefore investigated whether DNA vaccine-elicited immune responses in rhesus monkeys could be augmented by using either an IL-2/Ig fusion protein or a plasmid expressing IL-2/Ig. Sixteen monkeys, divided into four experimental groups, were immunized with (i) sham plasmid, (ii) HIV-1 Env 89.6P and simian immunodeficiency virus mac239 Gag DNA vaccines alone, (iii) these DNA vaccines and IL-2/Ig protein, or (iv) these DNA vaccines and IL-2/Ig plasmid. The administration of both IL-2/Ig protein and IL-2/Ig plasmid induced a significant and sustained in vivo activation of peripheral T cells in the vaccinated monkeys. The monkeys that received IL-2/Ig plasmid generated 30-fold higher Env-specific antibody titers and 5-fold higher Gag-specific, tetramer-positive CD8+ T cell levels than the monkeys receiving the DNA vaccines alone. IL-2/Ig protein also augmented the vaccine-elicited immune responses, but less effectively than IL-2/Ig plasmid. Augmentation of the immune responses by IL-2/Ig was evident after the primary immunization and increased with subsequent boost immunizations. These results demonstrate that the administration of IL-2/Ig plasmid can substantially augment vaccine-elicited humoral and cellular immune responses in higher primates.

Augmentation and suppression of immune responses to an HIV-1 DNA vaccine by plasmid cytokine/Ig administration.

The use of cytokines has shown promise as an approach for amplifying vaccine-elicited immune responses, but the application of these immunomodulatory molecules in this setting has not been systematically explored. In this report we investigate the use of protein- and plasmid-based cytokines to augment immune responses elicited by an HIV-1 gp120 plasmid DNA vaccine (pV1J-gp120) in mice. We demonstrate that immune responses elicited by pV1J-gp120 can be either augmented or suppressed by administration of plasmid cytokines. A dicistronic plasmid expressing both gp120 and IL-2 induced a surprisingly weaker gp120-specific immune response than did the monocistronic pV1J-gp120 plasmid. In contrast, systemic delivery of soluble IL-2/Ig fusion protein following pV1J-gp120 vaccination significantly amplified the gp120-specific immune response as measured by Ab, proliferative, and CTL levels. Administration of plasmid IL-2/Ig had different effects on the DNA vaccine-elicited immune response that depended on the temporal relationship between Ag and cytokine delivery. Injection of plasmid IL-2/Ig either before or coincident with pV1J-gp120 suppressed the gp120-specific immune response, whereas injection of plasmid IL-2/Ig after pV1J-gp120 amplified this immune response. To maximize immune responses elicited by a DNA vaccine, therefore, it appears that the immune system should first be primed with a specific Ag and then amplified with cytokines. The data also show that IL-2/Ig is more effective than native IL-2 as a DNA vaccine adjuvant.

Potent, protective anti-HIV immune responses generated by bimodal HIV envelope DNA plus protein vaccination.

It is generally thought that an effective vaccine to prevent HIV-1 infection should elicit both strong neutralizing antibody and cytotoxic T lymphocyte responses. We recently demonstrated that potent, boostable, long-lived HIV-1 envelope (Env)-specific cytotoxic T lymphocyte responses can be elicited in rhesus monkeys using plasmid-encoded HIV-1 env DNA as the immunogen. In the present study, we show that the addition of HIV-1 Env protein to this regimen as a boosting immunogen generates a high titer neutralizing antibody response in this nonhuman primate species. Moreover, we demonstrate in a pilot study that immunization with HIV-1 env DNA (multiple doses) followed by a final immunization with HIV-1 env DNA plus HIV-1 Env protein (env gene from HXBc2 clone of HIV IIIB; Env protein from parental HIV IIIB) completely protects monkeys from infection after i.v. challenge with a chimeric virus expressing HIV-1 env (HXBc2) on a simian immmunodeficiency virusmac backbone (SHIV-HXBc2). The potent immunity and protection seen in these pilot experiments suggest that a DNA prime/DNA plus protein boost regimen warrants active investigation as a vaccine strategy to prevent HIV-1 infection.

Anti-HIV env immunities elicited by nucleic acid vaccines.

Plasmid DNA vaccines encoding HIV-1 env were used to immunize mice and nonhuman primates. Plasmids were prepared that produced either secreted gp120 or full-length gp160. Mice immunized with gp120 DNA developed strong antigen-specific antibody responses, CD8+ cytotoxic T lymphocytes (CTL) (following in vitro restimulation with gp120-derived peptide), and showed in vitro proliferation and Th1-like cytokine secretion [gamma-interferon, interleukin (IL)-2 with little or no IL-4] by lymphocytes obtained from all lymphatic compartments tested (spleen, blood, and inguinal, iliac, and mesenteric lymph nodes). This indicated that systemic anti-gp120 cell-mediated immunity was induced by this DNA vaccine. Although similar antibody responses were observed in mice immunized by either intramuscular or intradermal routes, T cell responses were significantly stronger in mice injected intramuscularly. Rhesus monkeys immunized with both gp120 and gp160 DNAs exhibited significant CD8+ CTL responses, following in vitro restimulation of peripheral blood lymphocytes with antigen. These experiments demonstrate that DNA immunization elicits potent immune responses against HIV env in both a rodent and a nonhuman primate species.

Humoral and cellular immunities elicited by HIV-1 vaccination.

Recently it has been shown that immunization with plasmid DNA encoding genes for viral or bacterial antigens can elicit both humoral and cellular immune responses in rodents and nonhuman primates. In this study, mice and nonhuman primates were vaccinated by intramuscular injection with plasmids that express either a secreted form of HIV-1 gp120 or rev proteins. Mice receiving the tPA-gp120 DNA developed antigen-specific antibody responses against recombinant gp120 protein and the V2 peptide neutralization epitope as determined by ELISA. Vaccinated mice also exhibited gp120-specific T cell responses, such as in vitro proliferation of splenocytes and MHC Class I-restricted cytotoxic T lymphocyte (CTL) activities, following antigen restimulation. In addition, supernatants from these lymphocyte cultures showed high levels of gamma-interferon production compared with IL-4, suggesting that primarily type 1-like helper T (Th1) lymphocyte responses were induced by both vaccines. Th1-like responses were also obtained for mice vaccinated with rev DNA. Immune responses induced by gp120 or rev vaccines were dose-dependent, boostable, and long-lived (> or = 6 months). Nonhuman primates vaccinated with tPA-gp120 DNA also showed antigen-specific T lymphocyte proliferative and humoral responses, including moderate levels of neutralizing sera against homologous HIV. These results suggest that plasmid DNA may provide a powerful means for eliciting humoral and cellular immune responses against HIV.

Cytotoxic T lymphocyte and helper T cell responses following HIV polynucleotide vaccination.

Expression vectors encoding either HIV-1 gp160/rev, gp120, or rev alone were used for direct vaccination of mice and nonhuman primates. Each vaccine elicited long-lived (> 7 months) helper T cell responses in mice and monkeys as measured by in vitro proliferation of splenocytes following recombinant antigen treatment. Cytokine assays of the cell supernatants showed that approximately 100-fold more gamma-interferon than IL-4 was secreted during culture indicating that these vaccines elicited TH1-like responses. CD8+ CTL activities were also observed both in mice and rhesus. The gp120 and gp160/rev vaccines elicited antigen-specific antibodies, although these responses were more variable and lower magnitude for gp160/rev, and gp120 DNA-vaccinated African green monkeys had moderate levels of neutralizing antibodies. No antibodies were found against rev (an intracellular protein) with either rev vaccine. Similar antibody titers were obtained for gp120 by either intramuscular or intradermal injection although T cell responses were generally lower by intradermal route. These results indicate that DNA vaccines may provide a powerful means to elicit cellular and humoral immune responses against HIV.

Heterologous and homologous protection against influenza A by DNA vaccination: optimization of DNA vectors.

We have recently shown that direct injection of DNA can be an effective vaccine strategy eliciting both humoral and cell-mediated immune responses. Vectors were designed specifically for vaccination by direct DNA injection and refined to improve plasmid production in Escherichia coli. The vectors consist of a pUC-19 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A transcription regulatory elements and the BGH polyadenylation sequences driving the expression of the reporter gene CAT or influenza A nucleoprotein (NP) or hemagglutinin (HA). The respective vectors expressed high levels of chloramphenicol acetyltransferase (CAT) and NP in tissue culture, and yielded 14-15 mg of purified plasmid per liter of Escherichia coli culture. Immunization of mice with the NP and HA expression vectors resulted in protection from subsequent lethal challenges of influenza using either heterologous or homologous strains, respectively.

The DNA binding domain of herpes simplex virus type 1 origin binding protein is a transdominant inhibitor of virus replication.

The origin binding protein (OBP) of herpes simplex virus (HSV) type 1 specifically interacts with two high-affinity sites in each HSV DNA replication origin. The sequence-specific DNA binding activity of OBP maps to the carboxy-terminal one-third of the protein. For a single binding site, recombinantly expressed forms of this DNA binding domain have the same sequence specificity and binding affinity as the full-length OBP. However, unlike the full-length protein, truncated OBP does not bind HSV replication origins in a cooperative manner. To determine if cooperative interactions between DNA-bound OBP molecules are essential for viral DNA replication, the 317-amino-acid carboxy-terminal DNA binding domain of OBP was expressed in chick embryo fibroblasts. Cells were infected with HSV type 1, and viral DNA synthesis and virus production were monitored. We found that cells expressing truncated OBP were severely restricted for virus replication and that HSV DNA synthesis was undetectable. The results demonstrate that the amino-terminal two-thirds of OBP is essential for HSV DNA replication and that the OBP DNA binding domain acts as a transdominant inhibitor of viral DNA replication. The results also suggest that this experimental approach could be used to generate a refined map of essential OBP functions and that the approach may be generally applicable to the analysis of the multifunction HSV DNA replication complex.

Cooperative interactions between replication origin-bound molecules of herpes simplex virus origin-binding protein are mediated via the amino terminus of the protein.

The virally encoded origin binding protein (OBP) of herpes simplex virus (HSV) is required for viral DNA synthesis. OBP binds at the replication origin to initimultienzyme replication complex (Challberg, M. D., and Kelly, T. J. (1989) Annu Rev. Biochem. 58, 671-717), OBP binds to two sites at the replication origin. The sequence-specific interaction of OBP with each binding site is localized to the major groove, and in both HSV origins the two interaction surfaces are in phase, aligned on the same face of the helix (Hazuda, D. J., Perry, H. C., Naylor, A. M., and McClements, W. L. (1991) J. Biol. Chem. 261, 24621-24625). Using native gel electrophoresis, we now demonstrate that OBP binding to the origin is highly cooperative and that cooperativity requires the putative NH2-terminal leucine zipper. Neither the phase nor orientation of the binding sites affect cooperativity, suggesting that the interaction promotes wrapping of origin DNA around the OBP multimer. A comparison of OBP DNase I footprints with the DNase I footprints of a truncated protein defective in cooperativity demonstrates that the interaction between OBPs bound at sites I and II affects the conformation of the intervening DNA, particularly when the phase or orientation of the two sites is different from wild type. OBP may elicit a unique nucleoprotein structure which facilitates unwinding of the origin and/or assembly of the replication complex. We also demonstrate that OBP can exchange binding sites, forming interduplex complexes. This property may be important for reinitiation of DNA replication.

Characterization of the herpes simplex virus origin binding protein interaction with OriS.

The origin binding protein (OBP) of herpes simplex virus (HSV), which is essential for viral DNA replication, binds specifically to sequences within the viral replication origin(s) (for a review, see Challberg, M.D., and Kelly, T. J. (1989) Annu. Rev. Biochem. 58, 671-717). Using either a COOH-terminal OBP protein A fusion or the full-length protein, each expressed in Escherichia coli, we investigated the interaction of OBP with one HSV origin, OriS. Binding of OBP to a set of binding site variant sequences demonstrates that the 10-base pair sequence, 5' CGTTCGCACT 3', comprises the OBP-binding site. This sequence must be presented in the context of at least 15 total base pairs for high affinity binding, Ka = approximately 0.3 nM. Single base pair mutations in the central CGC sequence lower the affinity by several orders of magnitude, whereas a substitution at any of the other seven positions reduces the affinity by 10-fold or less. OBP binds with high affinity to duplex DNA containing mismatched base pairs. This property is exploited to analyze OBP binding to DNA heteroduplexes containing singly substituted mutant and wild-type DNA strands. For positions 2, 3, 5, 6, 7, 8, and 9, substitutions are tolerated on one or the other DNA strand, indicating that base-mediated interactions are limited to one base of each pair. For both Boxes I and II, these interactions are localized to one face of the DNA helix, forming a recognition surface in the major groove. In OriS, the 31 base pairs which separate Boxes I and II orient the two interaction surfaces to the same side of the DNA.

Synthesis and antiherpetic activity of (+/-)-9-[[(Z)-2-(hydroxymethyl)cyclopropyl]methyl]guanine and related compounds.

A series of analogues of acyclovir and ganciclovir were prepared in which conformational constraints were imposed by incorporation of a cyclopropane ring or unsaturation into the side chain. In addition, several related base-modified compounds were synthesized. These acyclonucleosides were evaluated for enzymatic phosphorylation and DNA polymerase inhibition in a staggered assay and for inhibitory activity against herpes simplex virus types 1 and 2 in vitro. Certain of the guanine or 8-azaguanine derivatives were good substrates for the viral thymidine kinase and were further converted to triphosphate, but none was a potent inhibitor of the viral DNA polymerase. Nevertheless, one member of this group, (+/-)-9-[[(Z)-2-(hydroxymethyl)cyclopropyl]methyl]guanine (3a), displayed significant antiherpetic activity in vitro, superior to that of the corresponding cis olefin 4a. Another group, typified by (+/-)-9-[[(E)-2-(hydroxymethyl)cyclopropyl]methyl]adenine (17b), possessed modest antiviral activity despite an apparent inability to be enzymatically phosphorylated. The relationship of side-chain conformation and flexibility to biological activity in this series is discussed.

The use of stimulant medication in the treatment of childhood behavioural and learning disorders. A descriptive survey.

The use of stimulant medication in a sample of 435 high-school pupils was investigated. Twenty-seven parents (6.2%) reported that their child had in the past been, or currently was being, treated with methylphenidate for childhood behavioural or learning disorders. The findings suggest that guidelines for the rational use of stimulant medication are not being followed in a significant proportion of cases.

Efficacy of 2'-nor-cyclicGMP in treatment of experimental herpes virus infections.

9-[(2-Hydroxy-1,3,2-dioxaphosphorinan-5-yl)oxymethyl]guanine P-oxide (2'-nor-cGMP), the cyclic phosphate of 2'-nor-deoxyguanosine (2'-NDG) was synthesized by phosphorylation of 2'-NDG and evaluated for antiherpetic activity in cell cultures and in animal protection studies. 2'-nor-cGMP was effective in cell culture against both thymidine kinase deficient and wild-type herpes simplex virus type 1 strains and also against herpes simplex virus type 2. The anti-herpes activity of 2'-nor-cGMP against thymidine kinase deficient HSV-1 was confirmed by animal protection studies. Also, in comparative cell culture protection studies, the ED50 (microM) of 2'-nor-cGMP was approximately 10-fold lower than that of 2'-NDG against three strains of varicella zoster virus. In addition, 2'-nor-cGMP was effective orally in preventing HSV-1 orofacial infection and HSV-2 genital infection of mice. Topical therapeutic applications of 2'-nor-cGMP prevented orofacial HSV-1 lesion development in mice and development of HSV-2 genital lesions in guinea pigs. Subcutaneous application of 2'-nor-cGMP to intracerebral HSV-1 challenged weanling mice significantly prolonged survival. These studies indicate that 2'-nor-cGMP is not dependent on viral thymidine kinase for its antiviral activity and is highly effective in preventing experimental HSV infections.

Synthesis and antiherpetic activity of (S)-, (R)-, and (+/-)-9-[(2,3-dihydroxy-1-propoxy)methyl]guanine, linear isomers of 2'-nor-2'-deoxyguanosine.

Racemic 9-[(2,3-dihydroxy-1-propoxy)methyl]guanine [(+/-)-iNDG], a new analogue of acyclovir (ACV) and a structural analogue of 2'-nor-2'-deoxyguanosine (2'NDG), was synthesized and found to inhibit the replication of herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). Subsequently, its optical isomers, (R)- and (S)-iNDG, were prepared from chiral intermediates. The chloromethyl ethers of 1,2-di-O-benzyl-D- and -L-glycerol were made and reacted with tris(trimethylsilyl)guanine to give the 9-alkylated guanines, which were deprotected by catalytic hydrogenolysis. Against HSV-1 and HSV-2 in cell culture, (S)-iNDG was approximately 10- to 25-fold more active than the R enantiomer and had an ED50 comparable to those for ACV and 2'NDG. The inferior activity of (R)-iNDG paralleled the poor inhibition of viral DNA polymerase by its phosphorylation products. In mice infected intraperitoneally or orofacially with HSV-1 or intravaginally with HSV-2, (S)-9-[(2,3-dihydroxy-1-propoxy)methyl]guanine [(S)-iNDG] was less efficacious than 2'NDG but comparable to or more active than ACV.

Effects of the nucleoside analog 2'-nor-2'-deoxyguanosine on human cytomegalovirus replication.

The nucleoside analog 2'-nor-2'-deoxyguanosine (2'NDG) effectively inhibits the replication of several laboratory and clinical isolates of human cytomegalovirus. These isolates included viruses obtained from congenitally infected infants and patients suffering from acquired immune deficiency syndrome. The dose of 2'NDG that inhibited cytomegalovirus plaque formation ranged from 0.1 to 1.6 micrograms/ml. At 10 micrograms/ml, 2'NDG completely blocked the production of virus progeny but not the expression of immediate early and early virus gene functions. Cytomegalovirus DNA was not detectable in 2'NDG-treated virus-infected human embryo lung cells when assayed by CsCl density gradient centrifugation. In contrast, the guanosine analog acyclovir at 100 micrograms/ml did not inhibit the production of virus or the synthesis of cytomegalovirus DNA. In virus-infected cells, 2'NDG and acyclovir at 10 and 100 micrograms/ml, respectively, inhibited the incorporation of [3H]thymidine and 32Pi into cellular DNA by ca. 50%. Uninfected human embryo lung cells grown in these concentrations of acyclovir or 2'NDG exhibited a slightly transient lag phase but, overall, cell growth was not retarded, and there was no decrease in cell viability. The extended lag in cell division was not due to inactivation or breakdown of the antiviral compounds but may be due in part to a temporary decrease in cellular DNA synthesis.

9-([2-hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine: a selective inhibitor of herpes group virus replication.

9-([2-Hydroxy-1-(hydroxymethyl)ethoxy]methyl)guanine (2'-nor-2'-deoxyguanosine; 2'NDG) selectively inhibits the replication of herpes group viruses. In cell culture studies 2'NDG was at least 10-fold more potent than acyclovir (ACV) in inhibition of human cytomegalovirus replication and Epstein-Barr virus-induced lymphocyte transformation and was about as effective as ACV in inhibition of herpes simplex viruses 1 and 2 and varicella zoster virus. Orally administered 2'NDG was 6- to 50-fold more efficacious than ACV in treating systemic or local HSV-1 infection or HSV-2 intravaginal infection in mice. The mode of action of 2'NDG appears to involve phosphorylation by herpes simplex virus thymidine kinase and subsequent phosphorylations by cellular kinases to produce 2'NDG triphosphate, which is a potent inhibitor of herpes virus DNA polymerase. Compared to ACV, 2'NDG was a more efficient substrate for HSV-1 thymidine kinase (Vmax/Km for 2'NDG 30-fold higher than that of ACV), whereas 2'NDG monophosphate is a more efficient substrate for GMP kinase (Vmax/Km for 2'NDG monophosphate 492-fold higher than that for ACV monophosphate). The combined effect is more rapid production of the inhibitory triphosphate from 2'NDG than from ACV.