Greene BM (1987) Ciba Found Symp "Primate model for onchocerciasis research."

Greene BM

[Ciba Found Symp, 1987]

A major impediment to progress in research in onchocerciasis has been the lack of a suitable animal model. However, chimpanzees can be reliably infected by injection of living third-stage larvae of Onchocerca volvulus, and develop a pattern of infection that closely resembles that seen in humans. This includes the formation of nodules by adult worms, the subcutaneous distribution of microfilariae and the apparent lack of development of resistance to infection after repeated larval challenge. Ocular lesions resembling those in humans have not been observed in animals studied so far, but this may reflect in part the low intensity of infection and the limited time of observation. We infected 18 chimpanzees by subcutaneous injection of 250 third-stage larvae of O. volvulus. Six received ivermectin on day 1, another six received ivermectin on day 28 after infection, and six received no drug. Four control animals received no infective larvae and no drug. During the first year after infection, all three infected groups, but not control animals, have shown a clear increase in their lymphocyte blastogenic response to crude O. volvulus antigen in vitro. Antibody responses have also been increasing with time. Further assessment of the cellular and antibody responses in the infected chimpanzees is under way, as is evaluation of the effects of ivermectin on the course of infection.

Greene BM (1988) Trop Med Parasitol "Handling of Onchocerca volvulus nodules and isolated worms for immunologic studies."

Greene BM

[Trop Med Parasitol, 1988]

Greene BM Rev Infect Dis "Selective primary health care: strategies for control of disease in the developing world. VI. Onchocerciasis."

Greene BM

[Rev Infect Dis]

Onchocerca volvulus, a major filarial parasite of humans, infects tens of millions of people and is a leading cause of blindness. It also causes disabling or disfiguring dermatitis and lymph node involvement. The infection is transmitted by the bite of female blackflies of Simulium species, which breed around freely flowing waterways. Vector control by aerial spraying of rivers and streams with larvicide has achieved some success in the Volta River Basin, but other areas are less well-suited for such an approach. Efforts to control onchocerciasis are plagued by emerging resistance of blackflies, excessive costs of spraying, and the lack of suitable chemotherapy for existing cases. Mass chemotherapy for infected persons as a means to limit the disease and its impact is not feasible because existing drug regiments are too complex, too toxic, or not effective enough. Selective chemotherapy directed at persons at high risk of complications may be a more effective means of minimizing the impact of the disease.

Greene BM et al. Rev Infect Dis "Humoral and cellular immune responses to Onchocerca volvulus infection in humans."

Greene BM, Gbakima AA, Albiez EJ, Taylor HR

[Rev Infect Dis]

Onchocerciasis is one of the major filarial diseases affecting humans and a leading cause of blindness. Control of the disease by chemotherapy and by elimination of the vector is not feasible in most areas of endemicity. The host immune response is thought to play a major role in the pathogenesis of complications. However, there is no clear evidence of protective immunity to reinfection in individuals who continue to be exposed to infective larvae. Antigens of Onchocerca volvulus are complex and show extensive cross-reactivity with other filarial parasites of humans and animals. Infection in humans results in the production of precipitating and reaginic antibodies to the parasite and in increases in levels of immunoglobulins that have no apparent specificity for parasitic antigens. Chronic antigenic stimulation in the presence of an antibody response leads to increased levels of circulating immune complexes. Cell-mediated immunity to parasite-derived antigens, as measured by migration inhibition, lymphocyte blastogenesis, and delayed skin-test reactivity, is decreased during infection. In addition, there is a decrease in delayed skin-test reactivity and in lymphocyte blastogenesis in response to unrelated antigens.

Greene BM et al. (1983) Clin Exp Immunol "Non-specific suppression of antigen-induced lymphocyte blastogenesis in Onchocerca volvulus infection in man."

Greene BM, Fanning MM, Ellner JJ

[Clin Exp Immunol, 1983]

Lymphocyte blastogenic responses to O. volvulus antigen (Oncho Ag), SKSD, and the mitogen PHA were tested in three groups of persons: light to moderately infected persons (INF); previously exposed but uninfected persons (EXP) and normal controls (NC). The exposed group showed significant responsiveness to Oncho Ag (delta ct/min = 6,002 +/- 1,375), while the infected (delta ct/min = 943 +/- 418) and normal control (delta ct/min = 428 +/- 418) groups did not. The mean blastogenic response to SKSD were EXP, 8,644 +/- 5,249; NC 6,039 +/- 2,880; INF, 2,619 +/- 1,012. The reduced reactivity in the INF group to Oncho Ag showed a significant correlation with reactivity to SKSD (P less than 0.05). To elucidate the mechanism of hyporesponsiveness in the infected group rigorous adherent cell depletion, by adherence to plastic followed by a nylon wool column, was utilized. When 20% plastic adherent cells were added back to the T cells prepared in this fashion, the mean blastogenic response to SKSD was significantly augmented (P less than 0.01). In contrast, the responsiveness to Oncho Ag was not significantly altered. The addition of indomethacin (1 microgram/ml) or autologous plasma had no significant effect on reactivity to either SKSD or Oncho Ag. There were no significant differences in the mean reactivity of the three groups to PHA-M (delta ct/min EXP 78,514 +/- 12,564; INF 62,393 +/- 14,447; NC 61,423 +/- 4,465). These results suggest that O. volvulus infection is associated with decreased lymphocyte reactivity to both parasite related and unrelated antigens, and imply that the mechanism for the two types of hyporesponsiveness may be distinct. While a weakly adherent suppressor cell may account for non-specific hyporesponsiveness, the mechanism of parasite specific decreased reactivity remains unknown.

Arumugam S et al. (2016) PLoS Negl Trop Dis "Vaccination of Gerbils with Bm-103 and Bm-RAL-2 Concurrently or as a Fusion Protein Confers Consistent and Improved Protection against Brugia malayi Infection."

Bottazzi ME, Klei TR, Wei J, Abraham D, Arumugam S, Liu Z, Lustigman S, Zhan B, Hotez PJ, Bell A

[PLoS Negl Trop Dis, 2016]

BACKGROUND: The Brugia malayi Bm-103 and Bm-RAL-2 proteins are orthologous to Onchocerca volvulus Ov-103 and Ov-RAL-2, and which were selected as the best candidates for the development of an O. volvulus vaccine. The B. malayi gerbil model was used to confirm the efficacy of these Ov vaccine candidates on adult worms and to determine whether their combination is more efficacious. METHODOLOGY AND PRINCIPLE FINDINGS: Vaccine efficacy of recombinant Bm-103 and Bm-RAL-2 administered individually, concurrently or as a fusion protein were tested in gerbils using alum as adjuvant. Vaccination with Bm-103 resulted in worm reductions of 39%, 34% and 22% on 42, 120 and 150 days post infection (dpi), respectively, and vaccination with Bm-RAL-2 resulted in worm reductions of 42%, 22% and 46% on 42, 120 and 150 dpi, respectively. Vaccination with a fusion protein comprised of Bm-103 and Bm-RAL-2 resulted in improved efficacy with significant reduction of worm burden of 51% and 49% at 90 dpi, as did the concurrent vaccination with Bm-103 and Bm-RAL-2, with worm reduction of 61% and 56% at 90 dpi. Vaccination with Bm-103 and Bm-RAL-2 as a fusion protein or concurrently not only induced a significant worm reduction of 61% and 42%, respectively, at 150 dpi, but also significantly reduced the fecundity of female worms as determined by embryograms. Elevated levels of antigen-specific IgG were observed in all vaccinated gerbils. Serum from gerbils vaccinated with Bm-103 and Bm-RAL-2 individually, concurrently or as a fusion protein killed third stage larvae in vitro when combined with peritoneal exudate cells. CONCLUSION: Although vaccination with Bm-103 and Bm-RAL-2 individually conferred protection against B. malayi infection in gerbils, a more consistent and enhanced protection was induced by vaccination with Bm-103 and Bm-RAL-2 fusion protein and when they were used concurrently. Further characterization and optimization of these filarial vaccines are warranted.

McIntyre DC et al. (2023) Development "Niche cells regulate primordial germ cell quiescence in response to basement membrane signaling."

McIntyre DC, Nance J

[Development, 2023]

Stem cell quiescence, proliferation and differentiation are controlled by interactions with niche cells and a specialized extracellular matrix called basement membrane (BM). Direct interactions with adjacent BM are known to regulate stem cell quiescence; however, it is less clear how niche BM relays signals to stem cells that it does not contact. Here, we examine how niche BM regulates C. elegans primordial germ cells (PGCs). BM regulates PGC quiescence even though PGCs are enwrapped by somatic niche cells and do not contact the BM; this can be demonstrated by depleting laminin, which causes normally quiescent embryonic PGCs to proliferate. We show that following laminin depletion, niche cells relay proliferation-inducing signals from the gonadal BM to PGCs via integrin receptors. Disrupting the BM proteoglycan perlecan blocks PGC proliferation when laminin is depleted, indicating laminin functions to inhibit a proliferation-inducing signal originating from perlecan. Reducing perlecan levels in fed larvae hampers germ line growth, suggesting BM signals regulate germ cell proliferation under physiological conditions. Our results reveal how BM signals can regulate stem cell quiescence indirectly, by activating niche cell integrin receptors.

Farghaly AM et al. (2016) J Egypt Soc Parasitol "DEVELOPMENT OF AN IN VITRO RNAI TO INVESTIGATE GENE FUNCTION IN BRUGIA MALAYI."

Abd El-Raouf Taha A, Abd El-Hai Afify H, Mostafa E, Farghaly AM

[J Egypt Soc Parasitol, 2016]

The RNA interference (RNAi) has the ability to turn off individual gene expression. So, it affords a remarkably specific tool for studying the effects of genes. It is regarded as a direct approach for determining such gene/genes functions and offers a valuable tool for modern drug discovery. The study aimed to develop in vitro RNAil in Brugia malayi with particular interest to study the function of Brugia malayi avr-14 (Bm-avr-14) and Brugia malayi f-tubulin (Bm-fi-tubulin) genes. Bm-avr-14 is a gene encoding glutamate gated chloride channel (GluCl) which binds ivermectin and Bm--tubulin is a gene encoding -tubulin which binds albendazole. Adult female worms were soaked in heterogeneous short interfering RNA (hsiRNA) with interest to study the role of two genes Bm-avr-14 and Bm--tubulin. Then, we assessed the knock down effects of target genes using worminator system and real time PCR. We found that worms treated with hsiRNA of Bm-avr-14 had a significant reduction in microfilariae (mf) production in comparison with untreated worms or worms treated with hsiRNA of green fluorescent protein (GFP). No significant reduction in mf production with Bm--tubulin gene was obtained. There were no changes in the movement of adults treated with either Bm-avr-14 or Bm- -tubulin hsiRNAs. Inconsistent RNAi mediated suppression was achieved with Bm-avr-14 and Bm-- tubulin using real time PCR. The data may be helpful in assessment of drug target potential of genes.

Matus DQ et al. (2014) Nat Commun "Cell division and targeted cell cycle arrest opens and stabilizes basement membrane gaps."

Chi Q, Makohon-Moore SC, Matus DQ, Sherwood DR, Chang E, Hagedorn MA

[Nat Commun, 2014]

Large gaps in basement membrane (BM) occur during organ remodelling and cancer cell invasion. Whether dividing cells, which temporarily reduce their attachment to BM, influence these breaches is unknown. Here we analyse uterine-vulval attachment during development across 21 species of rhabditid nematodes and find that the BM gap that forms between these organs is always bounded by a non-dividing vulval cell. Through cell cycle manipulation and live cell imaging in Caenorhabditis elegans, we show that actively dividing vulval cells facilitate enlargement of this breach by promoting BM movement. In contrast, targeted cell cycle arrest halts BM movement and limits gap opening. Further, we demonstrate that the BM component laminin accumulates at the BM gap edge and promotes increased integrin levels in non-dividing vulval cells, stabilizing gap position. Together, these studies reveal that cell division can be used as a mechanism to regulate BM breaches, thus controlling the exchange of cells between tissues.

McClatchey ST et al. (2016) Elife "Boundary cells restrict dystroglycan trafficking to control basement membrane sliding during tissue remodeling."

Shen W, Wang Z, Chen A, Sherwood DR, Chi Q, Linden LM, Hastie EL, Wang L, McClatchey ST

[Elife, 2016]

Epithelial cells and their underlying basement membranes (BMs) slide along each other to renew epithelia, shape organs, and enlarge BM openings. How BM sliding is controlled, however, is poorly understood. Using genetic and live cell imaging approaches during uterine-vulval attachment in C. elegans, we have discovered that the invasive uterine anchor cell activates Notch signaling in neighboring uterine cells at the boundary of the BM gap through which it invades to promote BM sliding. Through an RNAi screen, we found that Notch activation upregulates expression of ctg-1, which encodes a Sec14-GOLD protein and member of the Sec14 phosphatidylinositol-transfer protein superfamily that is implicated in vesicle trafficking. Through photobleaching, targeted knockdown, and cell-specific rescue, our results suggest that CTG-1 restricts BM adhesion receptor DGN-1 (dystroglycan) trafficking to the cell-BM interface, which promotes BM sliding. Together, these studies reveal a new morphogenetic signaling pathway that controls BM sliding to remodel tissues.