HIVACAT identifies a therapy that makes vaccines that did not work in HIV-infected patients effective

• Researchers from the IrsiCaixa Institute for AIDS Research, driven by the Social Program of "la Caixa" Foundation and the Department of Health of the Generalitat de Catalunya, have identified a hormone that improves the effectiveness of various vaccines in HIV-infected patients. The finding has been carried out as part of the HIVACAT program for the development of the AIDS vaccine, led by an unprecedented public-private consortium that has now become an international benchmark.
• The hormone identified is the growth hormone that allows weak immune systems such as those of HIV-infected people to reconstitute, thus making vaccines that were not working before due to inactive immune systems to become effective.
• This therapy may be used to supplement a future AIDS vaccine and may also be used to improve the effectiveness of various existing vaccines for people with depressed immune systems, either because of HIV infection or because of aging, radiation or chemotherapy sessions or other health problems.

The journal of the British Society of Immunology, Immunology, published in its latest issue a study led by Margarida Bofill, ICREA research professor and head of the Immune Reconstitution, Pathogenesis and Vaccines research group at the IrsiCaixa Institute for AIDS Research, driven by the Social Program of "la Caixa" Foundation and the Department of Health of the Generalitat de Catalunya. The study involved the participation of Felipe Garcia, IDIBAPS, and IrsiCaixa researchers Lidia Ruiz, Laila Darwich, Cecilia Cabrera, Marta Massanella, Esther Canto and Julià Blanco.

The study demonstrates for the first time that treating HIV patients with the growth hormone allows reconstitution of their immune systems and improves the effectiveness of certain vaccines that had not been effective before because they had to stimulate an immune system that was very weak.

The administration of the growth hormone improves the function of the thymus, a lymphoid organ located behind the breastbone where a type of white blood cells called T cells are produced, which are responsible for activating various immune system cells such as B cells, responsible for producing the necessary antibodies to fight infections. The study shows that partial reconstitution of the thymus gland before administering a vaccine to HIV patients allows activation of the immune system which is essential for the vaccine to carry out its role of activation of the immune system effectively to protect the patient from possible future infections.

Hence, this therapy would act as a complement or an adjunct to the action of certain vaccines, including  the AIDS vaccine that the HIVACAT is researching, and other existing vaccines such as the Hepatitis A, B or the tetanus vaccine, that have already been part of  the study. But unlike the adjuvant agents used in other vaccines, therapy with the growth hormone would have to be given before the administration of the vaccine and would not only be indicated in HIV positive patients, but also in those with a thymus diminished by other causes such as aging, treatment with chemotherapy or radiation therapy or other immunosuppressive therapies.

Specifically, the study was conducted on 278 HIV-infected patients. Of these, those who presented deficient immune responses to at least one of these three vaccines: hepatitis A, hepatitis B or tetanus, and still had deficient responses after two vaccinations, were selected.

The 20 selected patients, recruited from the Hospital Germans Trias i Pujol and the Hospital Clínico, were divided randomly into three groups. Group A received the growth hormone and the vaccine to which they did not respond priorly. Patients in group B received only the growth hormone; and those in group C received the vaccine to which they did not respond. Treatment was administered three times a week for six months. The results showed that the vaccine administered to patients in group A was the most effective, because the treatment stimulated the immune system thanks to the partial reconstitution of the thymus.