The churches of Asia salute you. Aquila and Priscilla salute you much in the Lord, with the church that is in their house.
Asia - not all Asia Minor, but Lydian Asia only, of which Ephesus was capital.
Much - with especial affection.
Aquila and Priscilla (cf. Acts 18:2; Romans 16:3-4). Originally driven out of Italy by Claudius, they had come to Corinth (whence their salutation of the Corinthians is appropriate), then had removed with Paul from Corinth to Ephesus (Acts 18:2; Acts 18:18-20); here, as at Rome subsequently, they set up a church (assembly of believers) at their house (Romans 16:3-5). A pattern to Christian husbands and wives. Their Christian self-devoting love appears whereever they were. Even the gifted Apollos, so highly admired at Corinth, owed much of his knowledge to them (Acts 18:24-26). In 1 Corinthians 16:20, "All the brethren" (i:e., the whole church) seem to be distinguished from "the church that is in their house," which was but a private assembly out of the general church at Corinth. Romans 16:23 may refer to "the whole church" meeting at the house of Gaius (cf. Colossians 4:15). Christ's followers when dispersed ceased to be a congregation (synagogue), but still are a church, having the common union to the same Head by the same faith and hope. This explains Paul's entering "into every house (namely, to search for the Christians met for worship there), and haling men and women."
In the Lord. They pray for all blessings on you from the common Lord, the source of every good, IN whom they and you are one. "In the Lord" refers to their union in Christ, their prayers for one another's good being in virtue of that union.